DPPH antioxidant assay revisited

Aqueous extracts of 30 plants were investigated for their antioxidant properties using DPPH and ABTS radical scavenging capacity assay, oxygen radical absorbance capacity (ORAC) assay, superoxide dismutase (SOD) assay, and ferric reducing antioxidant potential (FRAP) assay. Total phenolic content was also determined by the Folin−Ciocalteu method. Antioxidant properties and total phenolic content differed significantly among selected plants. It was found that oak (Quercus robur), pine (Pinus maritima), and cinnamon (Cinnamomum zeylanicum) aqueous extracts possessed the highest antioxidant capacities in most of the methods used, and thus could be potential rich sources of natural antioxidants. These extracts presented the highest phenolic content (300−400 mg GAE/g). Mate (Ilex paraguariensis) and clove (Eugenia caryophyllus clovis) aqueous extracts also showed strong antioxidant properties and a high phenolic content (about 200 mg GAE/g). A significant relationship between antioxidant capacity and total phe...

https://faculty.missouri.edu/~glaserr/3700s14/Antioxidant_ORAC_et_al_jf803011r.pdf

Comparative study of antioxidant properties and total phenolic content of 30 plant extracts of industrial interest using DPPH, ABTS, FRAP, SOD, and ORAC assays.

https://cyberleninka.org/article/n/1146770.pdf

Effect of extraction solvent on total phenol content, total flavonoid content, and antioxidant activity of Limnophila aromatica

Humans perceive thousands of compounds as bitter. In sharp contrast, only ;25 taste 2 receptors (TAS2R) bitter taste receptors have been identified, raising the question as to how the vast array of bitter compounds can be detected by such a limited number of sensors. To address this issue, we have challenged 25 human taste 2 receptors (hTAS2Rs) with 104 natural or synthetic bitter chemicals in a heterologous expression system. Thirteen cognate bitter compounds for 5 orphan receptors and 64 new compounds for previously identified receptors were discovered. Whereas some receptors recognized only few agonists, others displayed moderate or extreme tuning broadness. Thus, 3 hTAS2Rs together were able to detect ;50% of the substances used. Conversely, though 63 bitter substances activated only 1–3 receptors, 19 compounds stimulated up to 15 hTAS2Rs. Our data suggest that the detection of the numerous bitter chemicals is related to the molecular receptive ranges of hTAS2Rs.

The molecular receptive ranges of human TAS2R bitter taste receptors.

IT may occasion some surprise to those men of science who are ill-acquainted with India, and who so frequently express the view that Governments are unappreciative of the importance of science to learn that as far back as 1886 the Government of India arranged for Dr. George (later Sir George) Watt, professor of botany in the Presidency College, Calcutta, to prepare a "Dictionary of the Economic Products of India". The six volumes of this standard work were published during the years 1889-99. In 1908 Sir George Watt published a condensed version, "The Commercial Products of India". Whatever the defects of these 'dictionaries', they have been of inestimable value to all interested in Indian natural products. The Wealth of India A Dictionary of Indian Raw Materials and Industrial Products. Raw Materials, Vol. 1. Pp. xxvii+254+39 plates. 15 rupees ; 24s. Industrial Products, Part 1. Pp. xii+182+8 plates. 8 rupees ; 12s. (New Delhi : Council of Scientific and Industrial Research, 1948.)

The Wealth of India

Desmodium gangeticum is herbal species which is widely used in the indigenous system of medicine and is reported to contain flavone and isoflavanoid glycosides. In view of its wide use and it's chemical composition, this study was aimed at examining the antioxidant activity of the extract of D. gangeticum. The extract was studied for diphenyl picryl hydrazyl (DPPH), nitric oxide, ferryl-bipyridyl and hypochlorous acid scavenging activity along with lipid peroxidation. Nitric oxide was generated using sodium nitroprusside and was studied using Griess reagent. In order to study the iron chelating capacity of the extract, the percentage ferryl-bipyridyl inhibition was studied. Hypochlorous acid scavenging activity was tested by measuring the inhibition of 5-thio-2-nitrobenzoic acid oxidation. The extract was also studied for lipid peroxidation assay by thiobarbituric acid-reactive substances (TBARS) method using rat brain homogenate. The results indicate that D. gangeticum extract has potent antioxidant activity.

/pdf/studies-on-the-antioxidant-activities-of-desmodium-1voloihfda.pdf

Studies on the antioxidant activities of Desmodium gangeticum.

Antimicrobial, wound healing and antioxidant activity of Plagiochasma appendiculatum Lehm. et Lind.

Saussurea costus: Botanical, chemical and pharmacological review of an ayurvedic medicinal plant

During the last several years, various chemical methods have been used for synthesis of a variety of metal nanoparticles. Most of these methods pose severe environmental problems and biological risks; therefore the present study reports a biological route for synthesis of zinc oxide nanoparticles using Pseudomonas aeruginosa rhamnolipids (RLs) (denoted as RL@ZnO) and their antioxidant property. Formation of stable RL@ZnO nanoparticles gave mostly spherical particles with a particle size ranging from 35 to 80 nm. The RL@ZnO nanoparticles were characterized by UV-visible (UV-vis) spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and thermal gravimetric analysis. The UV-vis spectra presented a characteristic absorbance peak at ∼ 360 nm for synthesized RL@ZnO nanoparticles. The XRD spectrum showed that RL@ZnO nanoparticles are crystalline in nature and have typical wurtzite type polycrystals. Antioxidant potential of RL@ZnO nanoparticles was assessed through 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, and superoxide anion free radicals with varying concentration and time of the storage up to 15 months, while it was found to decline in bare ZnO nanoparticles. Similarly, the inhibitory effects on β-carotene oxidation and lipid peroxidation were also observed. These results elucidate the significance of P. aeruginosa RL as effective stabilizing agents to develop surface protective ZnO nanoparticles, which can be used as promising antioxidants in biological system.

/pdf/biosynthesis-of-stable-antioxidant-zno-nanoparticles-by-25biwxa4f1.pdf

Ajay Kumar Singh Rawat

Papers

Studies on the antioxidant activities of Desmodium gangeticum.

Antimicrobial, wound healing and antioxidant activity of Plagiochasma appendiculatum Lehm. et Lind.

Saussurea costus: Botanical, chemical and pharmacological review of an ayurvedic medicinal plant

Biosynthesis of Stable Antioxidant ZnO Nanoparticles by Pseudomonas aeruginosa Rhamnolipids

Antiulcer and antimicrobial activity of Anogeissus latifolia.