Characterization of phenolic content and antimicrobial activities of fern species used by Malays in traditional medicine

In the past, ferns were traditionally used by the people as food, medicine, domestic use, ornamental plants and in many handicrafts. However, studies have shown that ferns produce a variety of secondary metabolites that display many bioactivities that can help treat diseases. Thus, they are popularly used in Malay traditional medicines. In this study, the researchers evaluated 3 fern species namely piai raya (Acrostichum aureum), paku midin (Stenochlaena palustris) and paku resam (Dicranopteris linearis) for their total phenolic content, individual phenolic compounds and their probable antimicrobial activities. For this purpose, the leaves of the A. aureum, S. palustris and D. linearis were extracted using the water extraction technique, followed by the solvent re-extraction of the supernatant using petroleum ether, ethyl acetate and butanol. Thereafter, these fractional extracts qualitatively and quantitatively using the HPLC analysis and also tested their antimicrobial activities against pathogenic microorganisms. The findings of the study indicated that A. aureum extracts contained the highest total phenolic content, followed by the S. palustris and D. linearis extracts. Furthermore, the HPLC analysis indicated that the A. aureum extracts contained a higher number of phenolic acid compounds compared to the S. palustris and D. linearis extracts, such as Vanillic acid and 3-Coumaric acid (0.51 μg/g DW), 4-Hydroxybenzoic acid (0.35 μg/g DW), Ferulic acid (0.27 μg/g DW), Caffeic acid (0.18 μg/g DW) and trans-p-Coumaric acid (0.06 μg/g DW). When the researchers tested the compounds for their antimicrobial activities, all 3 fern species showed active antibacterial activity than antifungal activity. The researchers concluded that the medicinal herbs that showed good bioactivity with a higher phenolic content could be introduced as a medicinal drug for improving public health. However, additional research needs to be conducted for optimising the isolation and the purification of the bioactive compounds, for any future applications