Browsing by Author "Ul-Hassan, Syed Riyaz"

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Bioactive metabolites from an endophytic Cryptosporiopsis sp. inhabiting Clidemia hirta
(2013-11) Zilla, Mahesh; Qadri, Masroor; Pathania, Anup S.; Strobel, Gary A.; Nalli, Yedukondalu; Kumar, Sunil; Guru, Santosh K.; Bhushan, Shashi; Singh, Sanjay K.; Vishwakarma, Ram A.; Ul-Hassan, Syed Riyaz
An endophytic Cryptosporiopsis sp. was isolated from Clidemia hirta and analyzed for its secondary metabolites that lead to the isolation of three bioactive molecules. The compounds were purified from the culture broth of the fungus and their structures were determined by spectroscopic methods as (R)-5-hydroxy-2-methylchroman-4-one (1), 1-(2,6-dihydroxyphenyl)pentan-1-one (2) and (Z)-1-(2-(2-butyryl-3-hydroxyphenoxy)-6-hydroxyphenyl)-3-hydroxybut-2-en-1-one (3). Compound 1 exhibited significant cytotoxic activity against the human leukemia cell line, HL-60 with an IC50 of 4 μg/ml. This compound induced G2 arrest of the HL-60 cell cycle significantly. In addition, out of these compounds, 2 and 3 were active against several bacterial pathogens. Compound 2 was active against Bacillus cereus, Escherichia coli and Staphylococcus aureus with IC50 values varying from 18 to 30 μg/ml, and compound 3 displayed activity against Pseudomonas fluorescens with an IC50 value of 6 μg/ml. Compounds 2 and 3 are novel whereas compound 1 was reported earlier but the stereochemistry of its C-2 methyl is established for the first time.
An endophytic/pathogenic Phoma sp. from creosote bush producing biologically active volatile compounds having fuel potential
(2011-05) Strobel, Gary A.; Singh, Sanjay K.; Ul-Hassan, Syed Riyaz; Mitchell, Angela M.; Geary, Brad; Sears, Joe
A Phoma sp. was isolated and characterized as endophytic and as a pathogen of Larrea tridentata (creosote bush) growing in the desert region of southern Utah, USA. This fungus produces a unique mixture of volatile organic compounds (VOCs), including a series of sesquiterpenoids, some alcohols and several reduced naphthalene derivatives. Trans-caryophyllene, a product in the fungal VOCs, was also noted in the VOCs of this pungent plant. The gases of Phoma sp. possess antifungal properties and is markedly similar to that of a methanolic extract of the host plant. Some of the test organisms with the greatest sensitivity to the Phoma sp. VOCs were Verticillium, Ceratocystis, Cercospora and Sclerotinia while those being the least sensitive were Trichoderma, Colletotrichum and Aspergillus. We discuss the possible involvement of VOC production by the fungus and its role in the biology/ecology of the fungus/plant/environmental relationship with implications for utilization as an energy source.
Functionalized para-substituted benzenes as 1,8-cineole production modulators in an endophytic Nodulisporium species
(2014-08) Nigg, Jered; Strobel, Gary A.; Knighton, W. Berk; Hilmer, Jonathan K.; Geary, Brad; Ul-Hassan, Syed Riyaz; Harper, James K.; Valenti, Domenic J.; Wang, Yuemin
A Nodulisporium species (designated Ti-13) was isolated as an endophyte from Cassia fistula. The fungus produces a spectrum of volatile organic compounds (VOCs) that includes ethanol, acetaldehyde and 1,8-cineole as major components. Initial observations of the fungal isolate suggested that reversible attenuation of the organism via removal from the host and successive transfers in pure culture resulted in a 50 % decrease in cineole production unrelated to an overall alteration in fungal growth. A compound (CPM1) was obtained from Betula pendula (silver birch) that increases the production of 1,8-cineole by an attenuated Ti-13 strain to its original level, as measured by a novel bioassay method employing a 1,8-cineole-sensitive fungus (Sclerotinia sclerotiorum). The host plant produces similar compounds possessing this activity. Bioactivity assays with structurally similar compounds such as ferulic acid and gallic acid suggested that the CPM1 does not act as a simple precursor to the biosynthesis of 1,8-cineole. NMR spectroscopy and HPLC-ES-MS indicated that the CPM1 is a para-substituted benzene with alkyl and carboxyl substituents. The VOCs of Ti-13, especially 1,8-cineole, have potential applications in the industrial, fuel and medical fields.
Modulation of volatile organic compound formation in the Mycodiesel-producing endophyte Hypoxylon sp. CI-4
(2012-11) Ul-Hassan, Syed Riyaz; Strobel, Gary A.; Booth, Eric; Knighton, W. Berk; Floerchinger, Cody; Sears, Joe
An endophytic Hypoxylon sp. (strain CI-4) producing a wide spectrum of volatile organic compounds (VOCs), including 1,8-cineole, 1-methyl-1,4-cyclohexadiene and cyclohexane, 1,2,4-tris(methylene), was selected as a candidate for the modulation of VOC production. This was done in order to learn if the production of these and other VOCs can be affected by using agents that may modulate the epigenetics of the fungus. Many of the VOCs made by this organism are of interest because of their high energy densities and thus the potential they might have as Mycodiesel fuels. Strain CI-4 was exposed to the epigenetic modulators suberoylanilide hydroxamic acid (SAHA, a histone deacetylase) and 5-azacytidine (AZA, a DNA methyltransferase inhibitor). After these treatments the organism displayed striking cultural changes, including variations in pigmentation, growth rates and odour, in addition to significant differences in the bioactivities of the VOCs. The resulting variants were designated CI4-B, CI4-AZA and CI4-SAHA. GC/MS analyses of the VOCs produced by the variants showed considerable variation, with the emergence of several compounds not previously observed in the wild-type, particularly an array of tentatively identified terpenes such as α-thujene, sabinene, γ-terpinene, α-terpinolene and β-selinene, in addition to several primary and secondary alkanes, alkenes, organic acids and derivatives of benzene. Proton transfer reaction mass spectroscopic analyses showed a marked increase in the ratio of ethanol (mass 47) to the total mass of all other ionizable VOCs, from ~0.6 in the untreated strain CI-4 to ~0.8 in CI-4 grown in the presence of AZA. Strain CI4-B was created by exposure of the fungus to 100 µM SAHA; upon removal of the epigenetic modulator from the culture medium, it did not revert to the wild-type phenotype. Results of this study have implications for understanding why there may be a wide range of VOCs found in various isolates of this fungus in nature.
Muscodor sutura, a novel endophytic fungus with volatile antibiotic activities
(2012-07) Kudalkar, Priyanka S.; Strobel, Gary A.; Ul-Hassan, Syed Riyaz; Geary, Brad; Sears, Joe
Muscodor sutura is described as a novel species that is also an endophyte of Prestonia trifidi. Uniquely, this fungus produces a reddish pigment, on potato dextrose agar (PDA), when grown in the dark. In addition, the organism makes some volatile organic compounds that have not been previously reported from this genus, namely, thujopsene, chamigrene, isocaryophyllene, and butanoic acid, 2-methyl. These and other volatile compounds in the mixture possess wide-spectrum antifungal activity and no observable antibacterial activity. Most unusually, on PDA, the newly developing hyphae of this fungus grow in a perfect stitching pattern, in and out of the agar surface. The partial ITS–DNA sequence of this organism is identical to that of Muscodor vitigenus but it differs from all other Muscodor spp. Justification for a new species, as Muscodor sutura, is collectively based on morphological, cultural, chemical, and bioactivity properties.