Potential health implication of in vitro human low-density lipoprotein-vitamin E oxidation modulation by polyphenols derived from Côte d'Ivoire's oil palm species

Effect of Cu2+ and Al3+ on the interaction of chlorogenic acid and caffeic acid with serum albumin

Despite the phenolic acids' health benefits, their interactions with proteins are still unclear. In this study, the interactions of Bovine Serum Albumin (BSA) with chlorogenic acid (CHA), caffeic acid (CA), and their Al³⁺, Cu²⁺ complexes were studied by using circular dichroism (CD) spectroscopy, fluorescence spectroscopy, and UV/Vis spectroscopy. It was found that esterification of carboxyl group of CA with quinic acid increased the binding affinities for BSA. After chelating with Cu²⁺ and Al³⁺, both CHA and CA exhibited high binding affinities for BSA. CHA could form CHA-Cu₂ and CHA-Al₂ complex with Cu²⁺ and Al³⁺. The result of CD spectroscopy demonstrated that the binding of CHA and Al³⁺ with BSA contributed to the folding of BSA secondary structure. In addition, with the presence of CHA, binding with Al³⁺ could also induce changes in BSA conformation. The binding sites of both CHA and CA were closed to Trp213.

High dietary intake of palm oils compromises glucose tolerance whereas high dietary intake of olive oil compromises liver lipid metabolism and integrity

PURPOSE

Palm (PO) and olive oils (OO) are the two most consumed and/or used oils in the world for food elaboration. These oils should not be confused with the solid palm stearin which is widely used in pastry making. Large number of studies was reported dealing with adverse/beneficial cardiovascular effects of PO and OO, whereas few studies were conducted to compare their potential effects on hepatic steatosis and liver lipid metabolism. The aim of this study was to compare the metabolic effects of high intake of POs (both crude and refined) and virgin OO on surrogate parameters of glucose tolerance, hepatic lipid metabolism and liver integrity.

METHODS

Thirty-two young male Wistar rats were divided into four equal groups and fed either control diet (11% energy from fat) or three high-fat diets rich in crude or refined POs or in OO (56% energy from fat), during 12 weeks. Systemic blood and liver biochemical parameters linked to glucose and lipid metabolism as well as hepatic steatosis and liver fatty acid composition were explored. The inflammation and oxidative stress status as well as the expression of several genes/proteins were also analyzed.

RESULTS

The major effects of POs intake concerned glucose metabolism and liver fatty acid composition, whereas the major effects of OO intake concerned hepatic TG accumulation, inflammation, and cytolysis.

CONCLUSIONS

In conclusion, high dietary intake of PO compromises glucose tolerance whereas high dietary intake of OO compromises hepatic lipid composition and liver integrity. However, adverse hepatic effects of OO observed in this study may not be transposed to human since, (a) the rodent model could lead to different effects than those observed in humans and (b) the average normal OO amounts ingested in the population are lower than those corresponding to a high-fat diet. So, further studies are needed to determine a maximum non-invasive dietary intake of OO.

Antioxidant effects of extra virgin olive oil enriched by myrtle phenolic extracts on iron-mediated lipid peroxidation under intestinal conditions model

Chelating and free radicals scavenging activities of extra virgin olive oil (EVOO) enriched by Myrtus communis phenolic compounds (McPCs), α-tocopherol and Butylated hydroxytoluene (BHT) were evaluated using chemical assays, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Oxygen radical absorbance capacity (ORAC), and biological model as 2,2'-azobis (2-aminopropane) dihydrochloride (AAPH) or Fe⁺³/Ascorbic acid (Fe⁺³/AsA) system mediated peroxidation of l-α-phosphatidylcholine aqueous dispersions stabilized by bile salts (BS) under simulated intestinal conditions (pH 7.4). McPC-EEVOO increased significantly the neutralization of DPPH radical and AAPH-derived radicals in ORAC assay more than α-tocopherol and BHT. The phospholipid stability increased by a factor of 33.6%, 34.8%, 19.3% and 10.7% for myrtle microwave assisted extraction (MAE) and conventional extraction (CE) extracts, α-tocopherol and BHT, respectively, as compared to the control (EVOO without enrichment) in Fe⁺³/AsA system. But a slightly additive effect was observed when AAPH system was used. Our observation showed that McPCs may interact positively with EVOO to inhibit phospholipid peroxidation, and thus, McPC-EEVOO could be a potential functional food.

Antioxidative properties and ability of phenolic compounds of Myrtus communis leaves to counteract in vitro LDL and phospholipid aqueous dispersion oxidation

Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2'-9-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+) •) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low-density lipoprotein (LDL) and phospholipid aqueous dispersion (L-α-phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave-assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS(+) • assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α-tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3-O-rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu(2+)-induced LDL oxidation with a dose-response effect. The cryo-electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2'-azobis (2-amidinopropane) hydrochloride-induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α-tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α-tocopherol and myrtle extracts or caffeic acid in α-tocopherol-enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.

PRACTICAL APPLICATION

We show that microwave-assisted extraction could be an alternative method for plant phenolic compound recovery allowing important gain in time extraction.We report inhibition of low-density lipoprotein oxidation in vitro initiated by Cu(2+) ions. We report that myrtle extract may be a source of natural antioxidants to counteract phospholipid peroxidation as well as α-tocopherol.

Phytochemicals and Antioxidant Capacity from Nypa fruticans Wurmb. Fruit

Nypa fruticans Wurmb. is one of the important underutilized fruit of Malaysia, which lacks scientific attention. Total phenolics, flavonoid content, and antioxidant capacities from endosperm extracts of Nypa fruticans (unripe and ripe fruits) were evaluated. Endosperm extract of unripe fruits (EEU) exhibited the highest phenolics (135.6 ± 4.5 mg GAE/g), flavonoid content (68.6 ± 3.1 RE/g), and antioxidant capacity. Free radical scavenging capacity of EEU as assessed by 2-2'-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radicals showed inhibitory activity of 78 ± 1.2% and 85 ± 2.6%, respectively. Beta carotene bleaching coefficient of EEU was higher (2550 ± 123), when compared to endosperm extract of ripe fruits (1729 ± 172). Additionally, EEU exhibited high antioxidant capacity by phosphomolybdenum method and ferric reducing antioxidant power values. Eight phenolic compounds from Nypa fruticans endosperm extracts were identified and quantified by ultra-high-performance liquid chromatography. Chlorogenic acid, protocatechuic acid, and kaempferol were the major phenolic compounds. Thus this fruit could be used as a potential source of natural antioxidant.