Antiparasitic Activity of Bromotyrosine Alkaloids and New Analogues Isolated from the Fijian Marine Sponge Aplysinella rhax.

Emmanuel T Oluwabusola,Frederick Annang,Jioji N Tabudravu,Guiomar Pérez‐Moreno,Khalid S Al Maqbali,Marcel Jaspars,Fernando Reyes

doi:10.1002/cbdv.202000335

Abstract

Ten bromotyrosine alkaloids were isolated and characterised from the marine sponge Aplysinella rhax (de Laubenfels 1954) collected from the Fiji Islands, which included one new bromotyrosine analogue, psammaplin P and two other analogues, psammaplin O and 3-bromo-2-hydroxy-5-(methoxycarbonyl)benzoic acid, which have not been previously reported from natural sources. HR-ESI-MS, 1D and 2D NMR spectroscopic methods were used in the elucidation of the compounds. Bisaprasin, a biphenylic dimer of psammaplin A, showed moderate activity with IC50 at 19±5 and 29±6 μM against Trypanzoma cruzi Tulahuen C4, and the lethal human malaria species Plasmodium falciparum clone 3D7, respectively, while psammaplins A and D exhibited low activity against both parasites. This is the first report of the antimalarial and antitrypanosomal activity of the psammaplin-type compounds. Additionally, the biosynthesis hypotheses of three natural products were proposed.

Highlights

The scourge of tropical diseases caused by kinetoplastid parasites, Plasmodium falciparum and Trypanosoma cruzi has negatively impacted the health of a substantial group of the world population living mostly in the developing world and has led to the death of millions of people.[1]
The marine sponge extract was partitioned between water and dichloromethane (50 % v/v) using a modified Kupchan method[44] previously described[45,46] and further fractionated using reversed-phase solid-phase extraction (SPE)
Our results are in line with a recent study on two new bromotyrosine compounds isolated from an Australian marine sponge that showed potent activity against malarial parasites.[60]

Summary

Introduction

The scourge of tropical diseases caused by kinetoplastid parasites, Plasmodium falciparum and Trypanosoma cruzi has negatively impacted the health of a substantial group of the world population living mostly in the developing world and has led to the death of millions of people.[1]. In our search for new metabolites from marine sources against these diseases, the methanolic extract of the sponge Aplysinella rhax, collected from the Fiji Islands was subjected to sequential fractionation and purification, indicating that 3 of the 10 compounds have been isolated for the first time from natural sources.

Results

Conclusion