Valorization Using Box-Behnken Design for Phenylalkane-SJ1 from Syzygium jambos (L.) Alston Leaves and its In Vitro α-amylase and α-glucosidase Effects

Syzygium jambos (L.) Alston is widely cultivated for edible fruits, which possess antidiabetic activity, but the phytochemistry of S. jambos leaves has not yet been explored completely. This study explores a sustainable valorization of S. jambos leaves for secondary metabolites, especially phenylalkanes, and explores its antidiabetic activity. The S. jambos leaf extract was prepared in different green solvents such as water, aqueous methanol, and aqueous ethanol, and screened for the presence of phytochemicals. The suitable solvent for extraction was identified as water, with a total phenolic content of 157 ± 0.56 mg GAE/g dry extract and a total flavonoid content of 68 ± 0.54 mg RT/g dry extract. Salt-assisted optimization was performed for the precipitation of phenols and flavonoids with five different salt solutions and different concentrations. 1 M sodium acetate precipitated a phenylalkane (SJ1)—6-heptadeca-9′Z,12′z-dienyl salicylic acid. The Box–Behnken RSM method was designed to increase the yield of SJ1 from S. jambos leaf extract having variables such as sodium acetate concentration, solid–solvent ratio, Time, and yield of SJ1 as a response. The highest yield(11.18 mg) of SJ1 was precipitated under the optimum conditions of sodium acetate:1.057 M, solid–solvent%: 8.011, and time 43 .4 min. in vitro α-amylase and α-glucosidase antidiabetic assays exhibited SJ1 as the potent antidiabetic compound with IC₅₀ 0.104 ± 0.086 and IC₅₀ 0.229 ± 0.112 respectively.