CHAPTER ONE
1.1 BACKGROUND OF STUDY
Many plants have been screened for their medicinal properties; this includes yohimbine, which is an alkaloid chemically similar to reserpine. It is gotten from the bark of the yohimbe tree, it posses alpha-adrenergic blocking properties and is used as hydrochloride sympatholytic, mydriatic and for the treatment of impotence (Dorland’s medical dictionary 2007). Sexual dysfunction is a serious medical and social problem that occurs 10%- 52% in men and 25%-63% in women numerous central and peripheral neural circuits control sexual activity impairment one or more of these functional circuits may have a significant impact on personal , social and biological relationships. Although several aspects of sexual motivation and performance are known, complete picture of the various factors that control human sexual activity is still unknown and the available drugs and pleasant side effects and contraindications in certain disease conditions. A variety of botanical plants are known to have a potential effect on immunomodulatory (suppressive and stimulatory) functions thereby supporting older claims and offering newer hopes (Therakan and Manyam, 2005).
Presently, there is a growing interest in the use of various naturalplants parts and plants products as medicines and these folk medicines are being marked in almost all parts of Nigeria and the world at large.They range from herbal toothpaste to various drug supplements. Some of these herbal preparations may have some properties, which have contributed to their persistent use over the years,under scoring the need for validation of most them. It is said that only about 2% of all the plants on the earth have been subjected to pharmacological investigation. The rationalablefor utilization of medical plants has rested largely on long term clinical experience with little or no scientific data on their effect and safety (Zhu M, et.al 2002), with the upsurge in the use of herbal medicines through scientific investigation of these plants is imperative, based on the need to validate their folk usage (Sofowora E.A,1989).
Yohimbe bark extracts standardized to varying amounts of yohimbine are widely available in health food stores and through direct mail companies. Extracts are supplied as capsules tablets and liquids. Some of theseyohimbe preparations are sold in combination formula’s with other herbs. Yohimbine hydrochloride is a Food and Drug Administration (FDA) approved prescription drug for the treatment of impotence (BetJ.M, et.al, 1995).
Bet J.M and Coworkers (1995) also investigated yohimbe in commercialyohimbe products. Gas chromatography determinations were done on liquids and powders (from capsules and caplets). Virtually all the products tested did not specify on their labels that the products contained yohimbe bark extract concentration of yohimbine in the commercial products ranged from > 0.1 to 489pppm , compared with 7089ppm in authentic bark material  of the 26 products examined , nine contained no quantifiable amount of yohimbe ; eight contained only trace amounts (0.1-1ppm). The authors suggest that the absence of alkaloids in the products indicated that the original extracts was aqueous (because the alkaloids are not particularly water soluble), the extract was extremely diluted in the final dosage form or no yohimbebark was used to make the product.
Yohimbe is available in research quantities at 98% purity from Aldrich chemical company. Yohimbinehydrochloride from Aldrich and Sigma are available at 99 and 80%purity, respectively (Aldrich chemical co., 199; sigma, 1999).
1.2PAUSINYSTALIA YOHIMBE
Pausinystaliayohimbe is also known as corynantheyohimbe. Another common name is Yocon, the Yorubas’ know it as Idagbon, while theHausas’ call itDankamaru.
1.3 BOTANICAL INFORMATION
It is an evergreen tree which grows to a height of 30m with a spread of 8m, the stem is erect and branching the less are oval, acuminate and about 10cm long. The seed are small winged silvers, almost paper thin. Pausinystaliayohimbe is a native of the rain forest of Nigeria, Cameroon and the Congo. It prefers rich soils in a protected part sun to shady position, and is drought and frost tender. The propagation of pausinystaliayohimbe is by seed or cutting. Seeds are sown in a free draining seed micorshagnummoss and will need temperature above 250C to germinate quickly. Seeds have a very short viability, which declines rapidly in dry and warm conditions (Shaman Australia Botanicals 1998).
1.4 TRADITIONAL USE
