Biomedical subjects

G Mazza

Publications and source records attributed to G Mazza.

At least 19 recordsLinked to original sources

PubMed2006

Multislice CT in emergency room management of patients with chest pain and medium-low probability of acute coronary syndrome.

PURPOSE: The main cause of acute chest pain, which accounts for 6.5% of urgent medical examinations in emergency rooms in Italy, is acute coronary syndrome (ACS). We performed this prospective study to evaluate the diagnostic accuracy of a 16-channel computed tomography (CT) scanner with dedicated software in a group of patients with chest pain and medium to low risk of ACS. MATERIALS AND METHODS: This study involved a selected group of 31 patients reporting chest pain with a medium to low probability of ACS, defined on the basis of preliminary tests [electrocardiogram (ECG) and serum cardiac markers]. Coronary angiography, performed within 24 h of MSCT, was used as the gold standard. RESULTS: MSCT identified the presence of occlusions and significant (>50%) or nonsignificant stenoses in the main coronary segments, with a sensitivity of 65%, a specificity of 98.8%, a positive predictive value (PPV) of 81.2%, a negative predictive value (NPV) of 97.3% and an accuracy of 96.4%. Significant stenoses and occlusions were detected with a sensitivity of 71.4%, a specificity of 99.6%, a PPV of 93.7%, an NPV of 97.7% and an accuracy of 97.5%. CONCLUSIONS: Due to its high NPV, this technique can rule out significant stenoses or coronary occlusions provided that image quality is excellent. In patients with a medium to low coronary risk, MSCT is a more accurate indicator of the need for coronary angiography than is exercise stress testing, which is less expensive but has lower predictive values.

Acute Disease↗

PubMed2006

Optimization of extraction of phenolic compounds from flax shives by pressurized low-polarity water.

Pressurized low-polarity water (PLPW) extraction of phenolic compounds from flax shive was investigated using statistically based optimization and the "one-factor-at-a-time" method. Extraction variables examined using central composite design (CCD) included temperature, flow rate, and NaOH concentration of the extracting water. Extraction of phenolic compounds including p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, acetovanillone, and feruric acid was affected by temperature and NaOH concentration; and extraction of all phenolic compounds, except ferulic acid, increased with temperature and NaOH concentration of the extracting water. Flow rate had little effect on concentration of phenolic compounds at equilibrium, but the extraction rate at the early phase was higher for higher flow rates. The mechanism of PLPW extraction of flax shive phenolics was also investigated using a two-site kinetic model and a thermodynamic model. To determine the extraction mechanism, flow rate was varied from 0.3 to 4.0 mL/min while temperature and NaOH concentration were fixed at 180 degrees C and 0.47 M, respectively. The flow rate tests showed the extraction rates of total phenolic (TP) compounds increased with flow rate and can be described by a thermodynamic model. The results from the thermodynamic model demonstrated that a K(D) value of 30 agreed with the experimental data in the flow rate range of 0.3-4.0 mL/min. When the effect of the three independent variables was evaluated simultaneously using CCD, a maximum TP concentration of 5.8 g/kg of dry flax shive (DFS) was predicted from the combination of a high temperature (230.5 degrees C), a high initial concentration of NaOH (0.63 M), and a low flow rate (0.7 mL/min). Maximum TP concentration of 5.7 g/kg of DFS was obtained from extraction conditions of 180 degrees C, 0.3 or 0.5 mL/min, and 0.47 M NaOH at equilibrium. A second-order regression model generated by CCD predicted a maximum TP concentration of 5.8 g/kg of DFS under the same extraction conditions, which is well matched with the results from experimental data.

Flax↗

PubMed2006

Antimicrobial activity of vanillin against spoilage microorganisms in stored fresh-cut mangoes.

The antimicrobial activity of vanillin against four bacteria (Pantoea agglomerans, Aeromonas enteropelogenes, Micrococcus lylae, and Sphingobacterium spiritovorun), four fungi (Alternaria sp., Aspergillus sp., Penicillium sp., and Fusarium sp.), and three unidentified yeasts isolated from spoiling fresh-cut mango slices was verified in laboratory media adjusted to pH 5.0. MICs of vanillin against the fungi (12.5 to 13.3 mM), bacteria (10 to 13.3 mM), and yeasts (5.0 to 6.7 mM) indicated that all the test species were sensitive to the antimicrobial effects of vanillin. Fresh-cut mango slices were dipped for 1 min in solutions containing 40 and 80 mM vanillin before being packaged in rigid trays and stored at 5 and 10 degrees C to verify the effects of vanillin on the development of the spoilage microflora. Microbiological analysis for up to 14 days of storage revealed that treatment with 80 mM vanillin significantly delayed (P < 0.05) the development of total aerobic bacteria and yeast and mold populations. Vanillin may be a practical preservative for processing fresh-cut mango.

Anti-Bacterial Agents↗

PubMed2005

Analysis of aroma and phenolic components of selected Achillea species.

Dried flowers and leaves of four different Achillea species grown wild in several provinces of Iran, including one species collected from three different locations of Isfahan province were analyzed for the headspace volatile components, total phenolics (TP) and tartaric esters (TE). Capillary gas chromatography/mass spectrometry (GC/MS) combined with a purge and trap method was used for quantification of aroma components. Over 70 compounds were determined in the samples. Flower samples from all species contained 2-methyl butanal, alpha-pinene, alpha-thujene, camphene, hexanal, beta-pinene and 1,8-cineole; however, the major constituents of the aerial parts were determined as alpha-pinene, camphene, DL-limonene and 1,8-cineole. The largest number of aroma components were found in Achillea tenuifolia Lam. and Achillea millefolium L. In all species, except A. millefolium, the leaves contained more TP and TE than flowers. However, A. wilhelmsii from Semirom in Isfahan province showed the highest values for TP and TE.

Achillea↗

PubMed2005

[Effect of anthocyanin rich fruit extract on PGE2 produced by endothelial cells].

OBJECTIVE: To study the effect of anthocyanin rich fruit extract on PGE2 produced by endothelial cells. METHODS: Normal human endothelial cells, CRL-2606, were cultured in F12K medium (complemented with 10% FBS, 0.1 mg/ml heparin, 0.03 mg/ml ECGS, 50 microg/ml streptomycin and 500U/ml penicillin) in 5% CO2 with 95% air at 37 degrees C. When the cells grow close to confluence, anthocyanin rich fruit extract with/without 100 ng/ml of LPS were added to the medium. After 18 hours of incubation, cells were harvested and the supernatant were collected. Cell viability was assayed. After centrifugation, PGE2 concentration in the supernatant was measured with the STAT-Prostaglandin E2 EIA Kit. RESULTS: 300 microg/ml or higher Chokeberry extract showed cytotoxicity effect on CRL-2606 cells, the viability was lower than 60% and showed a dose-response manner. Under using dosage, Blackcurrant extract (100 - 700 microg/ml) and Blueberry extract (50 - 400 microg/ml) did not show any cytotoxicity. When stimulated by LPS, the production of PGE2 by endothelial cells were increased two fold. Blueberry extract inhibit such action. 100 microg/ml of Blueberry extract keeps the production of PGE2 in normal level. 700 microg/mL of Blackcurrant extract and 500 microg/ml Chokeberry extract also inhibit the releasing of PGE2. CONCLUSION: Anthocyanin rich fruit extract from Blueberry, Blackcurrant, and Chokeberry inhibit PGE2 produced by endothelial cells, there exist antiinflammation and antioxidation.

Anthocyanins↗

PubMed2004

Anthocyanin metabolites in human urine and serum.

In the present study we investigated the metabolic conversion of cyanidin glycosides in human subjects using solid-phase extraction,HPLC-diode array detector, MS, GC, and enzymic techniques. Volunteers consumed approximately 20 g chokeberry extract containing 1.3 g cyanidin 3-glycosides (899 mg cyanidin 3-galactoside, 321 mg cyanidin 3-arabinoside, 51 mg cyanidin 3-xyloside and 50 mg cyanidin 3-glucoside). Blood samples were drawn at 0, 0.5, 1, and 2 h post-consumption of the extract. Urine samples were also collected at 0, 4-5,and 22-24h. We have confirmed that human subjects have the capacity to metabolise cyanidin 3-glycosides, as we observed at least ten individual anthocyanin metabolites in the urine and serum. Average concentrations of anthocyanins and anthocyanin metabolites in the urine reached levels of 17.9 (range 14.9-20.9) l.mol/l within 5 h post-consumption and persisted in 24h urine samples at levels of 12.1 (range 11.1-13.0) nmol/l. In addition, average total levels of anthocyanins and anthocyanin metabolites detected in the serum were observed at 5917 (range 197.3-986.1) nmol/ within 2h post-consumption. Cyanidin 3-galactoside accounted for 55.4% (9.9(range 7-2-12-6) l.mol/) and 66.0% (390.6 (range 119.4-661-9) nmol V) of the detected anthocyanins in the urine and serum samples,respectively. The metabolites were identified as glucuronide conjugates, as well as methylated and oxidised derivatives of cyanidin 3-galactoside and cyanidin glucuronide. Conjugation probably affects the biological activity of anthocyanins and these metabolic products are likely in part responsible for the reported health benefits associated with the consumption of anthocyanins.

Adult↗

PubMed2004

[Application of modified ABTS+ assay method to monitor antioxidant extraction from fruit].

OBJECTIVE: Modify the ABTS method to measure the antioxidant activity of compound. Apply this method to optimize antioxidant extraction from fruit. METHODS: In microplate, Trolox served as reference. Antioxidant activity was measured according to their ability to scavenge ABTS+ in the reaction mixture. Under different temperatures, solvent solid ratios, solvent concentrations, antioxidants were extracted. RESULTS: The standard error for measuring Trolox antioxidant activity was under 0.2. The antioxidant activities of fourteen standard samples were consistent with that reported in literatures. Using ethanol as solvent, at about 17 degrees C, for 1 gram of blackcurrant 20 ml of 67% ethanol was appropriate. While using sodium metabisulphite as solvent, at about 30 degrees C, for 1 gram of blackcurrant 20 ml of 300 mg/L metabisulphite would be appropriate. CONCLUSION: Modified ABTS+ method for measuring antioxidant activity was simple and feasible. This method could be applied to monitor antioxidant extraction from fruit and high throughput screening for antioxidant.

Antioxidants↗

PubMed2002

Absorption of anthocyanins from blueberries and serum antioxidant status in human subjects.

In recent years, numerous studies have shown that the polyphenolics present in fruit and vegetable products exhibit a wide range of biological effects. However, there is little reliable information on the absorption of glycosylated and acylated anthocyanins in humans. In the present study, the absorption of anthocyanins in humans was investigated after the consumption of a high-fat meal with a freeze-dried blueberry powder containing 25 individual anthocyanins including 6 acylated structures. Nineteen of the 25 anthocyanins present in the blueberries were detected in human blood serum. Furthermore, the appearance of total anthocyanins in the serum was directly correlated with an increase in serum antioxidant capacity (ORAC(acetone), P < 0.01). These results show that anthocyanins can be absorbed in their intact glycosylated and possibly acylated forms in human subjects and that consumption of blueberries, a food source with high in vitro antioxidant properties, is associated with a diet-induced increase in ex vivo serum antioxidant status.

Absorption↗

PubMed2002

Extraction of anthocyanins and other phenolics from black currants with sulfured water.

Health benefits of fruits, vegetables, and red wine are attributed to anthocyanins and other phytochemicals. In this research, the extraction of phenolics from black currants was optimized using different SO(2) concentrations (28, 300, 700, 1100, and 1372 ppm), temperatures (6, 20, 40, 60, and 74 degrees C), and solvent to solid ratios (S/S) (6, 20, 40, 60, and 74 mL/g). Surface response methodology was used to optimize yields of anthocyanins and total phenolics, as well as their antiradical and antioxidant activities. The extraction of phenolics varied with the SO(2) concentration, S/S, and temperature. Maximum yields of total phenolics and anthocyanins were obtained at an SO(2) concentration of 1000-1200 ppm and 19 L of solvent/kg of milled frozen berries. The increase of extraction temperature increased the rate of extraction and, thus, times to reach equilibrium for the extraction of total phenolics and anthocyanins were reduced. However, for the extraction of anthocyanins it is recommended that temperatures of 30-35 degrees C be used, as higher temperatures will degrade these compounds. Antioxidant activity was affected by all three experimental variables evaluated; however, the main variable affecting it was S/S. The higher the S/S, the lower the antioxidant index.

Anthocyanins↗

PubMed2002

Effects of anthocyanins and other phenolic compounds on the production of tumor necrosis factor alpha in LPS/IFN-gamma-activated RAW 264.7 macrophages.

Flavonoids have been reported to demonstrate their benefits in lowering oxidative stress and beneficial effects on cardiovascular and chronic inflammatory diseases. Common phenolic compounds, including phenolic acids, flavonols, isoflavones, and anthocyanins, present in fruits, vegetables, and grains were investigated for their effects on the production of tumor necrosis factor alpha (TNF-alpha) in LPS/IFN-gamma-activated RAW 264.7 macrophages. Gallic acid and (+)-catechin showed small but significant effects, whereas chlorogenic acid had no effect on TNF-alpha production. The flavonol quercetin inhibited TNF-alpha production, but kaempferol and myricetin induced the secretion of TNF-alpha. The isoflavone genistein was an inhibitor of TNF-alpha, whereas daidzein induced TNF-alpha production. Glycosylation of genistein changed its inhibitory effects to TNF-alpha induction, and glycosylation of daidzein had no effect on its activity. Anthocyanidins/anthocyanins and anthocyanin-rich extracts induced TNF-alpha production and acted as modulators of the immune response in activated macrophages. This is the first study to report the effects of anthocyanins and berry extracts on TNF-alpha production.

Animals↗

PubMed2002

Antimicrobial activity of individual and mixed fractions of dill, cilantro, coriander and eucalyptus essential oils.

Essential oils from dill (Anethum graveolens L.), coriander (seeds of Coriandrum sativum L.), cilantro (leaves of immature C. sativum L.) and eucalyptus (Eucalyptus dives) were separated into heterogeneous mixtures of components by fractional distillation and were analyzed by gas chromatography-mass spectroscopy. Minimum inhibitory concentrations against gram-positive bacteria, gram-negative bacteria and Saccharomyces cerevisiae were determined for the crude oils and their fractions. Essential oil of cilantro was particularly effective against Listeria monocytogenes, likely due to the presence of long chain (C6-C10) alcohols and aldehydes. The strength and spectrum of inhibition for the fractions often exceeded those determined in the crude oils. Mixing of fractions resulted in additive, synergistic or antagonistic effects against individual test microorganisms.

Anethum graveolens↗

PubMed2002

Inhibitory effects of anthocyanins and other phenolic compounds on nitric oxide production in LPS/IFN-gamma-activated RAW 264.7 macrophages.

Flavonoids have been reported to lower oxidative stress and possess beneficial effects on cardiovascular diseases and chronic inflammatory diseases associated with nitric oxide (NO). Common phenolic compounds, including phenolic acids, flavonols, isoflavones, and anthocyanins, present in fruits were investigated for their effects on NO production in LPS/IFN-gamma-activated RAW 264.7 macrophages. Phenolic compounds at the range of 16-500 microM that inhibited NO production by > 50% without showing cytotoxicity were the flavonols quercetin and myricetin, the isoflavone daidzein, and the anthocyanins/anthocyanidins pelargonidin, cyanidin, delphinidin, peonidin, malvidin, malvidin 3-glucoside, and malvidin 3,5-diglucosides. Anthocyanins had strong inhibitory effects on NO production. Anthocyanin-rich crude extracts and concentrates of selected berries were also assayed, and their inhibitory effects on NO production were significantly correlated with total phenolic and anthocyanin contents. This is the first study to report the inhibitory effects of anthocyanins and berry phenolic compounds on NO production.

Animals↗

PubMed2002

Diversity and dynamics of the T-cell response to MBP in DR2+ve individuals.

It is generally accepted that multiple sclerosis (MS) is mediated by autoreactive T cells and that myelin basic protein (MBP) is one of the target autoantigens. The T-cell response to MBP has been analysed extensively, largely through the use of T-cell lines (TCL) and T-cell clones (TCC), and to date, three immunodominant regions (13-32, 84-103 and 144-163) have been described. However, given that TCL may represent a skewed pattern of peptide reactivity, we have developed a kinetic response assay in which the proliferation of peripheral blood mononuclear cells (PBMC) from MS patients and healthy individuals was measured directly against a panel of peptides spanning the full length of human MBP. Furthermore, PBMC from each subject were tested three times over the course of 18 months. A high proportion of MS patients exhibited a significant response to eight MBP regions (1-24, 30-54, 75-99, 90-114, 105-129, 120-144, 135-159 and 150-170). TCC were subsequently generated from MS subjects and were used to further define the epitope recognized in each case. Overall, normal individuals recognized significantly fewer peptides. In addition, we noted that the T-cell recognition of any one peptide can fluctuate, appearing at one time point, regressing, and subsequently reappearing at a later date. This study provides new insight into the recognition profile and dynamics of myelin-antigen-specific T cells in MS.

Adult↗

PubMed2001

Comparative electron paramagnetic resonance study of radical intermediates in turnip peroxidase isozymes.

The occurrence of isozymes in plant peroxidases is poorly understood. Turnip roots contain seven season-dependent isoperoxidases with distinct physicochemical properties. In the work presented here, multifrequency electron paramagnetic resonance spectroscopy has been used to characterize the Compound I intermediate obtained by the reaction of turnip isoperoxidases 1, 3, and 7 with hydrogen peroxide. The broad (2500 G) Compound I EPR spectrum of all three peroxidases was consistent with the formation of an exchange-coupled oxoferryl-porphyrinyl radical species. A dramatic pH dependence of the exchange interaction of the [Fe(IV)=O por(*+)] intermediate was observed for all three isoperoxidases and for a pH range of 4.5-7.7. This result provides substantial experimental evidence for previous proposals concerning the protein effect on the ferro- or antiferromagnetic character of the exchange coupling of Compound I based on model complexes. Turnip isoperoxidase 7 exhibited an unexpected pH effect related to the nature of the Compound I radical. At basic pH, a narrow radical species ( approximately 50 G) was formed together with the porphyrinyl radical. The g anisotropy of the narrow radical Delta(g) = 0.0046, obtained from the high-field (190 and 285 GHz) EPR spectrum, was that expected for tyrosyl radicals. The broad g(x) edge of the Tyr* spectrum centered at a low g(x) value (2.00660) strongly argues for a hydrogen-bonded tyrosyl radical in a heterogeneous microenvironment. The relationship between tyrosyl radical formation and the higher redox potential of turnip isozyme 7, as compared to that of isozyme 1, is discussed.

Anisotropy↗

PubMed2001

Differential responses of CD45+ve T-cell subsets to MBP in multiple sclerosis.

The proliferative response of preparations of whole PBMC populations from 20 healthy individuals and 28 multiple sclerosis (MS) patients to purified protein derivative (PPD) and myelin basic protein (MBP) was monitored in a kinetic assay over a period of up to 10 days. PPD produced a classical secondary response in both groups, the magnitude being significantly reduced in the MS cohort. The magnitude and pattern of response to MBP did not differ between the two populations. The kinetic profile characteristic of a primary response was observed in both groups. Enrichment of the CD45RO+ve and CD45RA+ve T-cell subsets in PBMC led to a secondary response to PPD in the RO+ve and primary response in the RA+ve population in both groups. The response to MBP in both RO+ve and RA+ve populations exhibited primary kinetics in both MS patients and healthy individuals. However, the use of T-cell subset enriched populations allowed a finer dissection of the response to MBP which highlighted the more active role of RO-positive cells in MS patients. The most striking difference between patients and healthy individuals occurred on day 4 of culture when a greater response to MBP occurred in the CD45RO enriched population, paralleling the response to PPD, in the majority of patients. Futhermore in 4/8 patients and only 1/8 healthy individuals the response in the RO+ve cultures was maintained at a higher level than that seen in the corresponding RA+ve cultures throughout the culture period. This data indicates that a measurable memory response to MBP exists in MS patients implying prior activation of MBP reactive T lymphocytes during the course of disease.

Adult↗

PubMed2001

Renal hemodynamic response to maximal vasodilating stimulus in healthy older subjects.

BACKGROUND: It is still unclear whether age per se is associated with preservation of renal functional reserve, that is, of the increase in glomerular filtration rate (GFR) induced by appropriate vasodilating stimulus. METHODS: To gain insights into this issue, we evaluated the renal response to a maximal vasodilating stimulus, represented by the combined infusion of mixed amino acid solution (AA) and dopamine at renal dose (D), in 10 young subjects (median age of 30 years, range of 19 to 32) and in 11 subjects of older age (median age of 67 years, range of 65 to 76). Two further age-matched groups of young (N = 15) and older (N = 11) living kidney donors underwent renal needle biopsy immediately before nephrectomy to perform semiquantitative scoring (0 to 3) of arteriosclerosis in intrarenal arteries. All of the study subjects were nonsmokers with healthy status proven by extensive diagnostic evaluation excluding any risk factor of renal dysfunction. RESULTS: Basal renal plasma flow (RPF) and GFR were proportionally lower in older subjects (RPF, 361 +/- 29 vs. 618 +/- 34 mL/min/1.73 m(2), P < 0.001; GFR, 79 +/- 4 vs. 127 +/- 5.8 mL/min/1.73 m(2), P < 0.001). After AA + D, a significant increase of RPF and GFR was observed in both groups, but the older subjects exhibited a smaller percentage increment (RPF, 25.5 +/- 4.8 vs. 42.4 +/- 5.8, P < 0.05; GFR, 19.6 +/- 5.7 vs. + 33.8 +/- 6.4, P < 0.05). Furthermore, the maximal vasodilating stimulus was not able to restore renal hemodynamics in older subjects to the level measured in young controls at baseline. Renal vascular resistances were higher (P < 0.05) in the older subjects both at baseline (0.19 +/- 0.02 vs. 0.09 +/- 0.004 mm Hg/mL/min) and after AA + D (0.14 +/- 0.01 vs. 0.06 +/- 0.004). Light microscopy examination detected the presence of a greater degree of arteriosclerosis at the level of interlobular and arcuate arteries (0.89 +/- 0.15 vs. 0.45 +/- 0.08) and interstitial fibrosis/tubular atrophy (1.18 +/- 0.13 vs. 0.53 +/- 0.13) in older than in young subjects. CONCLUSIONS: Therefore, aging has adverse effects on renal function despite the absence of any risk factor for renal disease, including chronic smoking: (1) GFR and RPF are lower, and (2) the renal response to maximal vasodilating stimulus is impaired. These aging-related alterations of renal hemodynamics are possibly due to organic lesions in renal vasculature.

Adult↗

PubMed2000

Current indications for renal biopsy: a questionnaire-based survey.

Indications for renal biopsy are still ill defined. We recently sent a detailed questionnaire to 360 nephrologists in different areas of the world with the aim of providing information on this critical issue by evaluating the replies. The questionnaire was organized in four sections that included questions on renal biopsy indications in patients with normal renal function, renal insufficiency, and a transplanted kidney. In addition, the questions included methods applied to each renal biopsy procedure and to specimen processing. We received 166 replies; North Europe (50 replies), South Europe (47 replies), North America (31 replies), Australia and New Zealand (24 replies), and other countries (14 replies). In patients with normal renal function, primary indications for renal biopsy were microhematuria associated with proteinuria, particularly greater than 1 g/d of protein. In chronic renal insufficiency, kidney dimension was the major parameter considered before renal biopsy, whereas the presence of diabetes or serological abnormalities was not considered critical. In the course of acute renal failure (ARF) of unknown origin, 20% of the respondents would perform renal biopsy in the early stages, 26% after 1 week of nonrecovery, and 40% after 4 weeks. In a transplanted kidney, the majority of nephrologists would perform a renal biopsy in the case of graft failure after surgery, ARF after initial good function, slow progressive deterioration of renal function, and onset of nephrotic proteinuria. The last section provided comprehensive information on the technical aspects of renal biopsy. This survey represents the first attempt to provide a reliable consensus that can be used in developing guidelines on the use of kidney biopsy.

Acute Kidney Injury↗

PubMed2000

Assessing antioxidant and prooxidant activities of phenolic compounds.

Methods for determining primary antioxidant activity were evaluated. A beta-carotene bleaching method and a free radical method using 2, 2-diphenyl-1-picrylhydrazyl (DPPH(*)) were modified to rapidly test samples for potential antioxidant activity. Malonaldehyde production in a linoleic acid emulsion system assayed by an HPLC method was also used to determine antioxidant and prooxidant activities initiated by a metal catalyst (Cu(2+)). All methods were used to assess activity of selected phenolic compounds including several anthocyanidins/anthocyanins and selected berry extracts. Most phenolic compounds had prooxidant activity at low concentrations, unlike synthetic antioxidants (BHA and BHT). Compounds with similar structures exhibited comparable trends in antioxidant activity. Antioxidant activity usually increased with an increase in the number of hydroxyl groups and a decrease in glycosylation. The antioxidant activity of many phenolic compounds and extracts was comparable to those of synthetic antioxidants using the beta-carotene bleaching and HPLC methods.

Antioxidants↗