Bioprospecting of understudied mangroves: phytochemical composition and pharmacological potential of Sonneratia caseolaris and Avicennia marina

Mangroves thrive in extreme environmental conditions, producing secondary metabolites with significant pharmacological potential, making them a valuable source of novel therapeutic agents. This study aimed to elucidate the phytochemical profiles and evaluate the pharmacological activitites of two underexplored mangrove species: Sonneratia caseolaris from the Maldives and Avicennia marina from the United Arab Emirates. S. caseolaris has been used in traditional medicine for its antioxidant, antimicrobial, and antifungal properties, while A. marina is recognized for its diverse secondary metabolites with promising pharmacological applications, particularly anticancer potential. The phytochemical profiles of ethanol/water (50% v/v) extracts from various parts of both species were analyzed using UPLC-ESI/HRMS, and antioxidant potential was assessed using ABTS, DPPH, and ORAC assays. The analyses revealed several compounds newly reported in each species and in mangroves generally. From S. caseolaris, 47 compounds were identified, predominantly polyphenols such as phenolic acids, flavonoids, and tannins. The extracts exhibited strong antioxidant activity, with IC50 values comparable to or lower than ascorbic acid. Similarly, the analysis of A. marina identified 49 compounds, including iridoid glycosides, hydroxycinnamic acids, phenylethanoid glycosides, flavonoid glycosides, and triterpene saponins. The propagule pericarp extract displayed the highest antioxidant activity, while the root extract demonstrated cytotoxicity against MDA-MB-231, SW480, and E705 cancer cell lines, with IC50 values of 58.46, 81.98, and 108.10 μg/mL, respectively. In silico analysis identified triterpene saponins as potential contributors to this activity. These findings enrich the phytochemical understanding of these species and underscore their medicinal potential, supporting further investigation into the unique natural products of mangroves.