BACKGROUND AND OBJECTIVE: Several epidemiological and experimental studies have associated the intake of antioxidants, which are abundant in the Mediterranean diet, with a low incidence of cardiovascular disease. One possible mechanism of this action is the oxidative protection in low density lipoproteins (LDL). The aim of our study was to compare the antioxidative activity of diverse phenolic compounds present in virgin olive oil on these lipoproteins.

SUBJECTS AND METHOD: LDL was isolated from blood plasma of healthy volunteers by sequential ultracentrifugation. This was followed by oxidation with CuC12 in the presence of different concentrations of phenolic compounds and virgin olive oil extract. Production of conjugated dienes was determined by the continuous monitoring of increased absorbency at 234 nm as an indicator of LDL oxidation.

RESULTS: Virgin olive oil extract prolonged the latency phase and significantly lowered the progression rate (p<0.05) at low concentrations (2 g/ml). This antioxidative effect was also observed with low concentrations (2 M) of caffeic acid and oleuropein (p<0.05). However, it was necessary to increase the concentration of flavone up to 50 times to observe a similar effect (p<0.05).

CONCLUSION: Both virgin olive oil extract enriched in phenolic compounds and phenolic compounds present in olive oil (caffeic acid and oleuropein) are potent antioxidants at very low concentrations. Thus, the beneficial effects of a Mediterranean diet may be partly due to the protective action of these compounds.

Metalloproteinases (MMPs) are zinc-dependent endopeptidases responsible for the hydrolysis of various component of extracellular matrix such as gelatin and collagen. MMPs, namely MMP-2 and MMP-9 correlate with cardiovascular events in patients. We sought to determine whether supplementation with polyphenol-rich Cynara cardunculus (wild artichoke, traditional component of the Mediterranean diet) modulates MMP-9 expression and activity in cell cultures. A fully characterized C. cardunculus extract was able to inhibit, in a dose-dependent manner, the gelatinolytic activity of secreted MMP-9 and both secretion and human MMP-9 promoter-driven transcription. Analysis by HPLC of the Cynara extract identified polyphenols such as luteolin, apigenin, and caffeic acid, among others. However, testing a mix of the individual components suggested that the inhibitory effects of C. cardunculus are due to minor constituent fraction(s) as a whole. In promoting the health benefits of the Mediterranean diet, the role of wild plants as important meal components deserves further reappraisal.

SCOPE:Substantial studies have shown that curcumin, a dietary compound from turmeric, has beneficial effects on many diseases. However, curcumin rapidly degrades at physiological pH, making it difficult to interpret whether the observed actions of curcumin are from curcumin itself or its degradation products. Therefore, it is important to better understand the mechanisms involved in curcumin degradation and the roles of degradation in its biological actions.

METHODS AND RESULTS:Here we show that a series of redox active antioxidants with diverse chemical structures, including gallic acid, ascorbate (vitamin C), tert-butylhydroquinone (TBHQ), caffeic acid, rosmarinic acid, and Trolox (a water-soluble analog of vitamin E), dramatically increased curcumin stability in phosphate buffer at physiological pH. When treated in basal cell culture medium in MC38 colon cancer cells, curcumin rapidly degraded with a half-life of several minutes and showed a weak anti-proliferative effect; co-addition of antioxidants enhanced stability and anti-proliferative effect of curcumin. Finally, co-administration of antioxidant significantly increased plasma level of curcumin in animal models.

CONCLUSIONS:Together, these studies strongly suggest that a redox-dependent mechanism plays a critical role in mediating curcumin degradation. In addition, curcumin itself, instead of its degradation products, is largely responsible for the observed biological actions of curcumin. This article is protected by copyright. All rights reserved.

Hepatic disorders such as steatosis and alcoholic steatohepatitis are common diseases that affect thousands of people around the globe. This study aims to identify the main phenol compounds using a new HPLC-ESI+-MS/MS method, to evaluate some oxidative stress parameters and the hepatoprotective action of green dwarf coconut water, caffeic and ascorbic acids on the liver and serum of rats treated with ethanol. The results showed five polyphenols in the lyophilized coconut water spiked with standards: chlorogenic acid (0.18µM), caffeic acid (1.1 µM), methyl caffeate (0.03 µM), quercetin (0.08 µM) and ferulic acid (0.02 µM) isomers. In the animals, the activity of the serum γ-glutamyltranspeptidase (γ-GT) was reduced to 1.8 I.U/L in the coconut water group, 3.6 I.U/L in the ascorbic acid group and 2.9 I.U/L in the caffeic acid groups, when compared with the ethanol group (5.1 I.U/L, p<0.05). Still in liver, the DNA analysis demonstrated a decrease of oxidized bases compared to ethanol group of 36.2% and 48.0% for pretreated and post treated coconut water group respectively, 42.5% for the caffeic acid group, and 34.5% for the ascorbic acid group. The ascorbic acid was efficient in inhibiting the thiobarbituric acid reactive substances (TBARS) in the liver by 16.5% in comparison with the ethanol group. These data indicate that the green dwarf coconut water, caffeic and ascorbic acids have antioxidant, hepatoprotective and reduced DNA damage properties, thus decreasing the oxidative stress induced by ethanol metabolism.

BACKGROUND:Ultraviolet (UV) irradiation is well known to promote inflammation and pigmentation of skin. UVB mainly affects dermatitis and pigmentation. Coffee contains a number of polyphenols, such as caffeic acid (CA) and chlorogenic acid (CGA) but their in vivo bioactivity for photobiology remains unclear.

METHODS:C57BL/6j male mice were irradiated with UVB (1.0 kJ/m2/day) for 3 days. Five days after the final session of UVB irradiation, the dorsal skin, ear epidermis, and blood samples were analyzed to investigate the inflammatory factors, melanogenesis factors and related hormones.

RESULTS:After the oral administration of CA (100 mg/day) or CGA (100 mg/day) for 8 days, only CA was found to inhibit dermatitis and pigmentation. The pathway by which CA inhibits dermatitis is related to the mitogen-activated protein kinase (MAPK)/extracellular signal regulated kinase (ERK)1/2/cAMP response element binding protein (CREB) pathway. Otherwise, the pathway by which CA inhibits pigmentation is related to the activation of theβ-endorphin-μ-opioid receptor and suppresses the cAMP-microphthalmia-associated transcription factor (MITF) pathway.

CONCLUSION:It is suggested that the oral administration of CA prevented dermatitis and pigmentation after UVB irradiation in mice.