Pluripharmacological potential of Mascarene endemic plant leaf extracts

Tropical forests of the islands of the West Indian Ocean region, have a rich and diverse collection of unique plants containing a multitude of chemical scaffolds that can potentially be developed into medicinal agents. Till date, endemic plants from the Mascarene Archipelago have been undervalued but they hold significant economic and biomedical potential. Hence, to better gauge the pharmacological potential of Mascarene Archipelago flora, the bioactivities of fourteen selected endemic species were investigated. Leaf extracts from species within the Ebeneceae, Myrtaceae, Sapotaceae and Combretaceae families were prepared via organic solvent extraction and evaluated for their polyphenolic content, antioxidant, antiproliferative, anti-tyrosinase, anti-elastase and antiplasmodial activities. The highest polyphenol content was observed in Terminalia bentzoë (385.0 ± 24.1 mg gallic acid equivalent (GAE)/g) followed by Sideroxylon sessiliflorum (340.5 ± 13.4 mg GAE/g) (p < 0.05). Each extract showed dose-dependent metal chelating and free radical scavenging activity, however, T. bentzoë demonstrated the most significant (p < 0.05) antioxidant activity in terms of ferric reducing antioxidant power, iron chelating activity, superoxide anion and nitric oxide free radical scavenging activity, followed by Syzygium glomeratum. Eugenia orbiculata and E. pollicina exhibited the highest anti-tyrosinase activity, while Diospyros chrysophyllos showed noteworthy anti-elastase activity. Terminalia bentzoë further showed potent dose-dependent antiplasmodial activity against Dd2luc Plasmodium falciparum with an EC50 value of 6.7 μg/mL. Moreover, the extracts showed moderate to low toxicity against the non-tumorigenic kidney (Vero) and keratinocyte (HaCat) cell lines. The findings highlight the potential of T. bentzoë and S. glomeratum as alternative sources of pharmaceutical compounds.