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In vitro determination of sun protection factor and chemical stability of Rosa kordesii extract gel
j o u r n a l o f p h a r m a c y r e s e a r c h 7 ( 2 0 1 3 ) 5 2 0 e5 2 4
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/jopr
Original Article
In vitro determination of sun protection factor and chemical stability of Rosa kordesii extract gel Pratik P. Maske*, Sachin G. Lokapure, Dhanashri Nimbalkar, Shobharaj Malavi, John I. D’souza Department of Pharmaceutics, Tatyasaheb Kore College of Pharmacy, Warananagar, Maharashtra, India
article info
abstract
Article history:
Aims: In the present study, to investigate its chemical stability and the in vitro sun pro-
Received 17 April 2013
tection factor (SPF) of Rosa kordesii petal extract in a gel formulation.
Accepted 14 May 2013
Methods: Due to its antioxidant and photoprotective properties, R. kordesii is a promising
Available online 18 July 2013
candidate for use in cosmetic and pharmaceutical formulations. A high performance liquid chromatography method was used to evaluate the chemical stability using R. kordesii
Keywords:
extract as marker at 5, 25 and 45 C for 3e4 months. The sun protection factors were
Flavonoid
analyzed by ultraviolet (UV) spectrophotometry using samples irradiated with UVB lamp.
Rosa kordesii
Results: The chemical stability of the R. kordesii root extract gel was determined according to
Stability
the concentration of R. kordesii extracts at different storage temperatures (5, 25 and 45 C)
Sun protection factor
for 3e4 months. It is screened for in vitro sun protection factor in the R. kordesii extract and of its gel formulation and determines Photostability of the isolated R. kordesii extract and SPF. Conclusion: This study has shown that the R. kordesii petal extract gel is stable for at least 3e4 months when stored at 5 and 25 C. It is essential for collection of similar data for different plants and their flowers, as well as other parts. This proved activity of plant showed its importance and prophylactic utility in anti-solar formulation. This will be a better, cheaper and safe alternative to harmful chemical sunscreens that used now a days in the industry. Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved.
1.
Introduction
The UV light is divided conventionally into UV-A (320e400 nm), UV-B (290e320 nm), UV-C (100e290 nm), and vacuo UV (10e100 nm). It has been reported that adverse effects by UV-B radiation on the human skin include erythema (or sunburn), accelerated skin aging, and induction of skin cancer. Sunscreens are chemicals that provide protection
against the adverse effects of solar and, in particular, UV radiation. Studies in animals have shown that a variety of sunscreens can reduce the carcinogenic and immunosuppressive effects of the sunlight.1 Natural substances extracted from plants have been recently considered as potential sunscreen resources because of their ultraviolet ray absorption on the UV region and of their antioxidant power. Green tea polyphenols, Aloe barbadensis extract, and aromatic
* Corresponding author. Tel.: þ91 08867113512. E-mail address: [email protected] (P.P. Maske). 0974-6943/$ e see front matter Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jopr.2013.05.021
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j o u r n a l o f p h a r m a c y r e s e a r c h 7 ( 2 0 1 3 ) 5 2 0 e5 2 4
compounds isolated from lichens are examples of natural substances evaluated for their sunscreen properties.2e4 Antioxidants from natural sources may provide new possibilities for the treatment and prevention of UV-mediated diseases.5 Skin has the intrinsic properties to protect itself from the sun, in the form of melanin. The sunlight which also stimulates melanin and the pigment that acts as the skin natural sunscreen. Sunlight stimulates hormone protection, and it allows synthesis of vitamin D promotes skin cell regeneration. Although it may be observed that the shorter wavelength and the lower the number, the greater the energy level of the light and the more damage it can do.6 Direct exposure to UV-C for a length of time would destroy the skin. Fortunately, UV-C is completely absorbed by gases in the atmospheres before it reaches the ground. In any time the longer wavelength of UVB and UV-A pass right through the atmosphere.7e9 The molecules in sunscreen absorb most of UV-B and prevent it from reaching the skin just as the molecules of the atmospheres absorbs UV-C and prevent it from reaching the ground.10e12 Therefore, we report here the promise of the Rosa kordesii petal extract in cosmetic formulations; there are no prior data available about several aspects of the cosmetic formulation. The goals of this research are to evaluate, its stability at 3e4 months stored at 5, 25 and 45 C; the in vitro sun protection factor; the Photostability of the isolated R. kordesii extract.
Table 1 e Composition (%, w/w) of gel formulations used for the chemical stability study and for the determination of SPF. Active ingredients Carbomer 973 Propylene glycol Triethanolamine Methyl paraben R. kordesii petal extract Distilled water qs
Quantity 1.5 mg 10 ml 0.5 ml 0.25 mg 1.42 mg 100 ml
flasks under different conditions: 5, 25 and 45 C (1 C). The amount of crude extract in samples was quantitatively determined at 3e4 months stability studies. Briefly, 1.0 ml of distilled water and 10 ml of hexane were added to 50 mg of the samples. A fraction of the hexane layer was evaporated under nitrogen, dissolved in ethanol and analyzed by HPLC with electrochemical detection.13
2.5.
Flavonoid identification test
The general flavonoid identification test was performed on the extract as previously described in Nevade Sidram et al.14,15
2.
Materials and methods
2.6.
2.1.
Test materials and extract preparation
The in vitro method measures the reduction of the irradiation by measuring transmittance after passing through a film of product. As in the operative conditions of the transmission measurement are correct, this to be a very precise and single value, always reproducible for the same product and expressed as a single UV curve, in the percent transmittance or absorbance scale (Fig. 1). The crude R. kordesii petal extract, the gel formulation (1.5% carbomer 937) containing R. kordesii petal extract were analyzed for the in vitro SPF. The crude R. kordesii petal extract gel formulation was dissolved in methanol UV solv:water (6:4). Scans of the samples in solution were run from 320 to 290 nm using 1 cm quartz cuvettes in a Shimadzu UV-1700 spectrophotometer.16 The commercial sunscreens, Himalaya SPF 30, were used for the calculation of the correction factor and a solution of 8% homosalate (v/v) diluted to 0.2 mg/ml was used as standard. The SPF model used in this study was based on the following equation proposed by Mansur et al.17
Powdered petals of flower were percolated ethanolewater (1:1) (100 ml/g of dried powdered petal) and the extract was freeze-dried. The final concentration of the R. kordesii in the crude extract was 7.1% (w/w), as evaluated by HPLC with electrochemical detection.13
2.2.
Formulations
For the chemical stability study, gel formulation containing R. kordesii petal extract with final concentration of 0.1% (w/w) and 1.5% (w/w) of carbomer 973 was prepared. All formulations were stored in well-closed dark glass flasks and were compounded fresh for all studies. The concentration was the minimal active antioxidant concentration. A formulation was prepared with the addition of active ingredient % (w/w) which is shown in Table 1.
2.3.
Physiochemical parameters of the extract gel
Physicochemical parameters of the extract gel were determined according to the standard method which is shown in Table 2.
2.4.
Determination of the in vitro sun protection factor
Chemical stability study
The stability of R. kordesii extract over time and the influence of temperature on the degradation of R. kordesii extract gel without and in the presence of antioxidant were investigated. Gel formulations were stored in well-closed 10 g dark glass
Table 2 e Physicochemical parameters of the extract gel. Parameters Foreign organic matter Ethanol soluble extractive Water soluble extractive Total ash Acid-insoluble ash Acid-insoluble ash Loss on drying Moisture content
%w/w () S.D. 0.035% 13.21% 31.15% 6.67% 2.34% 5.8% 7.125% 5.67%
0.210 0.419 1.520 0.534 0.122 0.244 0.215 0.257
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Table 4 e SPF calculated for commercial sunscreens (Himalaya SPF 30) using Eq. (1) (Section 2.5) and data given in Table 2. l (nm)
290 295 300 305 310 315 320 Total
Fig. 1 e In vitro spectroscopic indices SPF, UVA PF.
SPF ¼ CF
320 X
EEðlÞ IðlÞ absðlÞ
EE I (normalized)
(1)
0.0150 0.0817 0.2874 0.3278 0.1864 0.0839 0.0180
Himalaya SPF 30 Absorbance
SPF
0.7943 0.7723 0.7625 0.7443 0.7167 0.6906 0.6688
0.0198 0.0676 0.2145 0.2434 0.1356 0.0578 0.0199 0.7586
EE: erythemal efficiency spectrum; I: solar simulator intensity spectrum.
290
where CF is correction factor, determined by sunscreens with known SPF, so that a solution containing 8% of homosalate gives SPF ¼ 8; EE(l) the erythemal efficiency spectrum; I(l) the solar simulator spectrum as measured with a calibrated spectroradiometer; 320 X
EEðlÞ IðlÞ ¼ 290e320 nm
(2)
290
where, 290e320 nm in 5 nm increments; abs(l) is the spectroradiometer measure of sunscreen product absorbance. Table 3 shows the normalized values of the product function used in these studies and were calculated by Sayre et al.17,18 The data were analyzed statistically by factorial analysis of variance (ANOVA). The TukeyeKramer test was then used to determine significant differences between groups.
micrograms of R. kordesii extracts per gram of gel formulation. Carbomer frequently interacts with cationic drugs and excipients due to its numerous carboxylic acid groups.19 In vitro studies using carbomers 973 showed that its interaction with substances commonly used in the pharmaceutical industry, such as lidocaine and mebeverine hydrochloride, was a function of pH, drug, polymer concentration and electrolytes.20 All samples stored at 5 and 25 C were stable over the time of experiment (3e4 months). All of them showed an initial decrease (20%) between days 0 and 1 and then remain constant over time. The samples stored at 45 C were stable up 7 days then the degradation of gel structure was observed after 7 days.
3.2. In vitro sun protection factor in the R. kordesii extract and of its gel formulation
3.
Results and discussion
3.2.1.
3.1. Chemical stability of the R. kordesii extracts gel formulation The chemical stability of the R. kordesii root extract gel was determined according to the concentration of R. kordesii extracts at different storage temperatures (5, 25 and 45 C) for 3e4 months. The final concentration was expressed as
Table 3 e The normalized product function used in the calculation of SPF data. l (nm) 290 295 300 305 310 315 320
EE I (normalized) 0.0150 0.0817 0.2874 0.3278 0.1864 0.0839 0.0180 ¼1.000
EE: erythemal efficiency spectrum; I: solar simulator intensity spectrum.
Determination of the correction factor
The correction factor was calculated for commercial sunscreen (Himalaya SPF 30) using Eq. (1) data given in Table 3 and the total SPF given in Table 4.
3.2.2. Determination of SPF in the R. kordesii extract and of its gel formulation The crude R. kordesii petal extract has high SPF but after suitable formulation or by adding one or more ingredient like carbomer, it gives lower SPF value for R. kordesii petal extract gel formulation then crude R. kordesii petal extract. According to Table 5 summarizes the SPF values determined for each solution described. As expected, the SPF observed for the 8% homosalate solution was approximately 8.23 0.5. Thus, in vitro SPF value for the crude R. kordesii petal extract was
Table 5 e Results expressed as the average and S.D. of three determinations replicated of the SPF values. Sample Homosalate 8% R. kordesii extract gel Crude R. kordesii extract
SPF 8.23 0.5 3.25 0.01. 20.15 0.05
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523
Fig. 2 e Absorbance spectra of a methanol solution of 10 mg/ml R. kordesii extract: (A) just after preparation and (B) after 120 min of UVB irradiation.
20.15 0.05. When 1.42% R. kordesii petal extract was added to the carbomer gel formulation, the SPF value was 3.25 0.01.
to carry out this work and we thank JPR Solutions for partial funding in publishing this research.
3.3.
references
Photostability of the isolated R. kordesii extract
An ethanol solution of 10 mg/ml R. kordesii extract was irradiated with a UVB lamp. Absorbance spectra of the R. kordesii extract solution were stable over time of irradiation (Fig. 2). All values are means of three replicated experiments. The concentration difference between times was considered not significant in the statistical analysis.
4.
Conclusion
This study has shown that the R. kordesii petal extract gel formulation is stable for at least 3e4 months when stored at 4 and 30 C. Sometime heat is a possible factor responsible for the gel degradation over time. Further, R. kordesii petal extract gel has, the major antioxidant of R. kordesii, is also stable when exposed to UVB irradiation. It is essential for collection of similar data for different plants and their flowers, as well as other parts. This proved activity of plant showed its importance and prophylactic utility in anti-solar formulation. This will be a better, cheaper and safe alternative to harmful chemical sunscreens that used now a days in the industry.
Conflicts of interest All authors have none to declare.
Acknowledgments The author is thankful to Prof. J.I. Disouza of TYCP Faculty of Pharmacy, Warananagar for providing the necessary facilities
1. Ichihashi M, Ueda M, Budiyanto A, et al. UV-induced skin damage. Toxicology. 2003;189:21e39. 2. Melnikova VO, Ananthaswamy HN. Cellular and molecular events leading to the development of skin cancer. Mutat Res. 2005;571:91e106. 3. Bonina F, Lanza M, Montenegro L, et al. Flavonoids as potential protective agents against photo-oxidative skin damage. Int J Pharm. 1996;145:87e94. 4. Saija A, Tomaino A, Trombetta D, Giacchi M, De Pasquale A, Bonina F. Influence of different penetration enhancers on in vitro skin permeation and in vivo photoprotective effect of flavonoids. Int J Pharm. 1998;175:85e94. 5. F’guyer S, Afaq F, Mukhtar H. Photochemoprevention of skin cancer by botanical agents. Photodermatol Photoimmunol Photomed. 2003;19:56e72. 6. Lu H, Edwards C, Gaskell S, Pearse A, Marks R. Melanin content and distribution in the surface corneocyte with phototypes. Br J Dermatol. 1996;135:263e267. 7. Saraf S, Ashawat M. Anti-solar activity of flower extract of R. damascena and T. erecta Linn. Planta Indica. 2005;1:26e27. 8. Teixeira CC, Rava CA, Silva PM, et al. Absence of antihyperglycemic effect of jambolan in experimental and clinical models. J Ethnopharmacol. 2000;71:343e347. 9. Rahman AU, Zaman K. Medicinal plants with hypoglycemic activity. J Ethnopharmacol. 1989;26:1e55. 10. Teixeira CC, Pinto LP, Kessler FHP, et al. The effect of Syzygium cumini (L.) Skeels on post-prandial blood glucose levels in non-diabetic rats and rats with streptozotocin-induced diabetes mellitus. J Ethnopharmacol. 1997;56:209e213. 11. Warrier PK, Nambiar VPK, Ramankutty C. Indian Medicinal Plants. Hyderabad: Orient Longman Ltd.; 1996:225e228. 12. Bhandary MJ, Chandrashekar KR, Kaveriappa KM. Medical ethnobotany of the Siddis of Uttara Kannada district, Karnataka, India. J Ethnopharmacol. 1995;47:149e158. 13. Ropke CD, Kaneko TM, Rodrigues RM, et al. Evaluation of percutaneous absorption of 4-nerolidylcathecol from four topical formulations. Int J Pharm. 2002;249:109e116.
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14. Khandelwal KR. Practical Pharmacognosy. 12th ed. Pune: Nirali Prakashan; 2004. 15. Nevade Sidram A, Lokapure Sachin G, Kalyane NV. Study on anti-solar activity of ethanolic extract of flower of Hibiscus rosa-sinensis Linn. Res J Pharm Technol. 2011;4(3):472e473. 16. Ribeiro AM, Khury E, Gottardi D. Validac¸a˜o de testes de estabilidade para produtos cosme´ticos. In: Annals of the 10th National Cosmetology Congress of the Brazilian Cosmetology Association; 1996:349e375. 17. Mansur JS, Breder MNR, Mansur MCA, Azulay RD. Correlac¸a˜o entre a determinac¸a˜o do fator de protec¸a˜o solar em seres
humanos e por espectrofotometria. An Bras Dermatol. 1986;61:167e172. 18. Sayre RM, Agin PP, LeVee GJ, Marlowe E. A comparison of in vivo and in vitro testing of sunscreening formulas. Photochem Photobiol. 1979;29:559e566. 19. Blanco-Fuente H, Esteban-Fernandez B, Blanco-Mendez J, Otero-Espinar FJ. Use of beta-cyclodextrins to prevent modifications of the properties of carbopol hydrogels due to carbopoledrug interactions. Chem Pharm Bull. 2002;50:40e46. 20. Al-Gohary OM, Foda NH. Interaction of mebeverine hydrochloride and carbopol. Pharm Ind. 1993;55:523e527.
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/jopr
Original Article
In vitro determination of sun protection factor and chemical stability of Rosa kordesii extract gel Pratik P. Maske*, Sachin G. Lokapure, Dhanashri Nimbalkar, Shobharaj Malavi, John I. D’souza Department of Pharmaceutics, Tatyasaheb Kore College of Pharmacy, Warananagar, Maharashtra, India
article info
abstract
Article history:
Aims: In the present study, to investigate its chemical stability and the in vitro sun pro-
Received 17 April 2013
tection factor (SPF) of Rosa kordesii petal extract in a gel formulation.
Accepted 14 May 2013
Methods: Due to its antioxidant and photoprotective properties, R. kordesii is a promising
Available online 18 July 2013
candidate for use in cosmetic and pharmaceutical formulations. A high performance liquid chromatography method was used to evaluate the chemical stability using R. kordesii
Keywords:
extract as marker at 5, 25 and 45 C for 3e4 months. The sun protection factors were
Flavonoid
analyzed by ultraviolet (UV) spectrophotometry using samples irradiated with UVB lamp.
Rosa kordesii
Results: The chemical stability of the R. kordesii root extract gel was determined according to
Stability
the concentration of R. kordesii extracts at different storage temperatures (5, 25 and 45 C)
Sun protection factor
for 3e4 months. It is screened for in vitro sun protection factor in the R. kordesii extract and of its gel formulation and determines Photostability of the isolated R. kordesii extract and SPF. Conclusion: This study has shown that the R. kordesii petal extract gel is stable for at least 3e4 months when stored at 5 and 25 C. It is essential for collection of similar data for different plants and their flowers, as well as other parts. This proved activity of plant showed its importance and prophylactic utility in anti-solar formulation. This will be a better, cheaper and safe alternative to harmful chemical sunscreens that used now a days in the industry. Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved.
1.
Introduction
The UV light is divided conventionally into UV-A (320e400 nm), UV-B (290e320 nm), UV-C (100e290 nm), and vacuo UV (10e100 nm). It has been reported that adverse effects by UV-B radiation on the human skin include erythema (or sunburn), accelerated skin aging, and induction of skin cancer. Sunscreens are chemicals that provide protection
against the adverse effects of solar and, in particular, UV radiation. Studies in animals have shown that a variety of sunscreens can reduce the carcinogenic and immunosuppressive effects of the sunlight.1 Natural substances extracted from plants have been recently considered as potential sunscreen resources because of their ultraviolet ray absorption on the UV region and of their antioxidant power. Green tea polyphenols, Aloe barbadensis extract, and aromatic
* Corresponding author. Tel.: þ91 08867113512. E-mail address: [email protected] (P.P. Maske). 0974-6943/$ e see front matter Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jopr.2013.05.021
521
j o u r n a l o f p h a r m a c y r e s e a r c h 7 ( 2 0 1 3 ) 5 2 0 e5 2 4
compounds isolated from lichens are examples of natural substances evaluated for their sunscreen properties.2e4 Antioxidants from natural sources may provide new possibilities for the treatment and prevention of UV-mediated diseases.5 Skin has the intrinsic properties to protect itself from the sun, in the form of melanin. The sunlight which also stimulates melanin and the pigment that acts as the skin natural sunscreen. Sunlight stimulates hormone protection, and it allows synthesis of vitamin D promotes skin cell regeneration. Although it may be observed that the shorter wavelength and the lower the number, the greater the energy level of the light and the more damage it can do.6 Direct exposure to UV-C for a length of time would destroy the skin. Fortunately, UV-C is completely absorbed by gases in the atmospheres before it reaches the ground. In any time the longer wavelength of UVB and UV-A pass right through the atmosphere.7e9 The molecules in sunscreen absorb most of UV-B and prevent it from reaching the skin just as the molecules of the atmospheres absorbs UV-C and prevent it from reaching the ground.10e12 Therefore, we report here the promise of the Rosa kordesii petal extract in cosmetic formulations; there are no prior data available about several aspects of the cosmetic formulation. The goals of this research are to evaluate, its stability at 3e4 months stored at 5, 25 and 45 C; the in vitro sun protection factor; the Photostability of the isolated R. kordesii extract.
Table 1 e Composition (%, w/w) of gel formulations used for the chemical stability study and for the determination of SPF. Active ingredients Carbomer 973 Propylene glycol Triethanolamine Methyl paraben R. kordesii petal extract Distilled water qs
Quantity 1.5 mg 10 ml 0.5 ml 0.25 mg 1.42 mg 100 ml
flasks under different conditions: 5, 25 and 45 C (1 C). The amount of crude extract in samples was quantitatively determined at 3e4 months stability studies. Briefly, 1.0 ml of distilled water and 10 ml of hexane were added to 50 mg of the samples. A fraction of the hexane layer was evaporated under nitrogen, dissolved in ethanol and analyzed by HPLC with electrochemical detection.13
2.5.
Flavonoid identification test
The general flavonoid identification test was performed on the extract as previously described in Nevade Sidram et al.14,15
2.
Materials and methods
2.6.
2.1.
Test materials and extract preparation
The in vitro method measures the reduction of the irradiation by measuring transmittance after passing through a film of product. As in the operative conditions of the transmission measurement are correct, this to be a very precise and single value, always reproducible for the same product and expressed as a single UV curve, in the percent transmittance or absorbance scale (Fig. 1). The crude R. kordesii petal extract, the gel formulation (1.5% carbomer 937) containing R. kordesii petal extract were analyzed for the in vitro SPF. The crude R. kordesii petal extract gel formulation was dissolved in methanol UV solv:water (6:4). Scans of the samples in solution were run from 320 to 290 nm using 1 cm quartz cuvettes in a Shimadzu UV-1700 spectrophotometer.16 The commercial sunscreens, Himalaya SPF 30, were used for the calculation of the correction factor and a solution of 8% homosalate (v/v) diluted to 0.2 mg/ml was used as standard. The SPF model used in this study was based on the following equation proposed by Mansur et al.17
Powdered petals of flower were percolated ethanolewater (1:1) (100 ml/g of dried powdered petal) and the extract was freeze-dried. The final concentration of the R. kordesii in the crude extract was 7.1% (w/w), as evaluated by HPLC with electrochemical detection.13
2.2.
Formulations
For the chemical stability study, gel formulation containing R. kordesii petal extract with final concentration of 0.1% (w/w) and 1.5% (w/w) of carbomer 973 was prepared. All formulations were stored in well-closed dark glass flasks and were compounded fresh for all studies. The concentration was the minimal active antioxidant concentration. A formulation was prepared with the addition of active ingredient % (w/w) which is shown in Table 1.
2.3.
Physiochemical parameters of the extract gel
Physicochemical parameters of the extract gel were determined according to the standard method which is shown in Table 2.
2.4.
Determination of the in vitro sun protection factor
Chemical stability study
The stability of R. kordesii extract over time and the influence of temperature on the degradation of R. kordesii extract gel without and in the presence of antioxidant were investigated. Gel formulations were stored in well-closed 10 g dark glass
Table 2 e Physicochemical parameters of the extract gel. Parameters Foreign organic matter Ethanol soluble extractive Water soluble extractive Total ash Acid-insoluble ash Acid-insoluble ash Loss on drying Moisture content
%w/w () S.D. 0.035% 13.21% 31.15% 6.67% 2.34% 5.8% 7.125% 5.67%
0.210 0.419 1.520 0.534 0.122 0.244 0.215 0.257
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Table 4 e SPF calculated for commercial sunscreens (Himalaya SPF 30) using Eq. (1) (Section 2.5) and data given in Table 2. l (nm)
290 295 300 305 310 315 320 Total
Fig. 1 e In vitro spectroscopic indices SPF, UVA PF.
SPF ¼ CF
320 X
EEðlÞ IðlÞ absðlÞ
EE I (normalized)
(1)
0.0150 0.0817 0.2874 0.3278 0.1864 0.0839 0.0180
Himalaya SPF 30 Absorbance
SPF
0.7943 0.7723 0.7625 0.7443 0.7167 0.6906 0.6688
0.0198 0.0676 0.2145 0.2434 0.1356 0.0578 0.0199 0.7586
EE: erythemal efficiency spectrum; I: solar simulator intensity spectrum.
290
where CF is correction factor, determined by sunscreens with known SPF, so that a solution containing 8% of homosalate gives SPF ¼ 8; EE(l) the erythemal efficiency spectrum; I(l) the solar simulator spectrum as measured with a calibrated spectroradiometer; 320 X
EEðlÞ IðlÞ ¼ 290e320 nm
(2)
290
where, 290e320 nm in 5 nm increments; abs(l) is the spectroradiometer measure of sunscreen product absorbance. Table 3 shows the normalized values of the product function used in these studies and were calculated by Sayre et al.17,18 The data were analyzed statistically by factorial analysis of variance (ANOVA). The TukeyeKramer test was then used to determine significant differences between groups.
micrograms of R. kordesii extracts per gram of gel formulation. Carbomer frequently interacts with cationic drugs and excipients due to its numerous carboxylic acid groups.19 In vitro studies using carbomers 973 showed that its interaction with substances commonly used in the pharmaceutical industry, such as lidocaine and mebeverine hydrochloride, was a function of pH, drug, polymer concentration and electrolytes.20 All samples stored at 5 and 25 C were stable over the time of experiment (3e4 months). All of them showed an initial decrease (20%) between days 0 and 1 and then remain constant over time. The samples stored at 45 C were stable up 7 days then the degradation of gel structure was observed after 7 days.
3.2. In vitro sun protection factor in the R. kordesii extract and of its gel formulation
3.
Results and discussion
3.2.1.
3.1. Chemical stability of the R. kordesii extracts gel formulation The chemical stability of the R. kordesii root extract gel was determined according to the concentration of R. kordesii extracts at different storage temperatures (5, 25 and 45 C) for 3e4 months. The final concentration was expressed as
Table 3 e The normalized product function used in the calculation of SPF data. l (nm) 290 295 300 305 310 315 320
EE I (normalized) 0.0150 0.0817 0.2874 0.3278 0.1864 0.0839 0.0180 ¼1.000
EE: erythemal efficiency spectrum; I: solar simulator intensity spectrum.
Determination of the correction factor
The correction factor was calculated for commercial sunscreen (Himalaya SPF 30) using Eq. (1) data given in Table 3 and the total SPF given in Table 4.
3.2.2. Determination of SPF in the R. kordesii extract and of its gel formulation The crude R. kordesii petal extract has high SPF but after suitable formulation or by adding one or more ingredient like carbomer, it gives lower SPF value for R. kordesii petal extract gel formulation then crude R. kordesii petal extract. According to Table 5 summarizes the SPF values determined for each solution described. As expected, the SPF observed for the 8% homosalate solution was approximately 8.23 0.5. Thus, in vitro SPF value for the crude R. kordesii petal extract was
Table 5 e Results expressed as the average and S.D. of three determinations replicated of the SPF values. Sample Homosalate 8% R. kordesii extract gel Crude R. kordesii extract
SPF 8.23 0.5 3.25 0.01. 20.15 0.05
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523
Fig. 2 e Absorbance spectra of a methanol solution of 10 mg/ml R. kordesii extract: (A) just after preparation and (B) after 120 min of UVB irradiation.
20.15 0.05. When 1.42% R. kordesii petal extract was added to the carbomer gel formulation, the SPF value was 3.25 0.01.
to carry out this work and we thank JPR Solutions for partial funding in publishing this research.
3.3.
references
Photostability of the isolated R. kordesii extract
An ethanol solution of 10 mg/ml R. kordesii extract was irradiated with a UVB lamp. Absorbance spectra of the R. kordesii extract solution were stable over time of irradiation (Fig. 2). All values are means of three replicated experiments. The concentration difference between times was considered not significant in the statistical analysis.
4.
Conclusion
This study has shown that the R. kordesii petal extract gel formulation is stable for at least 3e4 months when stored at 4 and 30 C. Sometime heat is a possible factor responsible for the gel degradation over time. Further, R. kordesii petal extract gel has, the major antioxidant of R. kordesii, is also stable when exposed to UVB irradiation. It is essential for collection of similar data for different plants and their flowers, as well as other parts. This proved activity of plant showed its importance and prophylactic utility in anti-solar formulation. This will be a better, cheaper and safe alternative to harmful chemical sunscreens that used now a days in the industry.
Conflicts of interest All authors have none to declare.
Acknowledgments The author is thankful to Prof. J.I. Disouza of TYCP Faculty of Pharmacy, Warananagar for providing the necessary facilities
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