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Ethnobotanical Leaflets 13: 1216-21. 2009. Preliminary
Studies on Vernonia ambigua: Phytochemical and Antimicrobial Screening of the Whole
Plant *Kunle, Oluyemisi Folashade and Egharevba, Henry Omoregie Department of Medicinal Plant Research
and Traditional Medicine, National Institute for Pharmaceutical Research
& Development (NIPRD), Idu Industrial Layout, Idu, P.M.B. 21 Garki, Abuja,
Nigeria
*E-mail: yemisikunle@yahoo.co.uk Issued 01 October
2009 Abstract A
dry, whole plant of Vernonia ambigua Kotschy and Peyr was collected
from Suleja, Niger State, Nigeria and qualitatively
screened for the presence of secondary metabolites using standard methods.
Some proximate compositions were also determined. The result showed the
presence of alkaloid, tannin, saponin, flavonoid and carbohydrate while terpene,
sterol, anthraquinone, phlobatannin,
resin, cardiac glycoside, balsam, phenols and volatile oil were not
detected. The result of proximate
analysis which includes ash value, acid-insoluble ash value, water and
alcohol extractive values are reported. Crude extracts of the plant were
screened for activity against selected microorganisms. The result is also
reported. This work is aimed at providing some scientific data for this plant
since there is limited scientific report on it in literature. Key
words: Vernonia ambigua,
proximate analysis, biological screening, Introduction Vernonia ambigua
is an annual shrub belonging to the family Asteraceae/Compositae. The shrub is erect, coarse and bushy in
nature, growing up to 600 mm high. The
stem is erect, woody and ribbed as well as hairy and leafy especially at
flowering time. The leaves are simple and alternate oblanceolate
with a dimension of 20-60 mm long and 6-10 mm wide. The upper leaves have
serrated margins and are coarsely hairy.
The florescence consists of cluster of flower heads 10-15 mm in
diameter with pail bluish or mauve floret usually at the end of leafy
branches (Akobundu and Agyakwa,
1998). The
plant is easily propagated through seeds and stem cutting. The plant is
widely distributed in areas like Angola, Sudan, Tanzania, Uganda and tropical
West Africa. It occurs throughout the
drier part of these regions and also widely dispersed in similar parts of
tropical/Africa (Akobundu and Agyakwa,
1998). The
plant is called Orungo in Yoruba and Tab-taba/Tattaba in Hausa. In Suleja,
Nigeria, the root is chewed raw or taken as a decoction as an expectorant for
cough and fever or to regulate body temperature. Despite the wide local use
of V. ambigua for the management of
cough and fever, no information on this and other uses of the plant could be
obtained in literature. This work which is the beginning of a series of
research work to be carried out on the plant is aimed at evaluating the phytochemical and proximate composition of V. ambigua
with a view to bringing it to the vista of scientific research. Materials and Methods Plant Material:
A plant of this species was collected in February 2007 from Rafin Sanyi, Suleja, Niger State, Nigeria and identified by the Ethnobotanist in the Department of Medicinal Plant
Research and Traditional Medicine of the National Institute for
Pharmaceutical Research and Development (NIPRD) Abuja, Nigeria. A voucher
specimen with number NIPRD/H/6302 was deposited at the herbarium for
reference. The whole plant was pulverized fresh using mortar and pestle. Phytochemical screening:
The pulverized sample was dried for two weeks and was used for phytochemical analysis to determine the secondary
metabolites present using standard methods (Sofowora
2008; Evans 2002).
Proximate analysis was also carried out to determine the moisture content,
total ash value, acid insoluble ash value, alcohol
and water soluble extractive values. Results and Discussion The
phytochemical screening of V. ambigua whole plant (Table 1)
reveals the presence of tannins, saponins, flavonoids and alkaloids. The plant did not show the
presence of steroids, anthraquinones, resins,
volatile oils, terpenes, steroids, cardiac
glycosides and phlobatannins. The presence of these
secondary metabolites suggests that the plant might be of medicinal and
industrial importance. Preliminary antimicrobial screening of the water,
methanol, ethylacetate and hexane extracts against Staphylococcus aureus,
Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and
Salmonella sp. (clinical) at a test concentration of 2mg/ml showed no
activity. The secondary metabolites are
relevant in various areas for different purposes and some of these include: Saponin
is used as mild detergents and in intracellular histochemistry
staining to allow antibody access to intracellular proteins. In medicine, it
is used in hypercholesterolaemia, hyperglycaemia, antioxidant, anti-cancer,
anti-inflammatory and weight loss etc (Ngbede et al., 2008). Table 1. Result of the phytochemical screening.
Key:
+ = Present; - = Absent Table 2. Result of the proximate
analysis.
It
has also been reported to have anti-fungal properties (Sodipo et al., 1991). Saponin
inhibits Na+/Ca2+ antipoter
producing elevated cytosolic Ca2+ which
strengthens the contractions of heart muscle and thereby reducing congestive
heart failure (Oloyede, 2005). Seigler
(1998), also reported that saponnins have
anti-carcinogens’ properties, immune modulatory
activity and cholesterol lowering activity. Tannins
were reported to exhibit antiviral, antibacterial and anti-tumor activities.
It was also reported that certain tannins are able to inhibit HIV replication
selectively and is also used as diuretic. Plant tannins have been widely
recognized for their pharmacological properties and are known to make trees
and shrubs a difficult meal for many caterpillars (Haslem
1989). Alkaloids
are metabolites known to be produced by plants and animals and over 800 have
been isolated. They are of considerable pharmaceutical importance since they
are used as drugs for the treatment of several disease conditions known to man.
Example is quinine, hyoscyamine, nicotine, cocaine,
etc, most of which have pharmacological activity in man and animals as well
as microorganisms (Evans
2002). Flavonoids
suggest that the leaves might have an anti-oxidant, anti- inflammatory,
anti-cancer, anti-microbial and anti-allergic activity. Plants flavonoid has been referred to as nature’s biological
response modifiers because of strong experimental evidence of their inherent
ability to modify the body’s reaction to allergen, virus and carcinogens.
They show anti-allergic, anti-inflammatory, anti-microbial and anti-cancer
activities (Cook et al., 1996).
Many of these alleged effects of flavonoids are
reported to be linked to their strong antioxidants, free radical scavenging
and metal chelating properties (Jimoh and Oladiji 2005). Table
2 shows the moisture content of 8.20%. The moisture content is within
acceptable range thus implying that the plant can be stored for a long period
and would not easily be attacked by microbes. Total ash
value of 13.90%, which is low, implies that the plant has a good organic
content and fairly low inorganic component. Alcohol-soluble extractive value
of 5.49% which is less than water-soluble extractive value of 20.60% implies
that water is a better solvent of extraction of the plant than ethanol.
Acid-insoluble ash value of 2.35% shows that a very small amount of the
inorganic component is insoluble in acid and hence this may affect amount of
the component absorbed in the gastrointestinal canal when taken orally. In conclusion, V. ambigua
is a plant that is yet to be thoroughly explored and reported in the
literature. The presence of alkaloid and flavonoid
tends to suggest potentials for pharmacological and other biological
relevance in drug discovery. Work is ongoing in our laboratories on its use
in other disease conditions. Acknowledgement The
authors are grateful to Mallam Muazzam
Wudil, who brought the plant to our attention and
was responsible for its collection. References Akobundu
I. O. and Agyakwa, C. W. 1998. A Handbook of West African Weeds. IITA, Ibadan, Nigeria,
2nd Edition, pp 194-195. Cook,
N. S. and Samman, S. 1996. Flavonoids
– Chemistry, metabolism, cadioprotective effect and
dietary sources. J. Nutr.
Biochem. 7: 66-76. Evans,
W. C. 2002. Trease and Evans Pharmacognosy.
15th Edition, Elsevier, India, pp 137-393. Haslem,
E. 1989. Plant polyphenols:
Vegetable tannins revisited-chemistry and pharmacology of natural products.
Cambridge University Press, Cambridge, 169pp. Jimoh,
F. O. and Oladiji, A. T. 2005. Preliminary studies
on Piliostigma thionningii
seeds, proximate analysis, mineral
composition and phytochemical screening. African Journal of
Biotechnology 4(12): 1439-1442. Ngbede,
J., Yakubu, R. A. and Nyam,
D. A. 2008. Phytochemical Screening for Active Compounds in Canarium scheinfurthii (Atile)
leaves from Jos North, Plateau State, Nigeria.
Medwell Research Journal of Biological Science
3(9): 1076-1078. Oloyede,
O. I. 2005. Chemical Profile of unripe Pulp of Carica papaya. Pakistan Journal of Nutrition
4 (6): 379-381. Seigler,
D. S. 1998. Plants with saponins and cardiac
glycosides. www.lifwe.vinc.edu/plantbio/363/saponinslides Sodipo, O. A., Awanji,
M. A., Kolawole, F. B. and Oduntuga,
A. A. 1991. Saponin is the active fungal principle in Garcinia kola, Hekle
seed. BioSci.Res.Commun., 3:171. Sofowora,
A. 2008). Medicinal Plants and
Traditional Medicine in Africa. 3rd Edn.,
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pp: 199-204. |