A natural predominant flavanone naringenin, especially abundant in citrus fruits, has a wide range of pharmacological activities. The search for antiproliferative agents that reduce skin carcinoma is a task of great importance. The objective of this study was to analyze the anti-proliferative and apoptotic mechanism of naringenin using MTT assay, DNA fragmentation, nuclear condensation, change in mitochondrial membrane potential, cell cycle kinetics and caspase-3 as biomarkers and to investigate the ability to induce reactive oxygen species (ROS) initiating apoptotic cascade in human epidermoid carcinoma A431 cells. Results showed that naringenin exposure significantly reduced the cell viability of A431 cells (p<0.01) with a concomitant increase in nuclear condensation and DNA fragmentation in a dose dependent manner. The intracellular ROS generation assay showed statistically significant (p<0.001) dose-related increment in ROS production for naringenin. It also caused naringenin-mediated epidermoid carcinoma apoptosis by inducing mitochondrial depolarization. Cell cycle study showed that naringenin induced cell cycle arrest in G₀/G₁ phase of cell cycle and caspase-3 analysis revealed a dose dependent increment in caspase-3 activity which led to cell apoptosis. This study confirms the efficacy of naringenin that lead to cell death in epidermoid carcinoma cells via inducing ROS generation, mitochondrial depolarization, nuclear condensation, DNA fragmentation, cell cycle arrest in G₀/G₁ phase and caspase-3 activation.

Piperine is a nitrogenous pungent substance exhibiting multifunctional pharmacological properties. However, the mechanism underlying its anticancer potential is not well elucidated in human oral squamous carcinoma (KB) cell line. The anticancer potential of piperine was evaluated through potent biomarkers viz. reactive oxygen species (ROS), cellular apoptosis, and loss of mitochondrial membrane potential (MMP). In addition, cell cycle kinetics and caspases-3 activity were also carried out to confirm anticancer activity of piperine. Results showed that various concentrations (25–300 μM) of piperine exposure reduced the cell viability of KB cells significantly (P < 0.01). Piperine induced significant (P < 0.01) dose-related increment in ROS production and nuclear condensation. Moreover, piperine stimulated cell death by inducing loss of MMP, and caspase-3 activation. Cell cycle study revealed that piperine arrested the cells in G2/M phase and decreased the DNA content. Findings of this study suggest the efficacy of piperine in inducing cell death via the decrease in MMP and ROS liberation followed by caspase-3 activation and cell cycle arrest. Further assessment of the anticancer potency of piperine is needed for anticancer drug development.

Objective: Nanoemulsion of silymarin was developed and optimized. Materials and methods: Nanoemulsion was made by aqueous titration method. Sefsol 218 (5.8% v/v), Kolliphor RH40 and polyethylene glycol 400 (S_mix; 2:1; 28.99% v/v) were used as oil phase, surfactant and co-surfactant while distilled water (65.22% v/v) acted as an aqueous phase. Nanoemulsion was characterized on the basis of particle size, viscosity, electrical conductivity and refractive index. Further, in vitro release, in vivo pharmacokinetic study, stability study and cancer cell line studies were also performed. Results and discussion: The optimized formulation (NE9) with mean particle size of 21.24 nm showed a minimum viscosity of 9.59 cps, maximum drug release (97.75%) in 24 h. The NE9 formulation also showed higher AUC (p < .01) and C_max (p < .01) and shorter T_max (p < .05) compared with conventional and standard suspensions of silymarin. The stability study also showed considerably stable formulations at refrigerator temperature as compared with room temperature (p > .05). The cancer cell line studies also confirmed that silymarin nanoemulsion reduced the cell viability and increased ROS intensity and chromatin condensation (p < .05). Conclusion: Our results concluded that nanoemulsion may be an efficient carrier for oral delivery of silymarin against human hepatocellular carcinoma without damaging normal cells.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel etiological agent of coronavirus disease 2019 (COVID-19). Nigella sativa, commonly known as black seed or black cumin, has been a historical and traditional plant since thousands of years. Based on their therapeutic efficacy, the chief components of terpenoids and flavonoids were selected from N. sativa seeds and seed oil. This study was designed to check the antiviral efficacy of N. sativa main phytoconstituents against five potential targets of SARS-CoV-2 using in silico structure-based virtual screening approach. Out of twenty five phytocomponents, ten components showed best binding affinity against two viral proteins viz. N-terminal RNA binding domain (NRBD; PDB ID: 6M3M) of nucleocapsid protein and papain-like protease (PL-_PRO; PDB ID: 6W9C) of SARS-CoV-2 using AutoDock 4.2.6, AutoDock Vina and iGEMDOCK. PASS analyses of all ten phytocomponents using Lipinski’s Rule of five showed promising results. Further, druglikeness and toxicity assessment using OSIRIS Data Warrior v5.2.1 software exhibited the feasibility of phytocomponents as drug candidates with no predicted toxicity. Molecular dynamics simulation study of NRBD of SARS-CoV-2 nucleocapsid protein-alpha-spinasterol complex and PL-_PRO-cycloeucalenol complex displayed strong stability at 300 K. Both these complexes exhibited constant root mean square deviation (RMSDs) of protein side chains and Cα atoms throughout the simulation run time. Interestingly, PL-_PRO and NRBD are key proteins in viral replication, host cell immune evasion and viral assembly. Thus, NRBD and PL-_PRO have the potential to serve as therapeutic targets for N. sativa phytoconstituents in drug discovery process against COVID-19. Graphical Abstract Communicated by Ramaswamy H. Sarma