Elucidation of binding mechanism of rhodanine derivative P4OC on bovine serum albumin.

Rhodanine is an important scaffold in medicinal chemistry and it act as potent anticancer agent and other pharmacological effects. In pharmacokinetics and pharmacodynamics studies of the drug, the drug binding properties on serum protein is crucial for producing better drug. This study was designed to explore the binding interactions between the Rhodanine derivative (P4OC) on Bovine Serum Albumin (BSA). The interactions between P4OC and BSA were investigated using biophysical approach and molecular docking. The quenching mechanism and binding constants of P4OC on BSA were determined by biophysical approach through fluorescence spectroscopic experiments. Circular dichroism (CD) spectroscopy was used to study the secondary structural changes of BSA upon P4OC binding. The fluorescence experiments of P4OC binding on BSA show good drug binding with static quenching constants using stern Volmer plot and found the quenching constant value KP4OC = 1.12762 × 1013 M-1 with corresponding binding free energy (ΔG) -2.303 kcal/mol. The molecular displacement fluorescence emission on BSA-P4OC complex by site specific markers shows that P4OC binds at I A sub-domain of BSA further confirmed peak shift by synchronous fluorescence of P4OC on BSA with tyrosine, tryptophan and phenylalanine amino acids. Increasing concentration of P4OC on BSA found secondary structural changes, the percentage of α-helix was decreased as well increase percentage of ß-sheet and random coil. The binding of P4OC to BSA was computationally studied by molecular docking methods. Thus, results obtained are in excellent agreement with experimental and theoretical results with respect to the binding mechanism and binding constant of P4OC on BSA. We concluded that, the rhodanine derivative P4OC possesses good drug binding properties on BSA. Further P4OC may be evaluated its potential pharmacological activities on clinical trial.Communicated by Ramaswamy H. Sarma.

Capsanthin-Loaded Micelles: Preparation, Characterization and in vitro Evaluation of Cytotoxicity Using MDA-MB-231 Breast Cancer Cell Line.

Research background: Breast cancer is one of the most common cancers and remains a major cause of morbidity and mortality among women worldwide. In developed countries, breast cancer as a multifactorial disease is a major health concern, and its incidence is constantly rising in low and middle-income countries. Numerous studies have demonstrated that phytochemicals such as carotenoids inhibit breast cancer growth and induce apoptosis. We recently enhanced the solubility of capsanthin in water by encapsulating it in diosgenin polyethylene glycol succinate, a novel non-ionic surfactant. Thus, this study aims to evaluate the cytotoxicity of water-soluble capsanthin-loaded micelles in MDA-MB-231 cells in vitro through tetrazolium dye MTT assay. Experimental approach: In the current study, capsanthin, a hydrophobic carotenoid, is extracted from sweet red pepper (Capsicum annuum). Capsanthin-loaded diosgenin polyethylene glycol succinate 1000 (cap-DPGS-1000) micelles were prepared from capsanthin extract (cap) and diosgenin polyethylene glycol succinate 1000 (DPGS-1000) using the solid dispersion method. The capsanthin extract and cap-DPGS-1000 micelles were characterized by UV-visible spectroscopy, high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size distribution, polydispersity, and scanning electron microscopy (SEM). The effects of capsanthin extract and cap-DPGS-1000 micelles on a human triple-negative breast cancer cell line (MDA-MB-231) were tested to check the cell viability, proliferation and cytotoxicity of the micelles. Results and conclusions: The solubility of encapsulated cap-DPGS-1000 micelles in water is greatly enhanced and leads to an increased scope for localized drug delivery, a better delivery option for treating residual cancerous tumours. The encapsulated capsanthin showed a sustained release in simulated intestinal fluid (pH=6.8). Our research proposes a sustained drug delivery system that ensures effective and controlled release to the affected site. The characterization data revealed no change in the structure and functional groups in the encapsulated capsanthin. The IC50 value of the cap-DPGS-1000 micelles against MDA-MB-231 breast cancer cells was (3.10±1.09) µg/mL, which is much lower than of capsanthin extract ((81.1±1.5) µg/mL). Capsanthin extract and capsanthin-loaded micelles are promising drug candidates to induce apoptosis and increase reactive oxygen species (ROS) in cancer cells. Novelty and scientific contribution: The result shows the cytotoxic effect of capsanthin and capsanthin-loaded micelles on MDA-MB-231 cell line for the first time. Capsanthin from sweet red pepper (Capsicum annuum) showed remarkable cytotoxic effect on the triple-negative MDA-MB-231 cell line.

Comparison of the Anti-Obesity Effect of Enriched Capsanthin and Capsaicin from Capsicum annuum L. Fruit in Obesity-Induced C57BL/6J Mouse Model.

Research background: Obesity increases mortality and morbidity due to its impact on type 2 diabetes, cardiovascular and gastrointestinal diseases, arthritis and certain cancers. The epidemic of excessive mass and obesity require constant research to improve therapies without undesirable side effects. Therefore, exploring the anti-obesity phytochemicals from food sources is essential. Most pharmacological studies of the anti-obesity potential of Capsicum annuum have been directed towards capsaicin and very few towards capsanthin. However, these studies utilized uncoated capsaicin and capsanthin. This study aims to compare the anti-obesity effects of enteric-coated capsaicin and capsanthin in a high-fat diet-induced obesity in animal model. Experimental approach: In this study, we investigated the anti-obesity properties of capsanthin-enriched pellets and capsaicin pellets derived from red chili fruit (Capsicum annuum) on high-fat diet (HFD)-induced obesity in C57BL/6J mice. First, the animals received HFD to induce their obesity. Animals were supplemented orally with pellets. The food intake, body mass, obesity and clinical biomarkers were assessed. Results and conclusions: The mice fed with HFD gained body mass and white adipose tissue mass compared to the mice that consumed a normal diet. The oral administration of capsanthin-enriched pellets and capsaicin pellets significantly reduced the body mass gain. These pellets have a statistically significant (p<0.05) impact on obesity biomarkers by increasing adiponectin and decreasing leptin, free fatty acid and insulin concentrations relative to HFD control. There was no change in the liver mass in all groups, but there was a significant decrease in white adipose tissue amounts. Inguinal adipose tissue amount was reduced by 37.0% and that of epididymal adipose tissue by 43.64% after treatment with capsanthin-enriched pellets. These results suggest that capsanthin-enriched pellets and capsaicin pellets may be useful in combating metabolic diseases, including obesity, without adverse effects. Novelty and scientific contribution: We increased the content of capsanthin for more than 50% in capsanthin-enriched extract and extended the room temperature stability for more than one year by converting the crystals into capsanthin-enriched pellets. This study breaks new ground by examining the potential of capsanthin >50% in the management of obesity for the first time.

Capsanthin from Capsicum annum fruits exerts anti-glaucoma, antioxidant, anti-inflammatory activity, and corneal pro-inflammatory cytokine gene expression in a benzalkonium chloride-induced rat dry eye model.

Dry eye disease (DED) is a complex ocular surface inflammatory disease. Its occurrence varies widely over the world, ranging from 5% to 34%. The use of preservatives, specifically benzalkonium chloride, in the ocular drops worsens the DED conditions. Furthermore, the Covid-19 pandemic increased screen time and the use of face masks and shields. As a result, the number of people suffering from dry eye disease (DED) has increased significantly in recent years. The main objective of our study is to find a solution to manage the dry eye disease (DED) preferably from natural source without any adverse events. In this study, the beneficial effects of capsanthin from Capsicum annum (CCA) were evaluated on benzalkonium chloride (BAC)-induced dry eye disease (DED) in Albino Wistar rats. Oral supplementation of CCA resulted in a statistically significant decrease in intraocular pressure (IOP) (p < .0001), increase in tear break-up time (TBUT) (p < .01), decline in Schirmer test results (p < .01), and decrease in corneal surface inflammation (p < .01). Capsanthin ameliorated in reducing oxidative stress by increasing serum antioxidant levels such as glutathione peroxidase (GPX), nitric oxide (NO), and lactoferrin (LTF) and inhibiting matrix metalloproteinases 2 and 9 (MMP2 and MMP9) (p < .0001). Capsanthin treatment significantly inhibited the expression of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), interleukins (IL-2, IL-4, IL-6), and pro-inflammatory mediator, matrix metalloproteinase-9 (MMP9). Furthermore, the lacrimal gland expressed vascular cell adhesion molecule (VCAM-1), and prostaglandin-endoperoxide synthase 2 (PTGS2) was suppressed by CCA treatment. PRACTICAL APPLICATIONS: Benzalkonium chloride (BAC), a preservative widely used in the topical ocular drug delivery system (ODDS), causes undesirable effects such as dry eye disease as well as ameliorating intraocular pressure leading to optical nerve damage and irreversible vision loss. Capsanthin from Capsicum annum (CCA) can be used to treat symptoms related to dry eye disease such as inflammation, eye irritation, visual disturbance, ocular discomfort with potential damage to the ocular surface. The CCA may be beneficial in the treatment of glaucoma, an elevated intraocular pressure. Capsanthin from C. annum can be useful in managing DED by increasing tear break-up time (TBUT), declining in Schirmer test results and decreasing in corneal surface inflammation.