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Diversity of Endophytes and Biotechnological Potential
Published in Luzia Valentina Modolo, Mary Ann Foglio, Brazilian Medicinal Plants, 2019
Daiani Cristina Savi, Chirlei Glienke
We also described a new species, Phaeophleospora vochysiae (LGMF1215b), isolated from V. divergens that produced secondary metabolites with considerable antifungal activity. Although the strain LGMF1215 was isolated as endophyte, it produced phytotoxic perylenequinones as major compounds, cercosporin and isocercosporin, two toxic metabolites commonly produced by Cercospora species (Savi et al., 2018a). The resistance to cercosporins by P. vochysiae and by the host V. divergens may be due to cercosporin being produced associated with fungal hyphae, in this way the compound is present in reduced form, which makes the compound nontoxic or photoactive. In addition, strain LGMF1215 produced a new compound having antibacterial activity, 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone and absence of cytotoxic activity for human cell lines (Savi et al., 2018), suggesting the possibility to using this compound to treat clinical infections caused by bacteria.
Glutathione
Published in Ruth G. Alscher, John L. Hess, Antioxidants in Higher Plants, 2017
Alfred Hausladen, Ruth G. Alscher
The production of reactive oxygen species is an important part of the mode of action of environmental stresses such as the pollutants ozone74,76,78 and sulfur dioxide,73,74,77 as well as the photoactive compounds that directly absorb light and generate radicals (e.g., cercosporin).75 The bipyridilium compounds,86,87 such as paraquat, which divert electrons from ferredoxin (photosystem I), and the diphenyl ethers,81,84 which cause a build-up of protoporphyrin IX, all cause a build-up of oxidants in photosynthetic tissue. Each case is different with respect to the individual chemistry involved. For paraquat and diquat, both dicationic bipyridilium herbicides with redox potentials close to that of ferredoxin, the molecule is reduced to a radical through reduction by Photosystem I in competition with ferredoxin under conditions where linear photosynthetic electron transport is taking place. Monocationic paraquat is rapidly oxidized by molecular oxygen, forming superoxide anion and regenerating dicationic paraquat.70,85 Paraquat radical per se can directly reduce H202 in a reaction that is analogous to the Fenton reaction, thereby leading to the production of ·OH.86
Optimization of Myrothecium roridum tode: fries phytotoxin production and bioactivity on water hyacinth (Eichhornia crassipes)
Published in Toxin Reviews, 2021
Wahab Oluwanisola Okunowo, Akinniyi Adediran Osuntoki, Adedotun Adeyinka Adekunle, George Olabode Gbenle, Hamed K. Abbas, Wayne Thomas Shier
All values of light and dark regimens had a significant effect (F5, 30 = 18.92, p < 0.001, with Bonferroni post-tests) on phytotoxicity of lyophilized toxin preparations. The concentration of toxin preparation had a significant overall effect on phytotoxicity (F5, 30 = 12.22, p < 0.001), but the light and dark regimen did not (F1, 30 = 2.45, p = 0.1279) except at concentrations of 2% and 0.5% (w/v) (Figure 5). The ASI of 2% lyophilized toxin preparation produced in darkness was significantly greater than that obtained at lower concentrations (p < 0.001) (Figure 5). The ASI was maximal at 0.5% (w/v) toxin concentration on leaves under 12 h photoperiod and was significantly greater than those obtained at other dilutions (p < 0.001) (Figure 5). The results indicate that the toxicity of the M. roridum phytotoxin was greater in the light at reduced concentrations (0.02 to 1.00%, w/v) compared to toxicity produced in the dark. Some phytotoxins have been reported to be photosensitive, such as cercosporin produced by Cercospora sp. and perylenequinones produced by a number of important phytopathogens, all of which require photoactivation for biological activity (Daub and Chung 2007).