The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS create oxidative stress in different pathophysiological conditions. The reported chemical evidence suggests that dietary antioxidants help in disease prevention. The antioxidant compounds react in one-electron reactions with free radicals in vivo/in vitro and prevent oxidative damage. Therefore, it is very important to understand the reaction mechanism of antioxidants with the free radicals. This review elaborates the mechanism of action of the natural antioxidant compounds and assays for the evaluation of their antioxidant activities. The reaction mechanisms of the antioxidant assays are briefly discussed (165 references). Practical applications: understanding the reaction mechanisms can help in evaluating the antioxidant activity of various antioxidant compounds as well as in the development of novel antioxidants.

https://pubs.rsc.org/en/content/articlepdf/2015/RA/C4RA13315C

Free radicals, natural antioxidants, and their reaction mechanisms

The aim of this study was to screen various solvent extracts of whole plant of Torilis leptophylla to display potent antioxidant activity in vitro and in vivo, total phenolic and flavonoid contents in order to find possible sources for future novel antioxidants in food and pharmaceutical formulations. A detailed study was performed on the antioxidant activity of the methanol extract of whole plant of Torilis leptophylla (TLM) and its derived fractions {n-hexane (TLH), chloroform (TLC) ethyl acetate (TLE) n-butanol (TLB) and residual aqueous fraction (TLA)} by in vitro chemical analyses and carbon tetrachloride (CCl4) induced hepatic injuries (lipid peroxidation and glutathione contents) in male Sprague-Dawley rat. The total yield, total phenolic (TPC) and total flavonoid contents (TFC) of all the fractions were also determined. TLM was also subjected to preliminary phytochemical screening test for various constituents. The total phenolic contents (TPC) (121.9±3.1 mg GAE/g extract) of TLM while total flavonoid contents (TFC) of TLE (60.9 ±2.2 mg RTE/g extract) were found significantly higher as compared to other solvent fractions. Phytochemical screening of TLM revealed the presence of alkaloids, anthraquinones, cardiac glycosides, coumarins, flavonoids, saponins, phlobatannins, tannins and terpenoids. The EC50 values based on the DPPH (41.0±1 μg/ml), ABTS (10.0±0.9 μg/ml) and phosphomolybdate (10.7±2 μg/ml) for TLB, hydroxyl radicals (8.0±1 μg/ml) for TLC, superoxide radicals (57.0±0.3 μg/ml) for TLM and hydrogen peroxide radicals (68.0±2 μg/ml) for TLE were generally lower showing potential antioxidant properties. A significant but marginal positive correlation was found between TPC and EC50 values for DPPH, hydroxyl, phosphomolybdate and ABTS, whereas another weak and positive correlation was determined between TFC and EC50 values for superoxide anion and hydroxyl radicals. Results of in vivo experiment revealed that administration of CCl4 caused a significant increase in lipid peroxidation (TBARS) while decrease in GSH contents of liver. In contrast, TLM (200 mg/kg bw) and silymarin (50 mg/kg bw) co-treatment effectively prevented these alterations and maintained the antioxidant status. Data from present results revealed that Torilis leptophylla act as an antioxidant agent due to its free radical scavenging and cytoprotective activity.

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Antioxidant activity, total phenolic and total flavonoid contents of whole plant extracts Torilis leptophylla L

Oxidative stress has been identified as the root cause of the development and progression of several diseases. Supplementation of exogenous antioxidants or boosting endogenous antioxidant defenses of the body is a promising way of combating the undesirable effects of reactive oxygen species (ROS) induced oxidative damage. Plants have an innate ability to biosynthesize a wide range of non-enzymatic antioxidants capable of attenuating ROS- induced oxidative damage. Several in vitro methods have been used to screen plants for their antioxidant potential, and in most of these assays they revealed potent antioxidant activity. However, prior to confirming their in vivo therapeutic efficacy, plant antioxidants have to pass through several physiopharmacological processes. Consequently, the findings of in vitro and in vivo antioxidant potential assessment studies are not always the same. Nevertheless, the results of in vitro assays have been irrelevantly extrapolated to the therapeutic application of plant antioxidants without undertaking sufficient in vivo studies. Therefore, we have briefly reviewed the physiology and redox biology of both plants and humans to improve our understanding of plant antioxidants as therapeutic entities. The applications and limitations of antioxidant activity measurement assays were also highlighted to identify the precise path to be followed for future research in the area of plant antioxidants.

/pdf/significance-of-antioxidant-potential-of-plants-and-its-197epmv9yq.pdf

Significance of antioxidant potential of plants and its relevance to therapeutic applications.

Inflammation is a comprehensive array of physiological response to a foreign organism, including human pathogens, dust particles, and viruses. Inflammations are mainly divided into acute and chronic inflammation depending on various inflammatory processes and cellular mechanisms. Recent investigations have clarified that inflammation is a major factor for the progression of various chronic diseases/disorders, including diabetes, cancer, cardiovascular diseases, eye disorders, arthritis, obesity, autoimmune diseases, and inflammatory bowel disease. Free radical productions from different biological and environmental sources are due to an imbalance of natural antioxidants which further leads to various inflammatory associated diseases. In this review article, we have outlined the inflammatory process and its cellular mechanisms involved in the progression of various chronic modern human diseases. In addition, we have discussed the role of free radicals-induced tissue damage, antioxidant defence, and molecular mechanisms in chronic inflammatory diseases/disorders. The systematic knowledge regarding the role of inflammation and its associated adverse effects can provide a clear understanding in the development of innovative therapeutic targets from natural sources that are intended for suppression of various chronic inflammations associated diseases.

/pdf/role-of-antioxidants-and-natural-products-in-inflammation-4v41jz37i3.pdf

Role of Antioxidants and Natural Products in Inflammation

Advantages and challenges of the spray-drying technology for the production of pure drug particles and drug-loaded polymeric carriers

A review of the antioxidant potential of medicinal plant species

Microcapsules containing Morinda citrifolia L. microparticles were produced by a spray-drying technique using various proportions of κ-carrageenan and maltodextrin as the binding materials. In this work, the effects of spray-drying on the encapsulation yield, particle size, moisture content, DPPH scavenging activity, total phenolic content and total flavonoid content of the bioactive components of M. citrifolia L. were determined for different volume ratios in the inlet air temperature range of 90–140 °C. The results showed that the percentage of 2,2-diphenyl picrylhydrazyl (DPPH) scavenging activity of the spray-dried powder was the highest for the 1:2 ratio (volume ratio of M. citrifolia L. extract to additive solution) at 90 °C, with maltodextrin at a concentration of 33 mg/ml. The results also showed that the microcapsules had a regular spherical shape. The spray-dried M. citrifolia fruit extract showed high antioxidant activity (28.36% DPPH activity), thus suggesting that it might be useful as a food additive and/or ingredient under the above optimum operating conditions.

Microencapsulation of Morinda citrifolia L. extract by spray-drying

Spray drying accomplishes drying while particles are suspended in the air and is one method in the family of suspended particle processing systems, along with fluid-bed drying, flash drying, spray granulation, spray agglomeration, spray reaction, spray cooling, and spray absorption. This drying process is unique because it involves both particle formation and drying. The present paper reviews spray drying of fruit extracts, such as acai, acerola pomace, gac, mango, orange, cactus pear, opuntia stricta fruit, watermelon, and durian, and the effects of additives on physicochemical properties such as antioxidant activity, total carotenoid content, lycopene and β-carotene content, hygroscopy, moisture content, volatile retention, stickiness, color, solubility, glass transition temperature, bulk density, rehydration, caking, appearance under electron microscopy, and X-ray powder diffraction. The literature clearly demonstrates that the effect of additives and encapsulation play a vital role in determining the physicochemical properties of fruit extract powder. The technical difficulties in spray drying of fruit extracts can be overcome by modifying the spray dryer design. It also reveals that spray drying is a novel technology for converting fruit extract into powder form.

A Critical Review on the Spray Drying of Fruit Extract: Effect of Additives on Physicochemical Properties

A conventional solvent extract of Morinda citrifolia L. fruit was spray dried using adjuvant maltodextrin (5 wt.%). Spray drying was carried out according to the D-optimal design, and the independent variables selected were temperature and Mcore/Mwall. The spray drying process was optimised by using response surface methodology (RSM) for four different responses: moisture content (MC), DPPH scavenging activity, total phenolic content (TPC), and total flavonoid (TF). The effects of temperature and of the core to wall material ratio were found to be significant for all responses. The optimal spray drying condition for maltodextrin as binding material was found to be 1:1.5 (Mcore/Mwall, volume ratio of M. citrifolia L. extract to additive solution) at 95 Â°C. The experimental values of the response variables correspond well to the predicted values. The microparticles obtained in this study represent an interesting food additive for incorporation into functional foods due to the presence of antioxidants.

/pdf/optimisation-of-spray-drying-operating-conditions-of-morinda-4a3hdh3cwl.pdf

Optimisation of spray drying operating conditions of Morinda citrifolia L. fruit extract using response surface methodology

Both artificial and naturally occurring antioxidants have been reported to play major roles in protecting membranes and tissues from free radical and xenobiotic-induced oxidative damage (Burton, 1989; Carini et al, 1990) Most living organisms harbour both enzymatic and non-enzymatic systems that protect them against excessive reactive oxygen species However, various external factors (smoke, diet, alcohol and some drugs) and aging decrease the efficiency of these protective systems, thereby disrupting the redox equilibrium that is established under healthy conditions Thus, antioxidants that scavenge reactive oxygen species may be of great value in preventing the onset and propagation of oxidative diseases (Willet, 1994) Recently, more attention has been paid to the role of natural antioxidants, mainly phenolic compounds, which may have higher antioxidant activity than do conventional antioxidants, such as vitamins C, E and β-carotene (Vinson et al, 1995) The anti-oxidative effects of natural phenolic compounds, in pure form or in extracts from various plant sources (vegetables, fruits and medicinal plants), have been studied in vitro using a variety of model systems (Meyer et al, 1998; Pietta et al, 1998; Yen & Hsieh, 1998) Therefore, antioxidants, which can neutralize free radicals, may be of central importance in the prevention of carcinogenicity, cardiovascular disease and neurodegenerative changes associated with aging (Halliwell, 1994; Yu, 1994) Epidemiological studies have shown that the consumption of vegetables and fruits can protect humans against oxidative damage by inhibiting and/or quenching free radicals and reactive oxygen species (Ames et al, 1993)

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Rajesh Nithyanandam

Papers

A review of the antioxidant potential of medicinal plant species

Microencapsulation of Morinda citrifolia L. extract by spray-drying

A Critical Review on the Spray Drying of Fruit Extract: Effect of Additives on Physicochemical Properties

Optimisation of spray drying operating conditions of Morinda citrifolia L. fruit extract using response surface methodology

Phytochemical Constituents and Activities of Morinda citrifolia L.