Screening Of Antioxidant Activity Research Articles

Антиоксидантні властивості деяких С5 заміщених 4-ариліміно-тіазолідин-2-онів

Aim. Expanding the synthetic potential of 4-arylimino-thiazolidin-2-ones; a study of reactivity; and primary screening for antioxidant activity of synthesized compounds. Materials and Methods. All chemicals were of analytical grade and commercially available. When performing the synthetic part of the work, reagents manufactured by Merck (Germany) and Sigma-Aldrich (USA) were used. All the reagents and solvents were used without further purification and drying. Methods of organic synthesis, physical and physical-chemical methods of analysis of organic compounds (NMR spectroscopy, elemental analysis) were used in the study. Results and Discussions. The peculiar pharmacological activities of 4-iminothiazolidin-2-ones prompted us to synthesize certain С5 substituted 4-arylimino-thiazolidin-2-ones and test them for antioxidant activity. The specified scaffold represents a convenient intermediate in order to afford С5 substituteds 4-arylimino-thiazolidin-2-ones. The active methylene group presence in C5 position of the basic scaffold provides an entry for its utilization in azo coupling and aldol condensation reactions leading to appropriate 5-aryl-hydrazono and 5-arylidene derivatives of 4-arylimino-thiazolidin-2-one generation. The structures of the obtained compounds were confirmed by 1H NMR spectroscopy and elemental analysis. The spectroscopic data of all compounds correspond to the proposed structures. The antioxidant activity of the synthesized compounds was measured in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. DPPH radical found many applications due to its high stability in a methanolic solution and intense purple color. In its oxidized form, the DPPH radical has an absorbance maximum at a wavelength of 517 nm. For the first time, antioxidant activity was identified among С5 substituted 4-arylimino-thiazolidin-2-ones. Conclusions. Based on azo coupling and aldol condensation reactions, structural modification of the C5 position of certain 4-arylimino-thiazolidin-2-ones was conducted. For all synthesized compounds, primary pharmacological screening for antioxidant activity was performed. Three highly active compounds with a pronounced antioxidant effect have been identified, which approach or exceed ascorbic acid in terms of activity. Key words: organic synthesis, 4-arylimino-thiazolidin-2-ones, 2,2-diphenyl-1-picrylhydrazyl, antioxidant activity

Screening of antioxidant activities and antioxidant constituents in less expolored Allium species grown under middle hill conditions of western Himalayas

Screening of antioxidant activities and antioxidant constituents in less expolored Allium species grown under middle hill conditions of western Himalayas

Screening of antioxidant and antibacterial activity of methanolic extract of Ipomoea aquatica leaf and stem against bacteria causes skin infection

Screening of antioxidant and antibacterial activity of methanolic extract of Ipomoea aquatica leaf and stem against bacteria causes skin infection

In Vitro Screening for Acetylcholinesterase Inhibition and Antioxidant Activity of Quercus suber Cork and Corkback Extracts.

Purpose Acetylcholinesterase (AChE) inhibitors are used to treat Alzheimer's patients because they enhance cholinergic neurotransmission. It is urgent to find new and efficient inhibitors from natural sources, highly bioavailable with low or no toxicity. The plant kingdom is extremely rich in a variety of compounds that are potent AChE inhibitors: flavonoids and other phenolic compounds have been recognized as promising Alzheimer's treatment agents. In this study, in vitro acetylcholinesterase inhibition, antioxidant activities, and total flavonoid and phenolic contents of ethanol-water extracts from Quercus suber cork and corkback were evaluated. Methods The acetylcholinesterase activity was determined by a colorimetric assay based on Ellman's methodology. The Folin–Ciocalteu colorimetric method was used for total phenolic content determination and the aluminium chloride method for the determination of total flavonoid content. Antioxidant activity assays were performed using the DPPH and FRAP assays. Results The acetylcholinesterase inhibitory activity from Q. suber cork and corkback ethanol-water extracts was as follows: 62% inhibition with corkback extracts over 0.5 mg/mL and around 49% inhibition in cork extracts over 1.0 mg/mL extracts' concentration. Regarding the DPPH radical scavenging activity, the concentrations of cork and corkback ethanol-water extracts required for 50% DPPH inhibition (IC50) were 3.2 μg/mL and 4.0–5.2 μg/mL. Corkback extracts are less effective than Trolox standard (3.2 μg/mL) but cork extracts showed the same free radical scavenging activity compared to Trolox. Cork and corkback extracts have antioxidant power of 750.9–775.4 mg TEAC/g extract and 1051.2–2052.4 mg TEAC/g extract, respectively, which are significantly higher than the ones obtained with Trolox: 19.6–21.0 mg TEAC/g extract (cork assays) and 57.4–66.3 mg TEAC/g extract (corkback assays). The amounts of total phenolic (TPC) and flavonoid (TFC) compounds were 8.7–32.3 mg GAE/g and 4.8–10.7 mg CE/g dry mass for cork and 5.4–5.7 mg GAE/g and 42.5 mg CE/g dry mass for corkback extracts, respectively, using catechin (CE) and GAE (gallic acid) as standards. Conclusion These findings demonstrate the remarkable potential of these extracts as valuable source of antioxidants with interesting acetylcholinesterase inhibitory activity.

The screening of antioxidant activities and FTIR analysis of Christia Vespertilionis leaves extracts

Reactive oxygen species (ROS) or free radicals may be harmful to our body as it can cause many health problems. Antioxidants can act as radical scavengers to prevent these mechanisms. Christia vespertilionis or butterfly wings is widely found in South East Asia, traditionally used for many medical benefits. There are limited data that can be found about this plant from all possible scientific sources. Therefore, this study aimed to analyze multiple C. vespertilionis leaves extracts for its antioxidants’ capacity and infrared analysis. Five different extracts of different solvents viz, hexane, hexane: ethyl acetate, ethyl acetate, ethyl acetate: methanol, and methanol were obtained from C. vespertilionis leaves. All the extracts were assessed for 2, 2-diphenyl-1-pierylhydrazyl (DPPH) scavenging ability and ferric reducing antioxidant power (FRAP) followed by Fourier transform infrared analysis. The DPPH radical scavenging activity of ethyl acetate: methanol showed high radical scavenging activity with the lowest IC50 value of 0.549 ± 0.02 mg/mL compared to other extracts while ethyl acetate: hexane has the highest FRAP value of 271.67 ± 0.93 AAE µg ascorbic acid/g. The rapid FTIR analysis revealed the present of O-H, C-H, C=O, C=C, C-O, and N-H predominantly in the extracts. This study provides the information for further application of C. vespertilionis on various pharmacological and phytochemical aspects as not many scientific studies can be found.

Screening of antioxidant and cytotoxic activities of several microalgal extracts with pharmaceutical potential

The bioactive molecules from microalgae have important properties such as antioxidant, anticancer, antiviral, antibacterial, antihypertensive, skin regenerative, neuroprotective, sunscreen, and, immunostimulatory effects. Bioactive molecules derived from microalgae is getting intense attention from pharmaceuticals, cosmetics and nutraceuticals industries because of these properties and numerous researches have been done to investigate the role of these bioactive molecules that can enlighten microalgal biotechnology to result in new nature derived pharmaceutical formulations. In this study we investigate antioxidant activities of crude extracts of G. Galdieria sulphuraria, Ettlia carotinosa, Neochloris texensis, Chlorella minutissima, Stichococcus bacillaris, Schizochytrium limacinum, Crypthecodinium cohnii, and Chlorella vulgaris with determining radical scavenging activity (RSA) by DPPH (2,2-diphenyl-1-picrylhydrazyl hydrate radical) method and total phenolic content by Folin-Ciocalteu method. Selected extracts according to their antioxidant activities cytotoxicity was evaluated after exposure to human hepatocellular liver carcinoma cells (HepG2) for 48 h. Antioxidant activities of these species ranged from 89 to 95% RSA (radical scavenging activity) while their phenolic contents were also very high, varied from 41 to 312 mg GAE (gallic acid equivalents)/mg extract. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay also showed microalgae has a potential to be used as a novel therapeutic compound.

Screening of Antibacterial and Antioxidant Activity from the Soft Corals Sinularia sp. and Sarcophyton sp. Origin Palu Bay, Central Sulawesi, Indonesia

This study aimed to evaluate the potential antibacterial and antioxidant activities of Sinulariasp. and Sarcophyton sp. from the Palu Bay, Central Sulawesi, Indonesia. Soft corals were identified as Sinulariasp. (SC1), Sinularia sp. (SC2), andSarcophytonsp. (SC3). Antibacterial activity was examined using agar diffusion well method. Antioxidant activity was measured by the DPPH radical scavenging method. The samples were macerated in MeOH: DCM. The crude extracts were partitioned with DCM, EtOAc, and BuOH. The crude extract of Sinulariasp. (SC2) showed a very strong antibacterial activity as it was able to inhibit the growth of Staphylococcus aureusand Escherichia coliup to 10 mg/mL. Sinularia sp. (SC1) crude extract showed strong activity againstS. aureus, whereas it showed moderate against E. coli.Sarcophyton sp. (SC3) crude extract showed moderate activity against S. aureus, whereas it showed weak against E. coli. The partition fractions of the three soft coral extracts had the potential to be a potent antioxidant agent.

Evaluation of TLC antioxidant activity and pytochemical screening of leaf extracts of Dischistocalyx Hirsutus C. B. Clarke

The study of phenolic compounds remains an area of ​​the future because of the antiviral, anti-tumor, anti-inflammatory, anti-allergy, anti-cancer, healing, antiseptic and antioxidant properties they possess. The aim of our study was to evaluate the antioxidant activity and to evaluate the phytochemicals from the extracts (aqueous, hydroethanolic and ethanolic) of the leaves of Dischistocalyx hirsutus (Acanthaceae), a plant of the Congolese pharmacopeia. Our study showed the presence of several families, namely anthocyanins, flavonoids, tannins, cardiotonic heterosides and saponins. The presence of these different chemical families is more marked with the hydroethanolic extract. The TLC analysis by DPPH revealed the antioxidant potential of the extracts.

Primary Screening of Antioxidant Activity, Total Polyphenol Content, Carotenoid Content, and Nutritional Composition of 13 Edible Flowers from Japan.

Thirteen edible flowers, which are used as food ingredients in Japan, were evaluated as possible sources of antioxidants and biological compounds. The nutritional composition, total polyphenol content (TPC), carotenoid content, and antioxidant activity of the edible flowers were determined based on the oxygen radical absorbance capacity (ORAC). Water was the main constituent of edible flowers, and carbohydrates were the primary macronutrients. The TPC of the edible flowers varied from 1.47 to 13.08 mg gallic acid equivalent/g fresh weight (FW). Carotenoids, including β-carotene and β-cryptoxanthin, were detected mainly in the edible flowers with petal colors ranging from yellow to orange, but especially in primula and cosmos yellow flowers, which have yellow petals. The ORAC value of the hydrophilic extract (HORAC) of edible flowers was higher than the ORAC value of the lipophilic extract (LORAC). The total antioxidant capacity (TAC) ranged from 33.03 to 320.36 μM Trolox equivalent/g FW. The highest TPC and TAC were observed in cosmos yellow flowers. On the basis of Pearson’s correlation coefficient, the HORAC value and the TPC of the analyzed edible flowers were highly correlated (r=0.736). This preliminary study indicates that edible flowers are a potential source of antioxidants, and the addition of edible flowers to the human diet may be associated with health benefits.

Screening for potential antidiabetes and antioxidant activities of selected plants from East Kalimantan, Indonesia

Abstract. Ramadhan R, Kristanti AN, Amirta R, Kusuma IW, Phuwapraisirisan P, Haqiqi MT, Saparwadi. 2019. Screening for potential antidiabetes and antioxidant activities of selected plants from East Kalimantan, Indonesia. Biodiversitas 20: 1820-1826. Ten selected plants in this study have been used traditionally in West Kutai, East Kalimantan as medicinal plants. This study aimed to screen and evaluate the in vitro antidiabetic and antioxidant activity of methanol extracts of selected plants from East Kalimantan. The antidiabetic activity was carried out by α-glucosidase inhibitory activity with maltose and sucrose as substrates while antioxidant activity was determined by free radicals scavenging activity against DPPH, ABTS and Nitric Oxide (NO). The results showed that Garcinia riedeliana extract had strong inhibitory activity with an IC50 value of 0.04 mg/mL followed by Shorea laevis, Pternandra azurea and Bridelia tomentosa with IC50 values of 0.12; 0.15 and 0.16 mg/mL in maltose respectively, while quercetin as positive control had an IC50 value of 0.08 mg/mL. G.riedeliana extract also showed good α-glucosidase inhibitory activity with an IC50 value of 0.23 mg/mL in sucrose as substrate. The results on antioxidant activity showed that all extracts have IC50 value against free radicals DPPH, ABTS, and nitric oxide. The most active extract as α-glucosidase inhibitory activity and antioxidant activity was G. riedeliana extract. These findings provide the scientific evidence that one species of medicinal plants from East Kalimantan might be potential as an antioxidant and α-glucosidase inhibitor.

Synthesis and characterization of di-Schiff based boronic structures: Therapeutic investigation against cancer and implementation for antioxidant

In the present work, anticancer applications of boronic acid compounds containing di-Schiff groups were carried out. The synthesized compounds (((1Z,1′Z)-([1,1′-biphenyl]-4,4′-diylbis(azanylylidene))bis(methanylylidene))bis(4,1-phenylene))diboronic acid (1); (((1Z,1′Z)-([1,1′-biphenyl]-4,4′-diylbis(azanylylidene))bis(methanylylidene))bis(3,1-phenylene))diboronic acid (2); 2-((bis((E)-(4-boronobenzylidene)amino)methylene)amino)acetic acid (3); (((1E,1′E)-(naphthalene-1,8-diylbis(azanylylidene))bis(methanylylidene))bis(4,1-phenylene))diboronic acid (4) were characterized with 1H NMR, 13C NMR, FTIR, SEM-EDX, TGA and UV–Vis.These compounds containing the boronic acid group were investigated for their therapeutic effects on Ishikawa endometrial cancer cells. Solutions were prepared at diverse concentrations of each compound and applied in accordance with the biological process. It has been shown that the compounds obtained decrease cell viability of Ishikawa endometrial cancer cells at different percentages. The ((1E, 1′E)-(naphthalene-1,8-diylbis(azanylyldene))bis(methanylidene)bis(4,1-phenylene)diboronic acid (4) showed the highest activity among those (1–4) compounds. However, the antioxidant activity screening was also investigated by various methods such as CUPRAC, DPPH, and ABTS. Each has exhibited meaningful activity in different processes.

Development of software for prediction and virtual screening of antioxidant activity of new synthesized azaheterocyclic compounds

Background: Increasing introduction of innovation technologies into medicine and pharmacology makes it possible to modify and develop further the methods of the development of new medicines. Such methods include virtual screening. In this article approaches to building software for virtual screening of nitric oxide (NO)scavengers in an important class of azaheterocyclic compounds are discussed.Methods: During the study period (from October 2017 to January 2019) the methods for the evaluation of antioxidant activity, as well as quantum-mechanical and statistical calculations were conducted. Quantum-mechanical calculations on HOMO (highest occupied molecular orbital) energy and LUMO (lowest unoccupied molecular orbital) energy descriptors have been conducted using program complex WinMopac 7.2.Results: Evaluation methods of antioxidant activity, quantum-mechanical and statistical calculations have been presented. The algorithm for computer program of virtual screening has been proposed. Prospects and benefits of computer modeling of agent activity are considered.Conclusions: Establishment of computer program for virtual screening will significantly reduce time and resources during researching new synthesized compounds. The algorithm for a computer program of virtual screening has been developed Predictable antioxidant activity data on nitric oxide radical (NO·)inhibition may be calculated in percentage using HOMO and LUMO as the input data for this program.

HPTLC, HPTLC-MS/MS and HPTLC-DPPH methods for analyses of flavonoids and their antioxidant activity in Cyclanthera pedata leaves, fruits and dietary supplement

HPTLC silica gel, amino and C18 plates in combination with different developing solvents were explored for the first HPTLC chemical profiles of flavonoids and sugars in crude extracts from leaves and fruits of caigua (Cyclanthera pedata Scrabs) harvested in Slovenia and Italy. New HPTLC and HPTLC-MS methods for analyses of flavonoids are based on HPTLC silica gel (preconditioned with water) or C18 plates in combination with developing solvents ethyl acetate–water–formic acid (17:3:2, v/v) or 5% formic acid in methanol-water (7:3, v/v), respectively. Detection was performed before (for flavonoids) and/or after post-chromatographic derivatization with Natural product (NP) reagent for flavonoids and diphenylamine-aniline-phosphoric acid (DAP) reagent for sugars. HPTLC–MS/(MSn) analyses on silica gel and C18 stationary phases enabled tentative identification of several compounds in crude extracts from leaves and fruits. HPTLC-DPPH• assay combined with image analyses and HPTLC–MS/(MSn) analyses, applied for direct screening of antioxidant activity of separated chromatographic zones (compounds) on HPTLC silica gel plates, confirmed activity in several zones of all crude extracts, in which some active compounds were tentatively identified. Apigenin 6-C-glucoside (isovitexin) and luteolin 8-C-glucoside (orientin) were found in all crude extracts, but the last was the most active free radical scavenger. Both compounds were also identified in dietary supplement product produced from caigua fruits. Crude extracts from leaves showed much higher antioxidant activity than those from fruits. The highest antioxidant activity was determined for crude extract from leaves harvested in Slovenia, while among crude extract from fruits the highest activity was determined for the extract from fruits harvested in Italy.

Essential Oil from Aerial Parts of Wild Algerian Rosemary: Screening of Chemical Composition, Antimicrobial and Antioxidant Activities

Essential oils from the aerial parts of 15 samples of Algerian Rosmarinus officinalis L. were analysed by gas chromatography (GC) and Gas chromatography/mass spectroscopy. Thirty eight components have been characterized; among the monoterpene hydrocarbons α-pinene, camphene and limonene were individuated as the main components; camphor, 1,8-cineole and borneol were the principal oxygenated compounds, caryophyllene, α-bisabolol and partly humulene were the most represented sesquiterpenes. The scavenging activity of the oils was determined by the DPPH model system. The SC50 (Scavenging Concentration) values were in the range 120.4-326.1 μL/mL, representing a moderate antioxidant effectiveness. Essential oils were evaluated for their antimicrobial activity against Escherichia coli and Staphylococcus aureus; as well as against ten fungal strains belonging to Aspergillus, Alternaria, Candida, Fusarium, Penicillium and Saccharomyces genera. The results showed a moderate antimicrobial activity. The Algerian rosemary essential oils could be promising sources of biologically active compounds if they receive further studies on their biological properties.

Phytochemical screening for Antioxidant and Antifungal activity of Lagenaria siceraria (Molina) Standl. leaf extract

Phytochemical screening for Antioxidant and Antifungal activity of <i>Lagenaria siceraria</i> (Molina) Standl. leaf extract

A screening of anti-breast cancer effects and antioxidant activity of twenty medicinal plants gathered from Chaharmahal va Bakhtyari province, Iran

Context: Breast cancer is one of the most prevalent cancers that causes substantial numbers of deaths among women, worldwide. Medicinal plants can be used for discovering new anti-breast cancer drugs. Aim: To investigate the antioxidant effects of twenty Iranian herbs and their anticancer effects against breast cancer cell lines (i.e. MDA-MB231 and MCF-7) compared with a non-cancerous human cell line (HDF). Methods: In this study, the plant samples were collected from different regions of Chaharmahal va Bakhtyari province in Iran and their hydroalcoholic (ethanol: water; 70:30) extracts prepared by maceration method. Antioxidant activity was investigated by DPPH with reference to butylated hydroxytoluene (BHT). Anticancer effects were investigated by MTT colorimetric assay. Results: Most of the plants examined in this study had higher antioxidant activity than that of BHT. Satureja bachtiarica (37.27 ± 1.56 µg/mL), Plantago lanceolata (43.19 ± 4.67 µg/mL), Parietaria judaica (45.34 ± 8.08 µg/mL), Stachys inflata (53.70 ± 1.80 µg/mL), and Euphorbia szovitsii (55.78 ± 1.37 µg/mL) inhibited the DPPH free radicals in the lower concentration compared to BHT (120.48 ± 1.42 µg/mL) and other plants. MTT assay showed that the lowest IC50s values were observed for E. microsciadia and E. szovitsii among the examined plants on both breast cancer cell lines. There was no significant relationship between anticancer effects and antioxidant activity of the plants (p&gt;0.05). Conclusions: The examined plants might be considered as valuable resources of natural compounds that may possess anti-breast cancer properties.

Phytochemicals Screening, Phenolic Estimation and Evaluation for Anti-Oxidant, Anti-Inflammatory and Anti-Microbial Activities of Sequentially Soxhlet Extracted Coconut Testa

Background: In many coconut industries, the outer layer of thin brown skin of coconut kernel known as testa is peeled out as a byproduct. Despite the testa is rich in fat and plenty of polyphenolic compounds, it has been underutilized either as animal feed, serving as raw materials for bio-diesel production or discarded directly. Anticipating coconut testa (CT) as a natural source of multiple phyto-chemicals, its exploitation for the pharmacological activity or utilization as value added product is required which may reduce the disposal costs as well. Methods: Secondary metabolites from CT were extracted sequentially with different organic solvents based on polarity in the soxhlet apparatus followed by extraction with sterilized water. The crude dried extracts thus prepared were evaluated for qualitative screening of phytochemicals and quantitative estimation of total phenols, flavonoids and tannin content. Moreover, the antioxidant, anti-inflammatory and anti-microbial activities were also investigated. Results: Phytochemicals screening revealed the presence of polyphenolic compounds in methanolic fraction including phenols (822.60 ± 16.36 mg/g), flavonoids (103.30 ± 9.78 mg/g) and tannin (663.50 ± 19.26 mg/g), whereas non-phenolic compounds were present in other fractions. While methanolic fraction showed invariably the highest anti-oxidant activity in multiple assay methods, non-phenolic compounds in aqueous and chloroform fractions exhibited high anti-inflammatory activity. Antimicrobial activity was observed by both phenolic and non-phenolic compounds. Conclusion: The findings of the study reveal that CT is a rich source of various polyphenolic and non-phenolic natural antioxidants, anti-inflammatory and antimicrobial compounds. These findings are promising and form the basis to identify the number of active components and their characterization.

Antioxidant activity and phytochemical screening of Ficus benghalensis aerial roots fractions

Context: Ficus benghalensis (Moraceae) is an evergreen tree found in south and southeast of Iran as wild and cultivated plants. Different parts of this plant have different effects such as antitumor, antipyretic, analgesic and anti-inflammatory. Aims: The aim of this study was investigated the phytochemical screening and antioxidant activities of different fractions of plant roots. Materials and Methods: Phytochemical investigation was done by different methods in references. Antioxidant activity was evaluated by DPPH and FRAP assay. All chemical materials and solvents were prepared from Sigma-Aldrich, Scharlau and Merk. Statistical Analysis: All measurements were carried out in triplicate and the data were expressed as mean ± SD. Statistical analysis was performed using one-way analysis of variance (ANOVA) and tukey test. Results: Phytochemical screening showed steroids, flavonoids, tannins, phenolic compounds, and anthraquinone glycoside are F. benghalensis constituents. This plant had antioxidant activity, but it was lower than the Indian kinds. Conclusion: This study elucidated Ficus benghalensis could be useful plant with antioxidant activity. Further investigation needs for details.

Screening of antioxidant and antimicrobial activities on Plectranthus spp. extracts

The use of medicinal plants is a widespread tendency in folk medicine. The Lamiaceae family contains several genera such as sage (Salvia), basil (Ocimum) and mint (Mentha) with a rich diversity of ethnobotanical uses. This study presents the in vitro antibacterial and antioxidant activities evaluation of five species extracts of the Plectranthus genus: P. hadiensis (vr), P. madagascarensis, P. neochilus, P. verticillatus e P. barbatus. Aqueous and acetonic extracts were obtained by five different methods: infusion, decoction, ultrasounds, microwave and maceration (10% w / v of dry plant). The highest amount of dry extract was obtained by the infusion method for Plectranthus barbatus (22,0 ± 1,0 to 33,0 ± 3,0 mg/mL). The extracts obtained were tested for their antimicrobial activity against three Gram-positive bacteria and two Gram-negative bacteria using the well diffusion method. Only the acetonic extracts of P. madagascarensis, P. hadiensis (vd) and P. verticillatus showed antibacterial activity and this was exclusively against Gram-positive bacteria. The highest antimicrobial activity was exhibited by P. madagascarensis extract with inhibition zones ranging from 23 to 36 mm. The antioxidant activity of the extracts was qualitatively determined using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) radical assay in tlc and yielded positive results for the majority of the extracts studied.

Application of Gold Nanorods for the Evaluation of Antioxidant Activity

Background: Excessive active oxygen will suppress the antioxidant defense system, resulting in a series of negative effects. Antioxidant substances in the diet can protect important biological molecules by mitigating the harm caused by oxidative stress and reducing the occurrence of chronic diseases related to aging. Therefore, simple, reliable and rapid detection methods for screening potential antioxidants in the diet have become very important. Methods: 1.0 g scented tea was added into 25 mL boiling water, and the extracting solution was filtered through filter paper by normal funnel after 10 min stirring extraction. After cooled to room temperature, the filtrate was diluted with water. Then, 100 µL of the scented tea extract was added into 300 µL of GNR solution, and water was added until the total volume was 900 µL. Subsequently, 900 µL of CTAB solution (0.2 mol/L) and 10 µL of hydrochloric acid (3 mol/L) were added successively. After mixing, 800 µL of H2O2 solution (1.26 mol/L) was added for the reaction. The variation of the GNR absorption spectrum with time was measured to determine the inhibition of oxidation and IC50. Results: The rate of oxidation of GNRs was reduced by the addition of antioxidant substance, such as scented teas. The stronger the antioxidant activity was, the lower the rate of GNR oxidation and the smaller the change in the longitudinal absorption peak. The blue-shift of the longitudinal absorption wavelength was monitored by ultraviolet-visible spectroscopy, enabling evaluation of the antioxidant activity of scented teas. The IC50 values of AA, Lophatherum gracile Brongn, rose, lavender, hawthorn and lotus leaf were 0.0088, 0.0338, 0.0540, 0.0907, 0.2383 and 0.2533 mg/mL, respectively. Conclusion: The relative antioxidant activities from strong to weak for these five scented teas were as follows: Lophatherum gracile Brongn > rose > lavender > hawthorn > lotus leaf. The order was in good accordance with that obtained by the conventional DPPH method. This method is simple and easy to operate, interference-free, and provides a promising solution for filed screening of antioxidant activity of natural products. Keywords: Gold nanorods, longitudinal surface plasmon resonance, antioxidation activity, scented tea, ascorbic acid, rate of oxidation.