Kandenols A–E, Eudesmenes from an Endophytic Streptomyces sp. of the Mangrove Tree Kandelia candel

Abstract

Five novel eudesmene-type sesquiterpenes, kandenols A-E (1-5), have been isolated from Streptomyces sp. HKI0595 derived from the mangrove plant Kandelia candel. Their structures were established through NMR and mass spectrometry, and absolute configurations were established by the Mosher method and comparison of CD spectra with α-rotunol and β-rotunol. The kandenols are reminiscent of various plant-derived eudesmenes, yet kandenols B and C are unusual because of their hydroperoxide moieties. Kandenol E is the first bacterial agarofuran, which belongs to an important group of antibiotics. Whereas the kandenols display no cytotoxicity against 12 human cell lines, weak to moderate antimicrobial activities were detected against Bacillus subtilis ATCC 6633 and Mycobacterium vaccae IMET 10670.

Natural Products from Mangrove Actinomycetes

“…Its structure was elucidated as (1α, 4aα, 5α, 7β, 8aβ)-5, 8a-dimethyldecahydrona-phthalene-1, 4a, 7-triol and compound 64 showed moderate cytotoxicity against human hepatoma SMMC-7721 cell line. Kandenols A–E ( 65 – 69 ) were reported by Ding et al in 2012 [72]. These novel compounds were isolated from Streptomyces sp.…”

Peroxy natural products

“…derived from the mangrove plant Kandelia candel. 185 The aerial parts of Inula japonica contained two eudesmane sesquiterpenoids 327 and 328. Compound 328 was confirmed by means of single-crystal X-ray diffraction analysis.…”

Symbionts, a promising source of bioactive natural products

“…An endophytic Streptomyces sp. HKI0595 is a producer of five new antimicrobial eudesmane sesquiterpenes kandenols A−E (27−31, Scheme 2) [20]. An antibacterial nordammarane triterpenoid helvolic acid (32, Scheme 2) has been re-isolated from Pichia guilliermondii Ppf9 [21].…”