Isolation and Bioactivity of Secondary Metabolites from Solid Culture of the Fungus, .

The fungus, is considered to be a potential agent for the biocontrol of perennial sowthistle (). A new chlorinated xanthone, methyl 8-hydroxy-3-methyl-4-chloro-9-oxo-9-xanthene-1-carboxylate () and a new benzophenone derivative, 5-chloromoniliphenone (), were isolated together with eleven structurally related compounds (-) from the solid culture of the fungus, which is used for the production of bioherbicidal inoculum of . Their structures were determined by spectroscopic (mostly by NMR and MS) methods. Alternethanoxins A and B, which were reported in earlier, were re-identified as moniliphenone and pinselin, respectively. The isolated compounds were tested for phytotoxic, antimicrobial, insecticidal, cytotoxic and esterase-inhibition activities. They did not demonstrate high phytotoxicity (lesions up to 2.5 mm in diameter/length at a concentration of 2 mg/mL) when tested on leaf disks/segments of perennial sowthistle () and couch grass (). They did not possess acute toxicity to , and showed moderate to low cytotoxicity (IC > 25 µg/mL) for U937 and K562 tumor cell lines. However, chloromonilicin and methyl 3,8-dihydroxy-6-methyl-4-chloro-9-oxo-9-xanthene-1-carboxylate () were shown to have antimicrobial properties with MIC 0.5-5 µg/disc. Compound and chloromonilinic acid B were found to have contact insecticidal activity to wheat aphid () at 1 mg/mL. Compounds and methyl 3,8-dihydroxy-6-methyl-9-oxo-9-xanthene-1-carboxylate displayed selective carboxylesterase inhibition activity at concentration of 100 µg/mL. Therefore, the waste solid substrate for production of spores can be re-utilized for the isolation of a number of valuable natural products.