Antimicrobial Chlorinated 3-Phenylpropanoic Acid Derivatives from the Red Sea Marine Actinomycete LY001.

The actinomycete strain LY001 was purified from the sponge . Fractionation of the antimicrobial extract of the culture of the actinomycete afforded three new natural chlorinated derivatives of 3-phenylpropanoic acid, 3-(3,5-dichloro-4-hydroxyphenyl)propanoic acid (), 3-(3,5-dichloro-4-hydroxyphenyl)propanoic acid methyl ester (), and 3-(3-chloro-4-hydroxyphenyl)propanoic acid (), together with 3-phenylpropanoic acid (), -cinnamic acid (), and the diketopiperazine alkaloids cyclo(l-Phe--4-OH-l-Pro) () and cyclo(l-Phe--4-OH-d-Pro) () were isolated. Interpretation of nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data of - supported their assignments. Compounds - are first candidates of the natural chlorinated phenylpropanoic acid derivatives. The production of the chlorinated derivatives of 3-phenylpropionic acid (-) by provides insight into the biosynthetic capabilities of the marine-derived actinomycetes. Compounds - demonstrated significant and selective activities towards and , while displayed more sensitivity towards compounds and , suggesting a selectivity effect of these compounds against .