Multiple responses optimization of antioxidative components extracted from Fenugreek seeds using response surface methodology to identify their chemical compositions

Fenugreek seeds (Trigonella foenum‐graecum L.), one kind of traditional Chinese medicine, are reported to be of great potential as a new alternative in terms of their bioactive components. In our present study, an ultrasonic‐assisted method was applied in the extraction of antioxidative components from fenugreek seeds. Four factors: ethanol concentration, liquid–solid ratio, sonication time, and sonication power were selected and multiple responses were studied using the response surface methodology (RSM). The effects of factors along with the correlation between all responses (flavonoids content, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay, OH(−) assay) were studied. The regression model indicated that all four factors are of significant effect on all responses. The model predicted that the ethanol concentration of 72%, solvent‐to‐material ratio of 35 ml/g, ultrasonic time of 41 min, and 500 W of power would provide a flavonoid yield of 9.10 mg/g, DPPH clearance of 80.33%, and OH(−) clearance of 24.28%, respectively. The confirmation test showed the closeness of the predicted results with those of experimental values. And AB‐8 resin was successfully used to purify the fenuellus hulusi seed extract, and the flavonoid concentration of 78.14% was obtained. Six flavonoids (Swertisin, Puerarin apioside, Jasminoside B, Astragalin, Apigenin‐7‐O‐beta‐D‐glucoside, and Apiin) were successfully identified by the liquid chromatography–mass spectrometry (LC–MS) analysis.