Abiotic Elicitation of Sequoia sempervirens Shootlet Culture for Enhanced Production of Pharmacologically Active Phenolics and Flavonoids

The present study investigated the effect of precursor feeding and elicitation treatments on growth and biosynthesis of phenolic compounds and flavonoids in Sequoia sempervirens shoots cultured in vitro. Phenolic compounds were determined by High-Performance Liquid Chromatography (HPLC) analysis, while total phenolic and flavonoid contents were measured spectrophotometrically. The results demonstrated that extracts of in vitro grown shoots contained significantly higher amounts of total phenolics and flavonoids than mother plant shoot extracts. Microshoots cultured on MS medium supplemented with phenylalanine (6.0 mg/L) and elicited with polyethylene glycol (200 mg/L) produced the highest amounts of total phenolics and flavonoids. HPLC analysis revealed that four phenolic compounds—gallic acid, p-hydroxy benzoic acid, ferulic acid, and chrysin—were produced in vitro but not detected in the mother tree. Secondary metabolite production in cultured S. sempervirens shoots varied significantly according to elicitor type and concentration. Notably, protocatechuic acid, catechin, rutin, syringic acid, p-coumaric acid, apigenin-7-glucoside, and cinnamic acid were markedly increased in elicited cultures compared to both non-elicited cultures and the mother plant. This study demonstrates that appropriate combinations of precursors and elicitors can significantly enhance the production of pharmacologically active compounds in S. sempervirens tissue cultures, providing a sustainable source of valuable natural products.