Effects of heat treatment on the antioxidative and anti-inflammatory properties of orange by-products

Tangeretin Enhances Muscle Endurance and Aerobic Metabolism in Mice via Targeting AdipoR1 to Increase Oxidative Myofibers

Slow oxidative myofibers play an important role in improving muscle endurance performance and maintaining body energy homeostasis. However, the targets and means to regulate slow oxidative myofibers proportion remain unknown. Here, we show that tangeretin (TG), a natural polymethoxylated flavone, significantly activates slow oxidative myofibers-related gene expression and increases type I myofibers proportion, resulting in improved endurance performance and aerobic metabolism in mice. Proteomics, molecular dynamics, cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) investigations revealed that TG can directly bind to adiponectin receptor 1 (AdipoR1). Using AdipoR1-knockdown C2C12 cells and muscle-specific AdipoR1-knockout mice, we found that the positive effect of TG on regulating slow oxidative myofiber related markers expression is mediated by AdipoR1 and its downstream AMPK/PGC-1α pathway. Together, our data uncover TG as a natural compound that regulates the identity of slow oxidative myofibers via targeting the AdipoR1 signaling pathway. These findings further unveil the new function of TG in increasing the proportion of slow oxidative myofibers and enhancing skeletal muscle performance.

Natural essential oil mix of sweet orange peel, cumin, and allspice elicits anti-inflammatory activity and pharmacological safety similar to non-steroidal anti-inflammatory drugs

An inflammation response occurs when the body reacts to exogenous and endo enous noxious stimuli, and it helps the body respond to infection and repair tissues, adapt to stress, and remove dead or damaged cells. Anti-inflammatory drugs such as non-steroidal anti-inflammatory drugs are traditionally used to treat inflammation; however, these drugs often cause negative side effects. For this reason, developing and establishing effective alternative medicines for treating many chronic diseases with underlying inflammation is critically dependent on the identification of new organic molecules and bioactive substances. Aromatic and volatile compounds found in essential oils isolated from Pimenta dioica (allspice), Cuminum cyminum (cumin), and Citrus sinensis (sweet orange) are a source of bioactive compounds. Allspice essential oil reduces ear inflammation more than 65% and the anti-inflammatory activity of allspice essential oil is enhanced when combined with sweet orange peel and cumin essential oils, resulting in the reduction of edema inflammation by more than 85%, similar to indomethacin. As an alternative to anti-inflammatory treatment, essential oil mix is pharmacologically safe as it is neither toxic nor mutagenic.

Inhibition or Reversal of the Epithelial-Mesenchymal Transition in Gastric Cancer: Pharmacological Approaches

Epithelial-mesenchymal transition (EMT) constitutes one of the hallmarks of carcinogenesis consisting in the re-differentiation of the epithelial cells into mesenchymal ones changing the cellular phenotype into a malignant one. EMT has been shown to play a role in the malignant transformation and while occurring in the tumor microenvironment, it significantly affects the aggressiveness of gastric cancer, among others. Importantly, after EMT occurs, gastric cancer patients are more susceptible to the induction of resistance to various therapeutic agents, worsening the clinical outcome of patients. Therefore, there is an urgent need to search for the newest pharmacological agents targeting EMT to prevent further progression of gastric carcinogenesis and potential metastases. Therapies targeted at EMT might be combined with other currently available treatment modalities, which seems to be an effective strategy to treat gastric cancer patients. In this review, we have summarized recent advances in gastric cancer treatment in terms of targeting EMT specifically, such as the administration of polyphenols, resveratrol, tangeretin, luteolin, genistein, proton pump inhibitors, terpenes, other plant extracts, or inorganic compounds.

Polymethoxyflavones from citrus inhibited gastric cancer cell proliferation through inducing apoptosis by upregulating RARβ, both in vitro and in vivo

In order to discover the active anti-tumor ingredients during the flavonoids separation process of Ougan (Citrus reticulata cv. Suavissima), gastric cancer cell lines including AGS, BGC-823, and SGC-7901 were employed to evaluate the proliferation inhibition abilities of Ougan extracts, flavanone components, polymethoxyflavone components, neohesperidin, nobiletin, tangeretin, and 5-demethylnobiletin. Quantitative real-time PCR was used to detect the expression of three retinoic acid receptor genes, including RARA, RARB, and RARG. Western blot and immunohistochemistry were used to detect protein expressions. The results showed that the polymethoxyflavone components and the PMFs monomers inhibited the proliferation of three gastric cancer cell lines and induced apoptosis. The mechanism exploration found that PMFs up-regulated the expression of the RARB gene selectively and activated the Caspase3, 9, and PARP1 proteins. In addition to 5-demethylnobiletin, other PMFs also upregulated the expression of cleaved Caspase8. The mechanism was preliminarily verified by a RARβ inhibitor AGN 193109. Moreover, a nude mice tumor xenograft model confirmed the tangeretin could exhibit in vivo anti-tumor effect through inducing apoptosis and upregulating RARβ protein. All result suggested that tangeretin may be a potentially novel, safe and effective drugs with less toxicity and lesser side effects for gastric cancer therapeutics.

Effects of heat treatment of mandarin peel on flavonoid profiles and lipid accumulation in 3T3-L1 adipocytes

Citrus peel, a primary byproduct of citrus fruits, contains a variety of flavonoids. Heat treatment is a favorable food processing for solid peel to release bioactive compounds from tissues and intensify nutritional effects. In this study, we explored alterations of flavonoids by thermal treatment of mandarin peel and their effects on lipid accumulation and intracellular levels during differentiation of 3T3-L1 cells to adipocytes. The heat-treated sample showed stronger inhibition on the formation of lipid droplets than the non-treated sample, along with enhanced intracellular levels of flavonoids. Overall flavonoids, especially flavonoid aglycones showing better efficacy, were found to increase in the peel after heat-treatment. Our findings indicate thermal processing could help release flavonoids from citrus peel and convert them into aglycone forms, leading to efficient cellular uptake and suppression of lipid accumulation in 3T3-L1 cells. This study provides useful information of heat-treated citrus peel as potential dietary supplements with antiobesity-related effects.

Citrus Tangeretin Improves Skeletal Muscle Mitochondrial Biogenesis via Activating the AMPK-PGC1-α Pathway In Vitro and In Vivo: A Possible Mechanism for Its Beneficial Effect on Physical Performance

Mitochondrial biogenesis is a key factor, which influences the function of skeletal muscle. Increasingly, flavonoids are reported to have the potential ability of regulating mitochondrial biogenesis. In this study, we investigated the effects of tangeretin, a polymethoxylated flavonoid isolated from mandarin fruits, on mitochondrial biogenesis and its underlying mechanisms. The tangeretin was obtained from the peel of "Dahongpao" tangerine by macroporous adsorptive resins combined with preparative-high performance liquid chromatography. The activity of mitochondrial biogenesis was explored by using mouse-derived C2C12 myoblasts and Kunming mice. Results showed that the purity of tangeretin obtained was 98.64%, and it could effectively activate mitochondrial biogenesis signaling pathway both at gene and at protein levels in C2C12 myoblasts. Animal experiments showed that tangeretin pretreatment could markedly improve exercise performance (the time of hanging wire and run to fatigue was obviously increased 1.6-fold and 2.1-fold in the high-dose tangeretin group, respectively), and the transmission electron microscopy, Western blotting, and immunohistochemistry further indicated that tangeretin increased mitochondria number and activated mitochondrial biogenesis signaling axis. Our findings suggest that tangeretin enhanced mitochondrial biogenesis via activating the AMPK-PGC1-α pathway, resulting in the improvement of exercise performance, and tangeretin may be a potentially novel mitochondria regulator in foods.