PHARMACOGNOSTIC, ANTIOXIDANTAND ANTIMICROBIAL STUDIES OF THE LEAVES OF AMARANTHUS VIRIDIS LINN.(AMARANTHACEAE)
PHARMACOGNOSTIC, ANTIOXIDANTAND ANTIMICROBIAL STUDIES OF THE LEAVES OF AMARANTHUS VIRIDIS LINN.(AMARANTHACEAE)
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Date
2015-12
Authors
KAGARU, Daniel Christopher
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Abstract
Amaranthus viridis (Amaranthaceae), an annual herb, used in traditional medicine as diuretic
and emollient, in poultices on inflammations, boils or abscesses, as well as in the treatment of
gonorrhea, piles, fever, filaria, dysentery etc. This study focussed on the evaluation of various
pharmacognostic parameters including microscopic, physicochemical and phytochemical
properties of the leaves of this plant, as well as the antioxidant and antimicrobial properties. The
70% aqueous ethanol leaf extract was used for the antioxidant and antimicrobial studies. The
microscopy of the leaves revealed the presence of slightly wavy-walled epidermal cells on the
upper surface and larger wavy-walled epidermal cells on the lower surface, with both containing
anisocytic stomata; uniseriate glandular trichomes with unicellular head on both surfaces;
rosettes of calcium oxalate crystals within the cells. A transverse section through the midrib of
the leaf revealed it to be a dorsiventral type and a round type of vascular bundles, which possess
spiral and annular types of xylem vessels. Chemomicroscopically, the presence of lignins,
tannins and starch grains at different specific locations within the leaf; and the absence of fats
and oils are worthy of note. The physicochemical properties were determined as follows:
moisture content of 12.19 ± 0.06% w/w; total ash value of 19.92 ± 0.10% w/w; acid-insoluble
ash value of 1.07 ± 0.08% w/w; water-soluble ash value of 5.97 ± 0.06% w/w; ethanol – soluble
extractive value of 1.71 ± 0.26% w/w and water – soluble extractive value of 2.7 ± 0.36% w/w.
Phytochemical screening of the 70% aqueous ethanol leaf extract of the plant revealed the
presence of alkaloids, saponins, tannins, flavonoids, steroids and cardiac glycosides. The
evaluation of the antioxidant activity by the free radical scavenging effect on DPPH showed
that the extract has significant (P < 0.05) antioxidant activity which is comparable to that of
ascorbic acid. The aqueous ethanol leaf extract of the plant showed significant (P < 0.05) broad spectrum antibacterial activity, compared to the standard Gentamicin, against both gram
positive and gram negative bacteria, including Escherichia coli, Pseudomonas aeruginosa,
Salmonella typhi, Staphylococcus aureus and Bacillus subtilis, with the minimum inhibitory
concentrations; 62.5 mg/ml, 125 mg/ml, 15.63 mg/ml, 31.25 mg/ml and 31.25 mg/ml
respectively. Determination of the minimum bactericidal concentrations revealed that the
extract has no cidal effect against E. coli, S. typhi and B. subtilis, while it has against P.
aeruginosa and S. aureus with 125 mg/ml as MBC in both cases. The evaluation of the
antifungal activity of the crude leaf extract of the plant revealed its inability to inhibit the
growth of Penicillium notatum and Candida albicans as compared to the standard drug,
Griseofulvin. The findings in this work were able to establish important pharmacognostic
standards for correct identification of the plant, as well as its potentials for possible development
of yet another antioxidant and antimicrobial agents.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF
MASTER OF SCIENCE DEGREE IN PHARMACOGNOSY
DEPARTMENT OF PHARMACOGNOSY AND DRUG DEVELOPMENT, FACULTY
OF PHARMACEUTICAL SCIENCES, AHMADU BELLO UNIVERSITY,
ZARIA – NIGERIA
Keywords
PHARMACOGNOSTIC,, ANTIOXIDANTAND ANTIMICROBIAL STUDIES,, LEAVES,, AMARANTHUS VIRIDIS LINN,, (AMARANTHACEAE),