Extraction Optimization of Total Phenolic Content and Antioxidant Activity from Teaw (Cratoxylum formosum) by Central Composite Design

Abstract

: The extraction of bioactive compounds from Teaw (Cratoxylum formosum (Jack) Dyer) was carried out based on the central composite design and response surface methodology to optimize the three variables: solvent polarity index (5.5-9.0), temperature (50-70°C) and extraction time (35-55 min). The optimization condition was based on yield, total phenolic content (TPC), DPPH radical scavenging (DPPH), ABTS radical scavenging (ABTS) and thiobarbituric acid reactive substances (TBARs) assay. From five variables, only two responses (yield and TPC) were fitted to a quadratic equation with R-square of 0.8479 and 0.8891, respectively. DPPH response was not quite fitted (R 2 = 0.4420) while ABTS and TBARs were insignificantly fitted (p>0.05). The optimal extraction condition was obtained with a solvent polarity index of 8.64 at 70°C for 55 min. The software predicted under these optimal conditions that yield was 28.58% whereas the TPC and DPPH, were 289 and 402 mg/g dry sample, respectively. The desirability value was 0.933. The proposed method proves to be simple, cheap and good for natural bioactive extraction from Teaw, being a potential approach for natural antioxidants.