BackgroundThe chronic kidney disease of unknown etiology (CKDu) among paddy farmers in was first reported in 1994 and has now become most important public health issue in dry zone of Sri Lanka. The objective was to identify risk factors associated with the epidemic in an area with high prevalence.MethodsA case control study was carried out in Padavi-Sripura hospital in Trincomalee district. CKDu patients were defined using health ministry criteria. All confirmed cases (N = 125) fulfilling the entry criteria were recruited to the study. Control selection (N = 180) was done from people visiting the hospital for CKDu screening. Socio-demographic and data related to usage of applying pesticides and fertilizers were studied. Drinking water was also analyzed using ICP-MS and ELISA to determine the levels of metals and glyphosate.ResultsMajority of patients were farmers (N = 107, 85.6%) and were educated up to ‘Ordinary Level’ (N = 92, 73.6%). We specifically analyzed for the effect modification of, farming by sex, which showed a significantly higher risk for male farmers with OR 4.69 (95% CI 1.06-20.69) in comparison to their female counterparts. In the multivariable analysis the highest risk for CKDu was observed among participants who drank well water (OR 2.52, 95% CI 1.12-5.70) and had history of drinking water from an abandoned well (OR 5.43, 95% CI 2.88-10.26) and spray glyphosate (OR 5.12, 95% CI 2.33-11.26) as a pesticide. Water analysis showed significantly higher amount of hardness, electrical conductivity and glyphosate levels in abandoned wells. In addition Ca, Mg, Ba, Sr, Fe, Ti, V and Sr were high in abandoned wells. Surface water from reservoirs in the endemic area also showed contamination with glyphosate but at a much lower level. Glyphosate was not seen in water samples in the Colombo district.ConclusionThe current study strongly favors the hypothesis that CKDu epidemic among farmers in dry zone of Sri Lanka is associated with, history of drinking water from a well that was abandoned. In addition, it is associated with spraying glyphosate and other pesticides in paddy fields. Farmers do not use personnel protective equipments and wears scanty clothing due to heat when spraying pesticides.

Two new heptaketides, corynesporol (1) and 1-hydroxydehydroherbarin (2), along with herbarin (3) were isolated from an endolichenic fungal strain, Corynespora sp. BA-10763, occurring in the cavern beard lichen Usnea cavernosa. The structures of 1−3 were elucidated from their spectroscopic data. Aerial oxidation of corynesporol (1) yielded herbarin (3). Acetylation of 1 afforded the naphthalene derivative 4, whereas acetylation of 3 gave the corresponding naphthoquinone 6 and dehydroherbarin (5). All compounds were evaluated for their cytotoxicity and ability to inhibit migration of human metastatic breast and prostate cancer cell lines MDA-MB-231 and PC-3M, respectively. Dehydroherbarin (5) inhibited migration of both cell lines at concentrations not toxic to these cell lines. This is the first report of metabolites from an endolichenic fungus.

Aims: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. Methods and Results: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0AE6 and 1AE0 mg ml )1 , respectively. Aflatoxin production was completely inhibited at 0AE1 mg ml )1 . The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2AE80 and 3AE46 mg ml )1 , respectively. Conclusion: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. Significance and Impact of the Study: Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.

Chronic Kidney Disease of unknown etiology (CKDu) has escalated into an epidemic in North Central Province (NCP) and adjacent farming areas in the dry zone of Sri Lanka. Studies have shown that this special type of CKD is a toxic nephropathy and arsenic may play a causative role along with a number of other heavy metals. We investigated the hypothesis that chemical fertilizers and pesticide could be a source of arsenic. 226 samples of Fertilizers and 273 samples of pesticides were collected and analyzed using atomic absorption spectrometry and inductively coupled plasma mass spectrometry for arsenic and other heavy metals in two university laboratories. Almost all the agrochemicals available to the farmers in the study area are contaminated with arsenic. The highest amount was in triple super phosphate (TSP) with a mean value of 31 mg/kg. Also TSP is a rich source of other nephrotoxic metals including Cr, Co, Ni, Pb and V. Annually more than 0.1 million tons of TSP is imported to Sri Lanka containing approximately 2100 kg of arsenic. The next highest concentration was seen in the rock phosphate obtained from an open pit mine in NCP (8.56 mg/kg). Organic fertilizer contained very low amounts of arsenic. Arsenic contamination in pesticides varied from 0.18 mg/kg to 2.53 mg/kg although arsenic containing pesticides are banned in Sri Lanka. Glyphosate the most widely used pesticide in Sri Lanka contains average of 1.9 mg/kg arsenic. Findings suggest that agrochemicals especially phosphate fertilizers are a major source of inorganic arsenic in CKDu endemic areas. Organic fertilizer available in Sri Lanka is comparatively very low in arsenic and hence the farmers in CKDu endemic areas in Sri Lanka should be encouraged to minimize the use of imported chemical fertilizer and use organic fertilizers instead.

In an attempt to uncover the biosynthetic potential of plant-associated fungi, the effect of culture conditions on metabolite production by Paraphaeosphaeria quadriseptata and Chaetomium chiversii was investigated. These studies indicated that the production of the major metabolites by P. quadriseptata differ when the water used to make the media was changed from tap water to distilled water. It resulted in the isolation of six new secondary metabolites, cytosporones F-I ( 1- 4), quadriseptin A ( 5), and 5'-hydroxymonocillin III ( 6) together with monocillin III ( 7), a metabolite new to P. quadriseptata, in addition to monocillin I ( 8), a previously known metabolite from this organism. Aposphaerin B ( 9) encountered was suspected to be an artifact originating from cytosporone F ( 1). Incorporation of heavy metal ions to P. quadriseptata culture medium induced production of monocillin I ( 8) by this fungus. Cultivation of C. chiversii in liquid medium resulted in the isolation of chaetochromin A ( 12) as the major metabolite instead of radicicol ( 10), the major constituent of this organism when grown in a solid medium. Compounds 1- 7 and 12 were evaluated for their potential to inhibit Hsp90 and antiproliferative activity toward the cancer cell lines NCI-H460, MCF-7, and SF-268. Only compounds 6, 7, and 8 exhibited significant activity in both assays.