Quantification of 4′-geranyloxyferulic acid, a new natural colon cancer chemopreventive agent, by HPLC-DAD in grapefruit skin extract

Abstract

Oxyprenylated natural products (isopentenyloxy-, geranyloxy- and the less spread farnesyloxy-compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been consider for years merely as biosynthetic intermediates of the most abundant C-prenylated derivatives. Many of the isolated oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. 4′-Geranyloxyferulic acid [3-(4′-geranyloxy-3′-methoxyphenyl)-2-trans-propenoic] has been discovered as a valuable chemopreventive agent of several types of cancer. After development of a high yield and “eco-friendly” synthetic scheme of this secondary metabolite, starting from cheap and non-toxic reagents and substrates, we developed a new HPLC-DAD method for its quantification in grapefruit skin extract. A preliminary study on C18 column showed the separation between GOFA and boropinic acid (having the same core but with an isopentenyloxy side chain), used as internal standard. The tested column were thermostated at 28 ± 1 °C and the separation was achieved in gradient condition at a flow rate of 1 mL/min with a starting mobile phase of H 2O:methanol (40:60, v/v, 1% formic acid). The limit of detection (LOD, S/N = 3) was 0.5 μg/mL and the limit of quantification (LOQ, S/N = 10) was 1 μg/mL. Matrix-matched standard curves showed linearity up to 75 μg/mL. In the analytical range the precision (RSD%) values were ≤2% and the accuracy (bias%) between ±12%. This method was used to evaluate for the first time the presence of this analyte in natural extract of grapefruit. In conclusion, this method showed LOQ values able to selective quantification of this analyte in grapefruit skin extract.