Separation and evaluation of free radical-scavenging activity of phenol components of green, brown, and black leaves of Bergenia crassifolia by using HPTLC-DPPH* method

A new procedure has been developed to separate and quantify the free radical-scavenging activity of individual compounds from green, brown, and black leaves of Bergenia crassifolia based on the combination of high performance TLC (HPTLC) with a diode array detector (DAD) and postchromatographic 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(*)) derivatization. Free gallic and ellagic acids, arbutin, hydroquinone, and bergenin in the B. crassifolia leaves' extracts were separated by HPTLC and identified. All compounds of the extract excluding bergenin were capable of scavenging DPPH * radicals. From the estimated ID(50) values, it can be seen that the increasing order of activity was gallic acid > arbutin > ellagic acid > hydroquinone > ascorbic acid. The antiradical activity of leaves of B. crassifolia is probably associated to the presence of phenol.     

Antioxidant activity of brocchlin carboxylic acid and its methyl ester from Chrozophora brocchiana

The analogue of brevifolin carboxylic acid and its methyl ester were isolated and identified from the aqueous ethanolic extract of the leaves of Chrzophora brocchiana in addition to eight known compounds identified as gallic acid, methyl and ethyl gallate, ellagic acid, monomethoxy and methylenedioxy ellagic acid, apigenin 7-O-glucoside and luteolin 7-O-glucoside. The structures were determined primarily by ESI-MS and NMR spectroscopy. The assignment of NMR signals was preformed by means of 1H-H COSY, HMQC and HMBC experiments. The antioxidant activity of the new compounds was determined by checking the scavenging activity against DPPH free radical.     

Phytochemical analysis and antioxidant activity of the seed of Telfairia occidentalis Hook (Cucurbitaceae)

The 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical, nitric oxide, reducing power, hydrogen peroxide scavenging, and total antioxidant activities of the methanol extract, n-hexane, dichloromethane, ethyl acetate, butanol and aqueous fractions of the seed of Telfairia occidentalis were evaluated. Total phenolic content was determined using the Folin–Ciocalteu method. The dichloromethane fraction exhibited the highest DPPH radical scavenging, reducing power and total antioxidant activities. Two pure compounds which were identified by FTIR, H-and 2D NMR and Mass spectroscopy as 9-octadecenoic acid (TOS B) and 10-hydroxyoctadecanoic acid (TOS C) and four oily isolates, TOS A, TOS D, TOS E and TOS F were obtained from the dichloromethane fraction. TOS E had the highest DPPH radical scavening activity comparable to that of ascorbic acid. GC-MS analysis revealed the major compounds in TOS E as 4-(2,2-Dimethyl-6-methylene cyclohexylidene)-2-butanol; 3-(3-hydroxybutyl)-2,4,4-trimethyl-2-cyclohexene-1-one and 1,2-Benzenedicarboxylic acid disooctyl ester. Thus, the seed of T. occidentalis can be consumed for its antioxidant property.     

Biological activities of phenolic compounds isolated from galls of Terminalia chebula Retz. (Combretaceae)

The aqueous extract of galls from Terminalia chebula Retz. (Combretaceae) was fractionated on Diaion and refractionated on octadecyl silica column. Six phenolic compounds were isolated and identified as gallic acid (1), punicalagin (2), isoterchebulin (3), 1,3,6-tri-O-galloyl-β-D-glucopyranose (4), chebulagic acid (5) and chebulinic acid (6). All of the compounds showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and melanin inhibitory activities than ascorbic acid, butylated hydroxytoluene, α-tocopherol, arbutin and kojic acid, the reference compounds. Gallic acid (1) exhibited inhibitory activity against nitric oxide production in lipopolysaccharide-activated macrophages. However, all isolated compounds exhibited less activity than the reference compounds in mushroom tyrosinase inhibition and human tumour cytotoxicity assays. This study has demonstrated that the phenolic compounds isolated from galls of T. chebula might contribute significantly due to their antioxidant and whitening activities.     

4种黄酮小分子对DPPH自由基的清除作用及构效关系研究

通过紫外可见光谱测定了4种黄酮小分子芦丁、牡荆素、山奈素、金丝桃苷对DPPH自由基的清除率、稳定性及半抑制浓度(IC50),并以常用的天然抗氧化剂抗坏血酸作为对照,考察了其抗氧化效果,探讨了黄酮类化合物的抗氧化性与结构的关系。结果表明：不同的抗氧化剂清除DPPH自由基达到平衡的时间不同,芦丁所需时间最长。4种黄酮小分子及抗坏血酸均对DPPH自由基有清除效果,并存在一定的量效关系。对DPPH自由基的清除能力从大到小依次为金丝桃苷、抗坏血酸、芦丁、山奈素、牡荆素。结构分析表明,B环邻二酚羟基是黄酮类化合物抗氧化所必需的基团,其羟甲基化及A环羟基糖苷化不利于黄酮类化合物的抗氧化活性。而C环3-OH的糖苷化对抗氧化活性有利,且单糖苷优于双糖苷。     

In vitro and in silico interaction of faba bean (Vicia faba L.) seed extract with xanthine oxidase and evaluation of antioxidant activity as a therapeutic potential

Acetone extract of faba bean (Vicia faba L.) was found to be highest total phenol and flavonoid content among all extracts. Antioxidant activity for inhibition percentage (free radical scavenging activity) had 86.47% for acetone extract, and 97.36% for ascorbic acid respectively. IC₅₀ value of ascorbic acid and acetone extact were found to be 9 μg/mL ± 0.20 and 30 μg/mL ± 0.21. Faba bean seeds had catechin, epicatechin, gallic acid and ellagic acid which on molecular docking study revealed that it binds effectively with xanthine oxidase by binding energy of –7.78, –6.11, –6.39, –5.78 kcal/mol respectively compared to allopurinol drug having binding energy of –4.94 kcal/mol. Gallic acid, ellagic acid, catechin, epicatechin (polyphenols) and allopurinol bind other than catalytic residues (Glu-1261) of xanthine oxidase. In vitro and in silico analysis recommended that mode of enzyme inhibition was mixed type.     

Antioxidant phenolic compounds of cassava (Manihot esculenta) from Hainan

An activity-directed fractionation and purification process was used to isolate antioxidant components from cassava stems produced in Hainan. The ethyl acetate and n-butanol fractions showed greater DPPH˙and ABTS?+ scavenging activities than other fractions. The ethyl acetate fraction was subjected to column chromatography, to yield ten phenolic compounds: Coniferaldehyde (1), isovanillin (2), 6-deoxyjacareubin (3), scopoletin (4), syringaldehyde (5), pinoresinol (6), p-coumaric acid (7), ficusol (8), balanophonin (9) and ethamivan (10), which possess significant antioxidant activities. The relative order of DPPH? scavenging capacity for these compounds was ascorbic acid (reference) > 6 > 1 > 8 > 10 > 9 > 3 > 4 > 7 > 5 > 2, and that of ABTS?+ scavenging capacity was 5 > 7 > 1 > 10 > 4 > 6 > 8 > 2 > Trolox (reference compound) > 3 > 9. The results showed that these phenolic compounds contributed to the antioxidant activity of cassava.     

Bioassay‐guided Isolation and Antioxidant Activity of Sulfur‐containing Compounds from Clinacanthus nutans

Clinacanthus nutans has been used in traditional herbal medicine for cancer prevention, but the specific bioactive compounds responsible for the observed activities have not been explored. Different polar solvents such as methanol, chloroform, ethyl acetate, and hexane were used for the extraction. The extracts, fractions, and isolated compounds were subjected to DPPH and ferric reducing antioxidant potential (FRAP) assays. Methanol extracts show significant free‐radical scavenging activity of 69.09% in DPPH and 56.49% FRAP. Purification of MeOH extracts afforded the fraction FB28 and two new sulfur‐containing compounds, named clinamide D and E ( 1 , 2 ). Compound ( 1 ) proved to be more active with an IC₅₀ value for DPPH radical scavenging of 118.27 ± 0.01 µg/mL and reduction of Fe³⁺–TPTZ complex of 386.24 ± 0.02, higher than that of the standard ascorbic acid. Sulfur‐containing compounds isolated from C. nutans is a potential natural antioxidant.     

In vitro antiperoxidative, free radical scavenging and xanthine oxidase inhibitory potentials of ethyl acetate fraction of Saraca ashoka flowers

Saraca ashoka is a widely used medicinal herb claimed to cure many diseases. This study investigated the antiperoxidative, free radical scavenging and xanthine oxidase (XO) inhibitory potential of the ethyl acetate fraction of S. ashoka flowers (SAF) and compared it with standard compounds like gallic acid, ascorbic acid, butylated hydroxyl toluene and allopurinol. The ethyl acetate fraction of SAF exhibited free radical scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and superoxide radical, along with hydroxyl radical scavenging activity. Lipid peroxidation inhibitory potential of SAF was studied using a linoleic acid emulsion system, which shows significant antioxidant potential. SAF also demonstrated significant XO (key enzyme linked to inflammation) inhibitory activity, which revealed its therapeutic potential as an antioxidant and XO inhibitor. HPLC profiling of the ethyl acetate fraction of SAF revealed that it contains ellagic acid as a major compound and thus the beneficial effects of this fraction may be due to the presence of this compound.     

Salvia officinalis L.: composition and antioxidant-related activities of a crude extract and selected sub-fractions

The composition and antioxidant properties of a methanol: acetic acid (99:1, v/v) soluble crude extract isolated from S. officinalis L. leaves through maceration and selected fractions isolated thereof are presented in this study. The total phenol content was estimated as gallic acid equivalents, whilst qualitative-quantitative phenolic content was determined using high performance liquid chromatography with photodiode array detection. Antioxidant evaluation consisted of ferric reductive capacity and 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radical scavenging determinations. The crude extract contained hydroxybenzoic acids, hydroxycinnamic acids, flavonoids and diterpenoids, whilst caffeic acid, carnosic acid, luteolin, luteolin-7-O-glucoside and rosmarinic acid were identified from their chromatographic and spectral characteristics and quantified from their respective calibration curves. The crude extract and sub-fractions demonstrated varying degrees of efficacy in the antioxidant-related assays used, except the n-hexane fraction, which was unable to reduce iron(III) at reasonable concentrations. Although the positive controls, ascorbic acid, BHA and BHT, were more potent than the S. officinalis samples, two fractions were significantly (p < 0.05) more potent iron(III) reducing agents than pycnogenol, a proanthocyanidin-rich commercial preparation.     

In vitro antioxidant activities of the methanol extract and its different solvent fractions obtained from the fruit pericarp of Terminalia bellerica

Terminalia bellerica has been used as a traditional medicine in a variety of ailments including anaemia, asthma, cancer, inflammation, rheumatism and hypertension. In this study, the free radical scavenging and antioxidant activities of methanol extract (ME) and its different solvent fractions (namely hexane (HE), ethyl acetate (EA), butanol (BL) and water (WA)) of the T. bellerica fruit pericarp were evaluated and compared with standard antioxidant compounds like gallic acid (GA), catechin and ascorbic acid. Among the different fractions tested, the EA fraction exhibited higher antioxidant and radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals than the other fractions, which may be attributed to its higher phenolic and flavonoid content, since a linear relation was observed between the phenolic content and the antioxidant parameters. The HPTLC analysis of the EA fraction revealed that it mainly contains GA and ferulic acid (FA) as major phenolics, and the higher antioxidant activities of EA fraction may be due to the presence of these compounds.     

Antimicrobial,DPPH scavenging and tyrosinase inhibitory activities of Thymus vulgaris,Helichrysum arenarium and Rosa damascena mill. ethanol extracts by using TLC bioautography and chemical screening methods

Antimicrobial, DPPH scavenging and tyrosinase inhibitory activities of Thymus vulgaris, Helichrysum arenarium and Rosa damascena Mill. ethanol extracts by using TLC bioautography and chemical screening methods. The ethanol extracts of Thymus vulgaris (Tv), Helichrysum arenarium (Ha) and Rosa damascena Mill. (Rm) (red) were screened for their antimicrobial, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and tyrosinase inhibitory activities. The test microorganisms included bacteria of Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). Thin Layer Chromatography (TLC) - bioautography, disk diffusion and well diffusion methods were used for the antimicrobial activity assays. Rosa damascena Mill. extract was effective against E. coli and all plant extracts showed antimicrobial activity against S. aureus. The phenolic acids in the structure of the extracts were also identified by LC-MS analysis. Human blood agar well diffusion method and TLC-DPPH assays were used to identify the hemolytic and antioxidant activity of plant extracts, respectively, along with 10 compounds including phenolic acids as a standard. Among these compounds, caffeic acid (Rf = 0.68) was detected in all extracts while vanillic acid (Rf = 0.75), and gallic acid (Rf = 0.51) was found in Tv extract. Kojic acid (Rf = 0.36), on the other hand, was detected in Rm extract as a tyrosinase inhibitor. All plant extracts presented tyrosinase inhibitory activities on TLC-bioautography assay.     

Determination of rosmarinic acid in sage and borage leaves by high-performance liquid chromatography with different detection methods

Rosmarinic acid is separated and identified on the basis of high-performance liquid chromatography (HPLC)-UV-mass spectrometry data in 80% methanol in water extracts from the leaves of Salvia species (S. officinalis, S. glutinosa, S. aethiopis, S. sclarea, and Borago officinalis) as a dominant radical scavenger towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH*) stable radical in HPLC-DPPH* system. The content of rosmarinic acid in the plants is calibrated and quantitated from chromatograms obtained by UV detection at 280 nm. The concentration ranges from 13.3 to 47.3 mg of the phenolic acid per gram dried leaves of all plants is tested. S. glutinosa and S. sclarea have the highest concentration of rosmarinic acid. The amount of rosmarinic acid in borage leaves is similar compared with Salvia officinalis (15 mg/g). The HPLC-DPPH* system is calibrated for quantitative DPPH* scavenging assessment of rosmarinic acid. The results reveal excellent correlation (r2 = 0.98) between the rosmarinic acid concentration and antiradical activity.     

Antioxidant and Anticholinesterase Activities of Extracts and Phytochemicals of Syzygium antisepticum Leaves

Bioassay-guided separation of young leaves extracts of Syzygium antisepticum (Blume) Merr. & L.M. Perry led to the isolation of four triterpenoids (betulinic acid, ursolic acid, jacoumaric acid, corosolic acid) and one sterol glucoside (daucosterol) from the ethyl acetate extract, and three polyphenols (gallic acid, myricitrin, and quercitrin) from the methanol (MeOH) extract. The MeOH extract of S. antisepticum and some isolated compounds, ursolic acid and gallic acid potentially exhibited acetylcholinesterase activity evaluated by Ellman’s method. The MeOH extract and its isolated compounds, gallic acid, myricitrin, and quercitrin, also strongly elicited DPPH radical scavenging activity. In HEK-293 cells, the MeOH extract possessed cellular antioxidant effects by attenuating hydrogen peroxide (H₂O₂)-induced ROS production and increasing catalase, glutathione peroxidase-1 (GPx-1), and glutathione reductase (GRe). Furthermore, myricitrin and quercitrin also suppressed ROS production induced by H₂O₂ and induced GPx-1 and catalase production in HEK-293 cells. These results indicated that the young leaves of S. antisepticum are the potential sources of antioxidant and anticholinesterase agents. Consequently, S. antisepticum leaves are one of indigenous vegetables which advantage to promote the health and prevent diseases related to oxidative stress.     

Pycnalin, a new α-glucosidase inhibitor from Acer pycnanthum

A new compound, pycnalin (1), together with four known compounds, ginnalins A (2), B (3), C (4), and 3,6-di-O-galloyl-1,5-anhydro-D-glucitol (3,6-di-GAG) (5), were isolated from Acer pycnanthum. The structure of 1 was determined on the basis of 2D-NMR spectral data and synthesis of 1. Pycnalin (1) is the first 1,5-anhydro-D-mannitol linked to a gallic acid, while compounds 2-5 were 1,5-anhydro-D-glucitol linked to gallic acids. All compounds were tested in vitro for α-glucosidase inhibitory and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Pycnalin (1) exhibited moderate α-glucosidase inhibitory activity as well as free radical scavenging activity. Ginnalin A (2) and 3,6-di-GAG (5), which have two galloyl groups, exhibited potent α-glucosidase inhibition, compared to those of other compounds 1, 3, and 4 containing a galloyl group. These results suggest that α-glucosidase inhibition is influenced by the number of galloyl groups.     

A rapid densitometric method for simultaneous quantification of gallic acid and ellagic acid in herbal raw materials using HPTLC

Gallic acid and ellagic acid are two widely occurring phenolic compounds of plant origin, to which many biological activities including anticancer and antiviral activity have been attributed. A simple HPTLC method has been developed for the simultaneous quantification of gallic acid and ellagic acid. The method was validated for precision, repeatability, and accuracy. Instrumental precision was found to be 0.083 and 0.78, and the repeatability of the method was found to be 1.07 and 1.50 (% CV) for gallic acid and ellagic acid, respectively. The accuracy of the method was checked by a recovery study conducted at two different levels and the average percentage recovery was found to be 101.02% for gallic acid and 102.42% for ellagic acid. The above method was used for the quantification of gallic acid and ellagic acid content in seeds of Abrus precatorius Linn., whole plant of Phyllanthus maderaspatensis Linn., and flowers of Nymphaea alba Linn. The proposed HPTLC method for the simultaneous quantification of gallic acid and ellagic acid was found to be simple, precise, specific, sensitive, and accurate and can be used for routine quality control of herbal raw materials and for the quantification of these compounds in plant materials.     

Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.     

In vitro antioxidant and radical scavenging of Guinean kinkeliba leaf (Combretum micranthum G. Don) extracts

The antioxidant properties of the water and ethanol leaf extracts of kinkeliba (Combretum micranthum) were investigated, including scavenging of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (IC?? values: 8.02?±?0.34 for the ethanol extract [KE] and 9.1?±?0.28 for the water extract [KW]), the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical (IC(50) values: 7.4?±?0.14 for KE and 11.8?±?0.01 for KW) and the hydroxyl radical (58.1% for KE and 61.1% for KW). The ferric thiocyanate method, reducing power, metal chelating activity, an assay of protein oxidation and the β-carotene-linoleic bleaching assay were also used. Butylated hydroxytoluene and ascorbic acid were used as the reference antioxidant compounds. At 20 mg mL?1 concentration, KW and KE provided 36.8% and 75.1% inhibition of lipid peroxidation of linoleic acid emulsion, respectively. The IC?? values of the ethanol extract in ABTS and DPPH tests were significantly lower than those from the water extract. Furthermore, crude polyphenols were extracted from kinkeliba leaf with 90% ethanol solution using a water bath treatment and then purified by a macroporous resin, AB-8. The polyphenols from kinkeliba leaf were subjected to analyses by RP-HPLC and ESI-MS. The dominant polyphenols in kinkeliba leaf were identified as gallic acid, rutin trihydrate, (+)-catechin and benzoic acid.     

Salvia officinalis L. essential oils: effect of hydrodistillation time on the chemical composition, antioxidant and antimicrobial activities

Salvia officinalis L. oils were isolated from the plant's commercial dried aerial parts, by hydrodistillation, with different distillation times. The essential oils were analysed by gas chromatography and gas chromatography-mass spectrometry. The antioxidant ability was measured using a free radical scavenging activity assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), a thiobarbituric acid reactive substances (TBARS) assay, a deoxyribose assay for the scavenging of hydroxyl radical, an assay for site-specific actions and a 5-lipoxygenase assay. Antibacterial activity was determined by the agar diffusion method. 1,8-Cineole, α-pinene and camphor were the dominant components of all the essential oils. The different hydrodistillation times did not affect the oil yield nor the relative amount of the oil components. The time of hydrodistillation influenced the antioxidant activity. With the DPPH method, the oils isolated for 2 and 3 h were stronger free radical scavengers, while with the TBARS method, the highest antioxidant values were obtained in the oils isolated for 30 min, 2 and 3 h. Hydroxyl radical scavenging and lipoxygenase activity assays showed the best results with oils isolated for 1 and 3 h. With the deoxyribose method, sage oils at concentrations <1000 mg L(-1) showed better activity than mannitol. The essential oil of S. officinalis showed very weak antimicrobial activity.     

高效液相色谱测定石榴皮水提取物中4种多酚化合物的含量

建立了石榴皮水提取物中没食子酸、安石榴甙A、安石榴甙B和鞣花酸4种多酚化合物的高效液相色谱(HPLC)分析方法.样品经前处理并过滤后,采用HPLC检测,外标法定量.在最佳分析条件下,上述4种多酚化合物的线性范围分别为7.48 ～ 149.50、15.36～153.55、27.65 ～276.45、7.13 ～ 114....