While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) to maintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safety has motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/or interrupt propagation of autoxidation. Fat-soluble vitamin E (α-tocopherol) and water-soluble vitamin C (L-ascorbic acid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, often have strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is most often due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), phenolic diterpenes (carnosol, carnosic acid, rosmanol, and rosmadial), flavonoids (quercetin, catechin, naringenin, and kaempferol), and volatile oils (eugenol, carvacrol, thymol, and menthol). Some plant pigments (anthocyanin and anthocyanidin) can chelate metals and donate H to oxygen radicals thus slowing oxidation via 2 mechanisms. Tea and extracts of grape seeds and skins contain catechins, epicatechins, phenolic acids, proanthocyanidins, and resveratrol, all of which contribute to their antioxidative activity. The objective of this article is to provide an overview of natural antioxidants, their mechanisms of action, and potential applications.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1541-4337.2011.00156.x

Natural antioxidants: sources, compounds, mechanisms of action, and potential applications

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

Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products. Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many creative strategies emerged that deliver defined products via catalytic or biocatalytic depolymerization in good yields. The purpose of this review is to provide insight into these novel approaches and the potential application of such emerging new structures for the synthesis of biobased polymers or pharmacologically active molecules. Existing strategies for functionalization or defunctionalization of lignin-based compounds are also summarized. Following the whole value chain from raw lignocellulose through depolymerization to application whenever possible, specific lignin-based compounds emerge that could be in the fu...

Bright Side of Lignin Depolymerization: Toward New Platform Chemicals

A Novel Nanoparticle Drug Delivery System: The Anti-inflammatory Activity of Curcumin Is Enhanced When Encapsulated in Exosomes

Treatment of Brain Inflammatory Diseases by Delivering Exosome Encapsulated Anti-inflammatory Drugs From the Nasal Region to the Brain

http://www.thehealersbible.com/uploads/1/2/9/0/12907633/biological_activities_of_curcumin.pdf

Biological activities of curcumin and its analogues (Congeners) made by man and Mother Nature.

Abstract The conversion of arylaldehydes to 1,7-diaryl-5-hydroxyhepta-1,4,6-trien-3-ones (curcuminoids) and the mechanochemical cyclization of these products to 2,2-difluoro-4,6-bis(β-styryl)-1,3,2-dioxaborines using BF3-Et2O are described. Investigation of the cyanide ion sensing ability of the 2,2-difluoro-4,6-bis(β-styryl)-1,3,2-dioxaborines, in relation to the substituent groups on the aryl ring, showed that a hydroxy susbstituent is required, preferably para to the intervening carbon bridge.

Mechanochemical synthesis of 2,2-difluoro-4, 6-bis(β-styryl)-1,3,2-dioxaborines and their use in cyanide ion sensing

A high sensitivity refractive index semiconductor-insulator-semiconductor (SIS) waveguide with a ring resonator sensor at THz frequency is proposed. The topological study of the proposed filter is numerically simulated using the finite element method. A maximum sensitivity of 0.509 THz/ Refractive index unit (RIU) is obtained by filling the air-filled ring resonator cavity with different refractive index materials. Besides that, the transmission characteristics are studied by varying the structural dimensions and observed that the system can be treated as a frequency selective device. The device gets modified by incorporating another concentric ring inside the single ring. From the transmission characteristics, the multiple modes of the concentric dual ring are studied, and concluded that the even TM1 mode shows a better response towards frequency tuning.

High Sensitivity Refractive Index Sensor Based on Indium Antimonide Terahertz Plasmonic Ring Resonator

This paper proposes a tunable filter composed of a semiconductor-insulator-semiconductor (SIS) waveguide with a ring resonator at terahertz(THz) frequency. The two-dimensional study of the proposed structure has been done using the finite element method. It is observed that the device can be used for filtering THz frequency within the range of 0.4 THz to 0.9 THz by varying the structural parameters. The simulated structure is a promising candidate for an integrated optical circuit and terahertz devices as a filter. The results of the simulations are discussed in detail.

/pdf/indium-antimonide-based-terahertz-plasmonic-ring-resonator-15z7pq2t.pdf

Indium Antimonide Based Terahertz Plasmonic Ring Resonator Filter

/pdf/extraction-of-curcumin-from-turmeric-powder-through-1wfr4zgzmp.pdf

Sherin G. Thomas

Papers

Biological activities of curcumin and its analogues (Congeners) made by man and Mother Nature.

Mechanochemical synthesis of 2,2-difluoro-4, 6-bis(β-styryl)-1,3,2-dioxaborines and their use in cyanide ion sensing

High Sensitivity Refractive Index Sensor Based on Indium Antimonide Terahertz Plasmonic Ring Resonator

Indium Antimonide Based Terahertz Plasmonic Ring Resonator Filter

Extraction of Curcumin from Turmeric Powder Through Complexation