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Sedative properties of the decoction of the rhizome of Cyperus articulatus
Fitoterapia 72 Ž2001. 22᎐29
Sedative properties of the decoction of the rhizome of Cyperus articulatus Vincent Silvere ` Rakotonirinaa , Elisabeth Ngo Bumb,U , Alice Rakotonirinac , Marc Bopelet a a
Laboratory of Animal Physiology, Faculty of Sciences, Uni¨ ersity of Yaounde´ I, B.P. 812 Yaounde, ´ Cameroon b Department of Biological Sciences, Faculty of Sciences, B.P. 565, Uni¨ ersity of Ngaoundere, ´´ Yaounde, ´ Cameroon c Laboratory of Cellular Electrophysiology, Ecole Normale Superieure, Uni¨ ersity of Yaounde´ I, ´ Yaounde, ´ Cameroon
Received 17 May 2000; accepted in revised form 3 July 2000
Abstract The decoction of the rhizome of Cyperus articulatus is empirically used in several African countries in the treatment of a wide variety of human diseases. Studies were conducted in mice in order to determine scientifically the pharmacological properties of this medicinal herb. At the same time, the qualitative chemical characterisation of the total extract showed that C. articulatus contains flavonoids, saponins, tannins, terpenes and sugars. The total extract of the rhizome of C. articulatus does not appear to possess either anaesthetic or paralysing effects. In contrast, spontaneous motor activity is significantly reduced by the extract. However, when compared to diazepam, C. articulatus does not seem to have muscle relaxant effects. When associated with sodium thiopental or diazepam, the total extract facilitates sleep induction, and increases the total sleep time without any concomitant analgesic effect. These observations suggest that the rhizome of C. articulatus has pharmacological properties similar to those of sedatives. The sedative actions probably explain at least part of the therapeutic efficiency claimed for this plant in traditional medicine. 䊚 2001 Elsevier Science B.V. All rights reserved. Keywords: Cyperus articulatus; Sedative activity
U
Corresponding author. Tel.: q237-252773; fax: q237-252767r252599. E-mail address: [email protected] ŽE.N. Bum.. 0367-326Xr01r$ - see front matter 䊚 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 6 7 - 3 2 6 X Ž 0 0 . 0 0 2 4 3 - 4
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
23
1. Introduction Cyperus articulatus L. ŽCyperaceae. is a rhizome-bearing herb found in Africa, Latin America, Asia and Oceania w1,2x. The decoction of its rhizome is well known as a traditional medicine in Cameroon, Central Africa Republic, Gabon, and Senegal for the treatment of headaches, migraines, etc. w3x. In addition, there is evidence that Indians of Amazonia use the plant in a similar way w2x. However, despite these alleged interesting virtues, very few scientific studies have been carried out to determine the pharmacological action of this medicinal plant, even though work on its chemical constituents has been done w4,5x. Since the decoction of the rhizome of C. articulatus is commonly used to treat some diseases of the central nervous system, the present study was designed to determine whether it has psychotropic properties that could justify its empirical use. With this aim, we conducted experiments in mice, investigating the effects of the total extract of C. articulatus rhizome on the spontaneous motor activity, and exploring its possible muscle relaxant, hypnotic and analgesic activities. Two well-known products, diazepam and sodium thiopental, were chosen as reference products.
2. Experimental 2.1. Plant material Specimens of C. articulatus used in this study were collected in the dry season ŽMay 1990. in the vicinity of Yaounde, ´ Cameroon. A voucher specimen ŽRakotonirina 002, reference 1256rHNC. was deposited in the National Herbarium of Cameroon. The rhizomes were washed, dried at room temperature Žapprox. 25⬚C. in the laboratory for approximately 30 days and then grounded in a mill to a grain size of - 1 mm. 2.2. Preparation of the total extract Ten grams of the powdered plant material were added to 100 ml of distilled water. After 18 h of maceration at room temperature, the mixture was boiled for 10 min and centrifuged Ž1160 = g, 15 min. after cooling. The supernatant Ždry residue: 0.1 grml, corresponding to an 8% yield. was diluted with distilled water to the required concentration. Phytochemical characterisation according to the methods described by Ciulei w6x showed the presence of flavonoids, saponins, sugars, triterpenes and polyuronides. 2.3. Animals and treatment Swiss mice of either sex, weighing 25 " 1 g, were used. They were housed in
24
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
standardised environmental conditions and fed with standard food for rodents ŽLaboratoire National Veterinaire, Garoua, Cameroon. and water, ad libitum. ´´ Treatments were administered intraperitoneally in a volume of 20 mlrkg. 2.4. Spontaneous motor acti¨ ity This study was conducted with the help of an activity cage derived from the actograph of Krauthammer in which the test mouse is totally free w7,8x. The spontaneous motor activity was recorded for 15 min before and 25 min after treatment. The effect of C. articulatus was studied on five groups of five mice each that received 2 = 10y6 , 2 = 10y4 , 2 = 10y2 , 2 = 10y1 or 2 grkg of the extract, respectively. A control group of five mice was treated with 0.9% NaCl. 2.5. Muscle relaxant acti¨ ity The rotarod test was used w9,10x. Mice were placed on a rotarod and those staying on the rod Ž12 rev.rmin. longer than 5 min were selected for the experiment. The selected mice were treated and then placed again on rotarod. The time spent by mice on the rod was recorded. C. articulatus extract Ž2 grkg. was studied in comparison to diazepam Ž5 mgrkg.. A control group was treated with NaCl 0.9%. 2.6. Effect on the sodium thiopental- and diazepam-induced sleep The method described by Beretz et al. w11x was used. Sleep inducing or potentiating effects of the extract have been studied in mice treated by a subhypnotic dose Ž100 mgrkg. and a hypnotic dose Ž150 mgrkg. of sodium thiopental. The different doses of the extract of the test groups and the NaCl 0.9% of the control group were administered 30 min before the injection of the sodium thiopental. The number of mice that slept with the subhypnotic dose of sodium thiopental was counted. With the hypnotic dose of sodium thiopental, the sleeping time was measured by observing the recovery of the straightening reflex w12x. The same test was carried out using diazepam at 37.5 mgrkg for a subhypnotic dose and 56.25 mgrkg for a hypnotic dose. 2.7. Analgesic acti¨ ity Investigation of the analgesic activity was conducted by the hot plate test as modified by Swell and Spencer w13x. Briefly, the tail of the mouse is dipped in a hot water bath maintained at 50⬚C. Control animals pull back their tails in less than 8 s. An increase of this time by more than 30 s is considered an analgesic effect. The delay for maintaining the tail in hot water was measured 10 and 5 min before, and 10, 20, 30, 45, 60, 90, 120, 180 and 240 min after treatment. C. articulatus extract was tested at 2 grkg while the control group received the NaCl 0.9% solution.
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
25
Fig. 1. Effect of the aqueous extract of Cyperus articulatus rhizome on spontaneous motor activity in mice. Results, recorded for 25 min after treatment, are mean " S.D. Ž n s 5.; UUU P - 0.001 vs. control ŽCon.; Student’s t-test.
2.8. Statistical analysis Data were analysed using Student’s t-test. P values F 0.05 were considered as statistically significant.
3. Results 3.1. Effect on spontaneous motor acti¨ ity Mice treated with Cyperus articulatus rhizome aqueous extract were immobile, quiet and presented palpebral ptosis. However, they reacted by jumping following a mechanical stimulation of the auricle. At the dose of 2 = 10y2 grkg, C. articulatus significantly reduced the frequency of the spontaneous motor activity by 43%. The maximum reduction Ž97%. was observed at 2 grkg, with one oscillation per minute in comparison to 36 oscillations per minute in the control group. At this dose also the amplitude was reduced by 97%, changing from 7.4 mm in the control group to 0.2 mm in the treated group ŽFig. 1.. The reduction of the spontaneous motor activity was observed upon administering the extract and was maintained during the whole duration of the analysis Ž25 min.. The dose of 2 grkg totally abolished the spontaneous motor activity ŽFig. 2.. 3.2. Muscle relaxant acti¨ ity C. articulatus did not decrease muscular tonicity in a significant way while diazepam Ž5 mgrkg. decreased the muscle tone by 97.5% ŽTable 1..
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
26
Fig. 2. Effect of the aqueous extract of Cyperus articulatus rhizome on spontaneous motor activity in mice Ž1 min after intraperitoneal administration.. Illustration of the dose-dependent reduction of frequency and amplitude of spontaneous movements.
3.3. Effect on the sodium thiopental and diazepam-induced sleep When treated only with subhypnotic doses of sodium thiopental or diazepam, 20% of mice could sleep. The percentage of sleeping mice increased to 75% and
Table 1 Muscle relaxant activity Žrotarod test. of the aqueous extract of Cyperus articulatus rhizome in mice a Treatment
Control Ž0.9% NaCl, 20 mlrkg, i.p.. C. articulatus Diazepam a
Dose Žmgrkg, i.p..
Time spent on rotarod Žmin.
Reduction Ž%.
40 " 23 2 = 103 5
33 " 17 UUU 1.0 " 0.2
UUU Values are mean " S.D. Ž n s 5.; P - 0.001 vs. control, Student’s t-test.
17.5 UUU 97.5
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
27
Fig. 3. Effect of the aqueous extract of Cyperus articulatus rhizome on sodium thiopental- and diazepam-induced sleep in mice: Ža. results recorded in mice treated with subhypnotic doses of sodium thiopental Ž100 mgrkg. or diazepam Ž37.5 mgrkg.; Žb. results recorded from mice treated with hypnotic doses of sodium thiopental Ž150 mgrkg. or diazepam Ž56.25 mgrkg.. Values are mean " S.D. Ž n s 20.; UUU P - 0.001 vs. control ŽCon., Student’s t-test.
95% in the groups treated with 2 grkg of the extract when sleep was induced with sodium thiopental or diazepam, respectively ŽFig. 3a.. Using hypnotic doses of sodium thiopental or diazepam, 100% of mice could sleep with both agents. The total sleep time induced by sodium thiopental increased from 20 min in the control group to 56 min in the group treated with the extract at the dose of 2 grkg. A greater increase was observed on diazepam-
28
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
induced sleep. In this case, the total sleep time changed from 20 min in the control group to 83 min in the extract-treated group ŽFig. 3b.. 3.4. Analgesic acti¨ ity C. articulatus Ž2 grkg, i.p.. did not affect the time for upholding the tail in hot water Žapprox. 7 s., without significant variations from 10 min before till 240 min after treatment Ždata not shown..
4. Discussion It is well known that a product that renders animals quiet is either sedative or depressive for the central nervous system, or muscle relaxant, or paralysing, or anaesthetic w8,14x. The first observations recorded were palpebral ptosis and quietness on the mice treated with the aqueous extract of C. articulatus. It was also observed that the mice that were made very quiet by the treatment reacted to the stimulation of the auricle by jumping. Assuming that muscular relaxation and state of unconsciousness figure among the characteristics of an anaesthetic w15x, C. articulatus L. does not seem to possess anaesthetic properties. Moreover, since paralysis, even partial, is accompanied by a loss of voluntary motor activities and reflexes w7x, the jumping reaction to the stimulation of the auricle of the mice treated excludes any paralysing property from the extract. It is therefore possible that the quietness induced by C. articulatus was due either to a sedative or a depressive effect on the central nervous system, or to a muscle relaxant effect, or to a combination of the three. The study of the effects on the spontaneous motor activity show that C. articulatus could decrease by 97% the frequency and the amplitude of movements. But this reduction of the spontaneous motor activity could not be related to a muscle relaxant activity of the extract, due to the lack of effects on muscular tonicity. Since sedatives decrease motility w8x, the reduction of the spontaneous motor activity could be attributed to a sedative effect of the extract. This hypothesis was tested and the results show that C. articulatus potentiated the sleep induced by sodium thiopental and diazepam. The extract lengthened by three and four times the total sleep time induced by sodium thiopental and diazepam, respectively. It not only increased the total sleep time, but also the percentage of mice put to sleep. The potentiation of the barbiturate-induced sleep suggests that C. articulatus possesses some sleep inducing properties w8x. These properties would then explain the observed palpebral ptosis which lends further support for the sedative properties of the extract w14x. The two aspects of its sedative effect, lengthening total sleep time and facilitating sleep induction, would account at least partly for the decrease of the spontaneous motor activity. To conclude, our results show that the total aqueous extract of the rhizome of C. articulatus, administered intraperitoneally, possesses properties that decrease the spontaneous motor activity and potentiate the hypnotic effect of sodium thiopental
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
29
and diazepam. Although our administration route is not the one used traditionally Žper os. C. articulatus could then truly be endowed with the sedatives properties exploited in the traditional medicine in order to treat some diseases of the central nervous system.
Acknowledgements We are grateful to Dr Philippe Ngessimo Mutaka of the University of Yaounde ´I for his efficient collaboration.
References w1x Hooper SS. In: Hutchinson J, Dalziel JM, Hepper FN, editors. Flora of West Tropical Africa. Crown Agents for Overseas Governments, 1972:280᎐285. w2x Schultes RE, Raffaud RF. The healing forest: medicinal plants of the northwest Amazonia. Dioscorides Press, 1990. w3x Dalziel JM. The useful plants on West Tropical Africa. The Crown Agents for the Colonies, 1937. w4x Kerharo J. La Pharmacopee Traditionnelle: plantes medicinales et toxiques. Vigot ´ Senegalaise ´ ´ ´ Freres, 1974. ` w5x Nyasse B. Etude des constituants chimiques de Stereospermum kunthianun et de Cyperus articulatus. These ` de Doctorat de 3eme ` cycle, Faculte´ des Sciences, Universite´ de Yaounde, ´ 1987. w6x Ciulei I. Methodology for analysis of vegetable drugs. Ministry of Chemical Industry, 1982. w7x Cohen Y. Abrege ´ ´ de pharmacologie. Masson, 1981. w8x Guillemain J, Tetau M. Cah Biother ´ 1980;68:1. w9x Binsard AM, Guillemain J, Platel A, Savini EC, Tetau M. Ann Homeopath Fr 1980;22:35. ´ w10x Dunham NW, Miya TS. J Am Pharm Assoc 1957;46:208. w11x Beretz A, Haag-Berrurier M, Anton R. Plantes medicinales et phytoterapie 1978;4:305. ´ ´ w12x Paoli F. Cah Biother ´ 1985;85:4. w13x Swell RDE, Spencer P. Br J Pharmacol 1974;51:140. w14x Sofowora EA. Medicinal plants and traditional medicine in Africa. John Wiley and Sons Ltd, 1982. w15x Carraz G, Carraz J. Medicaments du systeme nerveux: pharmacodynamie speciale. Edition ´ ` ´ Marketing, 1985.
Sedative properties of the decoction of the rhizome of Cyperus articulatus Vincent Silvere ` Rakotonirinaa , Elisabeth Ngo Bumb,U , Alice Rakotonirinac , Marc Bopelet a a
Laboratory of Animal Physiology, Faculty of Sciences, Uni¨ ersity of Yaounde´ I, B.P. 812 Yaounde, ´ Cameroon b Department of Biological Sciences, Faculty of Sciences, B.P. 565, Uni¨ ersity of Ngaoundere, ´´ Yaounde, ´ Cameroon c Laboratory of Cellular Electrophysiology, Ecole Normale Superieure, Uni¨ ersity of Yaounde´ I, ´ Yaounde, ´ Cameroon
Received 17 May 2000; accepted in revised form 3 July 2000
Abstract The decoction of the rhizome of Cyperus articulatus is empirically used in several African countries in the treatment of a wide variety of human diseases. Studies were conducted in mice in order to determine scientifically the pharmacological properties of this medicinal herb. At the same time, the qualitative chemical characterisation of the total extract showed that C. articulatus contains flavonoids, saponins, tannins, terpenes and sugars. The total extract of the rhizome of C. articulatus does not appear to possess either anaesthetic or paralysing effects. In contrast, spontaneous motor activity is significantly reduced by the extract. However, when compared to diazepam, C. articulatus does not seem to have muscle relaxant effects. When associated with sodium thiopental or diazepam, the total extract facilitates sleep induction, and increases the total sleep time without any concomitant analgesic effect. These observations suggest that the rhizome of C. articulatus has pharmacological properties similar to those of sedatives. The sedative actions probably explain at least part of the therapeutic efficiency claimed for this plant in traditional medicine. 䊚 2001 Elsevier Science B.V. All rights reserved. Keywords: Cyperus articulatus; Sedative activity
U
Corresponding author. Tel.: q237-252773; fax: q237-252767r252599. E-mail address: [email protected] ŽE.N. Bum.. 0367-326Xr01r$ - see front matter 䊚 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 6 7 - 3 2 6 X Ž 0 0 . 0 0 2 4 3 - 4
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
23
1. Introduction Cyperus articulatus L. ŽCyperaceae. is a rhizome-bearing herb found in Africa, Latin America, Asia and Oceania w1,2x. The decoction of its rhizome is well known as a traditional medicine in Cameroon, Central Africa Republic, Gabon, and Senegal for the treatment of headaches, migraines, etc. w3x. In addition, there is evidence that Indians of Amazonia use the plant in a similar way w2x. However, despite these alleged interesting virtues, very few scientific studies have been carried out to determine the pharmacological action of this medicinal plant, even though work on its chemical constituents has been done w4,5x. Since the decoction of the rhizome of C. articulatus is commonly used to treat some diseases of the central nervous system, the present study was designed to determine whether it has psychotropic properties that could justify its empirical use. With this aim, we conducted experiments in mice, investigating the effects of the total extract of C. articulatus rhizome on the spontaneous motor activity, and exploring its possible muscle relaxant, hypnotic and analgesic activities. Two well-known products, diazepam and sodium thiopental, were chosen as reference products.
2. Experimental 2.1. Plant material Specimens of C. articulatus used in this study were collected in the dry season ŽMay 1990. in the vicinity of Yaounde, ´ Cameroon. A voucher specimen ŽRakotonirina 002, reference 1256rHNC. was deposited in the National Herbarium of Cameroon. The rhizomes were washed, dried at room temperature Žapprox. 25⬚C. in the laboratory for approximately 30 days and then grounded in a mill to a grain size of - 1 mm. 2.2. Preparation of the total extract Ten grams of the powdered plant material were added to 100 ml of distilled water. After 18 h of maceration at room temperature, the mixture was boiled for 10 min and centrifuged Ž1160 = g, 15 min. after cooling. The supernatant Ždry residue: 0.1 grml, corresponding to an 8% yield. was diluted with distilled water to the required concentration. Phytochemical characterisation according to the methods described by Ciulei w6x showed the presence of flavonoids, saponins, sugars, triterpenes and polyuronides. 2.3. Animals and treatment Swiss mice of either sex, weighing 25 " 1 g, were used. They were housed in
24
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
standardised environmental conditions and fed with standard food for rodents ŽLaboratoire National Veterinaire, Garoua, Cameroon. and water, ad libitum. ´´ Treatments were administered intraperitoneally in a volume of 20 mlrkg. 2.4. Spontaneous motor acti¨ ity This study was conducted with the help of an activity cage derived from the actograph of Krauthammer in which the test mouse is totally free w7,8x. The spontaneous motor activity was recorded for 15 min before and 25 min after treatment. The effect of C. articulatus was studied on five groups of five mice each that received 2 = 10y6 , 2 = 10y4 , 2 = 10y2 , 2 = 10y1 or 2 grkg of the extract, respectively. A control group of five mice was treated with 0.9% NaCl. 2.5. Muscle relaxant acti¨ ity The rotarod test was used w9,10x. Mice were placed on a rotarod and those staying on the rod Ž12 rev.rmin. longer than 5 min were selected for the experiment. The selected mice were treated and then placed again on rotarod. The time spent by mice on the rod was recorded. C. articulatus extract Ž2 grkg. was studied in comparison to diazepam Ž5 mgrkg.. A control group was treated with NaCl 0.9%. 2.6. Effect on the sodium thiopental- and diazepam-induced sleep The method described by Beretz et al. w11x was used. Sleep inducing or potentiating effects of the extract have been studied in mice treated by a subhypnotic dose Ž100 mgrkg. and a hypnotic dose Ž150 mgrkg. of sodium thiopental. The different doses of the extract of the test groups and the NaCl 0.9% of the control group were administered 30 min before the injection of the sodium thiopental. The number of mice that slept with the subhypnotic dose of sodium thiopental was counted. With the hypnotic dose of sodium thiopental, the sleeping time was measured by observing the recovery of the straightening reflex w12x. The same test was carried out using diazepam at 37.5 mgrkg for a subhypnotic dose and 56.25 mgrkg for a hypnotic dose. 2.7. Analgesic acti¨ ity Investigation of the analgesic activity was conducted by the hot plate test as modified by Swell and Spencer w13x. Briefly, the tail of the mouse is dipped in a hot water bath maintained at 50⬚C. Control animals pull back their tails in less than 8 s. An increase of this time by more than 30 s is considered an analgesic effect. The delay for maintaining the tail in hot water was measured 10 and 5 min before, and 10, 20, 30, 45, 60, 90, 120, 180 and 240 min after treatment. C. articulatus extract was tested at 2 grkg while the control group received the NaCl 0.9% solution.
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
25
Fig. 1. Effect of the aqueous extract of Cyperus articulatus rhizome on spontaneous motor activity in mice. Results, recorded for 25 min after treatment, are mean " S.D. Ž n s 5.; UUU P - 0.001 vs. control ŽCon.; Student’s t-test.
2.8. Statistical analysis Data were analysed using Student’s t-test. P values F 0.05 were considered as statistically significant.
3. Results 3.1. Effect on spontaneous motor acti¨ ity Mice treated with Cyperus articulatus rhizome aqueous extract were immobile, quiet and presented palpebral ptosis. However, they reacted by jumping following a mechanical stimulation of the auricle. At the dose of 2 = 10y2 grkg, C. articulatus significantly reduced the frequency of the spontaneous motor activity by 43%. The maximum reduction Ž97%. was observed at 2 grkg, with one oscillation per minute in comparison to 36 oscillations per minute in the control group. At this dose also the amplitude was reduced by 97%, changing from 7.4 mm in the control group to 0.2 mm in the treated group ŽFig. 1.. The reduction of the spontaneous motor activity was observed upon administering the extract and was maintained during the whole duration of the analysis Ž25 min.. The dose of 2 grkg totally abolished the spontaneous motor activity ŽFig. 2.. 3.2. Muscle relaxant acti¨ ity C. articulatus did not decrease muscular tonicity in a significant way while diazepam Ž5 mgrkg. decreased the muscle tone by 97.5% ŽTable 1..
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
26
Fig. 2. Effect of the aqueous extract of Cyperus articulatus rhizome on spontaneous motor activity in mice Ž1 min after intraperitoneal administration.. Illustration of the dose-dependent reduction of frequency and amplitude of spontaneous movements.
3.3. Effect on the sodium thiopental and diazepam-induced sleep When treated only with subhypnotic doses of sodium thiopental or diazepam, 20% of mice could sleep. The percentage of sleeping mice increased to 75% and
Table 1 Muscle relaxant activity Žrotarod test. of the aqueous extract of Cyperus articulatus rhizome in mice a Treatment
Control Ž0.9% NaCl, 20 mlrkg, i.p.. C. articulatus Diazepam a
Dose Žmgrkg, i.p..
Time spent on rotarod Žmin.
Reduction Ž%.
40 " 23 2 = 103 5
33 " 17 UUU 1.0 " 0.2
UUU Values are mean " S.D. Ž n s 5.; P - 0.001 vs. control, Student’s t-test.
17.5 UUU 97.5
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
27
Fig. 3. Effect of the aqueous extract of Cyperus articulatus rhizome on sodium thiopental- and diazepam-induced sleep in mice: Ža. results recorded in mice treated with subhypnotic doses of sodium thiopental Ž100 mgrkg. or diazepam Ž37.5 mgrkg.; Žb. results recorded from mice treated with hypnotic doses of sodium thiopental Ž150 mgrkg. or diazepam Ž56.25 mgrkg.. Values are mean " S.D. Ž n s 20.; UUU P - 0.001 vs. control ŽCon., Student’s t-test.
95% in the groups treated with 2 grkg of the extract when sleep was induced with sodium thiopental or diazepam, respectively ŽFig. 3a.. Using hypnotic doses of sodium thiopental or diazepam, 100% of mice could sleep with both agents. The total sleep time induced by sodium thiopental increased from 20 min in the control group to 56 min in the group treated with the extract at the dose of 2 grkg. A greater increase was observed on diazepam-
28
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
induced sleep. In this case, the total sleep time changed from 20 min in the control group to 83 min in the extract-treated group ŽFig. 3b.. 3.4. Analgesic acti¨ ity C. articulatus Ž2 grkg, i.p.. did not affect the time for upholding the tail in hot water Žapprox. 7 s., without significant variations from 10 min before till 240 min after treatment Ždata not shown..
4. Discussion It is well known that a product that renders animals quiet is either sedative or depressive for the central nervous system, or muscle relaxant, or paralysing, or anaesthetic w8,14x. The first observations recorded were palpebral ptosis and quietness on the mice treated with the aqueous extract of C. articulatus. It was also observed that the mice that were made very quiet by the treatment reacted to the stimulation of the auricle by jumping. Assuming that muscular relaxation and state of unconsciousness figure among the characteristics of an anaesthetic w15x, C. articulatus L. does not seem to possess anaesthetic properties. Moreover, since paralysis, even partial, is accompanied by a loss of voluntary motor activities and reflexes w7x, the jumping reaction to the stimulation of the auricle of the mice treated excludes any paralysing property from the extract. It is therefore possible that the quietness induced by C. articulatus was due either to a sedative or a depressive effect on the central nervous system, or to a muscle relaxant effect, or to a combination of the three. The study of the effects on the spontaneous motor activity show that C. articulatus could decrease by 97% the frequency and the amplitude of movements. But this reduction of the spontaneous motor activity could not be related to a muscle relaxant activity of the extract, due to the lack of effects on muscular tonicity. Since sedatives decrease motility w8x, the reduction of the spontaneous motor activity could be attributed to a sedative effect of the extract. This hypothesis was tested and the results show that C. articulatus potentiated the sleep induced by sodium thiopental and diazepam. The extract lengthened by three and four times the total sleep time induced by sodium thiopental and diazepam, respectively. It not only increased the total sleep time, but also the percentage of mice put to sleep. The potentiation of the barbiturate-induced sleep suggests that C. articulatus possesses some sleep inducing properties w8x. These properties would then explain the observed palpebral ptosis which lends further support for the sedative properties of the extract w14x. The two aspects of its sedative effect, lengthening total sleep time and facilitating sleep induction, would account at least partly for the decrease of the spontaneous motor activity. To conclude, our results show that the total aqueous extract of the rhizome of C. articulatus, administered intraperitoneally, possesses properties that decrease the spontaneous motor activity and potentiate the hypnotic effect of sodium thiopental
V.S. Rakotonirina et al. r Fitoterapia 72 (2001) 22᎐29
29
and diazepam. Although our administration route is not the one used traditionally Žper os. C. articulatus could then truly be endowed with the sedatives properties exploited in the traditional medicine in order to treat some diseases of the central nervous system.
Acknowledgements We are grateful to Dr Philippe Ngessimo Mutaka of the University of Yaounde ´I for his efficient collaboration.
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