Journal Article

Marmaricines A-C: Antimicrobial Brominated Pyrrole Alkaloids from the Red Sea Marine Sponge Agelas sp. aff. marmarica

Youssef, Diaa T. A., Shaala, Lamiaa A., Alqarni, Areej S., Almohammadi, Ameen M., Abujamel, Turki

2025

Overview

The Red Sea is the home of a rich diversity of sponge species with unique ecological adaptations that thrive in its saline, warm, and nutrient-poor waters. Red Sea sponges offer potential as sources of bioactive compounds and novel drugs. The organic extract of the Red Sea sponge Agelas sp. aff. marmarica was investigated for its antimicrobial constituents. Through bioassay-guided fractionation of the antimicrobial fraction of the extract on SiO2 and Sephadex LH-20, as well as HPLC purification, three bioactive compounds, marmaricines A-C (1–3), were isolated. Structural elucidation of the compounds was performed using 1D (1H and 13C) and 2D (COSY, HSQC, HMBC, and NOESY) NMR, as well as (+)-HRESIMS, leading to the identification of the compounds. The antimicrobial activities of the compounds were assessed through evaluation of their inhibition zones, MIC, MBC, and MFC, against Methicillin-Resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans. Marmaricines A and B exhibited the strongest antibacterial effects against MRSA, with inhibition zones ranging from 14.00 to 15.00 mm, MIC values of 8 µg/mL, and MBC values of 16 µg/mL. In comparison, marmaracine C showed slightly weaker activity (inhibition zone: 12 mm, MIC: 16 µg/mL, MBC: 32 µg/mL). In terms of antifungal activity, marmaricines B and C demonstrated the greatest effect against C. albicans, with inhibition zones of 14–15 mm, MIC values of 8 µg/mL, and MFCs of 16 µg/mL. Interestingly, none of the compounds showed any inhibitory effect against E. coli. The results indicate that marmaricines A-C are selectively active against MRSA, and marmaricines B and C demonstrate potential against C. albicans, making them promising candidates for the development of novel antimicrobial agents targeting resistant pathogens.

• Publisher: MDPI AG,MDPI
• Subject: Adenosine triphosphatase / Agelas / Agelas - chemistry / Agelas sp. aff. marmarica / Alkaloids - chemistry / Alkaloids - isolation & purification / Alkaloids - pharmacology / Animals / Anti-Bacterial Agents - chemistry / Anti-Bacterial Agents - isolation & purification / Anti-Bacterial Agents - pharmacology / Anti-Infective Agents - chemistry / Anti-Infective Agents - isolation & purification / Anti-Infective Agents - pharmacology / Antibacterial activity / Antibiotics / Antifungal activity / Antifungal agents / Antifungal Agents - chemistry / Antifungal Agents - pharmacology / Antiinfectives and antibacterials / antimicrobial activity / Antimicrobial agents / Bio-assays / Bioactive compounds / Bioassays / Biodiversity / Biological activity / Breast cancer / brominated pyrrole alkaloids / Bromination / Candida albicans - drug effects / Climate change / Cytotoxicity / Disease resistance / Drug resistance / E coli / Ecological adaptation / Escherichia coli / Escherichia coli - drug effects / Fractionation / Fungicides / HPLC / Indian Ocean / Marine invertebrates / marmaricines A-C / Metabolites / Methicillin / Methicillin-Resistant Staphylococcus aureus - drug effects / Microbial Sensitivity Tests / Minimum inhibitory concentration / NMR / Nuclear magnetic resonance / Nutrient sources / Pyrroles - chemistry / Pyrroles - isolation & purification / Pyrroles - pharmacology / Res Sea / Silica / Silicon dioxide / Species diversity / Water purification