PHARMACOGNOSTIC AND ANTIBACTERIAL STUDIES OF THE LEAF EXTRACTS OF SWARTZIA MADAGASCARIENSIS DESV (FABACEAE), A RESEARCH PROJECT TOPIC ON MICROBIOLOGY
ABSTRACT
This study evaluated the pharmacognostic standards and antibacterial properties of the leaf extracts of Swartzia madagascariensis Desv (Fabaceae). This plant is widely distributed in Northern part of Nigeria; it has been exploited for both its medicinal and economic importance. It is used in the treatment of infections such as cutaneous wounds. Microscopic, chemo-microscopic, quantitative microscopic studies, qualitative and thin layer chromatographic studies, toxicity studies and antibacterial evaluation were carried out using standard methods. Microscopical studies revealed the presence of straight – walled anticlinal walls, polygonal epidermal cells, trichomes, anomocytic stomata on abaxial surface. The transverse section of the leaf through the lamina and midrib tissue was examined and revealed different anatomical features include: epidermal layers, palisade and spongy mesophyll cells, vascular bundles consisting of xylem and phloem vessels. Microscopy of the powder revealed fragments of starch grain, calcium oxalate crystals, lignified collenchyma, unicellular covering trichome and lignified fibre as a characteristic of the plant. Chemomicroscopical studies of the powdered leaves were found to have cellulose, lignin, calcium oxalate, tannins, and starch. The quantitative microscopic results were observed to be: stomatal number (201), stomatal index (9.5), palisade ratio (7.3), vein islets (29.5) and vein termination numbers (15.0). The physicochemical constants evaluated were moisture contents (6.7%), total ash value (6.0%), water soluble ash (4.5%), acid insoluble ash (1.0%), ethanol extractive value (15%) and water extractive value (24%). Phytochemical screening on the plant extracts revealed the presence of alkaloids, cardiac glycosides, saponins, flavonoids, tannins and anthracenes. Thin layer chromatographic analysis of the ethyl acetate extract (most active extract) confirms the presence of some chemical constituents in the leaf extracts namely flavonoids, steroids and triterpenes. Acute toxicity study found the leaf extract to have an LD50 of 288.5mg/kg body weight (i.p) in mice. The antibacterial studies carried out on the leaf extracts showed zones of inhibition ranging from 17-18 mm, 24-27 mm and 21-22 mm for hexane, ethyl acetate and ethanol extracts respectively. These values were less than that of ciprofloxacin (32 – 37 mm) that was used as the standard antibacterial drug. Minimum Inhibitory Concentration (MIC) of the three extracts was determined at 0.5 scale Mc-farland‟s turbidity standard. The extracts at the concentrations of 20 mg/ml (hexane), 10 mg/ml (ethyl acetate) and 10 mg/ml (ethanol). They also gave Minimum Bactericidal Concentrations at 40 mg/ml each of hexane and ethanol extracts and 20 mg/ml for the ethyl acetate extract. It was observed that gram positive bacteria (Staph. aureus and Strep. pyogenes) were more sensitive to the extracts than the gram negative bacteria (E. coli). Results of the present studies had shown that S. madagascariensis is a promising medicinal plant with antibacterial property.
CHAPTER ONE
1.0Â Â INTRODUCTION
1.1Â Â Â Traditional Medicine
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 illnesses. This has been used for thousands of years with great contributions made by practitioners to human health, particularly as primary health care providers at the community level (WHO, 2000).
