Synthesis of quinoline derivatives as diabetic II inhibitors and molecular docking studies

In searchof the potenttherapeutic agent as an α-glucosidase inhibitor, we have synthesized twenty-five analogs (1–25) of quinoline-based Schiff bases as an inhibitoragainst α-glucosidase enzyme under positive control acarbose (IC₅₀ = 38.45 ± 0.80 µM). From the activity profile it was foundthat analogs 1, 2, 3, 4, 11, 12 and 20with IC₅₀values 12.40 ± 0.40, 9.40 ± 0.30, 14.10 ± 0.40, 6.20 ± 0.30, 14.40 ± 0.40, 7.40 ± 0.20 and 13.20 ± 0.40 µMrespectively showed most potent inhibition among the series even than standard drug acarbose (IC₅₀ = 38.45 ± 0.80 µM). Here in the present study analog 4 (IC₅₀ = 6.20 ± 0.30 µM) was found with many folds better α-glucosidase inhibitory activity than the reference drug. Eight analogs like 5, 7, 8, 16, 17, 22, 24 and 25 among the whole series displayed less than 50% inhibition. The substituents effects on phenyl ring thereby superficially established through SAR study. Binding interactions of analogs and the active site of ligands proteins were confirmed through molecular docking study. Spectroscopic techniques like ¹H NMR, ¹³C NMR and ESIMS were used for characterization.     

Partial cloning and production of polyclonal antiserum against recombinant capsid protein of Hepatopancreatic Parvovirus (HPV) and its application for diagnostics in penaeid shrimp

Hepatopancreatic Parvovirus (HPV) causes infection in the early stages of shrimp leading to retarded growth, ultimaltely resulting in monetary loss to the shrimp farmers. To over come this situation screening of post-larvae (PL) by immunology-based diagnostics is required. Hence, the specific gene of capsid protein for HPV was cloned into pRSET B expression vector and rHCP overexpressed with 6-histidine tagged fusion protein in Escherichia coli BL21(DE3). Immunology-based methods like Western blot, dot blot and ELISA techniques were employed to detect HPV in infected samples using the antiserum raised in rabbits against recombinant HCP of HPV. The dot blot assay using anti-rHCP was found to be capable of detecting HPV in HPV infected post-larvae as early as at 24 h post infection. The antiserum could detect the HPV in the infected samples at 1 ng of total protein. HPV infection estimated by ELISA using anti-HCP and pure r-HCP as a standard was found to increase gradually during the course of infection from 24 h post infection. The sensitivity of antibody-based diagnostics employed in the present study was compared with that of PCR diagnostic method to screen the post-larvae for the detection of HPV.     

Inhibitors tethered near the acetylcholinesterase active site serve as molecular rulers of the peripheral and acylation sites

The acetylcholinesterase (AChE) active site consists of a narrow gorge with two separate ligand binding sites: an acylation site (or A-site) at the bottom of the gorge where substrate hydrolysis occurs and a peripheral site (or P-site) at the gorge mouth. AChE is inactivated by organophosphates as they pass through the P-site and phosphorylate the catalytic serine in the A-site. One strategy to protect against organophosphate inactivation is to design cyclic ligands that will bind specifically to the P-site and block the passage of organophosphates but not acetylcholine. To accelerate the process of identifying cyclic compounds with high affinity for the AChE P-site, we introduced a cysteine residue near the rim of the P-site by site-specific mutagenesis to generate recombinant human H287C AChE. Compounds were synthesized with a highly reactive methanethiosulfonyl substituent and linked to this cysteine through a disulfide bond. The advantages of this tethering were demonstrated with H287C AChE modified with six compounds, consisting of cationic trialkylammonium, acridinium, and tacrine ligands with tethers of varying length. Modification by ligands with short tethers had little effect on catalytic properties, but longer tethering resulted in shifts in substrate hydrolysis profiles and reduced affinity for acridinium affinity resin. Molecular modeling calculations indicated that cationic ligands with tethers of intermediate length bound to the P-site, whereas those with long tethers reached the A-site. These binding locations were confirmed experimentally by measuring competitive inhibition constants KI2 for propidium and tacrine, inhibitors specific for the P- and A-sites, respectively. Values of KI2 for propidium increased 30- to 100-fold when ligands had either intermediate or long tethers. In contrast, the value of KI2 for tacrine increased substantially only when ligands had long tethers. These relative changes in propidium and tacrine affinities thus provided a sensitive molecular ruler for assigning the binding locations of the tethered cations.     

Endogenous hormonal and enzymatic responses of Catharanthus roseus with triadimefon application under water deficits

The effect of triadimefon was investigated in a medicinal plant, Catharanthus roseus subjected to water deficit stress. The abscisic acid (ABA) level, DNA and RNA contents and activities of ATPase and protease were found varying in different parts of the plants under treatment. Drought treatment increased the ABA level more than twofold in all parts of the plants. TDM treatment to the drought stressed plants showed highest contents. In roots, stem and leaves, drought stress caused a decrease in the DNA and RNA contents when compared with control and other treatments. TDM treatment with drought increased the nucleic acid contents to the level of the control roots. The activity of ATPase and protease were increased under drought treatment and lowered due to TDM applications. This information could be useful in the field of soil water deficits reclamation efforts by using plant growth regulators.     

Efficiency of N uptake by wheat,as affected by time and rate of application,using N15-labelled ammonium sulphate and sodium nitrate

Summary The efficiency of N uptake by wheat was studied in field experiment, using N¹⁵-labelled (NH₄)₂SO₄ and NaNO₃. The N rate used was 120 kg N/Ha. It was applied in three split doses (at seeding, tillering and boot stage), in two split doses (at seeding and tillering stage) and in a single dose at seeding.The N applied at seeding, tillering and boot stage was actively used by wheat. However N applied at tillering stage was utilized most effectively. The single application of N was least productive for grain yield. Splitting the N fertilization increased the efficiency of applied N. The NO₃–N was most productive when applied in three split applications and produced significantly higher yield than single application. The NH₄–N was not as effective and its splitting beyond two doses did not benefit wheat. The A values and calculated effective rate of application (E.R.A.) also established the superiority of NO₃–N over NH₄–N. The E.R.A. proved useful in evaluating time of application as well.     

Epidemiology and molecular typing of Candida isolates from burn patients

This study, spread over a span of 2 years describes Candida infections in burn patients of an Indian hospital. A total of 220 burn patients were monitored and Candida could be isolated from 138 patients. A total of 228 different Candida species were obtained from various body locations of these patients. Species identification revealed that Candida albicans was the most predominant (45) followed by Candida tropicalis(33), Candida glabrata (13.5), C. parapsilosis (4), C. krusei (2.75) and C. kefyr (1.75). DNA fingerprinting of all C. albicans isolates was done by using CARE-2 probe. Fingerprinting analyses of all the C. albicans strains revealed that strains collected from different patients were different. It is noteworthy that patients with disseminated candidiasis had a similar, but unique strain isolated from all body locations, suggesting a possibility that commensal isolates might be turning pathogenic. Taken together, this is probably the first ever detailed survey of Candidainfections in burn patients in India and is expected to lead to better clinical management of this group of patients.     

Comparative study of movement patterns of Mastomys natalensis in irrigated rice and fallow fields in eastern Tanzania

A 2‐year capture–mark–recapture study was conducted to estimate home ranges and weekly travel distance of Mastomys natalensis (Smith 1834) in an irrigated rice ecosystem and fallow fields. We found that adults have larger home ranges than subadults in fallow fields but not in rice fields, indicating that fallow fields are more suitable for breeding. Travel distances were larger in rice fields, especially in the transplanting stage, during which rice fields are flooded and provide less food, causing movements into neighbouring fallow fields that then temporarily experience higher population density. A decrease in travel distance was observed in rice fields during the maturity stage, which can be explained by higher food availability and a more suitable, nonflooded situation. Movement of M. natalensis in rice‐fallow mosaic landscapes thus seems to be driven by food availability and flooding status of the rice fields, which can be attributed to land use practices.     

Foraging patterns and kleptoparasitism among three sympatric cormorants (Phalacrocorax spp.) from the Delhi region, North India

Cormorants, described as ‘foot-propelled pursuit divers’, constitute an important component of aquatic food webs and exhibit unique foraging behaviour patterns, which can be properly understood through a comparative study. Since, after a foraging dive they surface to ingest the prey, the intensity of kleptoparasitic attacks on the surface can have a major impact upon the net energetic gain for each individual. Inspite of the fact that cormorants and their habitats are severely threatened in India, their foraging behaviour has not been adequately studied. Such considerations prompted us to undertake field studies on three sympatric cormorants (Phalacrocorax spp.) at 60 different sites in the Delhi region of North India, during 2004–2007. By means of video photography, some key foraging parameters including group size, prey size and patterns of kleptoparasitic attacks were quantified. Along a loose body size gradient, we observed significant differences among the three species with respect to not only their preference for wetland size but also prey size. The frequency of a kleptoparasitic attacks depended upon the group size and foraging behaviour of each species. It was observed that several foraging bouts were abruptly terminated due to human disturbances, mostly at sites lying outside the protected areas. This observation points towards the need to conserve small waterbodies in the countryside, currently threatened by pollution and urbanization, for the benefit of a variety of waterbirds including cormorants.