Securinega virosa (Roxb ex Willd) Baill (Euphorbiaceae) is a small, deciduous, graceful shrub that is widely distributed in Africa. It is used to treat snakebites, syphilis, rheumatism and malaria. Plant based medicines are limited in use because of inadequate standardization. Major snakebite envenomings and fatalities occur in tropical regions such as Sub-Saharan Africa. Leaf pharmacognostic standards and antivenin potentials of n-hexane (8.00g), ethyl acetate (11.22g) and methanol (46.64g) extracts of Securinega virosa on Naja nigricollis venom were studied. The pharmacognostic studies to determine the leaf microscopic features such as stomata, trichomes, vascular bundles, calcium oxalates, stomatal index, stomatal number, palisade ratio, vein islet number and vein termination number. Physical constants such as moisture constant, ash values, and water and alcohol extractive values were determined. And, chemomicroscopical studies for detection of features cell wall materials and cell inclusions were also carried out. These include; cellulose, inulin, suberin/cuticle, gum and mucilage, starch grain, aleurone grain, calcium oxalates and calcium carbonate. The preliminary and the thin layer chromatographic phytochemical screening and the fingerprinting were also conducted. The antivenin studies were divided into in vitro phospholipase A2 assay, acute toxicity, in vivo modulatory activity which is a rodent lethality test assay in mice and histopathological study. The leaf possessed abaxial anomocytic stomata, few trichomes and prism of calcium oxalate. Stomatal number; 56 and stomatal index; 13, palisade ratio; 20, vein termination number; 6, vein islet number; 3 were determined as quantitative microscopic leaf constants. Chemo-microscopically, the leaf was found to contain cellulose, lignin, suberin, gum and mucilage (as cell wall materials). The ergastic substances observed include: starch grains, calcium oxalate and calcium carbonate, inulin and tannins, while aleurone grain was absent. Moisture, total ash and acid insoluble ash were found to be 5.6%, 11.7% and 1.2% respectively. Ethanol extractive and water extractive values were found to be 22.00% and 34.00% respectively. Preliminary phytochemical screening of the n-hexane, ethyl acetate and methanol extracts revealed the presence of steroids/triterpenes and deoxy sugars in all the three extracts. In addition, saponins, flavonoids, tannins and alkaloids were present in ethyl acetate and methanol extracts respectively. The thin layer chromatographic fingerprints of n-hexane, ethylacetate and methanol extracts revealed eleven (11) spots in hexane: ethyl acetate (9:1), fourteen (14) spots in hexane: ethyl acetate (13:7) and eleven (11) spots in butanol: acetic acid: water (10:1:1). The thin layer phytochemical screening revealed the presence of alkaloids, phenols, saponins and triterpenes/ steroids but absence of flavonoids and anthraquinones in n-hexane and methanol extracts. Phenols, saponins and steroids/ triterpenes were present but absence of alkaloids, anthraquinones and flavonoids were noted in ethylacetate extract. N-Hexane extract produced the best protection against lethal dose (9.55mg) of Naja nigricollis venom which is significant at 20mg/kg at p-value < 0.05. Histopathology of brain, lungs, heart, liver and kidneys shows a near normal feature of the various organs examined after treatment of mice Important pharmacognostic characters were determined for proper identification of Securinega virosa, while the extracts presented a significant protection against venom of Naja nigricollis toxicity in mice.
PHARMACOGNOSTIC AND ANTIVENIN STUDIES ON LEAVES OF SECURINEGA VIROSA (ROXB EX WILLD) BAILL