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PIXE analysis of some Nigerian anti-diabetic medicinal plants (II)
Nuclear Instruments and Methods in Physics Research B 318 (2014) 187–190
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
PIXE analysis of some Nigerian anti-diabetic medicinal plants (II) S.O. Olabanji a,b,⇑, A.C. Adebajo c, O.R. Omobuwajo d, D. Ceccato a,e, M.C. Buoso a, G. Moschini a,e a
Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), I-35020 Padova, Italy ICTP Fellow on Sabbatical Leave from Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria c Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria d Department of Pharmacognosy & Herbal Medicine, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Nigeria e Dipartmento di Fisica, Universita di Padova, Padova, Italy b
a r t i c l e
i n f o
Article history: Received 14 March 2013 Received in revised form 27 May 2013 Accepted 13 June 2013 Available online 19 July 2013 Keywords: PIXE Trace elements Anti-diabetic Medicinal plants Nigeria
a b s t r a c t Diabetes mellitus, a metabolic disease characterized by high blood glucose levels (hyperglycemia) due to defects in insulin secretion, or action, or both, is a debilitating disease leading to other complications and death of many people in the world. Some of the medicinal plants implicated in the herbal recipes for the treatment of diabetes in Nigeria have been reported. Additional medicinal plants used for the treatment of diabetes in Nigeria are presented in this work. These medicinal plants are becoming increasingly important and relevant as herbal drugs due to their use as antioxidants, nutraceuticals, food additives and supplements in combating diabetes. Elemental compositions of these anti-diabetic medicinal plants were determined using PIXE technique. The 1.8 MV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL) Legnaro (Padova) Italy was employed for the work. The results show the detection of twenty-one elements which include Mg, P, Ca, K, Mn, Cu, Zn, S, Cr, Co, Ni and V that are implicated in the regulation of insulin and the control of the blood-sugar levels in the human body. The entire plant of Boerhavia diffusa, Securidaca longipedunculata stem, leaves of Peperomia pellucida, Macrosphyra longistyla, Olax subscorpioidea, Phyllanthus muerillanus, Jatropha gossypifolia, Cassia occidentalis, Phyllanthus amarus, and leaf and stem of Murraya koenigii, which have high concentrations of these elements could be recommended as vegetables, nutraceuticals, food additives, supplements and drugs in the control and management of diabetes, if toxicity profiles indicate that they are safe. However, significantly high contents of Al and Si in the entire plant of Bryophyllum pinnatum, and As, Cr, and Cu in Ocimum gratissimum leaf suggest that these plants should be avoided by diabetic patients to prevent complications. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction Diabetes mellitus is a metabolic disease characterized by high blood glucose levels (hyperglycemia) due to defects in insulin secretion, or action, or both and is a leading cause of death worldwide [1,2]. Insulin is a hormone produced by the b-pancreatic cells in the body with the primary function of controlling the blood glucose levels in the body [2]. The macro-vascular complications of diabetes include blindness, renal failure and nervous damage while the microvascular ones are atherosclerosis, strokes, coronary heart disease, etc. and finally death [2,3]. Hence, all efforts are geared towards managing or controlling it [1,2]. Plants used ethnomedicinally in managing diabetes are becoming increasingly used as drugs, nutraceuticals, food additives and supplements in combating chronic diseases, such as diabetes ⇑ Corresponding author at: Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), I-35020 Padova, Italy. Tel.: +234 803 532 1791. E-mail address: [email protected] (S.O. Olabanji). 0168-583X/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nimb.2013.06.052
[1,2]. Many pharmacological reports have suggested roles for their organic [3–7] and elemental [1,4,8] constituents in its management. The mechanisms of their anti-diabetic activities include pancreatic insulin stimulation or inhibition for the respective treatment of type 2 diabetes due to deficiency or insulin resistance, and extra-pancreatic, including inhibition of glucose absorption, increased glucose utilization and stimulation/inhibition of enzymatic actions [2,3,5–7]. The active chemical constituents of some plants have also been identified [3]. However, there are still many plants with only folkloric claims, such as Phyllanthus muerillanus, Jatropha gossypifolia, Macrosphyra longistyla, and Olax subscorpioidea [8]. In our previous work [1], the elements of anti-diabetic plants used ethnomedically in Nigeria for managing diabetes were given. Therefore, in continuation of this study, elemental compositions of various parts of additional fifteen Nigerian anti-diabetic plants (Table 1) were evaluated using PIXE technique to determine the presence of any ‘‘anti-diabetic element’’ that could justify their folkloric usage or toxic elements that may preclude their folkloric use.
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Table 1 Additional anti-diabetic plants used ethnomedicinally in Nigeria. Plant codes
Plant names
Family
Plant’s part
Place of collection
Method of use
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL
Murraya koenigii Murraya koenigii Phyllanthus amarus. Phyllanthus muerillanus Bridelia ferruginea Jatropha gossypifolia Boerhavia diffusa Securidaca longipedunculata Securidaca longipedunculata Securidaca longipedunculata Ocimum gratissimum Macrosphyra longistyla Bryophyllum pinnatum Cassia occidentalis Carica papaya Lantana camara Olax subscorpioidea Peperomia pellucida
Rutaceae Rutaceae Euphorbiaceae Euphorbiaceae Euphorbiaceae Euphorbiaceae Nyctaginaceae Polygalaceae Polygalaceae Polygalaceae Labiatae Rubiaceae Crassullaceae Caesalpinaceae Caricaceae Verbanaceae Olacaceae Piperaceae
Stem Leaf Leaf Leaf Leaf Leaf Entire plant Leaf Stem bark Stem Leaf Leaf Entire plant Entire plant Leaf Leaf Leaf Leaf
OAU campus Ife OAU campus Ife OAU campus Ife Iseyin Iseyin OAU campus Ife Ile-Ife town Iseyin Iseyin Iseyin Ile-Ife Onigambari forest, Ibadan OAU campus Ile-Ife OAU campus Ife OAU campus Ife Onigambari forest, Ibadan OAU campus Ife
Decoction Decoction Leaf juice taken orally/potherb Decoction Decoction Decoction Decoction Decoction Decoction Decoction Potherb Decoction Leaf juice taken orally Decoction Decoction Decoction Decoction Potherb
Table 2 Elemental compositions of additional Nigerian anti-diabetic plants analyzed by PIXE. Plant codes Concentrations of elements (ppm, or otherwise stated)
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL RDA(mg)
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL RDA (mg)
Mg
Al
Si
P
862 ± 94 4750 ± 173 3691 ± 160 2199 ± 124 6444 ± 139 5256 ± 1510 6372 ± 233 1428 ± 121 461 ± 95 528 ± 104 4482 ± 212 9753 ± 327 5835 ± 235 4870 ± 135 5662 ± 222 1980 ± 128 8550 ± 266 1.30 ± 0.03% 300–400
523 ± 70 648 ± 102 815 ± 90 1162 ± 89 467 ± 72 13 ± 8 1464 ± 129 634 ± 84 1000 ± 83 1387 ± 89 410 ± 117 1231 ± 111 8947 ± 258 2105 ± 106 494 ± 88 222 ± 93 751 ± 107 1281 ± 148 N.A.
1300 ± 77 1067 ± 61 2535 ± 96 3171 ± 94 2513 ± 101 2228 ± 84 1804 ± 75 1225 ± 53 2135 ± 63 1033 ± 43 77 ± 108 8±5 3163 ± 124 3503 ± 116 1754 ± 95 1286 ± 69 1268 ± 61 775 ± 43 1532 ± 62 793 ± 41 825 ± 89 5115 ± 176 2478 ± 101 979 ± 57 1.73 ± 0.02% 2949 ± 100 4448 ± 91 6740 ± 85 2731 ± 109 1964 ± 79 8838 ± 294 1847 ± 81 4501 ± 142 2159 ± 81 8665 ± 254 3219 ± 113 N.A. 800–1200
Cr
Mn
Fe
0.02–0.2
9±1 15 ± 1 <2 605 ± 9 1689 ± 21 671 ± 10 67 ± 3 5±1 <2 42 ± 2 415 ± 9 3±1 4±1 86 ± 2 40 ± 1 32 ± 1 411 ± 7 355 ± 5 1.0–5.0
215 ± 5 139 ± 3 43 ± 2 514 ± 9 193 ± 6 266 ± 6 427 ± 10 175 ± 4 45 ± 2 677 ± 10 2521 ± 37 102 ± 3 140 ± 4 1518 ± 17 306 ± 4 318 ± 6 234 ± 5 1069 ± 11 10.0–18.0
<2
104 ± 3 5±1 <2 4±1 591 ± 10 3±1 <3 5±1
S
Co
Cl
5±3 <4
17 ± 4 8±3 6±2 5±2 18 ± 3 N.A.
Ca
Ti
1054 ± 50 975 ± 45 6447 ± 108 1.22 ± 0.02% 3492 ± 87 5359 ± 125 1.83 ± 0.02% 1.68 ± 0.02% 3341 ± 104 1938 ± 62 113 ± 6 2580 ± 81 1341 ± 39 399 ± 18 1.56 ± 0.01% 2.01 ± 0.01% 2020 ± 35 3214 ± 40 4430 ± 46 1.72 ± 0.01% 9±4 46 ± 19 4.50 ± 0.01% 1.09 ± 0.01% 2105 ± 68 4024 ± 111 132 ± 5 918 ± 20 1217 ± 56 1225 ± 53 385 ± 8 3466 ± 59 1060 ± 30 3450 ± 38 135 ± 7 1440 ± 58 669 ± 25 754 ± 20 7744 ± 89 12,800 ± 100 3045 ± 106 3381 ± 112 190 ± 5 1388 ± 21 2199 ± 70 1566 ± 49 483 ± 11 3486 ± 70 2226 ± 61 6233 ± 115 217 ± 7 2206 ± 53 3631 ± 46 3177 ± 35 2.47 ± 0.01% 2.08 ± 0.01% 1867 ± 64 708 ± 28 3.285 ± 0.004% 3.66 ± 0.01% 1799 ± 61 2302 ± 66 2.66 ± 0.01% 1.68 ± 0.01% 3033 ± 84 204 ± 19 3.26 ± 0.01% 1.83 ± 0.01% 3394 ± 98 1898 ± 58 4.874 ± 0.007% 1.71 ± 0.01% N.A. 1400–5100 1525–5625 800–1,200 Ni
Cu
Zn
0.13–0.4
9±2 30 ± 3 17 ± 3 11 ± 5 <6 14 ± 6 194 ± 2 148 ± 3 10 ± 2 26 ± 2 1434 ± 7 72 ± 3 17 ± 2 19 ± 3 12 ± 3 29 ± 3 13 ± 2 <17 1.0–3.0
20 ± 1 48 ± 2 37 ± 2 97 ± 3 60 ± 3 64 ± 2 66 ± 3 111 ± 4 22 ± 2 36 ± 2 412 ± 12 89 ± 4 29 ± 2 43 ± 2 28 ± 2 51 ± 2 29 ± 2 697 ± 10 15.0
3±1 6±2 <2 7±2 6±2
K
4±1
6±1 8±1 4±1 8±1 48 ± 2 8±1 6±1
2±1
V
49 ± 1 21 ± 1 21 ± 1 1.5 ± 0.6 117 ± 2 15 ± 1 21 ± 1 23 ± 1 4.7 ± 0.8 7±1 6±1 2.9 ± 0.6 85 ± 2 20.3 ± 1.3 64 ± 1 21.9 ± 1.5 13 ± 1 16.6 ± 0.9 8±1 162 ± 2 19 ± 1 21 ± 1 26 ± 1 159 ± 2 N.A. 0.1–0.4
As
Br
Rb
Sr
4±1 5±1 3±1
5±2 47 ± 4 6±2 4±2 19 ± 4
33 ± 6 84 ± 9 5±2 14 ± 4 24 ± 6 96 ± 8
76 ± 10 98 ± 10 205 ± 13 153 ± 12 65 ± 8
15 ± 4
7±4 94 ± 9
3±1 3±1 9±2
19 ± 3 5±1
N.A.
5±2 7±2 6±2 7±2 7±2 5±2 10 ± 3 8±2 5±2 20 ± 3 15 ± 3 1.5–2.5
9±4 50 ± 7 72 ± 8 44 ± 6 105 ± 8 183 ± 11 N.A.
76 ± 9 142 ± 11 50 ± 8 93 ± 9 66 ± 8 N.A.
MKSt: Murraya koenigii Stem; MKL: Murraya koenigii leaf; PAL: Phyllanthus amarus leaf; PML: Phyllanthus muerillanus leaf; BFL: Bridelia ferruginea leaf; JGL: Jatropha gossypifolia leaf; BDE: Boerhavia diffusa entire plant; SLL: Securidaca longipedunculata leaf; SLSb: Securidaca longipedunculata stem bark; SLSt: Securidaca longipedunculata stem; OGL: Ocimum gratissimum leaf; MLL: Macrosphyra longistyla leaf; BPE: Bryophyllum pinnatum entire plant; COE: Cassia occidentalis entire plant; CPL: Carica papaya leaf; LCL: Lantana camara leaf; OSL: Olax subscorpioidea leaf; PPL: Peperomia pellucida leaf. RDA: Recommended Dietary Allowance; N.A.: data are not available.
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2. Experimental 2.1. Collection of samples The approach of sample collection and preparation in this work is similar to the ones reported earlier [1,8]. The additional anti-diabetic medicinal plants, after proper identification by a plant taxonomist, Dr. H.C. Illoh of Botany Department, Obafemi Awolowo University, Ile-Ife, were collected during the raining season (May–September) from different locations in Osun and Oyo States of Nigeria as shown in Table 1. The influence of the soil on the elemental composition of the plants was minimized by collecting the samples from their natural habitats and restricting the area of collection to about 50-m radius. Additionally, the samples were collected from not less than three plants in these areas and bulked to obtain a composite sample and ensuring that samples were representative with reduced micro-variability within the sampling [1]. The parts of interest of these plants were thoroughly washed in deionized water to eliminate contamination due to dust and environmental pollution, air-dried and thereafter dried in a hot air oven at 40 °C and stored in plastic bags until needed. 2.2. Preparation of samples The dried anti-diabetic plant samples were pulverized in a mill and thoroughly homogenized. About 250 mg of each of these samples were pelletized using a 15 ton Perkin-Elmer press and a 13 mm die to form about 1 mm thick pellets. In order to ascertain the quality of our measurements, three standards of similar matrix compositions from the National Institute of Standards and Technology (NIST) and National Bureau of Standards (NBS) namely NIST-SRM 1515 (apple leaves), NIST-SRM 1547 (peach leaves) and NBS-SRM 1572 (citrus leaves) were prepared in the same way and analyzed. All the pellets were coated with 5 lg/cm2 carbon to ensure good electrical contact and to prevent charge build up during measurements [1,8]. 2.3. PIXE analysis The 1.8 MeV collimated proton beam from the 2.5 MV AN-2000 Van de Graaff accelerator at the Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), Legnaro (Padova) Italy was used for the PIXE measurements. The diameter of the collimated beam was 6 mm. In enhancing the detection of some light and medium z elements, a 150 lm thick Mylar ‘‘funny’’ filter with 3.3% porosity was used for the measurements. This led to the reduction of the count-rates ensuring a dead time of less than 10% with beam currents of 20–80 nA. There was no apparent
damage seen on the samples after the irradiation. The details of the PIXE setup used in this work are similar to those earlier reported [1,8]. The emitted X-rays were detected using a 80 mm2 Si (Li) detector with energy resolution of 180 eV (FWHM) at 5.9 keV. The X-ray data generated were stored on disk and analyzed using the computer code GUPIX [9]. The accuracy and quality of our results was checked against the certified values from the standard reference materials and was found to be good (Table 3).
3. Results and discussion The results of our PIXE measurements on the medicinal plants listed in Table 1 are presented in Table 2, along with the RDA for adults. The twenty-one elements detected could be classified into major: magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K) and calcium (Ca); minor: manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), rubidium (Rb) and strontium (Sr); while the trace elements were titanium (Ti), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), arsenic (As), and bromine (Br). Their concentrations are presented in parts per million (ppm) or otherwise stated. The accuracy and quality of our results, checked against the certified values from the standard reference materials, was good (Table 3). The toxic elements of lead (Pb), cadmium (Cd), mercury (Hg), etc. were not detected in the plants, probably confirming their safety. However, the presence of arsenic, though in low concentrations, in the leaves of some plants, especially Ocimum gratissimum may indicate toxicity, industrial pollution and great caution in their uses. The Recommended Dietary Allowances (RDA) of some elements were not given while the roles of Rb, Sr, and Br in man are not clearly defined. The amounts of most of the elements detected were within the range of the RDA. However, the high concentrations of Al and Si in Bryophyllum pinnatum entire plant, Rb in Pepermonia pellucida leaf and Sr strontium in P. muerillanus leaf (Table 2) calls for great restraint in their use as antioxidants, nutraceuticals, food additives and supplements by the diabetics. Aluminum has been linked to Alzheimer’s disease in human brain while Si mitigates the effects of Al in the body, thereby helping to delay or prevent it. Apart from the use as diet, medicinal plants are potential sources of reasonable amount of the required elements to the diabetic patients. Daily consumption of 10 g of these dried plant parts would provide Mg, P, Cl, K, Ca, V, Ni, Zn and Br within the limits of RDA (Table 2). However, values that were above the RDA for Cr (2.5) in Boerhavia diffusa entire plant and O. gratissimum leaf, Mn (3.0) in leaves of P. muerillanus, Bridelia ferruginea and J. gossypifolia, Fe (1.5) in O. gratissimum leaf and Cu (5.0) in O. gratissimum leaf may make these plants unsafe at this dose (Table 2). A daily intake of 5 g
Table 3 Comparison of our PIXE measurements with certified values from NIST (SRM 1515) apple leaves, NBS (SRM 1572) citrus leaves, and NIST (SRM 1547) peach leaves respectively.
a b
Elements
Apple leaves measured
Apple leaves NIST (SRM)
Citrus leaves measured
Citrus leaves NBS SRM
Peach leaves measured
Peach leaves NIST (SRM)
Mg Al P S Cl K Ca Mn Fe Cu Zn Sr Ba
(0.241 ± 0.023)% 655 ± 40
(0.271 ± 0.008)% 286 ± 9
(0.49 ± 0.02)% 595 ± 59 (0.17 ± 0.03)% (0.384 ± 0.013)%
(0.58 ± 0.03)% 92 ± 15 (0.13 ± 0.02)% (0.407 ± 0.009)%
(0.425 ± 0.015)% 956 ± 57
0.432 ± 0.008)% 249 ± 8
529 ± 16 (1.519 ± 0.002)% (1.526 ± 0.003)% 40 ± 2 65 ± 2 5.45 ± 1.32 7.7 ± 1.7 30 ± 9 21 ± 6
579 ± 23 (1.61 ± 0.02)% (1.526 ± 0.015)% 54 ± 3 (80a) 5.64 ± 0.24 12.5 ± 0.3 25 ± 2 49 ± 2
(1.664 ± 0.002)% (3.242 ± 0.002)% 16 ± 2 73 ± 2 10.2 ± 2.1 19 ± 3 72 ± 15 13 ± 6
(1.82 ± 0.06)% (3.15 ± 0.10)% 23 ± 2 90 ± 10 16.5 ± 1.0 29 ± 2 (100b) 21 ± 3
(0.15 ± 0.02)% 212 ± 18 (2.064 ± 0.001)% (1.673 ± 0.003)% 80 ± 2 184 ± 3 4.0 ± 1.3 19.0 ± 1.9 33 ± 13 99 ± 7
(0.2a)% 360 ± 19 (2.43 ± 0.03)% (1.56 ± 0.02)% 98 ± 3 (220a) 3.7 ± 0.4 17.9 ± 0.4 53 ± 4 124 ± 4
Not certified. Uncertainties about 95%.
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will provide high Cr level for the entire plant of B. diffusa, high Cr, Fe and Cu levels for O. gratissimum leaf, and high Mn levels for P. muerillanus, B. ferruginea and J. gossypifolia leaves, calling for caution in their use, especially O. gratissimum leaf that is frequently drunk as beverage. Minerals play important roles in food metabolism as well as affect the antioxidant defense system [1,4]. The elements, Mg, P, S, K, Ca, Mn, Cr, Ni, Cu, Co, Zn and V, are implicated in the regulation of blood sugar levels in human body and production of insulin while their anti-oxidant activities have also been reported in managing diabetes [1,4]. Hence, the body needs to maintain a balance between these elements. Therefore, their detection in these medicinal plants (Table 2) may justify their ethnomedical use in treating diabetes [1,4], if proven that they do not contain any poisonous organic constituent(s). A maximum daily usage of 30 g of P. pellucida, M. longistyla and O. subscorpioidea leaves will give high levels (257–390 mg) of Mg, very high amounts (192 and 624 mg, respectively) of P and Ca in Cassia occidentalis, 1350 and 1462 mg, respectively of K in J. gossypifolia and P. pellucida leaves, and 1098 mg of Ca in Carica papaya (Table 2), which were all within the RDA range, and hence may adequately contribute to diabetes management. Furthermore, high contents (3341–3631 ppm, lg/g, mg/kg) of sulfur in leaves of Phyllanthus amarus, C. occidentalis and P. pellucida, Cl (6233 mg/kg) in entire plant of B. pinnatum, and of 3492 and 5359 mg/kg respectively of S and Cl in Murraya koenigii leaf (Table 2) may be useful in diabetes. The role of trace elements as co-factors of important enzymes in the biosynthesis of active organic constituents of medicinal plants is well documented [3]. In several controlled clinical trials, trace element supplementations in glycaemic control also revealed their benefits in the diabetic state due to their antioxidant effects [3,4]. Also, high Mn contents (355–671 mg/kg) in the leaves of J. gossypifolia, P. muerillanus, O. subscorpioidea and P. pellucida, respective high 1518, 1069 mg/kg contents of Fe in C. occidentalis and P. pellucida leaves, high (148–194 mg/kg) Cu values in B. diffusa entire plant and Securidaca longipedunculata leaf, and high (697 mg/kg) Zn content in P. pellucida leaf (Table 2) may make them indispensable in the management of diabetes. Lastly, entire plant of B. difusa with 5 times its RDA of Cr (104 mg/kg), high (17–20 mg/kg) content of V in S. longipedunculata stem and M. longistyla leaf would be useful in diabetes. Other trace elements of Ti, Co, Ni, and Br present in the plants were all within the RDA range and may similarly contribute to its management. 4. Conclusion The PIXE analysis of different parts of fifteen other Nigerian anti-diabetic plants showed the presence of twenty-one elements
at various concentrations, including Mg, P, Ca, K, Mn, Cu, Zn, S, Cr, Co, Ni and V (anti-diabetic elements) which are implicated in the regulation of insulin and the control of the blood-sugar levels in the human body. Consequently, entire plant of B. difusa, S. longipedunculata stem, leaves of M. longistyla, P. pellucida, M. longistyla, O. subscorpioidea, P. muerillanus, J. gossypifolia, C. occidentalis, P. amarus, and leaf and stem of M. koenigii, which have high amounts of these elements could be recommended as vegetables, nutraceuticals, food additives and supplements in the control and management of diabetes. However, significantly higher concentrations of Al and Si in the entire plant of B. pinnatum, and As, Cr, and Cu in O. gratissimum leaf than RDA suggest that these plants should be avoided by diabetic patients to prevent complications. Acknowledgments The authors wish to express their profound gratitude to AS-ICTP for Training and Research in Italian Laboratories (TRIL), Trieste, Italy for the financial support given to S.O. Olabanji for the work. They also wish to thank Mr. M. Loriggiola and Mr. G. Manente for sample preparation, Mr. A.T. Oladele for the collection of the plants and the Obafemi Awolowo University, Ile-Ife, Nigeria for the leave granted to S.O.Olabanji. References [1] S.O. Olabanji, O.R. Omobuwajo, D. Ceccato, A.C. Adebajo, M.C. Buoso, G. Moschini, Nucl. Instr. Meth. Phys. Res. B266 (2008) 2387. [2] American Diabetes Association (ADA), Diagnosis and classification of diabetes mellitus, Diab. Care 29 (Suppl. 1) (2006) S43–S48. [3] A.C. Adebajo, M.D. Ayoola, S.A. Odediran, A.J. Aladesanmi, T.J. Schmidt, E.J. Verspohl, Evaluation of ethnomedical claims III: anti-hyperglycaemic activities of Gongronema latifolium root and stem, J. Diab. (2013), http://dx.doi.org/ 10.1111/1753-0407.12019. [4] A. Kar, B.K. Choudhary, N.G. Bandyopadhyay, Preliminary studies on the inorganic constituents of some indigenous hypoglycaemic herbs on oral glucose tolerance test, J. Ethnopharmacol. 64 (1999) 179. [5] L. Pari, M.A. Satheesh, Antidiabetic activity of Boerhavia diffusa L.: effect on hepatic key enzymes in experimental diabetes, J. Ethnopharmacol. 91 (2004) 109. [6] A.C. Adebajo, O.F. Ayoola, E.O. Iwalewa, A.A. Akindahunsi, N.O.A. Omisore, C.O. Adewunmi, T.K. Adenowo, Anti-trichomonal, biochemical and toxicological activities of methanolic extract and some carbazole alkaloids isolated from the leaves of Murraya koenigii growing in Nigeria, Phytomedicine 13 (2006) 246. [7] L.O. Aka, R.I. Obidike, Time profile antidiabetic activity of the aqueous leaf extracts of Bridelia ferruginea in albino rats, Nig. J. Exp. Appl. Biol. 11 (1) (2010) 7. [8] S.O. Olabanji, O.R. Omobuwajo, D. Ceccato, M.C. Buoso, M. De Poli, G. Moschini, J. Radioanal. Nucl. Chem. 270 (2006) 515. [9] J.A. Maxwell, W.J. Teesdale, J.L. Campbell, Nucl. Instr. Meth. B 95 (1995) 407.
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Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
PIXE analysis of some Nigerian anti-diabetic medicinal plants (II) S.O. Olabanji a,b,⇑, A.C. Adebajo c, O.R. Omobuwajo d, D. Ceccato a,e, M.C. Buoso a, G. Moschini a,e a
Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), I-35020 Padova, Italy ICTP Fellow on Sabbatical Leave from Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria c Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria d Department of Pharmacognosy & Herbal Medicine, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Nigeria e Dipartmento di Fisica, Universita di Padova, Padova, Italy b
a r t i c l e
i n f o
Article history: Received 14 March 2013 Received in revised form 27 May 2013 Accepted 13 June 2013 Available online 19 July 2013 Keywords: PIXE Trace elements Anti-diabetic Medicinal plants Nigeria
a b s t r a c t Diabetes mellitus, a metabolic disease characterized by high blood glucose levels (hyperglycemia) due to defects in insulin secretion, or action, or both, is a debilitating disease leading to other complications and death of many people in the world. Some of the medicinal plants implicated in the herbal recipes for the treatment of diabetes in Nigeria have been reported. Additional medicinal plants used for the treatment of diabetes in Nigeria are presented in this work. These medicinal plants are becoming increasingly important and relevant as herbal drugs due to their use as antioxidants, nutraceuticals, food additives and supplements in combating diabetes. Elemental compositions of these anti-diabetic medicinal plants were determined using PIXE technique. The 1.8 MV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL) Legnaro (Padova) Italy was employed for the work. The results show the detection of twenty-one elements which include Mg, P, Ca, K, Mn, Cu, Zn, S, Cr, Co, Ni and V that are implicated in the regulation of insulin and the control of the blood-sugar levels in the human body. The entire plant of Boerhavia diffusa, Securidaca longipedunculata stem, leaves of Peperomia pellucida, Macrosphyra longistyla, Olax subscorpioidea, Phyllanthus muerillanus, Jatropha gossypifolia, Cassia occidentalis, Phyllanthus amarus, and leaf and stem of Murraya koenigii, which have high concentrations of these elements could be recommended as vegetables, nutraceuticals, food additives, supplements and drugs in the control and management of diabetes, if toxicity profiles indicate that they are safe. However, significantly high contents of Al and Si in the entire plant of Bryophyllum pinnatum, and As, Cr, and Cu in Ocimum gratissimum leaf suggest that these plants should be avoided by diabetic patients to prevent complications. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction Diabetes mellitus is a metabolic disease characterized by high blood glucose levels (hyperglycemia) due to defects in insulin secretion, or action, or both and is a leading cause of death worldwide [1,2]. Insulin is a hormone produced by the b-pancreatic cells in the body with the primary function of controlling the blood glucose levels in the body [2]. The macro-vascular complications of diabetes include blindness, renal failure and nervous damage while the microvascular ones are atherosclerosis, strokes, coronary heart disease, etc. and finally death [2,3]. Hence, all efforts are geared towards managing or controlling it [1,2]. Plants used ethnomedicinally in managing diabetes are becoming increasingly used as drugs, nutraceuticals, food additives and supplements in combating chronic diseases, such as diabetes ⇑ Corresponding author at: Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), I-35020 Padova, Italy. Tel.: +234 803 532 1791. E-mail address: [email protected] (S.O. Olabanji). 0168-583X/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nimb.2013.06.052
[1,2]. Many pharmacological reports have suggested roles for their organic [3–7] and elemental [1,4,8] constituents in its management. The mechanisms of their anti-diabetic activities include pancreatic insulin stimulation or inhibition for the respective treatment of type 2 diabetes due to deficiency or insulin resistance, and extra-pancreatic, including inhibition of glucose absorption, increased glucose utilization and stimulation/inhibition of enzymatic actions [2,3,5–7]. The active chemical constituents of some plants have also been identified [3]. However, there are still many plants with only folkloric claims, such as Phyllanthus muerillanus, Jatropha gossypifolia, Macrosphyra longistyla, and Olax subscorpioidea [8]. In our previous work [1], the elements of anti-diabetic plants used ethnomedically in Nigeria for managing diabetes were given. Therefore, in continuation of this study, elemental compositions of various parts of additional fifteen Nigerian anti-diabetic plants (Table 1) were evaluated using PIXE technique to determine the presence of any ‘‘anti-diabetic element’’ that could justify their folkloric usage or toxic elements that may preclude their folkloric use.
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Table 1 Additional anti-diabetic plants used ethnomedicinally in Nigeria. Plant codes
Plant names
Family
Plant’s part
Place of collection
Method of use
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL
Murraya koenigii Murraya koenigii Phyllanthus amarus. Phyllanthus muerillanus Bridelia ferruginea Jatropha gossypifolia Boerhavia diffusa Securidaca longipedunculata Securidaca longipedunculata Securidaca longipedunculata Ocimum gratissimum Macrosphyra longistyla Bryophyllum pinnatum Cassia occidentalis Carica papaya Lantana camara Olax subscorpioidea Peperomia pellucida
Rutaceae Rutaceae Euphorbiaceae Euphorbiaceae Euphorbiaceae Euphorbiaceae Nyctaginaceae Polygalaceae Polygalaceae Polygalaceae Labiatae Rubiaceae Crassullaceae Caesalpinaceae Caricaceae Verbanaceae Olacaceae Piperaceae
Stem Leaf Leaf Leaf Leaf Leaf Entire plant Leaf Stem bark Stem Leaf Leaf Entire plant Entire plant Leaf Leaf Leaf Leaf
OAU campus Ife OAU campus Ife OAU campus Ife Iseyin Iseyin OAU campus Ife Ile-Ife town Iseyin Iseyin Iseyin Ile-Ife Onigambari forest, Ibadan OAU campus Ile-Ife OAU campus Ife OAU campus Ife Onigambari forest, Ibadan OAU campus Ife
Decoction Decoction Leaf juice taken orally/potherb Decoction Decoction Decoction Decoction Decoction Decoction Decoction Potherb Decoction Leaf juice taken orally Decoction Decoction Decoction Decoction Potherb
Table 2 Elemental compositions of additional Nigerian anti-diabetic plants analyzed by PIXE. Plant codes Concentrations of elements (ppm, or otherwise stated)
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL RDA(mg)
MKSt MKL PAL PML BFL JGL BDE SLL SLSb SLSt OGL MLL BPE COE CPL LCL OSL PPL RDA (mg)
Mg
Al
Si
P
862 ± 94 4750 ± 173 3691 ± 160 2199 ± 124 6444 ± 139 5256 ± 1510 6372 ± 233 1428 ± 121 461 ± 95 528 ± 104 4482 ± 212 9753 ± 327 5835 ± 235 4870 ± 135 5662 ± 222 1980 ± 128 8550 ± 266 1.30 ± 0.03% 300–400
523 ± 70 648 ± 102 815 ± 90 1162 ± 89 467 ± 72 13 ± 8 1464 ± 129 634 ± 84 1000 ± 83 1387 ± 89 410 ± 117 1231 ± 111 8947 ± 258 2105 ± 106 494 ± 88 222 ± 93 751 ± 107 1281 ± 148 N.A.
1300 ± 77 1067 ± 61 2535 ± 96 3171 ± 94 2513 ± 101 2228 ± 84 1804 ± 75 1225 ± 53 2135 ± 63 1033 ± 43 77 ± 108 8±5 3163 ± 124 3503 ± 116 1754 ± 95 1286 ± 69 1268 ± 61 775 ± 43 1532 ± 62 793 ± 41 825 ± 89 5115 ± 176 2478 ± 101 979 ± 57 1.73 ± 0.02% 2949 ± 100 4448 ± 91 6740 ± 85 2731 ± 109 1964 ± 79 8838 ± 294 1847 ± 81 4501 ± 142 2159 ± 81 8665 ± 254 3219 ± 113 N.A. 800–1200
Cr
Mn
Fe
0.02–0.2
9±1 15 ± 1 <2 605 ± 9 1689 ± 21 671 ± 10 67 ± 3 5±1 <2 42 ± 2 415 ± 9 3±1 4±1 86 ± 2 40 ± 1 32 ± 1 411 ± 7 355 ± 5 1.0–5.0
215 ± 5 139 ± 3 43 ± 2 514 ± 9 193 ± 6 266 ± 6 427 ± 10 175 ± 4 45 ± 2 677 ± 10 2521 ± 37 102 ± 3 140 ± 4 1518 ± 17 306 ± 4 318 ± 6 234 ± 5 1069 ± 11 10.0–18.0
<2
104 ± 3 5±1 <2 4±1 591 ± 10 3±1 <3 5±1
S
Co
Cl
5±3 <4
17 ± 4 8±3 6±2 5±2 18 ± 3 N.A.
Ca
Ti
1054 ± 50 975 ± 45 6447 ± 108 1.22 ± 0.02% 3492 ± 87 5359 ± 125 1.83 ± 0.02% 1.68 ± 0.02% 3341 ± 104 1938 ± 62 113 ± 6 2580 ± 81 1341 ± 39 399 ± 18 1.56 ± 0.01% 2.01 ± 0.01% 2020 ± 35 3214 ± 40 4430 ± 46 1.72 ± 0.01% 9±4 46 ± 19 4.50 ± 0.01% 1.09 ± 0.01% 2105 ± 68 4024 ± 111 132 ± 5 918 ± 20 1217 ± 56 1225 ± 53 385 ± 8 3466 ± 59 1060 ± 30 3450 ± 38 135 ± 7 1440 ± 58 669 ± 25 754 ± 20 7744 ± 89 12,800 ± 100 3045 ± 106 3381 ± 112 190 ± 5 1388 ± 21 2199 ± 70 1566 ± 49 483 ± 11 3486 ± 70 2226 ± 61 6233 ± 115 217 ± 7 2206 ± 53 3631 ± 46 3177 ± 35 2.47 ± 0.01% 2.08 ± 0.01% 1867 ± 64 708 ± 28 3.285 ± 0.004% 3.66 ± 0.01% 1799 ± 61 2302 ± 66 2.66 ± 0.01% 1.68 ± 0.01% 3033 ± 84 204 ± 19 3.26 ± 0.01% 1.83 ± 0.01% 3394 ± 98 1898 ± 58 4.874 ± 0.007% 1.71 ± 0.01% N.A. 1400–5100 1525–5625 800–1,200 Ni
Cu
Zn
0.13–0.4
9±2 30 ± 3 17 ± 3 11 ± 5 <6 14 ± 6 194 ± 2 148 ± 3 10 ± 2 26 ± 2 1434 ± 7 72 ± 3 17 ± 2 19 ± 3 12 ± 3 29 ± 3 13 ± 2 <17 1.0–3.0
20 ± 1 48 ± 2 37 ± 2 97 ± 3 60 ± 3 64 ± 2 66 ± 3 111 ± 4 22 ± 2 36 ± 2 412 ± 12 89 ± 4 29 ± 2 43 ± 2 28 ± 2 51 ± 2 29 ± 2 697 ± 10 15.0
3±1 6±2 <2 7±2 6±2
K
4±1
6±1 8±1 4±1 8±1 48 ± 2 8±1 6±1
2±1
V
49 ± 1 21 ± 1 21 ± 1 1.5 ± 0.6 117 ± 2 15 ± 1 21 ± 1 23 ± 1 4.7 ± 0.8 7±1 6±1 2.9 ± 0.6 85 ± 2 20.3 ± 1.3 64 ± 1 21.9 ± 1.5 13 ± 1 16.6 ± 0.9 8±1 162 ± 2 19 ± 1 21 ± 1 26 ± 1 159 ± 2 N.A. 0.1–0.4
As
Br
Rb
Sr
4±1 5±1 3±1
5±2 47 ± 4 6±2 4±2 19 ± 4
33 ± 6 84 ± 9 5±2 14 ± 4 24 ± 6 96 ± 8
76 ± 10 98 ± 10 205 ± 13 153 ± 12 65 ± 8
15 ± 4
7±4 94 ± 9
3±1 3±1 9±2
19 ± 3 5±1
N.A.
5±2 7±2 6±2 7±2 7±2 5±2 10 ± 3 8±2 5±2 20 ± 3 15 ± 3 1.5–2.5
9±4 50 ± 7 72 ± 8 44 ± 6 105 ± 8 183 ± 11 N.A.
76 ± 9 142 ± 11 50 ± 8 93 ± 9 66 ± 8 N.A.
MKSt: Murraya koenigii Stem; MKL: Murraya koenigii leaf; PAL: Phyllanthus amarus leaf; PML: Phyllanthus muerillanus leaf; BFL: Bridelia ferruginea leaf; JGL: Jatropha gossypifolia leaf; BDE: Boerhavia diffusa entire plant; SLL: Securidaca longipedunculata leaf; SLSb: Securidaca longipedunculata stem bark; SLSt: Securidaca longipedunculata stem; OGL: Ocimum gratissimum leaf; MLL: Macrosphyra longistyla leaf; BPE: Bryophyllum pinnatum entire plant; COE: Cassia occidentalis entire plant; CPL: Carica papaya leaf; LCL: Lantana camara leaf; OSL: Olax subscorpioidea leaf; PPL: Peperomia pellucida leaf. RDA: Recommended Dietary Allowance; N.A.: data are not available.
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2. Experimental 2.1. Collection of samples The approach of sample collection and preparation in this work is similar to the ones reported earlier [1,8]. The additional anti-diabetic medicinal plants, after proper identification by a plant taxonomist, Dr. H.C. Illoh of Botany Department, Obafemi Awolowo University, Ile-Ife, were collected during the raining season (May–September) from different locations in Osun and Oyo States of Nigeria as shown in Table 1. The influence of the soil on the elemental composition of the plants was minimized by collecting the samples from their natural habitats and restricting the area of collection to about 50-m radius. Additionally, the samples were collected from not less than three plants in these areas and bulked to obtain a composite sample and ensuring that samples were representative with reduced micro-variability within the sampling [1]. The parts of interest of these plants were thoroughly washed in deionized water to eliminate contamination due to dust and environmental pollution, air-dried and thereafter dried in a hot air oven at 40 °C and stored in plastic bags until needed. 2.2. Preparation of samples The dried anti-diabetic plant samples were pulverized in a mill and thoroughly homogenized. About 250 mg of each of these samples were pelletized using a 15 ton Perkin-Elmer press and a 13 mm die to form about 1 mm thick pellets. In order to ascertain the quality of our measurements, three standards of similar matrix compositions from the National Institute of Standards and Technology (NIST) and National Bureau of Standards (NBS) namely NIST-SRM 1515 (apple leaves), NIST-SRM 1547 (peach leaves) and NBS-SRM 1572 (citrus leaves) were prepared in the same way and analyzed. All the pellets were coated with 5 lg/cm2 carbon to ensure good electrical contact and to prevent charge build up during measurements [1,8]. 2.3. PIXE analysis The 1.8 MeV collimated proton beam from the 2.5 MV AN-2000 Van de Graaff accelerator at the Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (LNL), Legnaro (Padova) Italy was used for the PIXE measurements. The diameter of the collimated beam was 6 mm. In enhancing the detection of some light and medium z elements, a 150 lm thick Mylar ‘‘funny’’ filter with 3.3% porosity was used for the measurements. This led to the reduction of the count-rates ensuring a dead time of less than 10% with beam currents of 20–80 nA. There was no apparent
damage seen on the samples after the irradiation. The details of the PIXE setup used in this work are similar to those earlier reported [1,8]. The emitted X-rays were detected using a 80 mm2 Si (Li) detector with energy resolution of 180 eV (FWHM) at 5.9 keV. The X-ray data generated were stored on disk and analyzed using the computer code GUPIX [9]. The accuracy and quality of our results was checked against the certified values from the standard reference materials and was found to be good (Table 3).
3. Results and discussion The results of our PIXE measurements on the medicinal plants listed in Table 1 are presented in Table 2, along with the RDA for adults. The twenty-one elements detected could be classified into major: magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K) and calcium (Ca); minor: manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), rubidium (Rb) and strontium (Sr); while the trace elements were titanium (Ti), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), arsenic (As), and bromine (Br). Their concentrations are presented in parts per million (ppm) or otherwise stated. The accuracy and quality of our results, checked against the certified values from the standard reference materials, was good (Table 3). The toxic elements of lead (Pb), cadmium (Cd), mercury (Hg), etc. were not detected in the plants, probably confirming their safety. However, the presence of arsenic, though in low concentrations, in the leaves of some plants, especially Ocimum gratissimum may indicate toxicity, industrial pollution and great caution in their uses. The Recommended Dietary Allowances (RDA) of some elements were not given while the roles of Rb, Sr, and Br in man are not clearly defined. The amounts of most of the elements detected were within the range of the RDA. However, the high concentrations of Al and Si in Bryophyllum pinnatum entire plant, Rb in Pepermonia pellucida leaf and Sr strontium in P. muerillanus leaf (Table 2) calls for great restraint in their use as antioxidants, nutraceuticals, food additives and supplements by the diabetics. Aluminum has been linked to Alzheimer’s disease in human brain while Si mitigates the effects of Al in the body, thereby helping to delay or prevent it. Apart from the use as diet, medicinal plants are potential sources of reasonable amount of the required elements to the diabetic patients. Daily consumption of 10 g of these dried plant parts would provide Mg, P, Cl, K, Ca, V, Ni, Zn and Br within the limits of RDA (Table 2). However, values that were above the RDA for Cr (2.5) in Boerhavia diffusa entire plant and O. gratissimum leaf, Mn (3.0) in leaves of P. muerillanus, Bridelia ferruginea and J. gossypifolia, Fe (1.5) in O. gratissimum leaf and Cu (5.0) in O. gratissimum leaf may make these plants unsafe at this dose (Table 2). A daily intake of 5 g
Table 3 Comparison of our PIXE measurements with certified values from NIST (SRM 1515) apple leaves, NBS (SRM 1572) citrus leaves, and NIST (SRM 1547) peach leaves respectively.
a b
Elements
Apple leaves measured
Apple leaves NIST (SRM)
Citrus leaves measured
Citrus leaves NBS SRM
Peach leaves measured
Peach leaves NIST (SRM)
Mg Al P S Cl K Ca Mn Fe Cu Zn Sr Ba
(0.241 ± 0.023)% 655 ± 40
(0.271 ± 0.008)% 286 ± 9
(0.49 ± 0.02)% 595 ± 59 (0.17 ± 0.03)% (0.384 ± 0.013)%
(0.58 ± 0.03)% 92 ± 15 (0.13 ± 0.02)% (0.407 ± 0.009)%
(0.425 ± 0.015)% 956 ± 57
0.432 ± 0.008)% 249 ± 8
529 ± 16 (1.519 ± 0.002)% (1.526 ± 0.003)% 40 ± 2 65 ± 2 5.45 ± 1.32 7.7 ± 1.7 30 ± 9 21 ± 6
579 ± 23 (1.61 ± 0.02)% (1.526 ± 0.015)% 54 ± 3 (80a) 5.64 ± 0.24 12.5 ± 0.3 25 ± 2 49 ± 2
(1.664 ± 0.002)% (3.242 ± 0.002)% 16 ± 2 73 ± 2 10.2 ± 2.1 19 ± 3 72 ± 15 13 ± 6
(1.82 ± 0.06)% (3.15 ± 0.10)% 23 ± 2 90 ± 10 16.5 ± 1.0 29 ± 2 (100b) 21 ± 3
(0.15 ± 0.02)% 212 ± 18 (2.064 ± 0.001)% (1.673 ± 0.003)% 80 ± 2 184 ± 3 4.0 ± 1.3 19.0 ± 1.9 33 ± 13 99 ± 7
(0.2a)% 360 ± 19 (2.43 ± 0.03)% (1.56 ± 0.02)% 98 ± 3 (220a) 3.7 ± 0.4 17.9 ± 0.4 53 ± 4 124 ± 4
Not certified. Uncertainties about 95%.
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will provide high Cr level for the entire plant of B. diffusa, high Cr, Fe and Cu levels for O. gratissimum leaf, and high Mn levels for P. muerillanus, B. ferruginea and J. gossypifolia leaves, calling for caution in their use, especially O. gratissimum leaf that is frequently drunk as beverage. Minerals play important roles in food metabolism as well as affect the antioxidant defense system [1,4]. The elements, Mg, P, S, K, Ca, Mn, Cr, Ni, Cu, Co, Zn and V, are implicated in the regulation of blood sugar levels in human body and production of insulin while their anti-oxidant activities have also been reported in managing diabetes [1,4]. Hence, the body needs to maintain a balance between these elements. Therefore, their detection in these medicinal plants (Table 2) may justify their ethnomedical use in treating diabetes [1,4], if proven that they do not contain any poisonous organic constituent(s). A maximum daily usage of 30 g of P. pellucida, M. longistyla and O. subscorpioidea leaves will give high levels (257–390 mg) of Mg, very high amounts (192 and 624 mg, respectively) of P and Ca in Cassia occidentalis, 1350 and 1462 mg, respectively of K in J. gossypifolia and P. pellucida leaves, and 1098 mg of Ca in Carica papaya (Table 2), which were all within the RDA range, and hence may adequately contribute to diabetes management. Furthermore, high contents (3341–3631 ppm, lg/g, mg/kg) of sulfur in leaves of Phyllanthus amarus, C. occidentalis and P. pellucida, Cl (6233 mg/kg) in entire plant of B. pinnatum, and of 3492 and 5359 mg/kg respectively of S and Cl in Murraya koenigii leaf (Table 2) may be useful in diabetes. The role of trace elements as co-factors of important enzymes in the biosynthesis of active organic constituents of medicinal plants is well documented [3]. In several controlled clinical trials, trace element supplementations in glycaemic control also revealed their benefits in the diabetic state due to their antioxidant effects [3,4]. Also, high Mn contents (355–671 mg/kg) in the leaves of J. gossypifolia, P. muerillanus, O. subscorpioidea and P. pellucida, respective high 1518, 1069 mg/kg contents of Fe in C. occidentalis and P. pellucida leaves, high (148–194 mg/kg) Cu values in B. diffusa entire plant and Securidaca longipedunculata leaf, and high (697 mg/kg) Zn content in P. pellucida leaf (Table 2) may make them indispensable in the management of diabetes. Lastly, entire plant of B. difusa with 5 times its RDA of Cr (104 mg/kg), high (17–20 mg/kg) content of V in S. longipedunculata stem and M. longistyla leaf would be useful in diabetes. Other trace elements of Ti, Co, Ni, and Br present in the plants were all within the RDA range and may similarly contribute to its management. 4. Conclusion The PIXE analysis of different parts of fifteen other Nigerian anti-diabetic plants showed the presence of twenty-one elements
at various concentrations, including Mg, P, Ca, K, Mn, Cu, Zn, S, Cr, Co, Ni and V (anti-diabetic elements) which are implicated in the regulation of insulin and the control of the blood-sugar levels in the human body. Consequently, entire plant of B. difusa, S. longipedunculata stem, leaves of M. longistyla, P. pellucida, M. longistyla, O. subscorpioidea, P. muerillanus, J. gossypifolia, C. occidentalis, P. amarus, and leaf and stem of M. koenigii, which have high amounts of these elements could be recommended as vegetables, nutraceuticals, food additives and supplements in the control and management of diabetes. However, significantly higher concentrations of Al and Si in the entire plant of B. pinnatum, and As, Cr, and Cu in O. gratissimum leaf than RDA suggest that these plants should be avoided by diabetic patients to prevent complications. Acknowledgments The authors wish to express their profound gratitude to AS-ICTP for Training and Research in Italian Laboratories (TRIL), Trieste, Italy for the financial support given to S.O. Olabanji for the work. They also wish to thank Mr. M. Loriggiola and Mr. G. Manente for sample preparation, Mr. A.T. Oladele for the collection of the plants and the Obafemi Awolowo University, Ile-Ife, Nigeria for the leave granted to S.O.Olabanji. References [1] S.O. Olabanji, O.R. Omobuwajo, D. Ceccato, A.C. Adebajo, M.C. Buoso, G. Moschini, Nucl. Instr. Meth. Phys. Res. B266 (2008) 2387. [2] American Diabetes Association (ADA), Diagnosis and classification of diabetes mellitus, Diab. Care 29 (Suppl. 1) (2006) S43–S48. [3] A.C. Adebajo, M.D. Ayoola, S.A. Odediran, A.J. Aladesanmi, T.J. Schmidt, E.J. Verspohl, Evaluation of ethnomedical claims III: anti-hyperglycaemic activities of Gongronema latifolium root and stem, J. Diab. (2013), http://dx.doi.org/ 10.1111/1753-0407.12019. [4] A. Kar, B.K. Choudhary, N.G. Bandyopadhyay, Preliminary studies on the inorganic constituents of some indigenous hypoglycaemic herbs on oral glucose tolerance test, J. Ethnopharmacol. 64 (1999) 179. [5] L. Pari, M.A. Satheesh, Antidiabetic activity of Boerhavia diffusa L.: effect on hepatic key enzymes in experimental diabetes, J. Ethnopharmacol. 91 (2004) 109. [6] A.C. Adebajo, O.F. Ayoola, E.O. Iwalewa, A.A. Akindahunsi, N.O.A. Omisore, C.O. Adewunmi, T.K. Adenowo, Anti-trichomonal, biochemical and toxicological activities of methanolic extract and some carbazole alkaloids isolated from the leaves of Murraya koenigii growing in Nigeria, Phytomedicine 13 (2006) 246. [7] L.O. Aka, R.I. Obidike, Time profile antidiabetic activity of the aqueous leaf extracts of Bridelia ferruginea in albino rats, Nig. J. Exp. Appl. Biol. 11 (1) (2010) 7. [8] S.O. Olabanji, O.R. Omobuwajo, D. Ceccato, M.C. Buoso, M. De Poli, G. Moschini, J. Radioanal. Nucl. Chem. 270 (2006) 515. [9] J.A. Maxwell, W.J. Teesdale, J.L. Campbell, Nucl. Instr. Meth. B 95 (1995) 407.