Antimicrobial activities of the bromophenols from the red alga Odonthalia corymbifera and some synthetic derivatives

A series of bromophenols was obtained by isolation from red alga Odonthalia corymbifera and by reactions of bis(hydroxyphenyl)methanes with bromine. New bromophenols including 3,3′,5,5′-tetrabromo-2,2′,4,4′-tetrahydroxydiphenylmethane (10), a regioisomer of the potent antimicrobial natural product, together with known derivatives were synthesized in high yield. All of the isolated and synthesized compounds were tested for antimicrobial activity against Gram-negative, Gram-positive bacteria and fungi. The preliminary structure–activity relationship, to elucidate the essential structure requirements for antimicrobial activity, has been described. Among the isolated natural products 2,2′,3,3′-tetrabromo-4,4′,5,5′-tetrahydroxydiphenylmethane (4) was found to be the most active derivative against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. The synthetic bromophenols 3,3′-dibromo-6,6′-dihydroxydiphenylmethane (13) and 3,3′,5,5′-tetrabromo-6,6′-dihydroxydiphenylmethane (14) showed potent antibacterial effect against Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Proteus vulgaris, and Salmonella typhimurium.

The isolation, synthesis, and bioactivity of bromophenols are described.Figure optionsDownload as PowerPoint slide