Chemical constituents, free radical scavenging and enzyme inhibitory potential of selected Nigerian bee (Apis mellifera) propolis

Abstract

Extracts of propolis from southwest Nigeria (Ondo and Ife) were analysed using GC-MS and were evaluated in vitro for free radical scavenging potentials and inhibitory activities on alpha-glucosidase and porcine lipase enzyme. Crude methanolic extracts of both propolis were separately defatted with n-hexane to give n-hexane fractions and defatted fractions. Each fraction was analysed using GC-MS. Diphenyl-2-picrylhydrazyl radical scavenging potentials of the crude and defatted extracts were evaluated while in vitro antihyperglycemic and antihyperlipidemic were also determined using spectrophotometric method. The GC-MS analysis indicated 18 (88.38 %) and 20 (99.99%) compounds for n-hexane fraction of propolis from Ife (BPIH) and Ondo (BPOH) respectively. For the defatted extracts propolis from Ife (BPID) and Ondo (BPOD), 21 compounds each were identified, accounting for 100% composition in each extracts. The IC DPPH radical scavenging activities of all 50 the propolis samples were moderate compared to the standard (32.61 ± 2.60 μg/mL) however, BPOD demonstrated highest radical scavenging activity (141.49±0.29 μg/mL) among the propolis fraction tested. All the extracts demonstrated better inhibition than the standard acarbose, however, BPOD inhibited the enzyme the most with IC value of 25.35±0.48 μg/mL. The anti-lipase activities of the propolis were fairly moderate but 50 much lower compared to the standard orlistat (0.88 ± 0.12 μg/mL). The excellent inhibitory performance of the propolis extracts on alpha-glucosidase enyzme gives credence to its traditional use in treatment of diabetic patients, also the moderate free radical scavenging and antipase activities make bee propolis an important bioresource for discovery of lead drugs.