Phytochemicals from Musa acuminata Colla peel exhibit cathepsin B inhibition and anti-inflammatory activity

Rheumatoid arthritis (RA) is a chronic inflammatory illness in which inflammatory mediators and cathepsin B and other proteases play a role in disease progression. The existing treatments may have negative side effects. Therefore, an alternative natural therapy for RA has been considered safe and beneficial. Secondary metabolites from plants have been suggested as one such alternative. In our present study phytochemicals from Musa acuminata (banana) peel have been explored for their anti-cathepsin B and anti-inflammatory potential. The crude phytochemical extract inhibited cathepsin B with an IC₅₀ value of 1.151 mg/ml. One hundred phytochemicals were identified by GC-MS in the extract. Cathepsin B inhibitory potential of each identified phytochemical was assessed using in-silico studies and revealed stigmasterol, campesterol, methyl linolenate, and methyl linoleate possessed more favourable binding energy than positive control (E-64-cathepsin B complex) and inhibited cathepsin B in-vitro. The combinatorial action of compounds resulted in synergistic cathepsin B inhibition where a combination of campesterol, stigmasterol, and methyl linolenate showed maximum inhibition of 97.80 %. Methyl linolenate showed the least inhibition constant among other compounds. Cell line studies with methyl linolenate showed no toxicity to SW982 cells and also downregulated p65 expression at 5 μM in TNF-α induced SW982 human synovial fibroblast cells indicating its anti-inflammation role. Thus, the study has shown that banana peel may serve as a resource for exploring phytochemicals for their anti-inflammatory role in RA as a nutraceutical. Being an edible plant, it may be suggested as a dietary supplement to combat RA and cathepsin B associated pathologies.