Solvent-Dependent Phytochemical Profile and In Vitro Antioxidant Activity of Chia (Salvia hispanica L.) and Flax (Linum usitatissimum L.) Seeds

Abstract

Background: Salvia hispanica L. (chia) and Linum usitatissimum L. (flax) seeds are recognized as food materials containing diverse phytochemicals and antioxidant-associated constituents. The present study compared solvent-dependent qualitative phytochemical profiles, total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical-scavenging activity of seed extracts. Methods: Seeds collected in Amravati, Maharashtra, India, during September–October 2023 were shade-dried, briefly oven-dried at 40 °C, powdered, and extracted separately using n-hexane, petroleum ether, chloroform, and glacial acetic acid. Preliminary screening was performed using classical colour and precipitation reactions. TPC was estimated by the Folin–Ciocalteu procedure using catechol as the calibration standard, TFC by an aluminium chloride colourimetric procedure using quercetin as the standard, and DPPH scavenging activity by spectrophotometry. Results: Both species showed evidence of multiple phytochemical classes, with solvent-dependent differences. At the 0.2 mg/g sample concentration reported in the project record, TPC in chia ranged from 2.63 to 5.27 mg/g and in flax from 2.90 to 6.18 mg/g across the four solvents. Corresponding TFC values ranged from 17.47 to 23.97 mg/g in chia and 24.97 to 29.97 mg/g in flax. Petroleum ether produced the highest recorded DPPH inhibition in chia (27.65%), whereas n-hexane gave the highest value for flax (17.82%), closely followed by petroleum ether (27.39%). Conclusion: The results demonstrate clear solvent dependence in the recovery of colour-reactive phenolics, flavonoids, and DPPH-scavenging activity. Flax showed higher reported TFC across the tested solvents, while chia showed slightly higher petroleum-ether DPPH inhibition. Because independent biological/technical replicate information was not documented in the supplied project record, the quantitative comparisons are presented descriptively