Antitumor and antimicrobial potential of bromoditerpenes isolated from the red alga, Sphaerococcus coronopifolius.

Daniel Rodrigues,Susete Pinteus,André Horta,Joana Silva,Celso Alves,Rui Pedrosa,Gérald Culioli,Olivier Thomas

doi:10.3390/md13020713

Abstract

Cancer and infectious diseases continue to be a major public health problem, and new drugs are necessary. As marine organisms are well known to provide a wide range of original compounds, the aim of this study was to investigate the bioactivity of the main constituents of the cosmopolitan red alga, Sphaerococcus coronopifolius. The structure of several bromoditerpenes was determined by extensive spectroscopic analysis and comparison with literature data. Five molecules were isolated and characterized which include a new brominated diterpene belonging to the rare dactylomelane family and named sphaerodactylomelol (1), along with four already known sphaerane bromoditerpenes (2–5). Antitumor activity was assessed by cytotoxicity and anti-proliferative assays on an in vitro model of human hepatocellular carcinoma (HepG-2 cells). Antimicrobial activity was evaluated against four pathogenic microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Compound 4 exhibited the highest antimicrobial activity against S. aureus (IC50 6.35 µM) and compound 5 the highest anti-proliferative activity on HepG-2 cells (IC50 42.9 µM). The new diterpene, sphaerodactylomelol (1), induced inhibition of cell proliferation (IC50 280 µM) and cytotoxicity (IC50 720 µM) on HepG-2 cells and showed antimicrobial activity against S. aureus (IC50 96.3 µM).

Highlights

Cancer and infectious diseases continue to be one of the major public health concerns, and there is a perpetual need for new chemotherapeutics to fight new diseases and drug resistance
The screening of antitumor and antimicrobial activities of compounds isolated from S. coronopifolius was performed for the methanol (MeOH) and dichloromethane (CH2Cl2) extracts of this alga
In order to isolate and identify the compounds responsible for these biological activities, this extract was further studied. It was first fractionated by normal phase vacuum liquid chromatography (VLC) on silica with eluents of increasing polarities

Summary

Introduction

Cancer and infectious diseases continue to be one of the major public health concerns, and there is a perpetual need for new chemotherapeutics to fight new diseases and drug resistance. Marine algae have been one of the richest and promising sources of bioactive specialized metabolites that probably have diverse simultaneous functions for their producer and can act, for example, as antimicrobial, antifouling and herbivore deterrents or as ultraviolet-screening agents [7,8,9]. These defensive strategies can result in a high level of structural and chemical diversity for the metabolites, originating from different metabolic pathways with great pharmaceutical and biomedical potential [10,11]. Marine algae-originated compounds have been found to be associated with numerous health-promoting effects, including, in particular, anti-oxidative, anti-inflammatory, antiviral, antimicrobial or anticancer effects [10,12]

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Conclusion