Free radicals and other oxidants have gained importance in the field of biology due to their central role in various physiological conditions as well as their implication in a diverse range of diseases. The free radicals, both the reactive oxygen species (ROS) and reactive nitrogen species (RNS), are derived from both endogenous sources (mitochondria, peroxisomes, endoplasmic reticulum, phagocytic cells etc.) and exogenous sources (pollution, alcohol, tobacco smoke, heavy metals, transition metals, industrial solvents, pesticides, certain drugs like halothane, paracetamol, and radiation). Free radicals can adversely affect various important classes of biological molecules such as nucleic acids, lipids, and proteins, thereby altering the normal redox status leading to increased oxidative stress. The free radicals induced oxidative stress has been reported to be involved in several diseased conditions such as diabetes mellitus, neurodegenerative disorders (Parkinson’s disease-PD, Alzheimer’s disease-AD and Multiple sclerosis-MS), cardiovascular diseases (atherosclerosis and hypertension), respiratory diseases (asthma), cataract development, rheumatoid arthritis and in various cancers (colorectal, prostate, breast, lung, bladder cancers). This review deals with chemistry, formation and sources, and molecular targets of free radicals and it provides a brief overview on the pathogenesis of various diseased conditions caused by ROS/RNS.

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Free Radicals: Properties, Sources, Targets, and Their Implication in Various Diseases

Normal Cognitive Aging

Oxidative stress is a normal phenomenon in the body. Under normal conditions, the physiologically important intracellular levels of reactive oxygen species (ROS) are maintained at low levels by various enzyme systems participating in the in vivo redox homeostasis. Therefore, oxidative stress can also be viewed as an imbalance between the prooxidants and antioxidants in the body. For the last two decades, oxidative stress has been one of the most burning topics among the biological researchers all over the world. Several reasons can be assigned to justify its importance: knowledge about reactive oxygen and nitrogen species production and metabolism; identification of biomarkers for oxidative damage; evidence relating manifestation of chronic and some acute health problems to oxidative stress; identification of various dietary antioxidants present in plant foods as bioactive molecules; and so on. This review discusses the importance of oxidative stress in the body growth and development as well as proteomic and genomic evidences of its relationship with disease development, incidence of malignancies and autoimmune disorders, increased susceptibility to bacterial, viral, and parasitic diseases, and an interplay with prooxidants and antioxidants for maintaining a sound health, which would be helpful in enhancing the knowledge of any biochemist, pathophysiologist, or medical personnel regarding this important issue.

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Oxidative Stress, Prooxidants, and Antioxidants: The Interplay

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

https://link.springer.com/content/pdf/10.1186/s12934-018-0879-x.pdf

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

Alzheimer's disease (AD) is a devastating neurodegenerative disorder without a cure. Most AD cases are sporadic where age represents the greatest risk factor. Lack of understanding of the disease mechanism hinders the development of efficacious therapeutic approaches. The loss of synapses in the affected brain regions correlates best with cognitive impairment in AD patients and has been considered as the early mechanism that precedes neuronal loss. Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurodegenerative diseases including AD. Increased production of reactive oxygen species (ROS) associated with age- and disease-dependent loss of mitochondrial function, altered metal homeostasis, and reduced antioxidant defense directly affect synaptic activity and neurotransmission in neurons leading to cognitive dysfunction. In addition, molecular targets affected by ROS include nuclear and mitochondrial DNA, lipids, proteins, calcium homeostasis, mitochondrial dynamics and function, cellular architecture, receptor trafficking and endocytosis, and energy homeostasis. Abnormal cellular metabolism in turn could affect the production and accumulation of amyloid-β (Aβ) and hyperphosphorylated Tau protein, which independently could exacerbate mitochondrial dysfunction and ROS production, thereby contributing to a vicious cycle. While mounting evidence implicates ROS in the AD etiology, clinical trials with antioxidant therapies have not produced consistent results. In this review, we will discuss the role of oxidative stress in synaptic dysfunction in AD, innovative therapeutic strategies evolved based on a better understanding of the complexity of molecular mechanisms of AD, and the dual role ROS play in health and disease.

Oxidative Stress, Synaptic Dysfunction, and Alzheimer’s Disease

Free radicals are common outcome of normal aerobic cellular metabolism. In-built antioxidant system of body plays its decisive role in prevention of any loss due to free radicals. However, imbalanced defense mechanism of antioxidants, overproduction or incorporation of free radicals from environment to living system leads to serious penalty leading to neuro-degeneration. Neural cells suffer functional or sensory loss in neurodegenerative diseases. Apart from several other environmental or genetic factors, oxidative stress (OS) leading to free radical attack on neural cells contributes calamitous role to neuro-degeneration. Though, oxygen is imperative for life, imbalanced metabolism and excess reactive oxygen species (ROS) generation end into a range of disorders such as Alzheimer's disease, Parkinson's disease, aging and many other neural disorders. Toxicity of free radicals contributes to proteins and DNA injury, inflammation, tissue damage and subsequent cellular apoptosis. Antioxidants are now being looked upon as persuasive therapeutic against solemn neuronal loss, as they have capability to combat by neutralizing free radicals. Diet is major source of antioxidants, as well as medicinal herbs are catching attention to be commercial source of antioxidants at present. Recognition of upstream and downstream antioxidant therapy to oxidative stress has been proved an effective tool in alteration of any neuronal damage as well as free radical scavenging. Antioxidants have a wide scope to sequester metal ions involved in neuronal plaque formation to prevent oxidative stress. In addition, antioxidant therapy is vital in scavenging free radicals and ROS preventing neuronal degeneration in post-oxidative stress scenario.

Oxidative stress and neurodegenerative diseases: a review of upstream and downstream antioxidant therapeutic options.

Context: Ficus carica Linn (Moraceae) has been used in traditional medicine for a wide range of ailments related to digestive, endocrine, reproductive, and respiratory systems. Additionally, it is also used in gastrointestinal tract and urinary tract infection.Objective: This review gathers the fragmented information available in the literature regarding morphology, ethnomedicinal applications, phytochemistry, pharmacology, and toxicology of Ficus carica. It also explores the therapeutic potential of Ficus carica in the field of ethnophytopharmacology.Materials and methods: All the available information on Ficus carica was compiled from electronic databases such as Academic Journals, Ethnobotany, Google Scholar, PubMed, Science Direct, Web of Science, and library search.Results: Worldwide ethnomedical uses of Ficus carica have been recorded which have been used traditionally for more than 40 types of disorders. Phytochemical research has led to the isolation of primary as well as secondary metabol...

https://www.tandfonline.com/doi/pdf/10.3109/13880209.2014.892515

Traditional uses, phytochemistry and pharmacology of Ficus carica: A review

Herbs have always been the natural form of medicine in India. Medicinal plants have curative properties due to presence of various complex chemical substances of different composition which contain secondary metabolites such as alkaloids, flavonoids, terpenoids, saponin and phenolic compounds distributed in different parts of the plants. Ziziphus jujuba Mill, a member of the family Rhamnaceae, commonly known as Bor, is used traditionally as tonic and aphrodisiac and sometimes as Hypnotic-sedative and Anxiolytic, anticancer (Melanoma cells), Antifungal, Antibacterial, Antiulcer, Anti-inflammatory, Cognitive, Antispastic, Antifertility/contraception, Hypotensive and Antinephritic, Cardiotonic, Antioxidant, Immunostimulant, and Wound healing properties. It possesses allied compounds viz. Ascorbic acid, thiamine, riboflavin-bioflavonoids and Pectin A and various chemical substances like Mauritine-A; Amphibine-H; Jubanine-A; Jubanine-B; Mucronine-D and Nummularine-B. Sativanine-E. Frangufoline, Ziziphine-A to Q, betulinic acid colubrinic acid, alphitolic acid, 3-O-cis-p-coumaroylalphitolic acid, 3-O-transp­coumaroylalphitolic acid, 3-O-cis-p-coumaroylmaslinic acid, 3-O-trans-pcoumaroylmaslinic acid, oleanolic acid, betulonic acid, oleanonic acid, zizyberenalic acid and betulinic acid, jujubosides A, B, A1 B1 and C and acetyljujuboside B and the protojujubosides A, B and B1, saponin, ziziphin, from the dried leaves of Z. jujube - 3-O-a-L-rhamnopyranosyl (1-2)-a­arabinopyranosyl-20-O- (2,3)-di-O-acetyl-a-L-rhamnopyranosyl jujubogenin. Saponin from leaves and stem are 3-O- ((2-O- alpha - D - furopyranosyl - 3-O- beta - D -glucopyranosyl) - alpha - L - arabinopyranosyl) jujubogenin and (6'''-sinapoylspinosin, 6'''-feruloylspinosin and 6'''-p-coumaroylspinosin. The present review discusses photo-chemistry, pharmacology, medicinal properties and biological activities of Za jujuba and its usage in different ailments.

Phyto-Pharmacology of Ziziphus jujuba Mill- A Plant Review

This review describes information on the role of endophytic microorganisms and some of naturally occurring bioactive compounds obtained from endophytic fungi isolated from various host plants. In the recent past years, a great deal of information on the role of endophytes in nature has been collected. The main topics addressed are isolation of endophytes, host endophyte relationship, fungal endophyte, their diversity, physiological role of endophyte, biological activities and chemistry. Key words: Endophytic microorganisms, biological activity, endophyte diversity, antioxidation activity.

Raghunath T. Mahajan

Papers

Oxidative stress and neurodegenerative diseases: a review of upstream and downstream antioxidant therapeutic options.

Traditional uses, phytochemistry and pharmacology of Ficus carica: A review

Phyto-Pharmacology of Ziziphus jujuba Mill- A Plant Review

A review: Natural products from plant associated endophytic fungi

Biological aspects of proteolytic enzymes: A Review