Acetylcholinesterase inhibitory activity of stigmasterol & hexacosanol is responsible for larvicidal and repellent properties of Chromolaena odorata.

BACKGROUND: Chromolaena odorata, has been traditionally known for its insect repellent property. Aim of this study was to determine larvicidal tendency of C. odorata on Culex quinquefasciatus and isolate compounds responsible for this activity and to determine the mechanism of action of these compounds. METHODS: C. odorata plant extract was screened for mosquito larvicidal activity. The extract was fractionated using chromatography and the bioactive fraction showing larvicidal activity was identified. The chemical nature of the compounds in the bioactive fraction was determined using NMR and Mass spectrometry. RESULTS: We identified phytosterols and alkanols to be the compounds regulating larvicidal activity in the bioactive fraction of the plant extract. Stigmasterol and 1-hexacosanol were identified to be the chief orchestrators of larvicidal activity and their mode of action has been observed to be neurotoxicity. At a molecular level both stigmasterol and 1-hexacosanol were found to be inhibiting acetylcholinesterase activity in C. quinquefasciatus & A. aegypti. The acetylcholinesterase inhibitory effect was validated in vitro using recombinant acetylcholinesterase and ex vivo in larval homogenates of Culex and Aedes. Electrophysiological studies using electroantennography have shown enhanced neural response to these compounds. CONCLUSIONS: Neurotoxic effect of C. odorata derived stigmasterol and 1-hexacosanol, exerted through acetylcholinesterase inhibition was responsible for the mortality of C. quinquefasciatus, A. aegypti &Chironomus riparius. EAG studies pointed out hyper-excitability of the olfactory system by these compounds. GENERAL SIGNIFICANCE: These compounds are natural agents for mosquito control that can be used in vector control as larvicidal compounds, pending further investigations.

Aspergillus Secondary Metabolite Database, a resource to understand the Secondary metabolome of Aspergillus genus.

Aspergillus is a genus of ubiquitous fungi that are pathologically & therapeutically important. Aspergillus Secondary Metabolites Database (A2MDB) is a curated compendium of information on Aspergillus & its secondary metabolome. A2MDB catalogs 807 unique non-redundantsecondary metabolites derived from 675 Aspergillus species. A2MDB has a compilation of 100 cellular targets of secondary metabolites, 44 secondary metabolic pathways, 150 electron and light microscopy images of various Aspergillus species. A phylogenetic representation of over 2500 strains has been provided. A2MDB presents a detailed chemical information of secondary metabolites and their mycotoxins. Molecular docking models of metabolite-target protein interactions have been put together. A2MDB also has epidemiological data representing Aspergillosis and global occurrence of Aspergillus species. Furthermore a novel classification of Aspergillosis along with 370 case reports with images, were made available. For each metabolite catalogued, external links to related databases have been provided. All this data is available on A2MDB, launched through Indian Institute of Chemical Technology, Hyderabad, India, as an open resource http://www.iictindia.org/A2MDB . We believe A2MDB is of practical relevance to the scientific community that is in pursuit of novel therapeutics.