Viridistratins A−C, Antimicrobial and Cytotoxic Benzo[j]fluoranthenes from Stromata of Annulohypoxylon viridistratum (Hypoxylaceae, Ascomycota)

During the course of our search for novel biologically active metabolites from tropical fungi, we are using chemotaxonomic and taxonomic methodology for the preselection of interesting materials. Recently, three previously undescribed benzo[j]fluoranthenes (1−3) together with the known derivatives truncatones A and C (4, 5) were isolated from the stromata of the recently described species Annulohypoxylon viridistratum collected in Thailand. Their chemical structures were elucidated by means of spectral methods, including nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS). The new compounds, for which we propose the trivial names viridistratins A−C, exhibited weak-to-moderate antimicrobial and cytotoxic activities in cell-based assays.

Biodegradation of hydrocarbon by marine-derived fungi isolated from oil-contaminated beach and mangrove soil in Western Visayas, Philippines

Napocor Power Barge 103 was dislodged from its moorings and then slammed onto the rocky shoreline of Barangay Botongon when Typhoon Yolanda made a landfall in northern Iloilo on November 8, 2013. The oil spilled contaminated about a kilometre of Estancia's coastline and partly that of neighbouring town of Batad in Northern Iloilo, Western Visayas, Philippines. The present study aimed to isolate and evaluate hydrocarbon-degrading (singly or in combination) abillities of indigenous fungal flora from oil contaminated beach and mangrove soils in these areas. Results showed a total of twenty genera of marine-derived fungi were isolated. These genera included Acremonium, Aspergillus, Cladosporium, Curvularia, Monilia, Paecilomyces, Penicillium, Trichoderma, Verticillium and Yeast. Among the species, Aspergillus fumigatus obtained the highest frequency of occurrence (43.06%). Penicillium sp1 (EB331) got the highest value for individual category on TPH (64.70%) and PAH (43.42%) degradation. The consortium of Aspergillus fumigatus and Paecilomyces sp1, A+D obtained the highest values of 69.38% and 66.59% on the degradation of TPH and PAH with the increased efficacy of 13.61% and 42.41% on two species consortia. Moreover, the consortium composed of Aspergillus fumigatus, Aspergillus cf. repens and Paecilomyces sp1, A+B+D also were the best degraders of TPH and PAH with the values of 67.87% and 66.95% and increased efficacy of . 13.33% and 47.10%, respectively.Aspergillus cf. repens (BB231) got the highest value (81.98%) on the degradation of alkanes. The consortium of Aspergillus fumigatus and A. niger, A+C were the best alkane degraders at 77.93%with increased efficacy of 8.0%. Finally, the consortium of Aspergillus niger, Paeclomyces sp1 and Penicillium sp1, C+D+E recorded the highest value at 76.99% on the degradation of total alkanes with increased efficacy of 2.20%. This study has demonstrated the hydrocarbon-biodegradtion potential of tropical fungi isolated from oil contaminated habitats useful for future bioremediation activities.

Screening for Antagonistic Tropical Fungi against Selected Maize and Bean Pathogens

Phytopathogens are known to be the leading cause of important plant diseases which result in significant losses in agricultural crops. The need to maintain the level of yield both quantitatively and qualitatively is vital in order to curb the losses. So far there has been a positive advance recognized in research to the use of tropical fungi as biocontrol agents. The objective of this study was to screen for antagonistic tropical fungi against selected phytopathogens of maize (Zea mays L.) and beans (Phaseolus vulgaris L.) namely Fusarium graminearum, Fusarium moniliforme, Pythium ultimum, and Colletotrichum lindemuthianum in vitro. A total of 87 tropical fungi isolates were collected from Kakamega tropical rainforest, Kenya. Dual culture experiment was carried out to screen the tropical fungi against the selected phytopathogens. The bioassay was performed in a completely randomised design in triplicate and the inhibition zones recorded after every week for three weeks. Differential biocontrol ability among nine tropical fungi was noticed against F. moniliforme with the percentage inhibition increasing over time. Fusarium solani was the most active antagonist with an inhibition of 64% while Phaeomarasmius sp. had the lowest activity of 19.1% against F. moniliforme. Epicoccum sp. inhibited the mycelial growth of P. ultimum by 38% and also inhibited C. lindemuthianum by 58%. None of the fungal antagonists inhibited the mycelial growth of F. graminearum. The outcome of this study indicates that tropical fungi can be used as biocontrol agents and can be further explored and developed into effective fungicides for management of phytopathogens.