Reactive species are produced in biological system because of redox reactions. The imbalance in pro-oxidant and antioxidant homeostasis leads to the production of toxic reactive oxygen and nitrogen species like hydrogen peroxide, organic peroxides, hydroxyl radicals, superoxide anion and nitric oxide. Inactivation of metabolic enzymes, oxidation of biomolecules and cellular damage are some of the prominent characteristics of reactive species. Similarly, oxidative stress has been associated with more than one hundred (100) pathologies such as atherosclerosis, diabetes, cardiovascular diseases, pancreatic and liver diseases, joint disorders, cardiac fibrosis, acute respiratory distress syndrome, neurological diseases (amyotrophic lateral sclerosis, Huntington's disorder, Parkinson's disease and Alzheimer's disease), ageing and cancer etc. The toxicity of reactive species is balanced by the integrated antioxidant systems, which include enzymatic and non-enzymatic antioxidants. Antioxidant therapies or defenses protect the biological sites by removing or quenching the free radicals (prooxidants). Medicinal plants can not only protect the oxidative damage, but also play a vital role in health maintenance and prevention of chronic degenerative diseases. This review will provide a valuable discussion of one hundred (100) well known medicinal plants, which may add to the optimization of antioxidants rank. Besides, some of the antioxidant evaluation techniques or mechanisms via which medicinal plants act as antioxidants are also described.

Background: Oxidative stress is one of the main contributing factors involved in cerebral biochemical impairment. The higher susceptibility of the central nervous system to reactive oxygen species mediated damage could be attributed to several factors. For example, neurons use a greater quantity of oxygen, many parts of the brain have higher concentraton of iron, and neuronal mitochondria produce huge content of hydrogen peroxide. In addition, neuronal membranes have polyunsaturated fatty acids, which are predominantly vulnerable to oxidative stress (OS). OS is the imbalance between reactive oxygen species generation and cellular antioxidant potential. This may lead to various pathological conditions and diseases, especially neurodegenerative diseases such as, Parkinson’s, Alzheimer’s, and Huntington’s diseases. Objectives: In this study, we explored the involvement of OS in neurodegenerative diseases. Methods: We used different search terms like “oxidative stress and neurological disorders” “free radicals and neurodegenerative disorders” “oxidative stress, free radicals, and neurological disorders” and “association of oxidative stress with the name of disorders taken from the list of neurological disorders. We tried to summarize the source, biological effects, and physiologic functions of ROS. Results: Finally, it was noted that more than 190 neurological disorders are associated with oxidative stress.

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Trachyspermum ammi (TA) is a traditional medicinal plant which can be considered as a source of natural antioxidants and can be used for a wide range of infectious diseases. Our objectives were to explore the biochemical efficacies of the aqueous and acetonic extract of TA with special emphasis on antimicrobial and antioxidant activities. Nutritional profile and phytochemical screening were performed by standard methods. The agar well diffusion method was used to assess the antimicrobial activity against ten (10) clinical bacterial strains and five (5) fungal stains. The free radical scavenging activity of the acetonic extract was estimated spectrophotometrically by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. In seeds of TA, the crude fat, crude fiber, vitamin C, moisture, ash contents, crude protein, TSS, total acidity, pH and total sugar were 4.6 ± 0.19%, 4.2 ± 0.1%, 13.5 ± 0.7%, 9.5 ± 0.19%, 11.5 ± 1.7%, 1.46 ± 0.2%, 1.1 ± 0.01%, 0.65 ± 0.01%, 5.75 ± 0.9% and 5.1 ± 0.9% respectively. TA tested positive for alkaloids, carbohydrates and sugar, phenolic compounds, flavonoids, protein and amino acid, gum and mucilage and tannins, while negative results were found for saponins. Antioxidant assessments by DPPH assay showed that acetonic extract of TA possess high radical-scavenging activity i.e., 71.0 ± 2.3%. Vitamin C was used as reference standard. Susceptibility testing of acetonic extract of TA revealed strong antibacterial activity against Staphylococcus aureus (zone of growth inhibition 13 mm), good activity against Salmonella typhi and Xanthomonas (with zone diameter of 12 mm), while TA was least active against Salmonella heidelberg (inhibition zone diameter of 5 mm), Klebsiella pneumoniae and Clostridium with 6 mm zone of inhibition. TA also exhibited maximum antifungal activity against Aspergillus niger (15 mm) and Entomola (11 mm). While least activity was observed against A. flavus and Alternaria alternata (inhibition zone diameter of 9 mm, each). Based on the experimental data, TA could be considered as a therapeutic agent to inhibit the free radical-mediated reactions in biological systems. However further molecular studies and mechanistic insights are needed.

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