Comparative qualitative and quantitative analysis of flavonoids in propolis samples from two regions in Nigeria

Propolis, a natural resinous produced by stingless bees has been in use in ethnomedicine against several ailments such as antimicrobial, anti-cancer, to mention but a few. Among the many compounds identified in propolis, flavonoids are considered to be responsible for their main biological activities. Therefore, determination of flavonoids in propolis is regarded as an important quality parameter and the very aim of this study especially the fact that the recent study carried out by our group isolated compounds mainly of flavonoids moieties indicating possible relation between Nigerian propolis and Dalbergia genus as shown in figures below.

The flavonoids contents of propolis collected from two different regions in Nigeria (South East, Abia) and (South West, Ibadan) were analysed using phytochemical assay, spectrophotometry and spectroscopic techniques (GC-MS, UV/VIS, HPLC). Flavones and flavnols were determined and expressed as quercetin and rutin equivalent while flavanones were expressed as naringenin equivalent. Cold maceration method used, yielded hexane extract Abia propolis (ABPHE), ethanol extract Abia propolis (ABPEE), hexane extract Ibadan propolis (IBPHE) and ethanol extract Ibadan propolis (IBPEE).The GC-MS analysis results carried out on hexane extracts (ABPHE) identified zingiberene, α-farnesene, β-bisabolene, β-sesquiphellandrene, phytol and trans-geranylgeraniol in ABPHE and β-caryophellene, humulene, trans-sesquisabinene hydrate, eremophilene. lauric acid, methyl ester,β-sesquiphellandrene, lauric acid, ethyl ester, spathulenol, methoxyeugenol, asarone and junipar camphor in IBPHE. The UV/VIS results gave Total Flavonoid Contents (TFCs) for ABPHE (5.592%) and ABPEE (3.107%) as 8.699% whereas TFCs for IBPHE (1.813%) and IBPEE (12.649) as 14.462%. The HPLC results gave TFCs for ABPHE (2.82%) and ABPEE (3.267%) as 6.087% whereas IBPHE (0.372%) and IBPEE (3.762%) as 4.134%. Statistical analysis showed slight statistically significant difference in the total determined flavonoids content of the South-Eastern propolis and that of the South-Western propolis (p > 0.10) from the two methods.

Keywords: Nigerian, propolis, flavonoids, spectroscopy and spectrophotometry.