DOI: 10.1177/1934578x261504945 ISSN: 1934-578X

Antimicrobial Chlorinated 3-Phenylpropenoic Acid Derivatives From the Red Sea Sponge Callyspongia fistularis

Ameen M. Almohammadi, Lamiaa A. Shaala, Mahmoud A. Elfaky, Dina A. I. Albadawi, Diaa T. A. Youssef
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Objectives

Bacterial resistance to current antibiotics is escalating at an alarming rate, rendering many conventional drugs ineffective and creating an urgent global health crisis; therefore, there is a critical need for the discovery of new antibacterial hits from underexplored natural sources such as marine sponges. This study aimed to isolate and characterize secondary metabolites from the Red Sea sponge Callyspongia fistularis and evaluate their antimicrobial activity against several pathogens.

Methods

The organic extract of the sponge was subjected to bioassay-guided fractionation using VLC and Dep-Pak C18, Sephadex LH-20 C18, and C18 HPLC. Compound structures were elucidated by NMR and (+)-HRESIMS. Antimicrobial activity was evaluated at 200 μg/disk and broth microdilution MIC assays.

Results

Four compounds were isolated including ( E )-3-(4-chlorophenyl)acrylic acid ( 1 ), ( Z )-3-(4-chlorophenyl)acrylic acid ( 2 ), 1-methyl( E )-3-(4-chlorophenyl)acrylate ( 3 ), and N -(4-hydroxyphenethyl)acetamide ( 4 ). In the Disk Diffusion and MIC determinations, 2 showed weak activity against S. aureus (10.5 mm; MIC = 213.33 μg/mL) and was inactive against E. coli , C. albicans , and MRSA, with a profile nearly identical to 1 (10.83 mm against S. aureus , MIC = 213.33 μg/mL; inactive against the other pathogens). Compound 3 exhibited improved activity against S. aureus (16.5 mm and 85.33 μg/mL), E. coli (14.5 mm and 213.33 μg/mL), and C. albicans (14.8 mm and 213.33 μg/mL), but remained inactive against MRSA, while 4 was essentially inactive against all pathogens. All compounds were significantly less potent than imipenem and clotrimazole ( P < 0.001).

Conclusion

This study reports the first natural occurrence of compounds 2 and 3 from a natural source and compounds 1 and 2 from a marine source. Compound 3 was the most active compound in this series, though still weak compared to clinical standards. None of the compounds exhibited anti-MRSA activity. Further structural optimization, including ester chain elongation and aromatic substitution, is required to improve potency.

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