A validated spectrophotometric method for quantification of prenylated flavanones in pacific propolis from Taiwan.
BACKGROUND
Because of its chemical diversity, the only way to standardise propolis is to specify multiple standards for different propolis types according to the corresponding chemical profile. So far, this has been done only for European propolis.


OBJECTIVE
To develop a rapid low-cost spectrophotometric procedure for quantification of bioactive prenylated flavanones in Taiwanese propolis.


METHODS
The proposed method quantifies the total flavanones 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 flavanones of the propolis samples (propolins C, D, F and G) were quantified by HPLC. Antiradical activity against DPPH was also measured. The DNP (dinitrophenylhydrazine) spectrophotometric method is applied for the first time for quantification of prenylated flavanones.


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 significant correlation with the antiradical activity against DPPH.


CONCLUSIONS
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 Pacific propolis.
Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str. Bl. 9, 1113 Sofia, Bulgaria.
Milena
M
Popova
Chia-Nan
CN
Chen
Pen-Yuan
PY
Chen
Chung-Yang
CY
Huang
Vassya
V
Bankova
D001713:Biphenyl Compounds / Q000737:chemistry; D019665:Euphorbiaceae / Q000737:chemistry*; D044950:Flavanones / Q000032:analysis* / Q000737:chemistry; D016166:Free Radical Scavengers / Q000032:analysis / Q000737:chemistry; D010659:Phenylhydrazines / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry; D011429:Propolis / Q000032:analysis*; D015203:Reproducibility of Results; D013051:Spectrometry, Gamma / Q000379:methods*; D018709:Statistics, Nonparametric; D013624:Taiwan
D001713:Biphenyl Compounds; D044950:Flavanones; D016166:Free Radical Scavengers; D010659:Phenylhydrazines; D010851:Picrates; C004787:2,4-dinitrophenylhydrazine; D011429:Propolis; C004931:1,1-diphenyl-2-picrylhydrazyl