The antifungal substances SH-1 and SH-2 were isolated from Streptomyces humidus strain S5-55 cultures by various purification procedures and identified as phenylacetic acid and sodium phenylacetate, respectively, based on the nuclear magnetic resonance, electron ionization mass spectral, and inductively coupled plasma mass spectral data. SH-1 and SH-2 completely inhibited the growth of Pythium ultimum, Phytophthora capsici, Rhizoctonia solani, Saccharomyces cerevisiae, and Pseudomonas syringae pv. syringae at concentrations from 10 to 50 g/ml. The two compounds were as effective as the commercial fungicide metalaxyl in inhibiting spore germination and hyphal growth of P. capsici. However, the in vivo control efficacies of the two antifungal compounds against P. capsici infection on pepper plants were similar to those of H 3 PO 3 and fosetyl-AI but less than that of metalaxyl.Streptomyces spp. are capable of producing microbial antibiotics with a wide variety of chemical structures. In particular, approximately 60% of antibiotics developed for agricultural use were isolated from Streptomyces spp. (32). It is interesting that Streptomyces strains continue to provide a larger number and wider variety of new antibiotics than any other actinomycete genus, suggesting that substantial numbers of Streptomyces species or strains with novel antibiotic productivity exist in nature (27). In searches for bioactive antibiotics, Streptomyces strains have been isolated from various types of soils, including rice paddy, lake mud and water, deciduous forest, tropical forest, wasteland, and cave soils (9,16,19,30,31,34).So far, various antifungal antibiotics active against the oomycete plant pathogen Phytophthora have been isolated and characterized from actinomycetes (2,12,13,15,(20)(21)(22)(23). In our previous search program for microorganisms producing antifungal antibiotics useful for the control of plant diseases, Streptomyces humidus strain S5-55 was isolated from soils in Korea, which showed substantial antagonistic activity against plant pathogens (25). The antifungal substances active against Phytophthora capsici and Magnaporthe grisea were partially purified from the culture filtrates of S. humidus strain S5-55. In the present study, the antifungal substances SH-1 and SH-2, active against some plant-pathogenic fungi, were purified from the culture broth of S. humidus strain S5-55 by various purification procedures. By analyzing various spectral and other physicochemical data, their chemical structures were elucidated and the two compounds were identified as phenylacetic acid (SH-1) and sodium phenylacetic acid (SH-2). In addition to an in vitro bioassay for antifungal activity, we also evaluated the control efficacy of SH-1 and SH-2 against phytophthora blight of pepper plants compared to those of commercial fungicides.Isolation of antifungal substances from S. humidus cultures. S. humidus strain S5-55 antagonistic to various plant-pathogenic fungi was isolated from soil from Kwangwon Province in Korea (25). The culture...

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(+)-Dehydrovomifoliol (1), 3-hydroxy-5alpha,6alpha-epoxy-beta-ionone (2), vitexin 7-O-beta-D-glucopyranoside (3), and vitexin 2''-O-beta-D-glucopyranoside (4) were isolated as new constituents from the aerial parts of Beta vulgaris var. cicla. Compounds 3 and 4 demonstrated hepatoprotective activity with values of 65.8 and 56.1%, respectively, in primary cultured rat hepatocytes with CCl4-induced cell toxicity, compared to controls. This was comparable to that of silibinin (69.8 %) which was used as a positive control.