Secondarymetabolitesof<italic>Xenorhabdusnematophila</italic>SN313andtheirinhibitoryactivitiesagainstplantpathogenicfungi

A strain from a soil sample was obtained by screening of chemical and biological activities. This strain was identified as Xenorhabdus nematophila using 16S rDNA method and it was named as SN313. The fermented broth of SN313 was isolated and purified using microorganism fermentation, liquid extraction, column chromatography, high performance preparative liquid chromatography and other techniques. Three compounds were obtained and identified as N-(2-hydroxyphenylacetyl) tryptamine ( 1 ), phenazine-1-carboxylic acid ( 2 ), cyclo(Pro-Trp) ( 3 ) based on the results of MS, NMR and published literatures. Compound 1 is a new derivative of β-indolyl ethylamine. Mycelium growth rate method was performed to determine the antifungal activities of the three compounds. The results showed that compound 1 significantly inhibited the growth of Phytophthoa capsici and Botrytis cinerea (IC₅₀ values were 11.20 μg/mL and 28.94 μg/mL, respectively). Compound 2 had significant inhibitive effect agianst B. cinerea, P. capsici, Thanatephorus cucumeris and Bipolaris sorokiniana (IC₅₀ < 40 μg/mL). And compound 3 could inhibit the growth of B. cinerea (IC₅₀ = 41.58 μg/mL). Of note, isolation of compound 2 from soil microorganism provides a new natural source of phenazine-1-carboxylic acid.