PHYTOCHEMICAL STUDIES AND EFFECT OF METHANOL LEAF EXTRACT OF LEPTADENIA HASTATA(PERS.) DECNE (ASCLEPIADACEAE) ON ACETIC ACID INDUCED WRITHES IN MICE AND VENOM OF ECHIS OCELLATUS, A RESEARCH PROJECT TOPIC ON BIOCHEMISTRY
ABSTRACT
Leptadeniahastata (Pers.) Decne (Asclepiadaceae) is widely African plant species used in traditional medicine as an anti-venom, antihypertensive, anti-diabetic, analgesic and also used for catarrh and skin disease. The powdered leaves of L. hastatawas extracted with methanol using maceration method and the resulting crude methanol extract (ME) was suspended in water and fractionated into hexane (HF), chloroform (CF), ethylacetate (EF) and n-Butanol (BF). Preliminary phytochemical screening of ME revealed the presence of carbohydrates, alkaloids, flavonoids, anthraquinones, saponins, tannins, glycosides, steroids and triterpenes while (HF) revealed the presence of steroids and triterpenes nucleus. HF was step-wisely eluted in a silica gel packed column to afford ten fractions H1-H10 and fraction H4 was selected for further purification using Preparative Thin Layer Chromatography, with the solvent system of hexane: ethyl acetate (8.5 : 2.5). This resulted in the isolation of a whitish crystalline compound M1 (β-Sitosterol). The structure of the compound was elucidated using chemical test and spectroscopic techniques (IR, 1D & 2D-NMR) and by comparison with reference spectral data. The LD50of the methanol extract (ME) and the LD99 of the Echisocellatus venom were estimated to be greater than 5000 mg/kg and 2.2 mg/kg respectively. Anti-venom studies suggest that ME possess significant anti-venom activity against Echisocellatusvenom both In vitro and In vivo. Analgesic effect was evaluated using acetic acid induced writhing in mice. The results showed that ME (150 mg/kg) decreased writhing response with 84.6 % inhibition. However, the extract when compared to control showed statistically significant difference at (p˂0.05).
CHAPTER ONE
1.0Â Â Â Â Â Â Â Â INTRODUCTION
A natural product is a chemical compound or substance produced by a living organism – found in nature that usually has a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design. A natural product can be considered as defined above even if it can be prepared by total synthesis (Newman and Cragg, 2007).
Traditional medicine is the sum total of the knowledge skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis improvement or treatment of physical and mental illness.
Traditional use of herbal medicines refers to the long historical use of these medicines. Their use is well established and widely acknowledged to be safe and effective, and may be accepted by national authorities (WHO, 2013).
