Larvicical and anti-plasmodial constituents of Carapa Procera Dc. (Meliaceae) and Hyptis Suaveolens L. Poit (Lamiaceae)
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Date
2015-03-30
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Abstract
Malaria is a serious health problem worldwide due to the emergence of parasite
resistance to well established antimalarial drugs. This has heightened the need for
the development of new antimalarial drugs as well as other control methods. Plant
based antimalarial drugs continue to be used in many tropical areas for the treatment
and control of malaria and hence the need for scientific investigation into their
usefulness as alternatives to conventional treatment.
The work presented in this thesis involves the scientific investigation of the
traditional uses of Carapa procera and Hyptis suaveolens as insecticidal agents.
Carapa procera was also investigated for its antiplasmodial activity. The petroleum
ether, ethyl acetate and 70% ethanol extracts of stem bark of Carapa procera and
aerial parts of Hyptis suaveolens were investigated for their larvicidal and
antiplasmodial activities.
The larvicidal activities of the plant extracts and isolates were investigated using the
method described by WHO against third instar Anopheles gambie larvae. The larvae
were exposed to various concentrations of the extracts and the percentage mortality
was recorded after 24 hours. Temephos, a synthetic insecticide was used as the
standard drug. All extracts exhibited dose dependent increase in larvicidal activity
with the Petroleum ether extracts of both Hyptis suaveolens and Carapa procera
having the highest activity (EC
50
34.96 mg/ml and 16.91 mg/ml respectively)
followed by ethyl acetate and ethanol extracts.
For the antiplasmodial assay, the Lactate dehydrogenase method was used against
chloroquine resistance strains of Plasmodium falciparum. The ethyl acetate extract
of Carapa procera showed the highest activity (EC
50
18.60 µg/ml) followed by
v
petroleum ether (EC
50
24.71 µg/ml ) and ethanol extracts (EC50
95.46 µg/ml) as
compared to artesunate the standard drug with EC50
of 4.90 µg/ml.
Carapolides A and B, evodulone and proceranolide were isolated from the bioactive
petroleum ether extract of Carapa procera stem bark. They exhibited various
degrees of larvicidal activities against the third instar Anopheles gambie larvae with
EC50 values of 15.01mg/ml, 53.74mg/ml, 198.9mg/ml and 273.6mg/ml for
Carapolide A, proceranolide, evodulone and carapolide B respectively. They also
exhibited dose dependant antiplasmodial activities with EC
50
values of 23.96 µg/ml,
26.66 µg/ml, 30.52 µg/ml and 32.68 µg/ml for carapolide A, evodulone, carapolide
B and proceranolide respectively. Carapolide A and B are being reported for the first
time in the stem bark of Carapa procera.
Description
A thesis submitted in partial fulfilment of the requirements
for the degree of
Mphil Pharmacognosy
in the
Department of Pharmacognosy, 2014