Sacha inchi (Plukenetia volubilis L.) husks and seed shells are sources of phenolic compounds with potential health benefits

Abstract

Sacha inchi (Plukenetia volubilis L.) is an oilseed plant that yields a highly nutritious oil. However, its husks and seed shells are under-utilized byproducts. In this study, ethanolic extracts of sacha inchi husks (SI-husk) and seed shells (SI-shell) were obtained using ultrasound-assisted extraction, evaluating the effects of extraction temperature and solvent-to-solid ratio on the yields. The extracts’ total phenolic contents, phenolic profiles, antioxidant activities, and antimicrobial activities against Gram-positive and Gram-negative bacteria were investigated. Under the selected extraction conditions for SI-husk (60 °C, 1:8 s/s, 280W, 120 min) and SI-shell (60 °C, 1:3 s/s, 280W, 120 min), the extracts’ total phenolic contents were 80.18 ± 0.32 and 50.94 ± 0.48 mg GAE (gallic acid equivalents)/g, respectively. Cyanidin, naringenin, and kaempferol were principally found in the SI-husk extract (79.4 %) and vanillic acid in the SI-shell extract (79.9 %). Both extracts exhibited antioxidant activity, with ORAC values of 360.36 ± 0.21 and 228.11 ± 0.14 µmol TE/g, respectively. The antimicrobial activity of the extracts was evaluated against S. aureus, P. aeruginosa, and E. coli using the agar disk diffusion assay. SI-husk (1 mg) exhibited antibacterial activity against Staphylococcus aureus, with an inhibition zone of 10.5 ± 1.8 mm. Our results provide new insights into sacha inchi byproducts as sources of bioactive compounds with potential health benefits.