Rhodethrin: a novel indole terpenoid ether produced by Rhodobacter sphaeroides has cytotoxic and phytohormonal activities

Abstract

A novel metabolite was isolated from the culture supernatants of Rhodobacter sphaeroides OU5 when grown on L-tryptophan as sole source of nitrogen under photoheterotrophic conditions. It was identified by IR, NMR ((1)H, (13)C) and MS as an indole terpenoid ether [3-hydroxy-6-(1H-indol-3-yloxy)-4-methylhexanoic acid] and is named as rhodethrin. Rhodethrin at 0.5 microM gave positive test in auxin bioassay and initiated early rooting in tissue-cultured plants than IAA at 5 microM. Rhodethrin has cytotoxic activity against Sup-T(1) lymphoma and Colo-125 cancer cell lines at 10 nM.