Isolation, Characterization, and Antioxidant Activity of Selliguea taeniata Secondary Metabolites

Abstract

This current study presents a chemical exploration of the methanolic extract of Selliguea taeniata leaves, a fern species endemic in certain regions in the Philippines, such as Ifugao, where it is used to treat cough for good health and well-being of the folks. Although botanical data of this fern are reported, there are still no reports regarding its chemical properties, such as phytochemicals and antioxidant activity, as of the time this study was conducted. The air-dried leaves of S. taeniata were extracted using absolute methanol. The crude extract was concentrated and subjected to the Folin-Ciocalteu method to determine the total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay to evaluate its antioxidant activity, and phytochemical screening. Subsequently, various chromatographic techniques and 1H Nuclear Magnetic Resonance spectroscopy were applied to isolate and partially characterize its secondary metabolites partially. Methanolic extract of S. taeniata leaves had a TPC of 1669.11 ± 0.07 mg GAE /g of dried sample and antioxidant activity (EC50= 85.79 ± 0.02 ppm). The crude extract contained alkaloids, flavonoids, cardiac glycosides, saponins, phenols, and tannins. Partial isolation of its secondary metabolites suggested that the crude extract may contain a mixture of proanthocyanidins or its monomer units and glycosides. The claims of the folks from Ifugao on the effectivity of Selliguea taeniata leaf decoction as an antitussive can be attributed to the plant's high antioxidant activity. The extract contained phenolic compounds that could be proanthocyanidins, inhibiting elastase that promotes inflammation.