Comparative extraction strategies for maximizing phytochemicals and antioxidant potential in red and yellow cashew (Anacardium occidentale L.) leaf varieties

Cashew ( Anacardium occidentale L.) leaves (CL) are a rich yet underutilized source of bioactives, particularly phenolics, which exhibit potent antioxidant and diverse biological properties. Despite growing interest in exploiting plant-based antioxidants, comparative data on how extraction methods influence the recovery of bioactives from different CL (yellow and red varieties) remain limited. The present study aimed to evaluate the effect of different extraction techniques on the bioactive composition and antioxidant potential of two CL varieties. Various sample pre-treatments were applied, followed by extraction using diverse solvent profiles through conventional (CE) and ultrasound-assisted (UAE) methods. The resultant extracts were analyzed for free and bound phenolic and flavonoid contents as well as antioxidant activity, with yellow leaves from CE showing free and bound flavonoid contents of 251.46 and 134.02 mg QE/g, respectively, compared to 189.8 and 97.95 mg QE/g for the 5- min UAE treatment. Our findings demonstrated that extraction efficiency varied significantly ( p < 0.05) with solvent and leaf variety. Between the two varieties, UAE of yellow variety showed higher antioxidant activity (343 μM Trolox equivalent/g) than red variety (337 μM Trolox equivalent/g) indicating a stronger correlation between phenolic concentration and radical scavenging ability. The CE and 10-min UAE (1 mg/mL) increased the RAW 264.7 cell survival rate upto 120% and exerted anti-inflammatory activity (around 99.02%) by inhibiting nitric oxide. Thus, our study underscores the importance of extraction parameters in recovering bioactives from yellow and red CL providing a methodological basis for optimizing extraction protocols. Further studies will focus on formulating functional ingredients or nutraceuticals from processed CL with potential anti-depressive and antioxidant activities.