Extraction of Phenolic Compounds from Fruits of Bitter Melon (Momordica charantia ) with Subcritical Water Extraction and Antioxidant Activities of These Extracts

Abstract

Bitter melon (Momordica charantia) is traditionally known for its medicinal properties such as antidiabetic, anticancer, anti-inflammation, antivirus, and cholesterol lowering effects. It contains many phenolic compounds that may have the potential as antioxidant and antimutagen. Although the value of bitter melon is realized, scientific information on phenolic composition of bitter melon and antioxidant and antimutagenic activities of its extracts from food grade solvents are limited. This study were investigated the total phenolic contents of bitter melon obtained by subcritical water extraction (SCWE) and antioxidant activities of these extracts. The effect of extraction temperature was considered and the results were compared with the extracts obtained by solvent extraction and soxhlet extraction. The total phenolic contents of bitter melon obtained by the SCWE at 130oC, the SCWE at 150oC, SCWE at 180oC, the SCWE at 200oC, the solvent extraction, and soxhlet extraction were 10.571, 25.219, 42.915, 48.177, 7.743, and 4.992 mg gallic acid equivalents (GAE)/g dry weight (DW), respectively. Overall, the extracts obtained by SCWE were significantly higher than solvent extraction and soxhlet extraction. The main phenolic acid contained in bitter melon was gallic acid. The phenolic acid was calculated from HPLC analysis of the extracts that the gallic acids of the extracts from bitter melon obtained by the SCWE at 130oC, the SCWE at 150oC, SCWE at 180oC, the SCWE at 200oC, the solvent extraction, and soxhlet extraction were 0.0913, 0.3169, 0.5502, 0.6462, 0.0271, and .0120 mg/g DW, respectively. Antioxidant was represented by IC 50 index which the IC50 values of extract obtained with the SCWE at 130oC, the SCWE at 150oC, the SCWE at 180oC, the SCWE at 200oC, the solvent extraction, and soxhlet extraction were 4.480, 3.970, 5.757, 5.720, 8.426, and 6.107 μg/ml, respectively. The IC50 values of the SCWE at all temperatures were lower than that of solvent extraction and soxhlet extraction, which means SCWE gave the extracts with higher antioxidantactivity.