IntroductionRosmarinic acid is a bioactive compound with various pharmaceutical effects and applications.ObjectiveThis work developed a new approach for aqueous enzymatic extraction of rosmarinic acid from the leaves of Salvia officinalis.MethodsDifferent enzymes (proteases and cellulase) were evaluated for their extraction activity. Response surface methodology (RSM) was subsequently employed to optimise the extraction conditions. Thin layer chromatography was also used to identify rosmarinic acid in the extract of S. officinalis.ResultsAmong the tested enzymes, a Cellulase A and Protamex mixture (1:1, w/w) exhibited maximum effectiveness in the extraction. Through the use of RSM, the maximum rosmarinic acid content of 28.23 ± 0.41 mg/g was obtained with enzyme loading of 4.49%, water‐to‐sample ratio of 25.76 mL/g, temperature of 54.3°C, and extraction time of 2 h.ConclusionThis study suggests that S. officinalis is a promising source of rosmarinic acid and aqueous enzymatic extraction is an efficient and ecofriendly method for extracting rosmarinic acid, with a short extraction time and without the contamination of a toxic solvent.
Summary
This study developed a new catalyst‐free process for producing ethyl levulinate, a biofuel additive. Noncatalytic levulinic acid esterification with ethanol using microwave irradiation (MW) was compared with that using traditional heating (TH) under different reaction conditions. The results demonstrated that the esterification process using MW was more effective than that using TH. A reaction conversion of 90.38% was obtained for the esterification using MW at 473 K and reaction time of 3 hours. Moreover, this study established a model for depicting the kinetics of levulinic acid esterification using MW and TH. A good fit to the data (R2 of >.9999) was achieved, indicating the validity of the developed model. The rate constants and pre‐exponential factor obtained for the esterification using MW were greater than those obtained using TH. Consequently, the microwave‐assisted noncatalytic synthesis is a green and promising method for preparing ethyl levulinate.
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