Ethical approval
All experimental protocols in the study were approved by the ethics committee of the Graduate School and Faculty of Medicine Kyoto University (R0091 and G259). The study was performed conforming to the guidelines of the Declaration of Helsinki and conducted after written informed consent was obtained from all participants.
Preparation of secondary metabolites extracted from soil microorganisms
The producing microorganisms were isolated from various kinds of environmental resource, e.g., soil, plants, etc., and were cultivated in 250-mL Erlenmeyer flasks, each containing 25 mL of a seed medium as previously described, depending on the different types of species33,34,35,36,37,38. The whole-culture broth was extracted with an equal volume of n-BuOH, and was fractionated by using silica gel medium-pressure liquid chromatography (MPLC). After step-wise filtration steps,…
