Pharmacognostic studies and anti -infective properties of hilleria latifolia (lam.) h. walt. (phytolaccaceae)
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Date
2015-03-24
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Abstract
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.
Description
A thesis submitted in partial fulfilment of the requirements
for the degree of MPhil in Pharmacognosy,