Extraction methods comparison and optimization for isoorientin and isovitexin from Thai jasmine rice leaves

Selected extraction techniques were first compared for young Jasmine rice leaves, which were evaluated as a novel source of flavone derivatives. Microwave-assisted extraction (MAE), which outperformed other tested methods in terms of phenolic content and antioxidant activity, was then evaluated and optimized. I-optimal design with response surface methodology was used to investigate the effects of and optimize MAE conditions in terms of the extraction time, solvent-to-solid ratio and MW power with extractable isoorientin and isovitexin contents as responses. A ratio of 37.7:1 (mL: g) and specific input MW power of 6.68 W/g for 7.5 min were noted as the optimal condition, yielding isoorientin and isovitexin at 7.23 ± 0.23 and 1.12 ± 0.04 mg/g DW, respectively. Validation of the optimal conditions confirmed that all responses closely aligned with the predictions (error < 5%). The study reveals potential of young Jasmine rice leaves as a good alternative source of flavone derivatives and successfully introduces I-optimal design for plant materials extraction optimization, showcasing its uniqueness and addressing certain limitations of other commonly used experimental designs.