Isolation of Labradorins 1 and 2 from Pseudomonas syringae pv. coronafaciens

Abstract
Investigation of Pseudomonas syringae pv. coronafaciens cancer cell growth inhibitory constituents led to the isolation of 2-isobutyl-5-(3-indolyl)oxazole (1) and 2-n-pentyl-5-(3-indolyl)oxazole (2f), designated labradorins 1 (1) and 2 (2f), related to pimprinine (2a). The structures were deduced by spectroscopic techniques and X-ray crystal structure determinations. Labradorin 1 (1) afforded GI50 μg/mL values of 9.8 and 6.2 against the human cancer cell lines NCI-H 460 (lung-NSC) and BXPC-3 (pancreas-a).