総説・解説等

Cellular slime molds are thought to be excellent model organisms for the study of cell and developmental biology because of their simple pattern of development. However, there have been few reports on secondary metabolites of them. We have focused on the utility of cellular slime molds as novel resources for natural product chemistry, and have studied the diversity of secondary metabolites produced by them as well as their physiological and pharmacological activities. We have recently isolated many novel compounds from the fruiting bodies of various species of Dictyostelium cellular slime molds. Total syntheses and biological evaluation of these compounds have been carried out. It was shown that dictyopyrones and dictyomedins may regulate Dictyostelium development. Amino sugar derivatives such as furanodictines and dictyoglucosamines induced neuronal differentiation of rat PC-12 cells. In addition, brefelarnide inhibited the cellular proliferation of 1321N1 human astrocytorna cells. These results show that cellular slime molds are promising sources in natural product chemistry.

As described in Japanese essay (Hojoki), written around 1200, various disasters such as big fires, earthquakes, and famines have occurred in Japan. Asian countries have been suffering from the disasters; furthermore, natural disasters are increasing due to global warming. Because tropical-infectious diseases are often disaster-related infectious diseases (DRIDs), the strategies against the former kind of disease could be applicable to DRIDs. Meteorological analysis of the occurrence of DRIDs using a method of time series analysis is important. In situations of disasters, it is desirable if you can identify the pathogen and identify disease severity simultaneously. A dipstick DNA chromatography assay termed as Single-Tag Hybridization—Printed Array Strip (STH—PAS) system was developed based on the DNA sequences of various mosquito-borne diseases. The plasma levels of matricellular proteins including galectin-9 (Gal-9) and osteopontin (OPN) were found to reflect the disease severities in the dengue virus and other DIRDs. Because both proteins have been reported to be immune-check molecules, their inhibition might enhance the immune system against pathogens. We found that brefelamide derivatives could inhibit OPN and other inflammatory molecules synthesis. Very recently, different derivatives were found to inhibit PD-L1 transcription. Applications of these agents should be considered as multi-step strategies against DRIDs.