STUDIES ON THE CHEMICAL CONSTITUENTS OF THE LEAVES AND SEEDS OF HYPTIS SPICIGERA LAM.
STUDIES ON THE CHEMICAL CONSTITUENTS OF THE LEAVES AND SEEDS OF HYPTIS SPICIGERA LAM.
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Date
2011-06
Authors
LADAN, ZAKARI
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Abstract
The extracts of the leaves of H.spicigera were screened for the presence of secondary
metabolites: alkaloids, glycosides, flavonoids, carbohydrates, tannins, sterols, terpenoids
and resins. The results of the phytochemical screening showed all the extracts with the
exception of hexane extract to contain the secondary metabolites analysed in high and
moderate amounts. Antimicrobial activities of the crude extracts of H.spicigera against a
broad spectrum of micro organisms namely: Staphylococcus aureus, Streptococcus
pyogenes, Bacillus subtilis, Corynebacterium ulcerans, Salmonella typii, Escherichia
coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Neisseria gonorrheae and
Candida albicans were carried out. All the extracts showed bactericidal activity against
the entire antibiotic resistant micro organisms tested with some degree of variations
against standard drug, penicillin. The methanolic extract of H.spicigera exhibited
significant bactericidal activity at low concentration of 2.5mg/ml while S.aureus,
N.gonnorhea and C.albicans were resistant at MBC of 5.0mg/ml. The insecticidal
properties of H.spicigera leaf extracts (hexane, ethyl acetate and methanol) tested against
Callosobruchus maculatus on cowpea was carried out. Azadirachtin was used as
standard check along with the extracts tested. Ethyl acetate extract showed the highest
percent mortality of 98% each at 72hrs, while 6% and 10% were recorded for the
emergence of the C.maculatus. Ethyl acetate extract and azadirachtin standard check
showed ovi-position deterrent at 4.16% and 2.78% respectively. Hexane extract showed
the least percent (2%) seed damage while the control gave the highest percent (88%) of
seed damage at 16 weeks. Hyptis spicigera seed oil was characterized using GC-MS and
UV-VIS spectrometry for its fatty acid profile, tocopherol and physicochemical
properties. The oil content was 21% while unsaturated fatty acids were linoleic acid
(71.85 %) and palmitic acid (16.06%) as predominant fatty acids. Tocopherol content
was 186.15mg/ml while Vitamin A was absent. The study showed potentials of Hyptis
spicigera seed oil to have high oxidative stability which could be suitable for food and
beverage as well as other industrial applications while the tocopherol content could
improve human health. Purification of the ethyl acetate fraction by High Performance
Liquid Chromatography (HPLC) yielded 3-buten-2-enol on the basis of GC-MS. The best
separation using the analytical High Performance Liquid Chromatography (HPLC) was
achieved at 0.8ml/min. The hydrodistillation of the fresh leaves of H.spicigera gave a
colourless volatile oil with yield of 0.65%.The volatile oil gave forty compounds on the
basis of GC-MS with low composition of cineole (4.11%) and caryophyllene (2.61%)
while α-pinene (12.16%) β-pinene (9.47%) and α-phellandrene (10.19%) were
predominant compounds. Crude ethyl acetate extract of H.spicigera leaves was
fractionated through solvent separation followed by thin layer and column
chromatography. Two relatively pure constituents were obtained and characterized
through spectral studies. The structure elucidation of the constituents was established as
ursolic acid and its derivative (3β-hydroxy-urs-12-en-28-oic acid) and 3β-hydroxy-20-
isopropyl-urs-12-an-28-oic using spectroscopic techniques including 1D and 2D NMR
such as 1HNMR, 13CNMR, DEPT, HMQC, HMBC, COSY, NOESY as well as MS, and
IR. Toxicity studies on the dichloromethane and methanolic extracts of Hyptis spicigera
were carried out on mice intraperitoneally. The LD50 was calculated using the method of
Karber (LD50, 2534mg/kg) which showed the plant to be moderately toxic based on the
WHO toxicity rating. The biological activity of one of the new compounds (ursolic acid)
was determined against a trypanosome (T.brucei brucei).The compound was evaluated in
vitro for activity against Trypanosoma brucei brucei (Tbb) and was found to possess antitrypanosoma
activity in vitro in a dose dependent pattern at 0.4μg/ml in 3 minutes.
Description
A DISSERTATION SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA.
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF DEGREE OF DOCTOR OF PHILOSOPHY IN CHEMISTRY
DEPARTMENT OF CHEMISTRY,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA.
Keywords
STUDIES,, CHEMICAL,, CONSTITUENTS,, LEAVES,, SEEDS,, HYPTIS SPICIGERA LAM