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Abstract

The genus Usnea was reported to synthesize the bioactive secondary metabolites, including cytotoxic and antibacterial activities. To continue our study on bioactive compounds from Usnea sp, we studied secondary metabolites and their bioactivities of Usnea sp. The aim of this study was to determine the chemical constituents of lichen Usnea sp. Methanol extract of Usnea sp. was prepared by solid liquid extraction followed by fractionation and purification of the crude extract by several chromatographic techniques using n-hexane and ethyl acetate as solvents to obtain two pure compounds (1 and 2). The structures of both secondary metabolites were analyzed by 1D and 2D (one and two-dimensional) NMR spectroscopy and identified as 2,6-dihydroxy-4-methylbenzoic acid (1) and (-)-placodiolic acid (2). Cytotoxic activity of compounds against MCF-7 cells was evaluated using the MTT assay (IC50 = 554.82 and 5.10 µM, respectively). Both compounds were also assayed for their antibacterial activity using disc diffusion method. Inhibition zones of compound 1 against S. aureus, E. coli, and S. pyogenes were 6.37 ± 0.21, 7.57 ± 0.15, and 5.43 ±0.12 mm, respectively. In addition, compound 2 inhibited the growth of S. aureus, E. coli, and S. pyogenes bacteria (Inhibition zones = 10.43 ± 0.25, 11.63 ± 0.21, and 10.63 ± 0.21). The result of biological activities demonstrated that 2 exhibited stronger cytotoxic activity against MCF-7 cells as well as antibacterial activity than compound 1. Based on the theses results, compound 2 could be a promising candidate of antibiotics in the near future.

Keywords

Antibacterial, cytotoxicity, MCF-7 cells, Secondary metabolites, Usnea sp

Subject Area

Chemistry

First Page

103

Last Page

109

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Receive Date

9-13-2023

Revise Date

3-15-2024

Accept Date

3-17-2024

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