Phytochemical Analysis of Red Betel (<i>Piper crocatum Ruiz & Pav</i>) Stem Extracts and its Antioxidant and Alpha-Glucosidase Inhibitory Potentials

Abstract

Red betel (Piper crocatum Ruiz & Pav) is commonly used in traditional medicine for therapeutic purposes. Although the active ingredients  in red betel leaves have been analyzed, there is still limited information on the phytochemical constituents of the stem. Therefore, this  research aimed to determine the compounds in red betel stem and evaluate its antioxidant and alpha-glucosidase inhibitory activity. Red  betel stem was extracted by successive maceration with n-hexane, ethyl acetate, and methanol. Preliminary phytochemical screening of  the extracts was done following standard procedures. The volatile compounds in the extracts were identified by gas chromatography –  mass spectrometry (GC-MS). The total phenolic contents of the extracts was determined by the Folin Ciocalteu’s method. The antioxidant  activity was evaluated using the cupric ion reducing antioxidant capacity (CUPRAC) assay, while the alpha-glucosidase inhibitory activity  was detrmined in vitro by spectrophotometric method. Phytochemical screening reveal the presence of alkaloids, phenolics and  flavonoids in the ethyl acetate and methanol extracts, while steroidal glycosides were found in the n-hexane and methanol extracts.  Caryophyllene, butyraldehyde hydroxytoluene, phenol, 2,4-bis (1,1-dimethyl ethyl), octadecadienal, octadecanoic acid, tricosane, 5- cholestene-3-ol, stigmasterol, and sitosterol were among the compounds identified in red betel stem extracts. The methanol extract had  the highest total phenolic contents of 939.01 ± 0.02 mg GAE/g. The extracts exhibited strong antioxidant activity with IC₅₀ < 50 mg/L. All  the extracts exhibited better alpha-glucosidase inhibitory activity compared to acarbose. These findings have shown red betel stem as a  potential source of natural antioxidant and alphaglucosidase inhibitor.