Abstract
Globally, the demand for herbal products with antioxidant capacity is increased due to many health benefits. The approach to discover new drugs through natural products has become a successful strategy in recent years. Aporosa lindleyana Baill. (Kebella) is used as a leafy vegetable in Sri Lanka. Although the root and bark of this plant showed many biological activities, only antioxidant activity by DPPH mechanism and anti-inflammatory activity are reported in leaf. The present study investigated the antioxidants [Total Phenolic Content (TPC) and Total Flavonoid Content (TFC)], antioxidant activities [Ferric Reducing Antioxidant Power (FRAP),1,1-diphenyl-2-picrylhydrazyl radicalscavenging assay (DPPH),2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging assay (ABTS) and Oxygen Radical Absorbance Capacity (ORAC)], anti-amylase activity(using acarbosestandard)and anti-lipidaemicactivities via anti-lipase (AL), anti-cholesterolesterase (AC) and bile acids binding (BAB) invitro of 95% ethanolic extract (EE) and water extract (WE) of A.lindleyanaleaves along with its nutritional value.Both extracts showed significant differences (P<0.05) among the investigated antioxidants and antioxidant activities. For all the studied antioxidant activities, the EE showed high activity compared to WE and lower antioxidants in TPC. EE showed higher anti-amylase activity (IC50:164.85±8.36 μg/mL) compared to WE (IC50: 746.25±53.64 μg/mL). The IC50 of the standard drug, a carbose is 133.88 ± 4.4 μg/mL. Both extracts had dose dependant anti-lipidaemic activities in terms of anti-lipase, anti-cholesterol esterase and bile acids binding. However, EE showed significantly higher(p<0.05)anti-lipase and anti-cholesterol esterase activities compared to WE. In contrast, WE showed significantly higher (p<0.05) BAB for studied bile acids compared to EE (excepttaurocholate binding). Both extracts showed high taurocholate binding,similar binding of glycodeoxycholate and chenodeoxycholate and moderate anti-lipase activity compared to the reference drug (orlistat) studied.The proximate composition: moisture, carbohydrate, protein, crude fat, crude fibre and ash were 12.2, 49.4, 13.2, 1.1, 16.0 and 8.1%respectively. The minerals (Na, Mn, Fe, P, Zn, Cu: 53.7, 49.3, 41.4, 27.6, 22.6 and 10.4mg/kg; K, Ca and Mg: 18, 3.2and 2.7 g/kg, respectively) were also present. The leavesof A. lindleyana possess marked antioxidant, anti-amylase and moderate lipid lowering activities. This is the first report on multiple mechanisms of antioxidant activities, anti-amylase and lipid lowering effects which indicates the potential of developing A. lindleyana leaves as a functional food in prevention and management of non-communicable diseases.