Purification, characterization and larvicidal activity of a potent bioactive compound asarone from leaves of Acorus calamus against the culician larval mosquitoes.

Mosquitoes are potent vectors by serving as agents to life-threatening diseases in humans. Increasing resistance in mosquitoes against existing insecticides and repellents brings new challenges and an opportunity to explore sustainable compounds. We chose six medicinal plants to screen potential bioactive compounds that could act as an insecticide. Among these, crude hexane leaf extract of Acorus calamus showed higher mortality percentage against Aedes aegypti and Culex quinquefasciatus. The LC50 and LC90 values were 151.86 ppm and 536.36 ppm, respectively, for the third instar A. aegypti larvae, and 174.70 ppm and 696.73 ppm, respectively, for C. quinquefasciatus. The treated larvae of both species showed morphological and physiological variations when compared to control. The GC-MS profile of purified fractions showed a single peak. Further, FT-IR and NMR analyses confirmed the propensity of the purified compound as trans asarone (phenylpropanoid; C12H16O3. LC50 and LC90 values of purified asasone-treated larvae were 2.35 ppm and 12.58 ppm, respectively, for A. aegypti and 2.15 ppm and 11.58 ppm, respectively, for C. quinquefasciatus. Treatment of different sub-lethal doses of asarone to mosquito larvae at various time intervals showed disruption of intestinal layers. By showing negligible toxicity to non-target organism, purified asarone has a great potential in vector management.

In silico analysis of carbohydrate-binding pockets in the lectin genes from various species of Canavalia.

Legumes are endowed with an opulent class of proteins called lectins that can detect tenuous variations in carbohydrate structures and bind them reversibly with high affinity and specificity. The genus Canavalia, in the family of Leguminosae, is considered to be an affluent source of lectin. An effort has been made to analyse the sequences encoded by the lectin gene and its carbohydrate binding pockets from three species of Canavalia, including C. virosa, C. rosea, and C. pubescens. Crude seed extract showed highest haemagglutination titer against buffalo RBCs and has high affinity to mannose and trehalose. Amplification of the lectin gene by gene-specific primers showed the presence of an 870 bp amplicon. Physicochemical characterization using various bioinformatic tools showed that the isoelectric point was below 7, suggesting that lectin molecules were acidic. A high aliphatic index and high instability index were observed, which indicated that lectin molecules were stable towards a wide range of temperatures. The occurrence of N-glycosylation sites at two sites was also identified in all three species. Prediction of secondary structure showed that approximately 59.05 %, 56.76 % and 54.88 % of the elements were random coils in the case of C. virosa, C. pubescens and C. rosea, respectively. Comparative modelling of the proteins and docking of hypothetical models with sugar moieties that inhibited the agglutination activity suggested that asparagine, serine, alanine, valine, tyrosine and threonine were the major residues involved in hydrogen bonding and other stacking interactions. This can further provide insights on its prospective antibiosis property.