Picric acid, due to its low p K _a value, possesses distinct physicochemical features from all other nitroaromatic derivatives, enabling the design of fluorescent probes for its sensitive and selective detection.

Chemosensors that demonstrate a ratiometric change in fluorescence are in demand, but are scarce for nitroaromatic compounds owing to fluorescence quenching by nitro-aromatic compounds (NACs). Here, we report that the aggregates of the tricationic fluorescent-red chemosensor DMAS-TP in buffer undergo simultaneous fluorescence quenching at 615 nm and an increase in fluorescence intensity between 510–540 nm, revealing an unprecedented ratiometric behaviour for 2,4,6-trinitrophenol (TNP). The amplified fluorescence change in the FI_615nm/FI_521nm ratio from 57.67 to 30.18 (∼50%) with only 0.2 equivalents (2 μM) of TNP allows determination of TNP at a concentration as low as 2 nM. Paper strips coated with DMAS-TP differentiate TNP from other NACs through a fluorescence colour change from pink-red to blue with TNP only and provide unprecedented recognition of TNP from other NACs. In comparison to the only reported ratiometric probe for TNP, DMAS-TP provides advantages in terms of its usability in water and lower limit of detection. Furthermore, DMAS-TP adsorbed on silica nano-particles (10–20 nm) reveals a high fluorescence quantum yield (ϕ = 10.72%) with an emission maxima at approximately 615 nm, in the far-red region. These fluorescent silica nanoparticles NPs can be used to visualize latent fingerprints on a variety of substrates such as aluminium foil, metal sheets, coins, ceramic tiles and so on, with a high resolution and could be used in modern forensic applications.

Onosma bracteata Wall. is an important medicinal and immunity-enhancing herbs. This plant is commonly used in the preparation of traditional Ayurvedic drugs to treat numerous diseases. Inspired by the medicinal properties of this plant, the present study aimed to investigate the antiproliferative potential and the primary molecular mechanisms of the apoptotic induction against human osteosarcoma (MG-63) cells. Among all the fractions isolated from O. bracteata, ethyl acetate fraction (Obea) showed good antioxidant activity in superoxide radical scavenging assay and lipid peroxidation assay with an EC₅₀ value of 95.12 and 80.67 µg/mL, respectively. Silica gel column chromatography of ethyl acetate (Obea) fraction of O. bracteata yielded a pure compound, which was characterized by NMR, FTIR, and HR-MS analysis and was identified as 1,2-benzene dicarboxylic acid, bis (2-methyl propyl) ester (BDCe fraction). BDCe fraction was evaluated for the antiproliferative potential against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung carcinoma A549 cell lines by MTT assay and exhibited GI₅₀ values of 37.53 μM, 56.05 μM, and 47.12 μM, respectively. In MG-63 cells, the BDCe fraction increased the level of ROS and simultaneously decreased the mitochondria membrane potential (MMP) potential by arresting cells at the G₀/G₁ phase, suggesting the initiation of apoptosis. Western blotting analysis revealed the upregulation of p53, caspase3, and caspase9 while the expressions of p-NF-κB, p-Akt and Bcl-xl were decreased. RT-qPCR studies also showed upregulation in the expression of p53 and caspase3 and downregulation in the expression of CDK2, Bcl-2 and Cyclin E genes. Molecular docking analysis displayed the interaction between BDCe fraction with p53 (−151.13 kcal/mol) and CDK1 (−133.96 kcal/mol). The results of the present work suggest that the BDCe fraction has chemopreventive properties against osteosarcoma (MG-63) cells through the induction of cell cycle arrest and apoptosis via Akt/NF-κB/p53 pathways. This study contributes to the understanding of the utilization of BDCe fraction in osteosarcoma treatment.

1,2,4‐Triazolopyrimidines scaffold spaciously acknowledged with anticancer, antimalarial, antitubercular and many other fascinating biological applications in recent years (2015–2022). Moreover, numerous mild synthetic methodologies reported, which has been summarized as (i) condensation of 2‐amino‐1,2,4‐triazole or 5‐amino‐1,2,4‐triazole with 1,3‐dielectrophilic equivalents like 1,3‐diketones, β‐ketoester (ii) oxidative‐cyclization of hydrazones or related analogues. This review would flourish the synthetic and medicinal chemist to design more bioactive 1,2,4‐triazolopyrimidines molecules for drug development with enhanced binding interactions, structural features with the help discussed SAR and cost effective methodologies in the coming years.

The present study provides an insight into the difference in binding of monopodal (MPMB) and dipodal (DPDM) fluorescent probes in the cavity of serum albumins (SAs). The aggregates of DPDM show nearly 4-fold preference towards BSA (66-fold enhancement) over HSA (17-fold enhancement) in fluorescence intensity but aggregates of MPMB exhibit a similar response towards BSA, HSA and RNA. DPDM and MPMB do not show fluorescence responses to other proteins and biomolecules. The mechanism of interaction of these probes with SAs has been investigated through drug binding, fluorescence lifetime, fluorescence anisotropy, FT-IR, DLS, circular dichroism and docking studies. The docking and drug binding studies in consonance with each other show that MPMB preferably binds at the bilirubin site (subdomain IB) of BSA but DPDM undergoes a Z- to U-like conformation change during binding in the cavity of BSA and binds near to both the bilirubin and ibuprofen sites. The increase in lifetime of both DPDM and MPMB in the presence of BSA/HSA points to a dynamic mechanism of interaction. Probe DPDM detects as low as 14 nM BSA and 141 nM HSA but in the case of MPMB, the detection limits are 90 nM BSA and 30 nM HSA. The decrease in size of aggregates of DPDM from 34 nm to 6 nm in the presence of BSA (DLS) confirms the complexation of DPDM in its cavity.

A BTNN probe undergoes a 146 times increase in fluorescence intensity at 530 nm on lowering the pH from 7.0 to 2.0 and has been deployed for the bioimaging of MG-63 live cells and E. coli bacteria at different pH levels.