Pharmacognostic studies and anti -infective properties of hilleria latifolia (lam.) h. walt. (phytolaccaceae)

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The study sought to investigate the Pharmacognostic properties and anti-infective activities of Hilleria latifolia (Lam.) H. Walt. which has immense medicinal use in the African sub-region, especially Ghana. The Pharmacognostic properties of the plant as well as the antimicrobial and antiplasmodial activities were assessed. Pharmacognostic studies carried out on the plant revealed the presence of abundant calcium oxalate crystals in all plant parts. Tetragonal crystals were found beneath the epidermal cells and were not embedded in the palisade cells. Different types of prismatic crystals and rosette crystals were found in the palisade cells of the leaf. The leaves had anomocytic stomatal arrangement and possessed abundant prismatic crystals (3.9-110.5 µm in length) and multicellular clothing trichomes (94.7-347.2 µm in length). Vein islet and veinlet termination numbers averaged 18 and 32 respectively. The physical parameters revealed the highest extractive value for alcohol in all plant parts; leaf (24.048 ± 0.208 % w / w ), stem (10.012 ± 1.652 % w / w ) and root (12.036 ± 0.564 % w / w ). The lea f gave the highest values for total ash (16.667 ± 0.286 % w / w) and water soluble ash (16.028 ± 0.434 % w / w ). Phytochemical screening revealed the presence of alkaloids, triterpenoids, tannins and glycosides in all parts of the plant. Flavonoids, phytosterols and saponins were present only in the roots and anthraquinones were absent in all parts of the plant. Pharmacopoeial standards for the plant have also been established through the pharmacognost ic studies. The methanolic, ethyl acetate and petroleum ether extracts of the leaves, stem and roots were tested against six micro-organisms; B. subtilis, E. coli, P. aeruginosa, S. aureus, S. pyogenes and C. albicans using the agar dilution method. The ethyl acetate extract of the leaves was the most active, inhibiting B. subtilis, E. coli, P. aeruginosa and C. albicans at MIC’s between 250 µg/ml and 500 µg/ml; the positive controls used were Ciprofloxacin vi and Ketoconazole for bacteria and fungus respectively. The methanol extract of the whole plant, tested against Mycobacterium smegmatis, recorded an MIC above 500 µg/ml with the positive control Rifampicin recording an MIC of 0.01 µg/ml. The antiplasmodial activities of the extracts were investigated in multidrug resistant P. falciparum (K1) parasites using the Parasite Lactate Dehydrogenase Assay. The petroleum ether extract of the leaf, gave the highest antiplasmodial activity with IC 50 value of 28.18 µg/ml. The petroleum and ethyl acetate root extracts showed moderate antiplasmodial activities with IC 50 values of 100 µg/ml each. Similarly, that of the stem was 89.25 µg/ml. The positive controls used, Artemether and Chloroquine, gave IC 50 values of 19.3 ng/ml and 412.01 ng/ml respectively. The present work has demonstrated that Hilleria latifolia possesses some level of anti-infective activity as suggested by folklore medicine, thus giving scientific credence to its use.
A thesis submitted in partial fulfilment of the requirements for the degree of MPhil in Pharmacognosy,