Publications by authors named "Wijesundera R"

Gastrointestinal parasitic nematode (GIN) infections are the cause of severe losses to farmers in countries where small ruminants such as sheep and goat are the mainstay of livestock holdings. There is a need to develop effective and easy-to-administer anti-parasite vaccines in areas where anthelmintic resistance is rapidly rising due to the inefficient use of drugs currently available. In this review, we describe the most prevalent and economically significant group of GIN infections that infect small ruminants and the immune responses that occur in the host during infection with an emphasis on mucosal immunity.

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Serpulanines A (1), B (2), and C (3) have been isolated from extracts of the rare Sri Lankan macrofungus Serpula sp. The structures of 1, 2, and 3 were elucidated by a combination of spectroscopic and single-crystal X-ray diffraction analyses. Serpulanines A (1) and B (2) both contain the rare (E)-2-hydroxyimino hydroxamic acid functional group array.

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It is essential that major carbohydrate polymers in the lignocellulosic biomass are converted into fermentable sugars for the economical production of energy. Xylan, the major component of hemicelluloses, is the second most naturally abundant carbohydrate polymer comprising 20-40% of the total biomass. Endoxylanase (EXN) hydrolyzes xylan into mixtures of xylooligosaccharides.

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Background: Cellulose, a linear polymer of β 1-4, linked glucose, is the most abundant renewable fraction of plant biomass (lignocellulose). It is synergistically converted to glucose by endoglucanase (EG) cellobiohydrolase (CBH) and β-glucosidase (BGL) of the cellulase complex. BGL plays a major role in the conversion of randomly cleaved cellooligosaccharides into glucose.

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Colletotrichum is an important fungal genus with great diversity, which causes anthracnose of a variety of crop plants including rubber trees. Colletotrichum acutatum and Colletotrichum gloeosporioides have been identified as the major causative agents of Colletotrichum leaf disease of rubber trees in Sri Lanka based on morphology, pathogenicity, and the analysis of internally transcribed spacer sequences of the nuclear ribosomal DNA. This study has been conducted to investigate the members of the C.

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Background: Mushrooms inspired the cuisines of many cultures and conventional medicaments for cancer. However, a substantial number of mushroom species are yet unexplored, possessing an unknown chemical, biological and pharmacological profiles. Fulviformes fastuosus is a terrestrial mushroom, which is commonly found in Sri Lankan woodlands.

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Twenty distinct endophytic fungi were isolated from the surface-sterilized plant parts of and were identified using morphological and molecular techniques. At 300 µg/disc concentration, eight of the 20 fungal extracts exhibited antimicrobial activities against (ATCC 25923) and (ATCC 11778) while two within the eight showed activity against (ATCC 9027) and (ATCC 35218). Furthermore, investigation of the crude extract of resulted in the isolation of two known cytochalasans, chaetoglobosin A and C, and their structures were elucidated and confirmed by mass and nuclear magnetic resonance (NMR) (H, C, COSY, HSQC, HMBC and tROESY) spectral data.

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Background: Macrofungi have an established history of use in traditional oriental medicine. Anthracophyllum lateritium is a terrestrial macrofungus found in the dry zone forest reserves in Sri Lanka. Yet there are no scientific reports on bioactive properties of this species.

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Article Synopsis
  • Fungi are essential to ecosystems but their diversity and geographic patterns are not well understood.
  • Using DNA metabarcoding from soil samples worldwide, researchers found that fungal richness is not directly linked to plant diversity.
  • Key factors like climate, soil properties, and location mainly influence fungal richness and community composition globally, revealing trends similar to other organisms with some differences.
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An endophytic fungus was isolated from surface sterilized leaf segments of an orchid endemic to Sri Lanka, and was identified as sp. by morphological characters and DNA sequencing. Bioassay-guided chromatographic fractionation of the organic extract of a laboratory culture of this fungus led to the isolation of the known antibacterial helvolic acid.

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A large collection of strains belonging to the Fusarium solani species complex (FSSC) was isolated from soil and perithecia in primary forests in Sri Lanka (from fallen tree bark) and tropical Australia (Queensland, from fallen tree fruits and nuts). Portions of the translation elongation factor 1-alpha (tef1) gene, the nuclear large subunit (NLSU) and internal transcribed spacer regions (ITS) of the nuclear ribosomal RNA genes were sequenced in 52 isolates from soil and perithecia. The FSSC was divided previously into three clades with some biogeographic structure, termed Clades 1, 2 and 3.

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Dhilirolides A (1) to D (4), a family of secondary metabolites with a putative meroterpenoid biogenetic origin and the unprecedented dhilirane and isodhilirane carbon skeletons, have been isolated from laboratory cultures of the fruit-infecting fungus Penicillium purpurogenum collected in Sri Lanka. The structures of 1 to 4 were elucidated by interpretation of NMR data and a single crystal X-ray diffraction analysis of 1.

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The prevalence of Toxoplasma gondii in 86 street dogs from Sri Lanka was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 58 (67.

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Two new lanostane-type triterpenoids, 3alpha,16alpha-dihydroxylanosta-7,9(11),24-trien-21-oic acid (1) and 3alpha,16alpha,26-trihydroxylanosta-7,9(11),24-trien-21-oic acid (2), along with three known lanostanoids, 16alpha-hydroxy-3-oxolanosta-7,9(11),24-trien-21-oic acid (3), 3alpha-carboxyacetoxy-24-methylen-23-oxolanost-8-en-26-oic acid (4), and 3alpha-carboxyacetoxy-24-methyl-23-oxolanost-8-en-26-oic acid (5), have been isolated from the EtOAc extract of the fruiting body of Ganoderma applanatum. The structures of 1, 2, and 3 were determined directly by the interpretation of spectroscopic data, while the structures of 4 and 5 were assigned by comparison of spectroscopic data against literature values.

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Rhizoctonia solani is a destructive fungal pathogen of many economically important plants all over the world and the causative organism of sheath blight of rice in many tropical countries including Sri Lanka. A repetitive sequence from the genome of R. solani was cloned and characterized with a view to develop a DNA probe and a PCR diagnostic assay for detection of the fungus.

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Genetic variation of 42 isolates of Corynespora cassiicola, a destructive fungal pathogen of many economically important crop plants including rubber, was investigated using RAPD-PCR analysis. Five genetic groups were identified using RAPD-PCR profiles generated by eight random primers. Results indicate that there is a significant genetic variation among C.

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Scopoletin (7-hydroxy-6-methoxy coumarin) which inhibited the conidial germination of Corynespora cassiicola was isolated from the uninfected mature leaves of Hevea brasiliensis. Scopoletin was not detected in uninfected immature rubber leaves. The immature leaves produced scopoletin after being infected with C.

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The hexane extract of the stem bark of Gordonia dassanayakei showed high antifungal activity against plant pathogenic fungi Curvularia sp., Colletotrichum gloeosporioides, Rhizoctonia solani, Corynespora cassiicola, and Fusarium sp. A compound responsible for the antifungal activity was isolated and identified as 3-formyl-2,4-dihydroxy-6-methylbenzoic acid 3-hydroxy-4-(methoxycarbonyl)-2,5-dimethylphenyl ester (1).

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Corynespora cassiicola is the causal organism of the most devastating leaf disease of rubber in Sri Lanka. Cotton, cowpea, cucumber, eggplant, sesame, soybean, tobacco, and tomato also have been reported as hosts of C. cassiicola.

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Several 2,5-disubstituted furans, which are known to react with peroxyacids, singlet oxygen and other active forms of oxygen were tested as potential inhibitors, co-oxidants, or substrates for soybean lipoxygenase. The furan, 10,13-epoxy-octadeca-10,12-dienoic acid, methyl ester (IV) was converted by lipoxygenase or singlet oxygen or peroxyacid to the acyclic product, methyl 10,13-dioxo-octadec-11-enoate. Apparently furan IV is able to interact with an active site of lipoxygenase (Km = 220 microM).

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