Abstract:
Antimicrobial potential is a common tool to assess medicinal value of the plant. Mangrove
plants have several bioactive compounds and considered as medicinal plants. Thus, this study
was aimed to investigate the antimicrobial activity of two mangrove plants, Avicennia marina
and Rhizophora mucronata and to compare the antimicrobial potential of both plants between
fresh and dried powdered extracts. Fresh, healthy, mature, and tender leaves of A marina and
R. mucronata were collected from the Mandaitivu coastal area, Jaffna. Collected leaves were
dried in an oven at 60oC for 24 - 48 hours to get dried powder. Fresh and dried aqueous extracts
of both plants were prepared by using fresh leaves and dried plant powder in sterile distilled
water (1 mg/ml) separately and were tested against Bacillus subtilis, Enterococcus faecalis,
Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Aspergillus niger,
Fusarium sp. and Phoma sp. by using an agar plate assay. All four plant extracts showed
promising antimicrobial activity against all tested microbes. R. mucronata possessed higher
antifungal potential on tested fungi than the A. marina. The highest activity was recorded in
fresh aqueous extract of R. mucronata against Phoma sp. (53.95%) whereas the lowest
antifungal activity was shown by A. niger (9.56%) against the dried powder extract of A.
marina. A. marina extract showed higher bacterial inhibition against S. aureus (14.08%) and
the lowest inhibition was observed by B. subtilis (3.42%) for the dried powdered extract of A.
marina. Both fresh aqueous extracts showed more sensitivity than dried powdered extracts
against all tested microbes and there was significant difference (p =0.05) observed in between
the fresh and dried powdered extracts. Therefore, fresh extracts could be more effective than
dried powder extracts and can be used as an alternative source for inhibiting the growth of the
selected fungal and bacterial species.
