Environmentally benign, ultrasonication assisted, sustainable valorization for commercially important nutraceutical-Daucosterol from the heartwood of invasive Prosopis juliflora (Sw.) DC

Abstract

Steroidal saponins are amphiphilic glycosidic chemical constructs, which possess diverse biological activities, that are attributable to the structural variations in the aglycone part and in the carbohydrate part. Daucosterol, a steroidal saponin, is a nutraceutical possessing various pleiotropic effects such as food preservative, immunomodulatory, anticancer and hypoglycemic effects. Non-conventional extraction methods have gained more importance as they provide target specific isolation, and thus, an eco-friendly sustainable process, optimized using Response surface methodology can be a viable proposition. P. juliflora, is an invasive plant, is seen as a major threat to agricultural lands, and is known to be a rich source for these saponins. Here we have reported a greener valorization procedure for Daucosterol from the heartwood of the invasive weed P. juliflora, various factors such as solvent, Solid-solvent ratio, extraction time, temperature, as well as aided valorization methods with microwave and ultrasonication were tested. Based on ‘one variable at a time’ experiments, which could influence the extraction process, an ultrasound-assisted valorization for daucosterol was developed. Response surface methodology was designed using a Box-Behnken method. Acetonic precipitation of Daucosterol yielded 8.02 mg/g of PJ, with the optimized conditions being 49.5 °C temperature, 14.6% solid loading and 0.76 M HCl in ethanol (v/v). It is also found that solvent had a greater influence on the extraction process. In order to understand the effect of acid treatment on the material, the cell wall constituents were quantified, and an acid-ethanol treatment method, improved the cell wall degradation and thereby increased the extraction efficiency of the nutraceutical, as evidenced by SEM images.