Abstract:
The use of functional foods and their bioactive constituents have been considered as a new approach in the prevention and management of type-2 diabetes and its complications. In this study, the effects of extracts of jute and padauk leaves on enzymes linked to type-2 diabetes and oxidative stress were examined. The free and bound phenolic extracts from the vegetables were used for the in vitro analyses. The total phenol, total flavonoid contents and in vitro antioxidant properties were evaluated. Thereafter, the inhibitory effect of the phenolic extracts on key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) and hypertension [Angiotensin-I-Converting Enzyme (ACE)] were also assessed. Furthermore, the antihyperglycemic and antioxidative properties of the vegetables were also determined in vivo and the phenolic constituents characterized using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). The total free soluble phenolic content of the vegetables ranged from 88.05 mg/g (Padauk leaf) to 389.03 mg/g (Jute leaf) and 48.92mg/g (Padauk leaf) to 450.00mg/g for bound phenolics. Similarly, the total flavonoids ranged from 30.73 mg/g (Padauk leaf) to 314.00 mg/g (Jute leaf) in free forms and 26.31 mg/g (Padauk leaf) to 35.50 mg/g in bound forms. Both extracts possessed antioxidant properties (DPPH and ABTS radicals scavenging ability, Fe2+ chelating, reducing power and inhibition of reactive oxygen species production) which also showed inhibitory effects on α-amylase, α-glucosidase and ACE activities in vitro. The distribution of various phenolic constituents was shown by the HPLC-DAD (chlorogenic acid, caffeic acid, gallic acid, rutin, quercetin, kaempferol, quercetrin and isoquercitrin). Supplementation of vegetable diets in type-2 diabetic rats showed antihyperglycemic, antihyperlipidemic and antioxidative effects. It also exhibited modulatory effects on purinergic enzymes involved in the prevention of platelet abnormality and consequent vascular complications in diabetic state. Thus, these vegetables could
be good sources of functional foods for dietary intervention in the management of type-2 diabetes and oxidative stress.
