Reconstruction of June–September precipitation based on tree-ring data of teak (Tectona grandis L.) from Hoshangabad, Madhya Pradesh, India

An attempt has been made to explore dendroclimatological potentiality of teak (Tectona grandis L.) towards the reconstruction of climate from a new geographical region. Growth of this tree has been found to be limited by the low monsoon precipitation. Based on ring-width data of teak, mean monsoon precipitation of June–September has been reconstructed back to AD 1835. The reconstructed climate records show several alternating periods of high and low monsoon episodes. Many of these low monsoon years have been recorded to coincide with most of the known principal drought years of India.     

2D- and 3D-QSAR modelling,molecular docking and in vitro evaluation studies on 18β-glycyrrhetinic acid derivatives against triple-negative breast cancer cell line

Abstract

Triple-negative breast cancers (TNBCs) are one of the most aggressive and complex forms of cancers in women. TNBCs are commonly known for their complex heterogeneity and poor prognosis. The present work aimed to develop a predictive 2D and 3D quantitative structure–activity relationship (QSAR) models against metastatic TNBC cell line. The 2D-QSAR was based on multiple linear regression analysis and validated by Leave-One-Out (LOO) and external test set prediction approach. QSAR model presented regression coefficient values for training set (r²), LOO-based internal regression (q²) and external test set regression (pred_r²) which are 0.84, 0.82 and 0.75, respectively. Five properties, Epsilon4 (electronegativity), ChiV3cluster (valence molecular connectivity index), chi3chain (retention index for three-membered ring), TNN5 (nitrogen atoms separated through 5 bond distance) and nitrogen counts, were identified as important structural features responsible for anticancer activity of MDA-MB-231 inhibitors. Five novel derivatives of glycyrrhetinic acid (GA) named GA-1, GA-2, GA-3, GA-4 and GA-5 were semi-synthesised and screened through the QSAR model. Further, in vitro activities of the derivatives were analysed against human TNBC cell line, MDA-MB-231. The result showed that GA-1 exhibits improved cytotoxic activity to that of parent compound (GA). Further, atomic property field (APF)-based 3D-QSAR and scoring recognise C-30 carboxylic group of GA-1 as major influential factor for its anticancer activity. The significance of C-30 carboxylic group in GA derivatives was also confirmed by molecular docking study against cancer target glyoxalase-I. Finally, the oral bioavailability and toxicity of GA-1 were assessed by computational ADMET studies.

Communicated by Ramaswamy H. Sarma     

Interaction of Salivary and Midgut Proteins of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> with Soybean Trypsin Inhibitor

Feeding of Helicoverpa armigera larvae on semi-synthetic diet containing Soybean trypsin inhibitor (STI) resulted in disappearance of STI sensitive protease in salivary and midgut protease extract. This might be due to in situ inhibition by dietary STI. STI was largely degraded within 1 h of incubation with total salivary protease (1:1). Degradation was relatively low in midgut proteases. STI interacting proteins were isolated from saliva and midgut extracts of larvae fed on STI supplemented diet using affinity column. Most of the isolated proteins showed caseinolytic activity in zymogram. Denovo sequencing data of seven different peptides selected from trypsin digested total protein showed similarity to chymotrypsinogen, serine protease, aminopeptidase N, peroxidase, hypothetical protein and muscle specific protein.