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

https://opus.lib.uts.edu.au/bitstream/10453/30657/4/Final%20Revision_2_Unmarked%20without%20endnote%202014%2007%2028.pdf

Fouling and its control in membrane distillation-A review

Oil/water separation is a field of high significance as it has direct practical implications for resolving the problem of industrial oily wastewater and other oil/water pollution. Therefore, the development of functional materials for efficient treatment of oil-polluted water is imperative. In this feature article, we have reviewed the recent progress of oil/water separation technologies based on filtration and absorption methods using various materials that possess surface superwetting properties. In each section, we present in detail representative work and describe the concepts, employed materials, fabrication methods, and the effects of their wetting/dewetting behaviors on oil/water separation. Finally, the challenges and future research directions of this promising research field are briefly discussed.

Oil/water separation techniques: a review of recent progresses and future directions

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.

/pdf/antioxidant-activity-total-phenolic-and-total-flavonoid-3r0rqk74y6.pdf

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.

A review of the antioxidant potential of medicinal plant species

a b s t r a c t This paper primarily presents an overall review of the use of microalgae as a biofuel feedstock. Among the microalgae that have potential as biofuel feedstock, Chlorella, specifically, was thoroughly discussed because of its ability to adapt both to heterotrophic and phototrophic culture conditions. The lipid content and biomass productivity of microalgae can be up to 80% and 7.3 g/l/d based on the dried weight of biomass, respectively, making microalgae an ideal candidate as a biofuel feedstock. The set-up of the system and the biomass productivity of microalgae cultivated in an open pond and a photobioreactor were also compared in this work. The effect of the culture condition is discussed based on the twostage culture period. The issues that were discussed include the light condition and the CO2, DO and N supply. The microalgal productivities under heterotrophic and phototrophic culture conditions were also compared and highlighted in this work. The harvesting process and type of flocculants used to aid the harvesting were highlighted by considering the final yield of biomass. A new idea regarding how to harvest microalgae based on positive and negative charges was also proposed in this work. The extraction methods and solvents discussed were primarily for the conventional and newly invented techniques. Conversion processes such as transesterification and thermochemical processes were discussed, sketched in figures and summarized in tables. The cost–benefit analysis of heterotrophic culture and the cultivation system was highlighted at the end of this work. Other benefits of microalgae are also mentioned in this work to give further support for the use of microalgae as a feedstock for biofuel production.

Conversion of microalgae to biofuel

Tannins, phlobatannins, saponins, flavonoids, terpenoids, cardiac glycosides and alkaloids distribution in six Malaysian medicinal plants, where each medicinal plant belongs to different families were examined and compared. The plants used areAzadirachta indica, Centella asiatica, Emblica officinalis, Hibiscus rosa-sinensis, Imperata cylindrica, and Moringa oleifera. Qualitative analysis carried out on each plant shows that tannins, saponins, flavonoids, terpenoids and alkaloids were present in all the plants. Phlobatannins were found to be present in C. asiatica andM. oleifera only and were absent in the rest of the plants. Cardiac glycosides were present in A. indica, C. asiatica and I. cylindrica and found to be absent in E. officinalis, H. rosa-sinensis and M. oleifera. The significance of the phytochemical constituents with the respect to the role of these plants in traditional medicine treatment is discussed.

	 

	Key words: Medicinal plants, traditional medicine, phytochemical constituents.

https://www.academicjournals.org/article/article1380370874_Krishnaiah et al.pdf

Studies on phytochemical constituents of six Malaysian medicinal plants

Oxidants or reactive oxygen species are produced in our body during aerobic metabolism leading to many diseases such as cancer, cardiovascular diseases etc. Antioxidants are the chemicals that neutralize these oxidants. Natural antioxidants are the secondary metabolites of phytochemicals and are preferred over synthetic antioxidants, which are found to impose side effects. A review has been done on the effect of oxidants on human health and their neutralization by natural antioxidants. Major natural antioxidants and their plant sources, different recovery processes for antioxidants from plant matrices and the advantage of indirect supercritical fluid extraction over other processes are presented.

	 

	Key words: Free radical, secondary metabolites, oxidative stress, recovery processes, process parameters.

Rosalam Sarbatly

Papers

A review of the antioxidant potential of medicinal plant species

Conversion of microalgae to biofuel

Studies on phytochemical constituents of six Malaysian medicinal plants

Phytochemical antioxidants for health and medicine A move towards nature

A review of polymer nanofibres by electrospinning and their application in oil-water separation for cleaning up marine oil spills.