Ultrasound-assisted extraction of Catharanthus roseus (L.) G. Don (Patricia White cultivar) stem for maximizing saponin yield and antioxidant capacity

Large quantities of Catharanthus roseus leaf have been used for the extraction of alkaloids, which results in a significant amount of waste that includes the stems, roots, and the extracted leaves. This study aimed to determine the optimal extraction conditions, by applying response surface methodology with Box-Behnken design to assess the interactive effect of ultrasonic parameters, including ultrasonic temperature, time, ratio of sample-to-solvent, and ultrasonic power on the extraction efficiency of saponins and antioxidants from the stems of C. roseus. The results revealed that a maximized saponin yield (138.21 mg ESE/g) and strong antioxidant activities (8.34, 12.06, 10.53, and 19.15 mg TE/g for DPPH, ABTS scavenging capacity, FRAP, and CUPRAC, respectively) could be obtained under the optimal extraction conditions: ultrasonic temperature of 55 degrees C, ultrasonic time of 35 min, sample-to-solvent ratio of 1/100 (g/ml), and ultrasonic power of 150 W. Practical applicationsRecovering bioactive compounds from Catharanthus roseus stems, especially saponins which have been linked with various biological activities such as antimicrobial, antiherbivore, and/or cytotoxic activities, is necessary to avoid wasting bioresource from the alkaloid exploration of the leaves. This study suggested the optimal ultrasonic conditions that could be used for further extraction and isolation of saponins from C. roseus stems for potential application in the food, nutraceutical, cosmeceutical, and pharmaceutical industries.