Fig Leaf Bioactivity and Safety: Temperature Optimization and FTIR Authentication

Ficus carica L. leaves represent an underutilized agricultural byproduct despite growing consumer interest in functional foods. Four fig leaf cultivars representing diverse geographic origins (BTM, Black Violet, Longue d'Aout, and Sultane) were compared to investigate drying temperature (50°C-80°C) effects on bioactivity through water extraction. The extract demonstrating superior antioxidant activity was subsequently evaluated for safety using cell-based cytotoxicity testing. Bioactive profiling assessed total phenolic content (TPC) and total flavonoid content (TFC). Fourier-transform infrared (FTIR) spectroscopy with principal component analysis (PCA) accomplished cultivar discrimination. Cell-based cytotoxicity testing via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay evaluated safety on Caco-2, HepG2, and THLE-2 cells. Results identified 60°C as the optimal drying temperature across all cultivars (p < 0.05). Longue d'Aout demonstrated superior bioactivity: TPC = 53.8 mg GAE/g extract, DPPH (2,2-diphenyl-1-picrylhydrazyl) IC₅₀ = 0.96 mg/mL. Higher temperatures (70°C-80°C) significantly reduced bioactivity. Conversely, ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric reducing antioxidant power) revealed cultivar-specific temperature responses. FTIR-PCA successfully discriminated cultivars with 96.8% accuracy (PC-1: 85%, PC-2: 7%). All extracts demonstrated excellent safety (IC₅₀ = 7-15.3 mg/mL, safety factor 70-1530×). Selective cytotoxicity to cancer cells emerged: HepG2 (IC₅₀ = 7 mg/mL) versus hepatocytes THLE-2 (IC₅₀ = 15.3 mg/mL), showing 2.18-fold selectivity. FTIR achieved 96.8% discrimination accuracy for quality control. Water-based extraction assessment confirmed excellent safety profiles in normal hepatocytes and selective cancer cell toxicity. Superior bioactivity and excellent safety profiles validate fig leaf extracts as safe functional food ingredients, warranting investigation into their potential anti-cancer mechanisms.