Observations on the herbivore diversity in a managed tea plantation and population dynamics of major insect pest in tea with regional weather

Globally, the pattern of incidence of insect pest complex has been changing in all agroecosystem due to climate change and variability. It is essential to know the incidence pattern of insect pest complex in tea for adopting successful management practice. An investigation was carried out to know the present incidence pest scenario of tea at Assam during March 2019 to Feb 2020. The results show the presence of four mite species belonging to single order and 4 families, and a total of 33 insect species belonging to 7 orders and 27 families. Among them red spider mite, tea mosquito bug, whitefly, leafhopper complex and thrips were recorded as important sucking pests. Leaf roller, tea tortrix, and flush worm were recorded as significant chewing pests. Observation shows that the tea whitefly, leaf hopper, thrips, leaf roller and flush worm has become a serious threat to the tea cultivation. The population dynamics of red spider mite and tea mosquito bug recorded a maximum incidence of 30.27 mites/ leaf and 27.17 infested flush/ bush respectively, during the month of November. Both insects were negatively regulated by maximum temperature and rainfall however relative humidity positively influenced population dynamics, as revealed by the correlation coefficient. This study paves way for the development of a new plant protection module to manage the emerging insect pests in tea plantation

Microwave-promoted one-pot synthesis of 4H-thiopyrans from a,b-unsaturated ketones via a three-component reaction

—An efficient one-pot synthesis of substituted 4H-thiopyrans has been accomplished from a three-component reaction of a,b-unsaturated ketones, Lawesson’s reagent and alkynes under microwave irradiation

Betel nut and tobacco chewing; potential risk factors of cancer of oesophagus in Assam, India

Cancer of the oesophagus is the most commonly diagnosed cancer in males in Assam, in north-eastern India, and ranks second for females. The chewing of betel nut, with or without tobacco and prepared in various ways, is a common practice in the region and a case–control study has been designed to study the pattern of risk associated with different ways of preparing and chewing the nuts. 358 newly diagnosed male patients and 144 female have been interviewed together with 2 control subjects for each case chosen at random from among the attendants who accompanied patients to hospital. There were significant trends in risk ratios associated with the frequency of chewing each day, with the duration of chewing in years and with the age at which the habit was started that were apparent for both males and females and which remained significant after allowance was made for other known risk factors, notably tobacco smoking and alcohol consumption. The adjusted ratios, in comparison with non-chewers, were 13.3 M and 5.7 F for chewing more than 20 times a day, 10.6 M and 7.2 F for persons who had chewed for more than 20 years and 10.3 M and 5.3 F for those who had started before the age of 20. Among the different combinations of ingredients that were chewed the adjusted odds ratios were highest for those who had been using fermented betel nut with any form of tobacco (7.1 M and 3.6 F). The risk associated with tobacco smoking and alcohol consumption, which are high in some parts of the world, were less in Assam than those associated with the chewing of betel nut. © 2001 Cancer Research Campaign http://www.bjcancer.co

Morphological characterization of sali rice accessions of North East India

Rice is a major cereal crop of Assam, North East India. The local rice accessions grown in this region possess unique traits of breeder’s choice i.e., tolerance to biotic and abiotic stresses. In the present investigation, 712 sali rice accessions of Assam were characterized using 20 qualitative and 13 quantitative traits. Among these, 19 qualitative traits showed distinct polymorphism except for the ligule colour. The maximum polymorphism was observed for apiculus colour followed by the colour of lemma palea and sterile lemma. The significant variation for the quantitative traits was recorded among the accessions. Lakhi Bilash and Borkamal were identified as the high yielding genotypes, which may be used further in breeding programmes. The cluster analysis using morphological traits based on the Euclidean distance matrix classified the accessions into the two distinct sub-groups. The high yielding accessions were grouped together in one cluster. A significant positive correlation was observed among the grain yield with the various panicle associated traits therefore, these may be used as selection criteria for development of high yielding rice varietiies

Morphological characterization of sali rice accessions of North East India

838-845Rice is a major cereal crop of Assam, North East India. The local rice accessions grown in this region possess unique traits of breeder’s choice i.e., tolerance to biotic and abiotic stresses. In the present investigation, 712 sali rice accessions of Assam were characterized using 20 qualitative and 13 quantitative traits. Among these, 19 qualitative traits showed distinct polymorphism except for the ligule colour. The maximum polymorphism was observed for apiculus colour followed by the colour of lemma palea and sterile lemma. The significant variation for the quantitative traits was recorded among the accessions. Lakhi Bilash and Borkamal were identified as the high yielding genotypes, which may be used further in breeding programmes. The cluster analysis using morphological traits based on the Euclidean distance matrix classified the accessions into the two distinct sub-groups. The high yielding accessions were grouped together in one cluster. A significant positive correlation was observed among the grain yield with the various panicle associated traits therefore, these may be used as selection criteria for development of high yielding rice varietiies

Endoperoxide antimalarials: development, structural diversity and pharmacodynamic aspects with reference to 1,2,4-trioxane-based structural scaffold

Mithun Rudrapal, Dipak Chetia Department of Pharmaceutical Sciences, Dibrugarh University, Dibrugarh, India Abstract: Malaria disease continues to be a major health problem worldwide due to the emergence of multidrug-resistant strains of Plasmodium falciparum. In recent days, artemisinin (ART)-based drugs and combination therapies remain the drugs of choice for resistant P. falciparum malaria. However, resistance to ART-based drugs has begun to appear in some parts of the world. Endoperoxide compounds (natural/semisynthetic/synthetic) representing a huge number of antimalarial agents possess a wide structural diversity with a desired antimalarial effectiveness against resistant P. falciparum malaria. The 1,2,4-trioxane ring system lacking the lactone ring that constitutes the most important endoperoxide structural scaffold is believed to be the key pharmacophoric moiety and is primarily responsible for the pharmacodynamic potential of endoperoxide-based antimalarials. Due to this reason, research into endoperoxide, particularly 1,2,4-trioxane-, 1,2,4-trioxolane- and 1,2,4,5-teraoxane-based scaffolds, has gained significant interest in recent years for developing antimalarial drugs against resistant malaria. In this paper, a comprehensive effort has been made to review the development of endoperoxide antimalarials from traditional antimalarial leads (natural/semisynthetic) and structural diversity of endoperoxide molecules derived from 1,2,4-trioxane-, 1,2,4-trioxolane- and 1,2,4,5-teraoxane-based structural scaffolds, including their chimeric (hybrid) molecules, which are newer and potent antimalarial agents. Keywords: endoperoxide, structural diversity, 1,2,4-trioxane, pharmacophore, pharmacodynamic, antimalaria

Design, molecular docking, drug-likeness, and molecular dynamics studies of 1,2,4-trioxane derivatives as novel Plasmodium falciparum falcipain-2 (FP-2) inhibitors

Despite significant progress made in drug discovery and development over the past few decades, malaria remains a life-threatening infectious disease across the globe. Because of the widespread emergence of drug-resistant strains of Plasmodium falciparum, the clinical utility of existing drug therapies including Artemisinin-based Combination Therapies (ACTs) in the treatment of malaria has been increasingly limited. It has become a serious health concern which, therefore, necessitates the development of novel drug molecules and/or alternative therapies to combat, particularly resistant P. falciparum. The objective of the present study was to develop 1,2,4-trioxane derivatives as novel antimalarial agents that would be effective against resistant P. falciparum. In our study, 15 new trioxane derivatives were designed by molecular modification of the 1,2,4-trioxane scaffold as possible antimalarial agents. Molecular modeling studies of trioxane derivatives were performed based on the CADD approach using Biovia Discovery Studio (DS) 2018 software. The protein-ligand docking study was performed against P. falciparum falcipain 2 (FP-2) using the simulation-based docking protocol LibDock by the flexible docking method. The assessment of drug-likeness, ADMET properties, and toxicity was also performed. Furthermore, the compounds CC3 and CC7, which showed the best binding affinity against the target P. falciparum FP-2, were investigated by molecular dynamics (MD) simulation studies followed by the calculation of MM-PBSA binding free energy of protein-ligand complexes using DS 2020. Results of the docking study showed that among the 15 compounds, three trioxane derivatives were found to possess promising binding affinity with LibDock scores ranging from 117.16 to 116.90. Drug-likeness, ADMET, and toxicity properties were found to be satisfactory for all the compounds. Among the 15 compounds, two compounds, namely CC3 and CC7, showed the highest binding affinity against FP-2 with LibDock score of 117.166 and 117.200, respectively. The Libdock score of the co-crystal inhibitor was 114.474. MD studies along with MM-PBSA calculations of binding energies further confirmed the antimalarial potential of the compounds CC3 and CC7, with the formation of well-defined and stable receptor-ligand interactions against the P. falciparum FP-2 enzyme. Additionally, the selectivity of trioxane hits identified as potential inhibitors of P. falciparum cysteine protease FP-2 was determined on human cysteine proteases such as cathepsins (Cat K and Cat L), which are host homologous. Finally, it was concluded that the newly designed 1,2,4-trioxane derivatives can be further studied for in vitro and in vivo antimalarial activities for their possible development as potent antimalarial agents effective against resistant P. falciparu