Salinity as an Inducer of Antioxidant Activity Exerted by Mangrove Species from Campeche, Mexico

The mangrove ecosystem is reported to have a large diversity of species that develop in environments with high salinity levels. Plant species from mangroves are used in traditional medicine and are potential sources of chemicals entities with therapeutic applications. The present work aims to assess and document the influence of salinity on the antioxidant activity exerted by extracts of mangrove species through spectroscopic and chemical analysis. The highest salinity is recorded in Río Verde (RV) in Petén Neyac (PN), an LPBR site. The leaves of Laguncularia racemosa (from RV and PN) recorded the highest extraction yield (35.29 ± 0.45%). Phytochemical analysis indicated the presence of several families of secondary metabolites in the leaves of Rhizophora mangle, Avicennia germinans, and L. racemosa collected in PN and RV, and the chromatographic profile confirms the complexity of the extracts, especially in L. racemosa-RV. The highest content of chlorophylls, carotenoids, and simple phenols was recorded in R. mangle (in RV and PN); flavonoids were high in A. germinans (RV), and the highest antioxidant activity was recorded in L. racemosa (RV) using the DPPH model (EC₅₀: 39.74 ± 0.91 μg/mL; E_max: 67.82 ± 1.00%). According to HPLC, gallic acid (GA), and quercetin (Q) are important metabolites in L. racemosa. FTIR spectra can identify several chemical groups and fingerprint regions in complex mixtures, such as methanolic extracts of the species under study. In this context, this is the first report on chemical changes resulting from species collected at sites with different degrees of salinity. GA is the main metabolite affected by salinity and participates in the antioxidant activity exerted by the original extract, which could explain the physiological adaptations of L. racemosa and its traditional uses. L. racemosa (RV) is ideal for a bioguided phytochemical study that would yield valuable knowledge about its medicinal properties, support ecological conservation, and drive innovation across multiple industries. Further analytical studies are needed to corroborate the impact of salinity on the biosynthesis of secondary metabolites.