3,5-Dimethoxy-4-benzoic acid (syringic acid) a natural phenolic acid reduces reactive oxygen species in differentiated 3T3-L1 adipocytes

Syringic acid promotes cartilage extracellular matrix generation and attenuates osteoarthritic cartilage degradation by activating TGF-β/Smad and inhibiting NF-κB signaling pathway

Osteoarthritis (OA) is a common chronic degenerative disease which is characterized by the disruption of articular cartilage. Syringic acid (SA) is a phenolic compound with anti-inflammatory, antioxidant, and other effects including promoting osteogenesis. However, the effect of SA on OA has not yet been reported. Therefore, the purpose of our study was to investigate the effect and mechanism of SA on OA in a mouse model of medial meniscal destabilization. The expressions of genes were evaluated by qPCR or western blot or immunofluorescence. RNA-seq analysis was performed to examine gene transcription alterations in chondrocytes treated with SA. The effect of SA on OA was evaluated using destabilization of the medial meniscus model of mice. We found that SA had no obvious toxic effect on chondrocytes, while promoting the expressions of chondrogenesis-related marker genes. The results of RNA-seq analysis showed that extracellular matrix-receptor interaction and transforming growth factor-β (TGF-β) signaling pathways were enriched among the up-regulated genes by SA. Mechanistically, we demonstrated that SA transcriptionally activated Smad3. In addition, we found that SA inhibited the overproduction of lipopolysaccharide-induced inflammation-related cytokines including tumor necrosis factor-α and interleukin-1β, as well as matrix metalloproteinase 3 and matrix metalloproteinase 13. The cell apoptosis and nuclear factor-kappa B (NF-κB) signaling were also inhibited by SA treatment. Most importantly, SA attenuated cartilage degradation in a mouse OA model. Taken together, our study demonstrated that SA could alleviate cartilage degradation in OA by activating the TGF-β/Smad and inhibiting NF-κB signaling pathway.

Monoamine oxidase mediated oxidative stress: a potential molecular and biochemical crux in the pathogenesis of obesity

Obesity has become a global health concern with an increasing prevalence as years pass by but the researchers have not come to a consensus on the exact pathophysiological mechanism underlying this disease. In the past three decades, Monoamine Oxidases (MAO), has come into limelight for a possible involvement in orchestrating the genesis of obesity but the exact mechanism is not well elucidated. MAO is essentially an enzyme involved in the catabolism of neurotransmitters and other biogenic amines to form a corresponding aldehyde, hydrogen peroxide (H2O2) and ammonia. This review aims to highlight the repercussions of MAO's catabolic activity on the redox balance, carbohydrate metabolism and lipid metabolism of adipocytes which ultimately leads to obesity. The H2O2 produced by these enzymes seems to be the culprit causing oxidative stress in pre-adipocytes and goes on to mimic insulin's activity independent of its presence via the Protein Kinase B Pathway facilitating glucose influx. The H2O2 activates Sterol regulatory-element binding protein-1c and peroxisome proliferator activated receptor gamma crucial for encoding enzymes like fatty acid synthase, acetyl CoA carboxylase 1, Adenosine triphosphate-citrate lyase, phosphoenol pyruvate carboxykinase etc., which helps promoting lipogenesis at the same time inhibits lipolysis. More reactive oxygen species production occurs via NADPH Oxidases enzymes and is also able activate Nuclear Factor kappa B leading to inflammation in the adipocyte microenvironment. This chronic inflammation is the seed for insulin resistance.

Virgin coconut oil: A comprehensive review of antioxidant activity and mechanisms contributed by phenolic compounds

Virgin coconut oil (VCO) is obtained by processing mature coconut cores with mechanical or natural methods. In recent years, VCO has been widely used in the food, pharmaceutical, and cosmetic industries because of its excellent functional activities. VCO has biological functions such as antioxidant, anti-inflammatory, antibacterial, and antiviral, and also has potential therapeutic effects on many chronic degenerative diseases. Among these functions, the antioxidant is the most basic and important function, which is mainly determined by phenolic compounds and medium-chain fatty acids (MCFAs). This review aims to elucidate the antioxidant functions of each phenolic compound in VCO, and discuss the antioxidant mechanisms of VCO in terms of the role of phenolic compounds with fat, intestinal microorganisms, and various organs. Besides, the composition of VCO and its application in various industries are summarized, and the biological functions of VCO are generalized, which should lay a foundation for further research on the antioxidant activity of VCO and provide a theoretical basis for the development of food additives with antioxidant activity.

Folate derivatives, 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, protect BEAS-2B cells from high glucose-induced oxidative stress and inflammation

Folate (vitamin B₉) and its biologically active derivatives are well-known antioxidant molecules protecting cells from oxidative degradation. The presence of high glucose, often found in diabetic patients, causes oxidative stress resulting in cellular stress and inflammatory injury. Cells in organs such as the lung are highly prone to inflammation, and various protective mechanisms exist to prevent the progressive disorders arising from inflammation. In the present study, the synthetic form of folate, i.e. folic acid, and active forms of folate, i.e. 5-methyltetrahydrofolate and 10-formyltetrahydrofolate, were evaluated for their antioxidant and antiinflammatory potential against high glucose (50 mM)–mediated oxidative stress and inflammation in BEAS-2B cells, an immortalised bronchial epithelial cell line. High glucose treatment showed a 67% reduction in the viability of BEAS-2B cells, which was restored to the viability levels seen in control cultures by the addition of active folate derivatives to the culture media. The DCFH-DA fluorometric assay was performed for oxidative stress detection. The high glucose–treated cells showed a significantly higher fluorescence intensity (1.81- and 3.8-fold for microplate assay and microscopic observation, respectively), which was normalised to control levels on supplementation with active folate derivatives. The proinflammatory NF-κB p50 protein expression in the active folate derivative–supplemented high glucose–treated cells was significantly lower compared to the folic acid treatment. In support of these findings, in silico microarray GENVESTIGATOR database analysis showed that in bronchiolar small airway epithelial cells exposed to inflammatory condition, folate utilization pathway genes are largely downregulated. However, the folate-binding protein gene, which encodes to the folate receptor 1 (FOLR1), is significantly upregulated, suggesting a high demand for folate by these cells  in inflammatory situations. Supplementation of the active folate derivatives 5-methyltetrahydrofolate and 10-formyltetrahydrofolate resulted in significantly higher protection over the folic acid from high glucose–induced oxidative stress and inflammation. Therefore, the biologically active folate derivatives could be a suitable alternative over the folic acid for alleviating inflammatory injury-causing oxidative stress.

Inhibition of palmitic acid induced adipogenesis by natural polyphenols in 3T3-L1 adipocytes

Dietary free fatty acids induce preadipocyte differentiation in the presence of a hormonal cocktail in 3T3-L1 adipocytes. Plant polyphenols are curb adipocyte differentiation and protect from metabolic stress. In the present study, we examined the effects of the saturated fatty acid, palmitic acid (PA) in presence of flavonoids, chrysin (CR) and hesperidin (HD) and phenolic acid, syringic acid (SYA) and sinapic acid (SIA). Adipocytes were incubated for 10 d with 100 μmol of PA along with 10-100 µmol CR/HD and 100-1000 µmol SYA/SIA. PA induced clonal expansion of preadipocytes, differentiation and oxidative stress in 3T3-L1 cells following 10 d of differentiation. Adipocytes treated with PA exhibited an increase of 300% in clonal population, 110% lipid and 172% reactive oxygen species accumulation. But treatment with CR, HD, SYA and SIA in the presence of PA concentration-dependent effect was observed. Concentrations of CR/HD and SYA/SIA inhibited PA-induced mRNA expression of PPARγ, C/EBPα, SREBP-1c, FAS and NOX4. Moreover, CR, HD, SYA and SIA did not exhibit toxicity in Drosophila DNA. In summary, these results suggest that dietary fatty acids act directly on adipocytes and addition of CR, HD, SYA and SIA resulted in reduction of PA-induced negative effects on 3T3-L1 adipocytes. HIGHLIGHTS: • Palmitic acid, the common dietary free fatty acid, is known to induce adipogenesis in 3T3-L1 adipocytes. • Treatment of differentiating adipocytes with flavonoids and phenolic acids reduced palmitic acid-induced clonal expansion of preadipocytes. • Phytocompounds reduced lipid accumulation and triglyceride production as well as ROS accumulation. • Thus, the phytocompounds showed effective anti-adipogenic activity even in palmitic acid challenged environment in adipocytes.

Metabolites of oregano (Origanum vulgare) seed and their anti-obesity effects on 3T3-L1 adipocytes through down-regulated adipogenesis

Metabolites of the 80% ethanol extract (OSE) and ethyl acetate fraction (OSEA) of oregano seed were analyzed by GC-MS, and anti-obesity effects of OSE and OSEA were evaluated in 3T3-L1 adipocyte. OSE possessed high content of glucose, fructofuranose, and sucrose while OSEA had high content of phenolic chemicals. OSEA contained higher levels of gallic acid, syringic acid, protocatechuic acid, and catechin than OSE. OSEA inhibited lipid droplet accumulation with concentration dependent manner in 3T3-L1 preadipocytes during differentiation. OSEA showed more inhibition ability than OSE by 13.7-fold at the level of 125 μg/mL. Additionally, relative mRNA and protein expression levels of pparγ, c/ebpα, fas, and srebp-1c which are related to adipogenesis were significantly lower in OSEA treatment group than in OSE treatment group (p < 0.05). Therefore, OSEA could be used as anti-obesity functional ingredient.

Dietary syringic acid reduces fat mass in an ovariectomy-induced mouse model of obesity

OBJECTIVE

Postmenopausal women are at increased risk of metabolic diseases such as obesity and diabetes. Therefore, the chemoprevention of postmenopausal changes in health via dietary supplements is important. Syringic acid (SA) is a phenolic compound present in the fruit of the assai palm, Euterpe oleracea, and in the mycelium of the shiitake mushroom, Lentinula edodes. This compound shows no affinity for estrogen receptors and may exert disease-preventive effects. Reportedly, dietary SA ameliorates high-fat diet-induced obesity in mice; however, its effects on estrogen deficiency-induced obesity are still unclear. Therefore, in this study, we investigated whether and how dietary SA affects these factors in ovariectomized (OVX) mice.

METHODS

Ten-week-old OVX mice were fed SA-containing diets (100 mg/kg body weight/d) for 12 weeks. Their body weights, food intake, and uterus weights as well as other parameters were measured and comparisons were made with mice in the control group.

RESULTS

Dietary SA did not affect the body weight, food intake, or uterus weight of OVX mice over the study period; however, the SA-fed group showed lower fat mass (ie, visceral, subcutaneous, and total fat) than the OVX-control group (11.1 ± 3.3 vs. 8.3 ± 2.4, P < 0.05; 7.9 ± 1.1 vs. 5.9 ± 1.6, P < 0.05; 19.0 ± 4.2 vs. 14.1 ± 3.8, P < 0.05, respectively). Furthermore, blood analysis revealed that SA-treatment resulted in a dose-dependent decrease and increase in serum triglyceride (59.2 ± 8.3 vs. 43.9 ± 12.2 mg/dL P < 0.05) and adiponectin (7.7 ± 0.3 vs. 9.5 ± 0.6 μg/mL, P < 0.05) levels, respectively.

CONCLUSIONS

These results suggest that the SA diet improves lipid metabolism without affecting the uterus in OVX mice. Therefore, dietary SA has potential applicability for the prevention of postmenopausal obesity and type 2 diabetes.