Phenolic contents, antioxidant capacities and inhibitory activities against key metabolic syndrome relevant enzymes of herbal teas from Eastern Anatolia

Abstract

Six traditional herbal infusions from Eastern Anatolia region of Turkey were investigated for their potential to suppress metabolic syndrome. Hydrophilic lyophilized extracts representing herbal infusions exhibited comparable or superior levels of phenolic compounds and antioxidant capacity [ferric reducing antioxidant power (FRAP assay) and oxygen radical absorbance capacity (ORAC assay)] to commercially available black tea (Camellia sinensis) and numerous herbal infusions. All teas successfully suppressed the activities of key enzymes involved in metabolic syndrome: α-amylase, α-glucosidase, pancreatic lipase and angiotensin converting enzyme (ACE). Phlomis armeniaca, Salvia limbata and Plantago lanceolata exhibited weak inhibitory activities against α-amylase and pronounced inhibitory activities against α-glucosidase, which suggests potential anti-diabetic properties. Moreover, P. lanceolata exhibited pronounced inhibitory activity against pancreatic lipase. This study suggests potential anti-diabetic and anti-obesity activity of P. lanceolata herbal infusion, and supports its traditional use as anti-diabetic tea.