Cytotoxic effects of oosporein isolated from endophytic fungus cochliobolus kusanoi

In the present study, oosporein, a fungal toxic secondary metabolite known to be a toxic agent causing chronic disorders in animals, was isolated from fungus Cochliobolus kusanoi of Nerium oleander L. Toxic effects of oosporein and the possible mechanisms of cytotoxicity as well as the role of oxidative stress in cytotoxicity to Madin-Darby canine kidney kidney cells and RAW 264.7 splene cells were evaluated in vitro. Also to know the possible in vivo toxic effects of oosporein on kidney and spleen, Balb/C mouse were treated with different concentrations of oosporein ranging from 20 to 200 mu M). After 24 h of exposure histopathological observations were made to know the effects of oosporein on target organs. Oosporein induced elevated levels of reactive oxygen species (ROS) generation and high levels of malondialdehyde, loss of mitochondrial membrane potential, induced glutathione hydroxylase (GSH) production was observed in a dose depended manner. Effects oosporein on chromosomal DNA damage was assessed by Comet assay, and increase in DNA damage were observed in both the studied cell lines by increasing the oosporein concentration. Further, oosporein treatment to studied cell lines indicated significant suppression of oxidative stress related gene (Superoxide dismutasel and Catalase) expression, and increased levels of mRNA expression in apoptosis or oxidative stress inducing genes HSP70, Caspase3, Caspase6, and Caspase9 as measured by quantitative real time-PCR assay. Histopathological examination of oosporein treated mouse kidney and splenocytes further revealed that, oosporein treated target mouse tissues were significantly damaged with that of untreated sam control mice and these effects were in directly proportional to the the toxin dose. Results of the present study reveals that, ROS is the principle event prompting increased oosporein toxicity in studied in vivio and in vitro animal models. The high previlance of these fungi in temperate climates further warrants the need of safe food grain storage and processing practices to control the toxic effects of oosporein to humans and live stock

Mycosynthesis of ZnO Nanoparticles UsingTrichodermaspp. Isolated from Rhizosphere Soils and Its Synergistic Antibacterial Effect againstXanthomonas oryzaepv.oryzae

The Plant Growth Promoting Fungi (PGPF) is used as a source of biofertilizers due to their production of secondary metabolites and beneficial effects on plants. The present work is focused on the co-cultivation ofTrichodermaspp. (T. harzianum(PGT4),T. reesei(PGT5) andT. reesei(PGT13)) and the production of secondary metabolites from mono and co-culture and mycosynthesis of zinc oxide nanoparticles (ZnO NPs), which were characterized by a UV visible spectrophotometer, Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDAX) and Transmission Electron Microscope (TEM) and Selected Area (Electron) Diffraction (SAED) patterns. The fungal secondary metabolite crude was extracted from the mono and co-culture ofTrichodermaspp. And were analyzed by GC-MS, which was further subjected for antibacterial activity againstXanthomonas oryzaepv.Oryzae, the causative organism for Bacterial Leaf Blight (BLB) in rice. Our results showed that the maximum zone of inhibition was recorded from the co-culture ofTrichodermaspp. rather than mono cultures, which indicates that co-cultivation of beneficial fungi can stimulate the synthesis of novel secondary metabolites better than in monocultures. ZnO NPs were synthesized from fungal secondary metabolites of mono cultures of Trichoderma harzianum (PGT4), Trichoderma reesei (PGT5), Trichoderma reesei (PGT13) and co-culture (PGT4 + PGT5 + PGT13). These ZnO NPs were checked for antibacterial activity against Xoo, which was found to be of a dose-dependent manner. In summary, the biosynthesized ZnO NPs and secondary metabolites from co-culture ofTrichodermaspp. are ecofriendly and can be used as an alternative for chemical fertilizers in agriculture

Characterisation and bioactivity of oosporein produced by endophytic fungus <i>Cochliobolus kusanoi</i> isolated from <i>Nerium oleander</i> L.

<div><p>Bioactive compounds comprising secondary metabolites produced by endophytic fungi have wide applications in pharmacology and agriculture. Isolation, characterisation and evaluation of biological activities of secondary metabolites were carried out from <i>Cochliobolus kusanoi</i> an endophytic fungus of <i>Nerium oleander</i> L. The fungus was identified based on 18S rDNA sequence analysis. There are no reports available on the compounds of <i>C.</i><i>kusanoi</i> hence, antimicrobial metabolite produced by this fungus was extracted and purified by fractionation using hexane, diethyl ether, dichloromethane, ethyl acetate and methanol. Out of all the solvent fractions, the methanol fraction exhibited better antimicrobial activity which was further purified and characterised as oosporein. Oosporein from <i>C.</i><i>kusanoi</i> exhibited broad spectrum <i>in vitro</i> antimicrobial, antioxidant and cytotoxic activities. The characterisation and antioxidant activity of oosporein from <i>C</i>. <i>kusanoi</i> are reported for the first time.</p></div

Antimicrobial secondary metabolites from agriculturally important fungi as next biocontrol agents

Synthetic chemical pesticides have been used for many years to increase the yield of agricultural crops. However, in the future, this approach is likely to be limited due to negative impacts on human health and the environment. Therefore, studies of the secondary metabolites produced by agriculturally important microorganisms have an important role in improving the quality of the crops entering the human food chain. In this review, we have compiled information about the most important secondary metabolites of fungal species currently used in agriculture pest and disease management