Phytochemicals And Antioxidative Properties Of Edible Fern, Stenochlaena Palustris (Burm. F.) Bedd
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Date
2015-02
Authors
JENG YEOU, NELSON CHEAH
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Abstract
Stenochlaena palustris (local name: “Paku Midin”) is a vegetable fern popular in Malaysia, Southern Thailand and Indonesia due to its crispy texture. It is also used traditionally to treat fever and ulcer. The fern has been reported to exhibit significant antioxidant effect, however, there is lack of information concerning the active principles. As such, the present work was carried out to identify the compounds responsible for the antioxidant effect of S. palustris. In order to evaluate whether there are any differences in phytochemicals between the fronds of different maturity, young and mature fronds of S. palustris were studied separately. The MeOH extract of mature fronds was two times more active than the young fronds in term of their radical scavenging and FRAP reducing ability and this could be correlated to its high polyphenols content. Using a DPPH radical scavenging activity-guided isolation approach, a series of seven kaempferol glycosides were isolated, namely kaempferol 3-O-α-rhamnopyranoside (A), kaempferol 3-O-(6’’-O-E-p-coumaroyl)-β-glucopyranoside (B), kaempferol 3-O-(3’’-O-E-p-coumaroyl)-β-glucopyranoside (C), kaempferol 3-O-(3’’, 6’’-di-O-E-p-coumaroyl)-β-glucopyranoside (D), kaempferol 3-O-(3’’-O-E-p-coumaroyl)-(6’’-O-E-feruloyl)-β-glucopyranoside (E), kaempferol 3-O-β-glucopyranoside (F) and kaempferol 3-O-(6’’-O-α-rhamnopyranosyl)-β-glucopyranoside (G). The DPPH radical scavenging activity (IC50) of these compounds ranged from 0.13 to 0.88 mM with compound E showing the highest activity (IC50 0.13 mM), comparable to the synthetic antioxidant, BHT (IC50 0.09 mM). This suggested that the feruloyl moiety acylated at 6”-O position of the glucose
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residue was the most favorable structure for exhibiting antiradical property. However, compared to the MeOH extract, as well as the active fractions from which the compounds were isolated, the antiradical activity of the individual compounds was found to be weaker. This indicated that the kaempferol glycosides worked synergistically to provide stronger antioxidant activity. A comparison of the phytochemicals by HPTLC indicated that kaempferol 3-O-β-glucopyranoside was the only flavonoid present in the early developmental stage of S. palustris fronds. More complex constituents were synthesized by the plant from kaempferol 3-O-β-glucopyranoside as the plant matures. In conclusion, the present study indicated that the not commonly eaten mature fronds are a good source of natural antioxidants. Future research to further support the potential use of mature fronds or its active principles against oxidative stresses related disorders such as inflammation and cancer is warranted but the young and mature fronds should be studied separately due to their differences in phytochemicals compositions.
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Phytochemicals And Antioxidative Properties Of Edible Fern , Stenochlaena Palustris (Burm. F.) Bedd