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 (IC50 = 2.79 ± 0.03 µg/mL) and oxidative hemolysis (IC50 = 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.
Keywords: Chemical composition; Extraction optimization; Fruit by-product; Natural colorants; Phenolic compounds.
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