1 H and 13 C assignments of two new macrocyclic lactones isolated from Streptomyces sp. 211726 and revised assignments of Azalomycins F 3a , F 4a and F 5a

Azalomycin F 4a 2‐ethylpentyl ester (1) and Azalomycin F 5a 2‐ethylpentyl ester (2), two new macrocyclic lactones, along with three known compounds of Azalomycins F 3a (3), F 4a (4) and F 5a (5), were identified from metabolites of Streptomyces sp. 211726 isolated from mangrove rhizosphere soil. The complete 1 H and 13 C assignments of these compounds were achieved by using 1 H, 13 C, DEPT, HSQC, 1 H‐ 1 H COSY and HMBC spectra, and the relative stereochemistry of 5 was first elucidated on the basis of proton–proton coupling constants, NOESY and IR spectra. Moreover, some errors in the 1 H and 13 C assignments published of 3, 4 and 5 were found and revised. 1 and 2 were active against Candida albicans , and exhibited moderate cyctotoxicity against HCT‐116 cell line. Copyright © 2010 John Wiley & Sons, Ltd.