A validated spectrophotometric method for quantification of prenylated flavanones in pacific propolis from Taiwan

Introduction – Because of its chemical diversity, the only way to standardise propolis is to specify multiple standards for diff erent propolis types according to the corresponding chemical profi le. So far, this has been done only for European propolis. Objective – To develop a rapid low-cost spectrophotometric procedure for quantifi cation of bioactive prenylated fl avanones in Taiwanese propolis. Methodology – The proposed method quantifi es the total fl avanones on the basis of their absorption as coloured phenylhydrazones formed by interaction with 2,4-dinitrophenylhydrazine. The procedure was validated through model mixture of compounds representing the composition of Taiwanese propolis according to previous studies. The major fl avanones of the propolis samples (propolins C, D, F and G) were quantifi ed by HPLC. Antiradical activity against DPPH was also measured. The DNP (dinitrophenylhydrazine) spectrophotometric method is applied for the fi rst time for quantifi cation of prenylated fl avanones. Results – Spectophotometric procedure applicable to new type propolis (Macaranga type) was developed with recovery between 105 and 110% at the concentration range of 0.573–1.791 mg/mL. Six propolis samples were analysed by spectrophotometry using the procedure developed and validated, and by HPLC as the results demonstrated satisfactory agreement. Neither the spectrophotometric data nor the values measured by HPLC showed signifi cant correlation with the antiradical activity against DPPH. Conclusion – The proposed spectrophotometric procedure is useful for routine analyses of Macaranga-type propolis, because of its simplicity, repeatability and acceptable accuracy. Its application to a number of commercial samples could be used as a basis for standardisation and quality control of Pacifi c propolis. Copyright © 2009 John Wiley & Sons, Ltd.