Secondary metabolites and biochemical adaptations of Scilla lakusicii and S. litardierei to karst environments: a metabolomic perspective

Abstract

Comprehensive metabolomic analysis on the leaf extracts of Scilla lakusicii and S. litardierei revealed the presence of 175 secondary metabolites. The identified compounds were categorized into several groups based on their chemical structures: hydroxybenzoic acids, hydroxycinnamic acids, saponins, flavonoid glycosides, flavonoid aglycones, homoisoflavonoid glycosides, homoisoflavonoid aglycones, and other metabolites. Saponins were the most abundant in both species, with some detected for the first time in plant tissues. Regarding volatile compounds, extracts from both species contained α- and β-pinene, neophytadiene, and phytol. S. litardierei showed a higher capacity to neutralize DPPH radicals, while S. lakusicii was more effective in scavenging hydroxyl radicals and reducing Fe³⁺ and Cu²⁺ ions. Both species exhibited similar capacities for H<inf>2</inf>O<inf>2</inf> removal and Fe chelation. In terms of anticandidal activity, S. lakusicii was particularly effective against Candida glabrata and resistant C. auris, the latter of which showed no response to the standard drug ketoconazole. S. litardierei was more effective against C. glabrata. Both extracts demonstrated significant efficacy against resistant Escherichia coli in terms of antibacterial activity, while S. litardierei proved more effective against resistant Pseudomonas aeruginosa. Overall, leaf extracts of both Scilla species displayed significant antioxidant and antimicrobial activity, attributable to their specific chemical composition. The richness of secondary metabolites and pronounced biological activity enable the adaptation of these Scilla species to karst environments.