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 (H-1, C-13) 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 mu M gave positive test in auxin bioassay and initiated early rooting in tissue-cultured plants than IAA at 5 mu M. Rhodethrin has cytotoxic activity against Sup-T-1 lymphoma and Colo-125 cancer cell lines at 10 nM.