UHPLC-MS/MS identification, quantification of flavonoid compounds from Areca catechu L. extracts and in vitro evaluation of antioxidant and key enzyme inhibition properties involved in hyperglycemia and hypertension

Arecanut (Areca catechu L.) is an important commercial crop extensively used in traditional and modern medicine. The studies on bioactive compounds and bioactivities of arecanut extracts are a fundamental requirement for future pharmacological research. This study focused on the flavonoid compounds of arecanut and their in vitro bioactivities, including antioxidant activities and inhibitory potential towards enzymes involved in the treatment of hyperglycemia and hypertension. Furthermore, ultra-high-performance liquid chromatography coupled with mass spectrometry (UHPLC–MS/MS) was utilized to characterize the flavonoid compositions in extracts of arecanut. The results showed that all extracts from different parts of arecanut (flower, husk, seed) had high contents of polyphenols, flavonoids and proanthocyanins. In total, seventy-two flavonoid compounds were identified and among them twenty-eight flavonoid compounds were quantitated. The dominated flavonoid compounds in three extracts were significantly different. The major flavonoids recognized in flower extract were cynaroside, luteolin and diosmetin, while the flavonoid compositions were dominated by schaftoside and diosmetin in husk extract. The flavonoids with higher contents in seed extract were catechin, procyanidin B1, procyanidin B2 and L-epicatechin. The results of scavenging activities towards DPPH·, ABTS·+, OH·−and O2·− demonstrated that all extracts from arecanut displayed good free radical scavenging abilities. All extracts also exhibited strong reducing power, especially arecanut seed extract. Additionally, arecanut seed extract were characterized by the strongest α-amylase and α-glucosidase inhibitory capacities, which were significantly superior to acarbose. Arecanut seed extract were also found to possess the highest angiotensin-converting enzyme (ACE) inhibitory properties compared to flower and husk extracts. In conclusion, arecanut is enriched in natural bioactive compounds with potent antioxidant activities and inhibitory effects on the enzyme related to hypertension and hyperglycemia. It can be a potential source for application in the relevant medicinal aspects.