Flavipin in Chaetomium globosum CDW7, an endophytic fungus from Ginkgo biloba, contributes to antioxidant activity.

1,2-Benzenedicarboxaldehyde-3,4,5-trihydroxy-6-methyl (flavipin) was found to be antagonistic against nematodes and fungi. Here we demonstrated that flavipin is a potent antioxidant in vitro and in vivo, which has great potential in the therapy for free radical-associated diseases. Therefore, flavipin-producing bio-source was screened from 80 endophytes in Ginkgo biloba. Seven endophytic fungi were able to synthesize antioxidant substances and identified by ITS rDNA sequences. Among them, Chaetomium globosum CDW7 was a remarkable producer of flavipin. The fermentation parameters of CDW7 were then optimized for high flavipin production. Cultured under the optimal condition (25 °C, 100/250 mL flask, 12 discs/flask, 150 rpm, pH 6.5) for 14 days, CDW7 was able to synthesize flavipin at a production of 315.5 mg/L. In addition, flavipin output was positively correlated to antioxidant activities of crude extracts with a correlation coefficient of 0.8235, indicating that flavipin was the major antioxidant component of CDW7's metabolites. These data demonstrated that CDW7 was a highly yielded bio-source of antioxidant flavipin.

Molecular bases for resistance to acetyl-coenzyme A carboxylase inhibitor in Japanese foxtail (Alopecurus japonicus).

BACKGROUND: Haloxyfop-R-methyl is a widely used herbicide to control Poaceae weeds. Alopecurus japonicus, a widespread annual grass, can no longer be controlled by haloxyfop-R-methyl after continuous use of this herbicide for several years. RESULTS: Dose-response experiments have established that the Js-R biotype of A. japonicas has evolved resistance to aryloxyphenoxypropionates (APPs). Target-site enzyme sensitivity experiments have established that the haloxyfop (free acid) rate causing 50% inhibition of acetyl-CoA carboxylase (ACCase) activity (I(50)) for the resistant (Js-R) biotype is 11 times higher than that for the susceptible (Js-S) biotype. In many cases, resistance to ACCase-inhibiting herbicides is due to a resistant ACCase enzyme. Full-length DNA and mRNA sequences of the plastidic ACCase gene were amplified. Eight single-nucleotide differences were detected in this region. Four of the nucleotide changes were silent mutations. However, the other four nucleotide mutations caused four amino acid substitutions, replacing Arg-1734 with Gly, Met-1738 with Leu, Thr-1739 with Ser and Ile-2041 with Asn in the R biotype respectively; the substitution at position 2041 had been reported, while the other three had not. CONCLUSION: The ACCase in the Js-R biotype was less susceptible to haloxyfop-R-methyl than that in the Js-S biotype. Moreover, the amino acid substitution of Ile-2041 with Asn might confer resistance to haloxyfop-R-methyl in A. japonicas.