Antibacterial Oligomeric Polyphenols from the Green Alga Cladophora socialis

• DOI: 10.1021/acs.joc.8b03218
• Publication Date: 2019-03-25T22:22:07Z
• Authors: Serge Lavoie; Anne Marie Sweene...; Nazia Mojib; Brandon Dale; Kerstin Gagaring; Case W. McNamara; Cassandra L. Quave; Katy Soapi; Julia Kubanek
• Keywords: EC50; Natural product; Picric acid

A series of oligomeric phenols including the known natural product 3,4,3′,4′-tetrahydroxy-1,1′-biphenyl (3), previously synthesized 2,3,8,9-tetrahydroxybenzo[c]chromen-6-one (4), and eight new related products, cladophorols B–I (5–12), were isolated from Fijian green alga Cladophora socialis identified by a combination NMR spectroscopy, mass spectrometric analysis, computational modeling using DFT calculations. J-resolved spectroscopy line width reduction picric acid addition aided in resolving heavily overlapped aromatic signals. panel Gram-positive Gram-negative pathogens used to evaluate pharmacological potential led determination that cladophorol C (6) exhibits potent antibiotic activity selective toward methicillin-resistant Staphylococcus aureus (MRSA) with an MIC 1.4 μg/mL. Cladophorols B (5) D–H (7–11) had more modest but also potency. Activities A–I (4–12) assessed against asexual blood stages Plasmodium falciparum revealed (4) have EC50 values 0.7 1.9 μg/mL, respectively.