Isolation, Optimization of Production and Structure-Activity Relationship Studies of Monocillin I, the Cytotoxic Constituent of Paraphaeosphaeria quadriseptata

Natural Products from Plant-Associated Microorganisms: Distribution, Structural Diversity, Bioactivity, and Implications of Their Occurrence

“…84 Our pioneering work on nine strains of Sonoran desert plant-associated rhizosphere fungi has thus far resulted in the characterization of 41 metabolites of which 18 are new natural products. [85][86][87][88][89][90] Presented in Table 2 are the rhizosphere microorganisms investigated, their host plants, culture conditions employed for isolation of secondary metabolites, natural products encountered, and their biological activities.…”

“…14 Aspernigrin A, previously isolated from a marine strain of Aspergillus niger 32c has been re-isolated from Cladosporium herbarum endophytic in Cynodon dactylon and its structure was revised as 88. 32b Another endophytic fungus, Aspergillus fumigatus, occuring in C. dactylon has afforded the new antifungal metabolite, asperfumoid (89). 22a The nematicidal alkaloid, peniprequinolone (90), first isolated from the soil fungus Penicillium cf.…”

“…99b Several Sonoran desert plant-associated fungi that produce heat shock protein-90 (Hsp90) inhibitors were recently identified in an extensive program of screening these organisms for biologically relevant small molecule natural products. 30 In an attempt to investigate if production of these small molecule secondary metabolites by fungal symbionts might enhance the stress tolerance of their host plants by inducing the evolutionarily conserved heat shock response, monocillin I (30a) elaborated by the rhizosphere fungus, Paraphaeosphaeria quadriseptata, 89 was found to bind to Hsp90 and induce components of the heat shock response at the transcriptional and translational levels leading to the acquisition of a thermotolerant phenotype in seedlings of the model plant Arabidopsis thaliana; more significantly, it was also found that the growth of A. thaliana with the fungus can also confer thermotolerance. 100 These findings are consistent with previous observations (see above) that plant-fungal symbiosis can enhance thermotolerance in the wild 99 and they define a specific molecular mechanism of potential agricultural significance whereby mutualistic fungi may manipulate plant Hsp90 to enhance host plant survival in stressful environments.…”

A Rhizosphere Fungus Enhances Arabidopsis Thermotolerance through Production of an HSP90 Inhibitor

“…Extracts of the rhizosphere fungal strain Paraphaeosphaeria quadriseptata, which inhabits the Sonoran desert Christmas cactus (Opuntia leptocaulis DC. ; Cactaceae), contained MON in surprisingly high amounts-about 30% by weight of dry extract (Wijeratne et al, 2004). Extracts of the endophytic fungal strain Chaetomium chiversii, which colonizes the stem tissues of Mormon tea (Ephedra fasciculata A.…”

Novel antimicrobial secondary metabolites from a Penicillium sp. isolated from Brazilian cerrado soil

“…The isolation of 1 in such high yield is also of great importance since this compound can easily be used as a marker for the identification of this Penicillium species. Yield improvement can still take place since modifications in the growing conditions can adequately improve the amount of synthesized secondary metabolites (Wijeratne et al 2004;Nigam et al 2007). Cockrum et al (1979) used weetbix, yeast extract, sucrose and Difco mycological broth for a comparative study between an Australian and a North American isolate of Penicillium paxilli.…”