In vitro inhibitory activity of Annona squamosa leaves against enzymes associated with metabolic disorders

Annona squamosa L. is a popular medicinal plant of Bangladesh having several traditional uses. To give the scientific clarification for ethnomedicinal uses of this plant, this study was aimed to analyze the phytochemical profile of methanol extract of Annona squamosa leaves (designated as MEAL) and evaluate its inhibitory properties against a-amylase, pancreatic lipase, and angiotensin converting enzyme (ACE). Different in vitro methods were used to perform enzyme inhibition assays and kinetic studies for MEAL and its phytochemical profile was analyzed by gas chromatography-mass spectroscopy (GC-MS). In enzyme inhibition assays, MEAL showed significant ACE inhibitory activity whereas it had moderate inhibition against pancreatic lipase. The IC50 of MEAL was found to be 9.26 +/- 0.71 mu g/mL and 6.90 +/- 0.58 mu g/mL for ACE and lipase enzymes, respectively. MEAL was also found as mixed type inhibitor of ACE in enzyme kinetic study. In case of a-amylase, MELA (IC50: 608.8 +/- 7.02 mu g/mL) showed poor inhibition activity when compared with standard drug acarbose (IC50: 28.53 +/- 1.35 mu g/mL). In addition, presence of some compounds in MEAL identified by GC-MS, were also consistence with these enzyme inhibitory activities. Thus, this study proves the enzyme inhibitory abilities of Annona squamosa leaves for the first time and it might be a potential tool for the treatment of hypertension and obesity.