Valorization of rambutan (Nephelium lappaceum L.) peel: Chemical composition, biological activity, and optimized recovery of anthocyanins
Bianca R. Albuquerque, José Pinela, María Inês Días, Carla Pereira, Jovana Petrović, Marina Sokóvić, Ricardo C. Calhelha, M. Beatriz P.P. Oliveira, Isabel C.F.R. Ferreira, Lillian Barros
Abstract
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.