PHYTOCHEMICAL AND SOME BIOLOGICAL STUDIES OF THE METHANOL LEAF EXTRACT OF ASPILIA AFRICANA (PERS.) C. D. ADAMS (ASTERACEAE)
PHYTOCHEMICAL AND SOME BIOLOGICAL STUDIES OF THE METHANOL LEAF EXTRACT OF ASPILIA AFRICANA (PERS.) C. D. ADAMS (ASTERACEAE)
No Thumbnail Available
Date
2016-11
Authors
JOHNSON, Ekarika Clement
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Aspilia africana, (Pers) C.D. Adams; (Asteraceae), a semi perennial woody plant, commonly
known as haemorrhage plant is widely distributed across tropical Africa and all parts of Nigeria.
The plant is well known in folkloric medicine for its anti-haemorrhagic uses and for the
treatment of cardiovascular diseases, diabetes, malarial fever, wounds, coughs, microbial
infections and gastro-intestinal disorders.This research was undertaken inorder to isolate some of
the bioactive compounds responsible for the anti-microbial and anti-diabetic activities of this
plant. The dried powdered leaf material was subjected to cold maceration with 70% aqueous
methanol to obtain the methanol extract which waspartitioned with n-hexane, dichloromethane,
ethyl acetate and n-butanol. The methanol extract and the fractions were screened for
phytochemical constituents, anti-microbial and anti-diabetic properties and then subjected to
chromatographic separation. Preliminary phytochemical screening results showed the presence
of carbohydrate, cardiac glycosides, flavonoids, polyphenols, saponins, steroids, tannins and
terpenoids in the methanol extract and the fractions. Chemical investigation of the methanol
extract and fractions of the leaves led to the isolation of three pentacyclic triterpenic acids
namely; 3β – hydroxyolean – 12 – en – 28 – oic acid (Oleanolic acid), 3β – hydroxyurs – 12 – en
– 28 – oic acid (ursolic acid) and 2, 3 - dihydroxyurs – 12 en – 28 – oic acid (corosolic acid)
from the butanol fraction and 3β-hydroxyurs-12-en-28-oic (ursolic acid) from the
dichloromethane fraction through silica gel column chromatography. The structures of the
isolated compounds were elucidated based on the analysis of 1-D and 2-D NMR (including 1H,
13C, HMBC, HMQC, COSY, and DEPTexperiments), FTIR spectral data, physicochemical
properties and comparison with authentic data of these compounds from literature. In Agar welldiffusion
anti-microbial screening using isolated clinical strains of pathogens
namelyStaphylococcus aureus, Methicillin Resistant Staphylococcus aureus (MRSA),
Streptococcus pyogenes, Bacillus substilis, Proteus vulgaris, Salmonella typhi, Shigella
dysenteriae, Escherichia coli, Klebsiella pneumoniae Candida albicans and Candida
stellafoidea; the methanol extract and the butanol fraction (which was more active than other
fractions) inhibited the growth of nine of the eleven bacterial strains and one of the three fungal
strains with zones of inhibition ranging from 10 – 25mm. However, the activity of one of the
isolated compounds (oleanolic acid) surpassed that of crude extract and n-butanol fraction; it
inhibited the growth of all the bacteria and two of the fungal strains with inhibition zones ranging
from 25 – 33mm compared with the standard drugs used. The MIC, MBC/MFC of the plant
extracts ranged from between 5.00 and 10.00 mg/mL while that of the isolated compounds
ranged between 0.0125 and 0.0500mg/mL. In the in-vitro anti-diabetic studies, the isolated
oleanolic acid (IC50 = (25.45±0.45 μg/mL; 47.57±0.40 μg/mL) was more potent in the inhibition
of α-amylase and α-glucosidase than the crude methanol extract (IC50 = 96.40±0.20μg/mL;
95.10±0.20μg/mL), butanol fraction (the only active fraction, IC50 = 72.50±0.65μg/mL;
72.65±3.2μg/mL) and the reference drug (acarbose) (IC50 = 46.31±0.58 μg/mL; 48.10±0.130
μg/mL) for α-amylase and α-glucosidase respectively. The results of the anti-microbial and antidiabetic
studies have authenticated the traditional use of the plant to treat microbial infection and
diabetes.The research work has also identified the oleanolic acid to be responsible for the antimicrobial
and anti-diabetic activities of the plant.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES
AHMADU BELLO UNIVERSITY IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE AWARD OF ADOCTOR OF PHILOSOPHY DEGREE IN
PHARMACEUTICAL CHEMISTRY
DEPARTMENT OF PHARMACEUTICAL AND MEDICINAL CHEMISTRY,
FACULTY OF PHARMACEUTICAL SCIENCES,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
PHYTOCHEMICAL,, BIOLOGICAL STUDIES,, METHANOL LEAF EXTRACT,, ASPILIA AFRICANA,, (PERS.),, C. D. ADAMS,, (ASTERACEAE).