Evaluation of androgenic activity of Zingiber officinale and Pentadiplandra brazzeana in male rats

Pierre Kamtchouing¹; Gisle Yolande Mbongue Fandio¹; Thophile Dimo¹; Hermine Boukeng Jatsa²

¹Laboratoire de Physiologie Animale, Facult?des Sciences, Universit de Yaound I, B.P.812 Yaound,  Cameroun

²Dpartement de Biologie et de Physiologie Animales, Facult?des Sciences, Universit de Douala, B.P. 24157 Douala, Cameroun

Asian J Androl 2002 Dec; 4: 299-301           

Keywords: P. brazzeana; Z. officinale; testosterone; androgenic activity

Abstract

Aim: Aqueous extracts of Zingiber officinale and Pentadiplandra brazzeana were tested for their possible androgenic activity in male Wistar rats. Methods: The aqueous extracts of the two plants were gavaged separately to 2 groups of rats at a similar dose of 600 mg.kg-1.day-1 for 8 days. At the end of the treatment, the animals were killed and the blood, testis, epididymis, seminal vesicles and prostate were collected for biochemical analysis. Results: The aqueous extract of Z. officinale significantly increased in the relative weight of the testis, the serum testosterone level, testicular cholesterol level and epididymal a-glucosidase activity. The aqueous extract of P. brazzeana significantly increased the weights of the testis, seminal vesicles and prostate. It also significantly increased the serum and testicular testosterone level. The fructose, a-glucosidase and cholesterol levels in P. brazzeana-treated rats were increased by 28 %, 35 % and 114 %, respectively. Conclusion: The aqueous extracts of both P. brazzeana and Z. officinale have an androgenic activity, which seems to be more potent with P. brazzeana than with Z. officinale.

Zingiber officinale (Zingiberaceae) and Pentadiplan-dra brazzeana (Pentadiplandraceae) are highly reputed in African folk medical practices for many purposes. Z. officinale is used for the treatment of flatulence, colic, diarrhoea, spasm, cold and influenza. Z. officinale is used as an appetite stimulant, a narcotic antagonist and an anti-inflammatory agent [1]. P. brazzeana is used as an antiseptic in the treatment of wounds, as an analgesia in the treatment of dental caries and rheumatic disorders and as a vermifuge [2]. Besides, in African traditional medicine, especially in Cameroun, Z. officinale and P. brazzeana are used as aphrodisiac and male sexual stimulation [3]. Since androgens are the main hormones implicated in male sexual behaviour, the present study was undertaken to evaluate a possible androgenic effect of both plants.

2 Materials and methods

2.1 Animals

Adult male Wistar rats, weighing 180 g~210 g, were used in the study. The rats were raised at room tempera-ture with a reverse natural light-dark cycle, as practiced in the Animal House of this University. Rats were maintained on standard rat chew and tap water ad libitum.

2.2 Plant and preparation

The rhizome of Z. officinale and the root of P. brazzeana were brought from the city of Yaounde and were identified by the botanists of this University. They were shade dried at room temperature and were crushed to powder separately. The powder (125 g) of each plant were macerated in 200 mL of distilled water for 12 h at room temperature and were then filtered to obtain the final aqueous extract (concentration: 120 mg/ml) for use in the experiment.

2.3 Experimental protocol

Fifteen rats were divided at random into three groups of 5 animals each. The two treated groups were gavaged 2 ml of either plant extract (approximate dose: 600 mg.kg^-1.day^-1 or the controls, 2 ml of distilled water per day, both for 8 days. Animals were sacrificed on day 9 by decapitation. Blood samples were collected and the serum was prepared and kept at -20 for biochemical analysis. The prostate, seminal vesicle, left testis and epididymis were excised, freed from the attached fat and connective tissue and kept at -20 as well.

The serum and testicular testosterone levels were determined by radioimmunoassay [4] using testosterone 125I kit. The total protein level was determined in the serum and sexual organs (testis and epididymis) by methods described by Gornal et al [5] and Bradford [6], respectively. The seminal vesicle and epididymal fructose and a-glucosidase levels were determined using protocols in a WHO manual [7]. The cholesterol level in testis was determined using the colorimetric method of Forbes [8].

2.4 Statistical analysis

The results were expressed as meanSEM. The significance of differences was analysed using the Student's t-test and P<0.05 was considered significant.

3 Results

The aqueous extract of P. brazzeana caused a significant increase (P<0.05) in the weights of testis, seminal vesicle and prostate of rats, while that of Z. officinale only caused a significant increase (P<0.05) in testicular weight (Table 1).

Table 1. Effect of Z. officinale and P. brazzeana on weights of reproductive organs (g/100g body weight, meanSE) in male rats. bP<0.05, compared with control.

Z. officinale did not significantly affect the fructose level in the seminal vesicle, testosterone levels in the testis and the protein levels in the epididymis and the testis; meanwhile, the levels of testosterone and cholesterol in the testis and a-glucosidase in the epididymis were increased significantly (P<0.05). P. brazzeana induced a significant increase (P<0.05~0.01) in the serum and testicular testosterone levels; the testicular cholesterol, the seminal vesicular fructose and the epididymal a-glucosidase were increased by 114 %, 28 % and 35 %, respectively, while the testicular and epididymal protein levels were increased by 12 % and 29 %, respectively (Figure 1).

Figure 1. Biochemical changes in serum, testis, epididymis and seminal vesicle of rats. ^bP<0.05, ^cP<0.01, compare with control.

4 Discussion

The increase in the weights of the accessory sex organs caused by the plant extracts is probably the result of increased secretory activity, which is supported by an increase in the a-glucosidase in the epididymis and fructose in the seminal vesicle as indicated in the present study. The increase in the weights and secretory activity of these androgen-dependent organs could be due to the increase in androgen biosynthesis shown by the significant increase in serum and testicular testosterone levels in the treated rats. Results also revealed a significant increase in testicular cholesterol, the starting material for androgen biosynthesis [9].

In conclusion, the aqueous extracts of both P. brazzeana and Z. officinale have an androgenic activity, which seems to be more potent with P. brazzeana than with Z. officinale. Further studies are warranted to isolate the active principles of the plants and to clarify their mechanism of action.

References

[1] WHO. WHO monographs on selected medicinal plants. Malta, 1999; Vol 1. p 277-86.

[2] Bouquet A. Fticheurs et mdcine traditionnelle du Congo (Brazzaville). Paris: O.R.S.T.O.N. ; 1969. p 199.

[3] Noumi E, Amvan ZPH, Lontsi D. Aphrodisiac plants used in Cameroon. Fitotherapia 1998; 69:125-34.

[4] WHO. Programme for the provision of matched assay reagents for radioimmunoassay of hormones in reproductive physiology, 15th ed, Geneva; 1991. p 1-60.

[5] Gornal AG, Bardwil GS, David MM. Determination of serum proteins by the means of biuret reactions. J Biol Chem 1949; 177: 751-66.

[6] Bradford MM. A rapid and sensitive method for the quantitation microgram quantities of proteins utilising the principle of protein binding. Anal Biochem 1976; 72: 248-54.

[7] OMS. Manuel de laboratoire de l'OMS: Analyse du sperme humain et de l'interaction des spermatozoïdes avec le mucus cervical. Paris: Les ditions INSERM; 1969. p 85-9.

[8] Forbes JC. Dosage du cholesterol. J Lab Med 1930; 16: 520.

[9] Carreau S. Paracrine control of human Leydig cell and Sertoli cell functions. Folia Histochem cytol 1996; 34 :111-9.

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Correspondence to: Dr. Gisle Yolande Mbongue Fandio, Laboratoire de Physiologie Animale, Facult des Sciences, Universit?de Yaound I, B.P. 812 Yaound Cameroun.

Tel: +237-780-9525

E-mail: mbongue@yahoo.com

Received 2002-03-15     Accepted 2002-11-01