복분자 추출물의 항산화 활성 및 지표성분 표준화를 위한 ellagic acid 검증

Abstract

The content of ellagic acid obtained from the extracts of Rubus occidentalis (RC) and its antioxidant activity were measured to secure basic data for developing functional materials. The extract was prepared by boiling RC in water for 3 h at 90°C. The polyphenol content and 2,2'-azinbis-(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity (IC50) of RC was 30.60±1.27 mg/g and 176±3.95 μg/mL, respectively. RC acid hydrolysate (RCH) was analyzed using HPLC and ellagic acid as a marker compound. HPLC was used to separate the content using the following experimental conditions. Gradient solvent made of 0.1% formic acid and acetonitrile/methanol (85:15 v/v) was used with elution solvent gradient. Separation was performed on a C18 MGII column (4.6×250 mm, 5 μm) and with a 254 nm PDA detector. Limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and recall rate were measured. Ellagic acid and RCH were separated from other substances with a consistent detection time and peak retention time. Ellagic acid and RCH were eluted as a single peak on the chromatogram at approximately about 17.9 min. The maximum absorbance of ellagic acid and RCH was consistent at 254 nm PDA spectrum. These results indicate that ellagic acid and RCH are similar and there are some specific differences. The correlation coefficient (R2) of the calibration curve showed a 0.9999 linearity, 0.1330 μg/mL LOD, and 0.4029 μg/mL LOQ. Inter-day precision, and intermediate precision were 12.95-13.48 mg/g (1.38-3.70% RSD) and 13.16-13.41 mg/g (1.19-2.51% RSD), respectively. The ellagic acid and RCH contents were 6.17±0.80 mg/g and 19.56±3.56 mg/g, respectively. The content of ellagic acid increased with increasing extraction and hydrolysis time. Our findings suggest that HPLC analysis could be used for validating ellagic acid as a marker compound of RC.