Introduction: Arsenic, an established poisonous metalloid has widespread occurrence in the environment which is posing a constant threat to health and survival of all living organisms. In view of arsenic induced oxidative stress and toxicity, this study focuses on the mitigatory role of thymoquinone, a major active component in the volatile oil of Nigella sativa (commonly known as black cumin); as its nutraceutical value can fulfil the demand of such dietary supplements in high risk population areas. Methods: In the current study, brain preparations of male wistar rats were used to assess different biochemical markers of oxidative stress and genotoxicity. Results: Significant and dose-dependent alterations in the level of enzymatic and biochemical biomarkers of oxidative stress were observed in the As-treated system. However, pre-treatment with thymoquinone brought about significant reduction in the As-induced neurotoxicity. Also, a significant decline in arsenic-induced DNA damage was recorded on pre-treatment with thymoquinone in comet assay. Conclusion: This study proves usefulness of antioxidant potential of thymoquione in mitigating the arsenic induced neurotoxicity.

The rising tide of antibacterial drug resistance has given rise to the virtual elimination of numerous erstwhile antibiotics, intensifying the urgent demand for novel agents. A number of drugs have been found to possess potent antimicrobial action during the past several years and have the potential to supplement or even replace the antibiotics. Many of these ‘non-antibiotics’, as they are referred to, belong to the widely used class of neuroleptics, the phenothiazines. Another chemically and pharmacologically related class is the thioxanthenes, differing in that the aromatic N of the central phenothiazine ring has been replaced by a C atom. Such “carbon-analogues” were primarily synthesized with the hope that these would be devoid of some of the toxic effects of phenothiazines. Intensive studies on syntheses, as well as chemical and pharmacological properties of thioxanthenes, were initiated in the late 1950s. Although a rather close parallelism with respect to structure activity relationships could be observed between phenothiazines and thioxanthenes; several thioxanthenes were synthesized in pharmaceutical industries and applied for human use as neuroleptics. Antibacterial activities of thioxanthenes came to be recognized in the early 1980s in Europe. During the following years, many of these drugs were found not only to be antibacterial agents but also to possess anti-mycobacterial, antiviral (including anti-HIV and anti-SARS-CoV-2) and anti-parasitic properties. Thus, this group of drugs, which has an inhibitory effect on the growth of a wide variety of microorganisms, needs to be explored for syntheses of novel antimicrobial agents. The purpose of this review is to summarize the neuroleptic and antimicrobial properties of this exciting group of bioactive molecules with a goal of identifying potential structures worthy of future exploration.

Objective: Oxidative stress contributes to the pathophysiology of exposure to environmental pollutants and to different free radical generating biochemical reactions in a human system leading to various types of age-related ailments. An antioxidant is a substance capable of preventing or slowing down oxidation of other molecules. Administration of different natural or synthetic antioxidants can ably lead to prevention and attenuation of such stress-induced biochemical alterations. Best examples of natural antioxidants are plant-derived flavonoids. The present study has been designated to determine antioxidant properties in antidepressant compound doxepin which is structurally similar to flavonoid quercetin.Methods: Antioxidant capacity in doxepin was determined with help of several standard conventional procedures such as phosphomolybdenum assay, Ferric ion and cupric ion reducing power assays, ferrous ion chelating activity assay, hydrogen peroxide, and nitric oxide scavenging activity assays.Results: Doxepin showed a stable rise in its antioxidant activity in a dose-dependent manner as determined by ferric as well as cupric ion reducing capacity and by phosphomolybdenum assay. An almost identical observation was noted while determining ferrous ion chelating activity. Furthermore, doxepin showed a strong nitric oxide scavenging activity in all the concentrations used in the study while its hydrogen peroxide scavenging activity was only observed at 500 µg/ml of doxepin.Conclusion: Thus, our study opens up a new vista in search for antioxidants not only from plant sources but also from clinically established pharmaceutical compounds that are already in practical use among patients.