Antibacterial activity of selected orchid species of Nepal
Date
2023
Authors
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Journal ISSN
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Publisher
Department of Botany
Abstract
Orchidaceae, a highly advanced and widely spread family of monocotyledonous plants. Orchids
have been found to contain a rich source of natural compounds with significant therapeutic
activities against various disease. So this study mainly focused on antibacterial activity to generate
natural medicines to substitute synthetic drugs. The orchid plants were collected from various
regions of Nepal and subsequent extract preparation and laboratory work conducted at the
Annapurna Research Center.
A total of fifteen orchid species were selected for the purpose of this study. The different parts of
orchids were used for extraction using methanol through a combination of the Percolation and
intermittent sonication methods. After that in vitro antibacterial evaluation was conducted using
the agar well diffusion technique with different concentration.
Out of 15 species, the highest yield was obtained from Habenaria marginata 15%, and the lowest
was from Coelogyne stricta 1%. In the qualitative analysis, various reagents were used to quantify
tannins, flavonoids, glycosides, phenols and alkaloids. A qualitative phytochemical screening
indicate that alkaloids and flavonoids were present in the extracts of all the orchid species that
were tested. Both Phenol and Carbohydrate were absence in Coelogyne stricta and Eria
graminifolia. The antibacterial activity of the methanol extracts from these plants was evaluated
against medically significant bacteria. Enterococcus faecalis, Acinetobacter baumannii,
Escherichia coli and Shigella sonnei were Gram negative whereas Staphylococcus aureus was
Gram positive bacteria. All 15 plants showed activity against at least one bacterium. The two
orchid plants, Coelogyne stricta and Otochilus albus, exhibited broad-spectrum activity by
showing a high zone of inhibition against all tested bacteria with zone of inhibition (20mm) and (21mm) against Acinobacter baumannii respectively. Similarly, The MIC values for the tested
orchid extracts range from 1.25 mg/ml to 2.5 mg/ml, while the MBC values range from 0.3125
mg/ml to 0.625 mg/ml.
So Otochilus albus exhibits strong antibacterial properties against Acinobacter baumannii species,
and its corresponding MIC and MBC values provide further evidence of its antibacterial
effectiveness. Therefore, it is worthy to conduct additional investigations into this specific species
to reveal its potential benefits. Furthermore, there is scope for conducting additional laboratory
experiments and research work to develop new pharmaceutical products.
Keywords: Orchids, Phytochemical compounds, Antibacterial activity, MBC, MIC
Description
Keywords
Orchids, Phytochemical compounds, Antibacterial activity, MBC, MIC