LAUSR

Abstract Arecanut (Areca catechu L.) seed is an important by-product of commercial crop Arecanut planted in tropical or sub-tropical regions. This study for the first time investigated the phyto-chemical compositions and bio-activities of the Arecanut seed extracts extracted by conventional solvents and deep eutectic solvents (DESs). Results showed that the Arecanut seed extracts obtained by the screened DESs exhibited the highest total alkaloid content (TAC, 33.92 mg ARE/g DW), moderate total phenolic content (TPC) and total flavonoid content (TFC). However, high TPC (57.92 mg GAE/g DW) and TFC (427.56 mg RE/g DW) were obtained by acetone and 50 % EtOH, respectively. Ethyl acetate extracts yielded the lowest TPC (0.74 mg GAE/g DW), TFC (4.24 mg RE/g DW) and TAC (0.62 ARE/g DW). A total of 32 compounds (phenolics, flavonoids, and alkaloids) were identified in the Arecanut seed extracts by using high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF/MS) method. Among them, gallic acid, (-)-gallocatechin, (-)-epigallocatechin, D-catechin, isorhamnetin-3-O-galactoside, arecaine, arecoline, and guvacoline were the main compounds. Additionally, two kinds of DESs (L-Proline-Ethylene glycol and L-Proline-Lactic acid) extracts exhibited superior properties on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS+ ), hydroxyl (OH−) and 2,2-diphenyl-1-picrylhydrazyl (DPPH ) free radical scavenging activities, ferric reducing antioxidant power (FRAP), reducing power, cupric reducing antioxidant capacity (CUPRAC), inhibitory ability of α-glucosidase and anti-bacterial activity as compared with the extracts extracted by other solvents. Multivariate analysis results revealed that the extraction solvents significantly affected the phytochemical constituents and biological activities of the Arecanut seed extracts. In conclusion, Arecanut seed is a potential source enriched in natural antioxidants for application in the medicinal aspects. Additionally, the present work provided eco-friendly DESs for high-efficient extracting the useful active compounds from Arecanut seed.