Valorization of rambutan (Nephelium lappaceum L.) peel: Chemical composition, biological activity, and optimized recovery of anthocyanins.

[Display omitted] • Chemical constituents and in vitro bioactivities of rambutan peel were investigated. • Ellagitannins, geraniin isomers, and anthocyanins were major phenolic compounds. • Rambutan peel extract displayed antioxidant, antibacterial, and antifungal activities. • Heat/ultrasound-assisted extractions (HAE/UAE) of anthocyanins were optimized. • HAE was the more efficient than UAE, yielding 16.2 mg of anthocyanins/g extract. Chemical constituents and bioactive properties of rambutan (Nephelium lappaceum L.) peel were characterized and heat-/ultrasound-assisted extractions (HAE/UAE) of anthocyanins were optimized by response surface methodology. Five organic acids, the α-, γ-, and δ-tocopherol isoforms, and twenty-five fatty acids (36.8 % oleic acid) were identified, as well as a phenolic profile composed of ellagitannin derivatives, geraniin isomers, ellagic acid, and delphinidin- O derivatives. The extract showed antioxidant activity via lipid peroxidation (IC 50 = 2.79 ± 0.03 µg/mL) and oxidative hemolysis (IC 50 = 72 ± 2 µg/mL) inhibition, and displayed antibacterial and antifungal properties (MIC ≤ 1 mg/mL). On the other hand, no cytotoxicity was observed in tumor and non-tumor cell lines up to 400 µg/mL. The recovery of anthocyanins was more effective using HAE than UAE, allowing greater yields (16.2 mg/g extract) in just 3 min and using lower ethanol proportions. Overall, rambutan peel could be upcycled into bioactive ingredients and natural colorants for industrial applications. [ABSTRACT FROM AUTHOR]