Inhibition of enzymes linked to type-2 diabetes and hypertension by essential oils from peels of orange and lemon

This study was designed to evaluate and compare the interactions of essential oils from orange (Citrus sinensis [L.] Osbeck) and lemon (Citrus limon) peels on enzymes linked to type-2 diabetes (alpha-amylase and alpha-glucosidase) and hypertension (angiotensin-I-converting enzyme [ACE]). The essential oils were obtained from the peels by hydrodistillation and were passed over anhydrous sodium sulphate. The interaction of the oil on alpha-amylase, alpha-glucosidase, and ACE activities was subsequently determined. The results revealed that the essential oils inhibited alpha-amylase and alpha-glucosidase activities. However, lemon peel (IC50 = 8.16 mu g/mL and 7.56 mu g/mL) essential oil exhibited stronger inhibitory activity on -amylase and alpha-glucosidase activities compared to orange peels (IC50 = 11.51 mu g/mL and 11.53 mu g/mL), respectively. Similarly, both essential oils reduced the activity of ACE. Moreover, lemon peel (IC50 = 26.17 mu g/mL) essential oil showed higher inhibitory effect compared to orange peel (IC50 = 31.79 mu g/mL). Our findings revealed that essential oils from lemon and orange peels are potential antidiabetic and antihypertensive agents. Moreover, essential oil from lemon peels was more potent than orange peels.