Dietary Supplementation with Isoflavones Prevents Muscle Wasting in Tumor-Bearing Mice

A Review of Nutraceuticals in Cancer Cachexia

Cancer cachexia is largely characterized by muscle wasting and inflammation, leading to weight loss, functional impairment, poor quality of life (QOL), and reduced survival. The main barrier to therapeutic development is a lack of efficacy for improving clinically relevant outcomes, such as physical function or QOL, yet most nutraceutical studies focus on body weight. This review describes clinical and pre-clinical nutraceutical studies outside the context of complex nutritional and/or multimodal interventions, in the setting of cancer cachexia, in view of considerations for future clinical trial design. Clinical studies mostly utilized polyunsaturated fatty acids or amino acids/derivatives, and they primarily focused on body weight and, secondarily, on muscle mass and/or QOL. The few studies that measured physical function almost exclusively utilized handgrip strength with, predominantly, no time and/or group effect. Preclinical studies focused mainly on amino acids/derivatives and polyphenols, assessing body weight, muscle mass, and occasionally physical function. While this review does not provide sufficient evidence of the efficacy of nutraceuticals for cancer cachexia, more preclinical and adequately powered clinical studies are needed, and they should focus on clinically meaningful outcomes, including physical function and QOL.

Accounting Gut Microbiota as the Mediator of Beneficial Effects of Dietary (Poly)phenols on Skeletal Muscle in Aging

Sarcopenia, the age-related loss of muscle mass and function increasing the risk of disability and adverse outcomes in older people, is substantially influenced by dietary habits. Several studies from animal models of aging and muscle wasting indicate that the intake of specific polyphenol compounds can be associated with myoprotective effects, and improvements in muscle strength and performance. Such findings have also been confirmed in a smaller number of human studies. However, in the gut lumen, dietary polyphenols undergo extensive biotransformation by gut microbiota into a wide range of bioactive compounds, which substantially contribute to bioactivity on skeletal muscle. Thus, the beneficial effects of polyphenols may consistently vary across individuals, depending on the composition and metabolic functionality of gut bacterial communities. The understanding of such variability has recently been improved. For example, resveratrol and urolithin interaction with the microbiota can produce different biological effects according to the microbiota metabotype. In older individuals, the gut microbiota is frequently characterized by dysbiosis, overrepresentation of opportunistic pathogens, and increased inter-individual variability, which may contribute to increasing the variability of biological actions of phenolic compounds at the skeletal muscle level. These interactions should be taken into great consideration for designing effective nutritional strategies to counteract sarcopenia.

Role for Plant-Derived Antioxidants in Attenuating Cancer Cachexia

Cancer cachexia is the progressive muscle wasting and weakness experienced by many cancer patients. It can compromise the response to gold standard cancer therapies, impair functional capacity and reduce overall quality of life. Cancer cachexia accounts for nearly one-third of all cancer-related deaths and has no effective treatment. The pathogenesis of cancer cachexia and its progression is multifactorial and includes increased oxidative stress derived from both the tumor and the host immune response. Antioxidants have therapeutic potential to attenuate cancer-related muscle loss, with polyphenols, a group of plant-derived antioxidants, being the most widely investigated. This review describes the potential of these plant-derived antioxidants for treating cancer cachexia.

Polyphenols and Their Effects on Muscle Atrophy and Muscle Health

Skeletal muscle atrophy is the decrease in muscle mass and strength caused by reduced protein synthesis/accelerated protein degradation. Various conditions, such as denervation, disuse, aging, chronic diseases, heart disease, obstructive lung disease, diabetes, renal failure, AIDS, sepsis, cancer, and steroidal medications, can cause muscle atrophy. Mechanistically, inflammation, oxidative stress, and mitochondrial dysfunction are among the major contributors to muscle atrophy, by modulating signaling pathways that regulate muscle homeostasis. To prevent muscle catabolism and enhance muscle anabolism, several natural and synthetic compounds have been investigated. Recently, polyphenols (i.e., natural phytochemicals) have received extensive attention regarding their effect on muscle atrophy because of their potent antioxidant and anti-inflammatory properties. Numerous in vitro and in vivo studies have reported polyphenols as strongly effective bioactive molecules that attenuate muscle atrophy and enhance muscle health. This review describes polyphenols as promising bioactive molecules that impede muscle atrophy induced by various proatrophic factors. The effects of each class/subclass of polyphenolic compounds regarding protection against the muscle disorders induced by various pathological/physiological factors are summarized in tabular form and discussed. Although considerable variations in antiatrophic potencies and mechanisms were observed among structurally diverse polyphenolic compounds, they are vital factors to be considered in muscle atrophy prevention strategies.

Daidzein alleviates cisplatin-induced muscle atrophy by regulating Glut4/AMPK/FoxO pathway

Cisplatin (DDP) is widely used in cancer treatment, but DDP can cause skeletal muscle atrophy and cachexia. This study explored the effect and mechanism of daidzein (DAI) in reducing DDP-induced skeletal muscle atrophy and cachexia in vivo and in vitro. DAI alleviated the weight, food intake, muscle, adipose tissue, kidney weight and forelimb grip of LLC tumour-bearing mice after DDP treatment, and did not affect the antitumour effect of DDP. DAI can reduce the decrease of the cross-sectional area of skeletal muscle fibre-induced by DDP and prevent the change of fibre type proportion. In skeletal muscle, it can inhibit Glut4/AMPK/FoxO pathway, down-regulate the expression of atrogin1 and MuRF1, and inhibit skeletal muscle protein degradation. In DDP treated C2C12 myotubes, DAI could inhibit Glut4/AMPK/FoxO pathway to reduce myotubes atrophy, while AMPK agonist MK-3903 could reverse the protective effect of DAI. These results suggest that DAI can alleviate DDP-induced skeletal muscle atrophy by downregulating the expression of Atrogin1 and MuRF1 through the regulation of Glut4/AMPK/FoxO pathway.

Astaxanthin Prevents Atrophy in Slow Muscle Fibers by Inhibiting Mitochondrial Reactive Oxygen Species via a Mitochondria-Mediated Apoptosis Pathway

Astaxanthin (AX) is a carotenoid that exerts potent antioxidant activity and acts in the lipid bilayer. This study aimed to investigate the effects of AX on muscle-atrophy-mediated disturbance of mitochondria, which have a lipid bilayer. Tail suspension was used to establish a muscle-atrophied mouse model. AX diet fed to tail-suspension mice prevented loss of muscle weight, inhibited the decrease of myofiber size, and restrained the increase of hydrogen peroxide (H₂O₂) production in the soleus muscle. Additionally, AX improved downregulation of mitochondrial respiratory chain complexes I and III in the soleus muscle after tail suspension. Meanwhile, AX promoted mitochondrial biogenesis by upregulating the expressions of adenosine 5′-monophosphate–activated protein kinase (AMPK) α-1, peroxisome proliferator–activated receptor (PPAR)-γ, and creatine kinase in mitochondrial (Ckmt) 2 in the soleus muscle of tail-suspension mice. To confirm the AX phenotype in the soleus muscle, we examined its effects on mitochondria using Sol8 myotubes derived from the soleus muscle. We found that AX was preferentially detected in the mitochondrial fraction; it significantly suppressed mitochondrial reactive oxygen species (ROS) production in Sol8 myotubes. Moreover, AX inhibited the activation of caspase 3 via inhibiting the release of cytochrome c into the cytosol in antimycin A–treated Sol8 myotubes. These results suggested that AX protected the functional stability of mitochondria, alleviated mitochondrial oxidative stress and mitochondria-mediated apoptosis, and thus, prevented muscle atrophy.

Influence of the interposition of pink muscle fibers in the dorsal ordinary muscle on the postmortem hardness of meat in various fishes

We previously showed that the tenderization of ordinary muscle during ice storage is affected by the interposition of pink muscle fibers in the ordinary muscle. However, little is known about whether or not the interposition of pink muscle fibers affects the hardness of raw fish meat. To clarify the influence of the interposition of pink muscle fibers in the dorsal ordinary muscle on hardness of meat, the breaking strengths and the fiber types of the dorsal ordinary muscle of eight fish species (a total of 37 specimens) were discriminated. The breaking strengths among fish species were within a range of 6.5-19.1 N/cm² . Pink muscle fibers were found in the dorsal ordinary muscle of six out of the eight fish species ranging from 0.0 to 56.0% in quantity ratio, and 0.0 to 19.3% in area ratio, respectively. The quantity ratio and area ratio of pink muscle fibers in the dorsal ordinary muscles of all eight fish species samples positively correlated with the breaking strength. Relative to the quantity ratio (p < .05), the area ratio (p < .02) of pink muscle fibers was more representative of postmortem texture hardness. In conclusion, the high interposition ratio of pink muscle fibers in ordinary muscle could potentially improve the postmortem hardness, the texture, and even the flesh quality of raw fish meat.

Nutritional Interventions in Cancer Cachexia: Evidence and Perspectives From Experimental Models

Cancer cachexia is a complex metabolic syndrome characterized by involuntary skeletal muscle loss and is associated with poor clinical outcome, decreased survival and negatively influences cancer therapy. No curative treatments are available for cancer cachexia, but nutritional intervention is recommended as a cornerstone of multimodal therapy. Optimal nutritional care is pivotal in the treatment of cancer cachexia, and the effects of nutrients may extend beyond provision of adequate energy uptake, targeting different mechanisms or metabolic pathways that are affected or deregulated by cachexia. The evidence to support this notion derived from nutritional intervention studies in experimental models of cancer cachexia is systematically discussed in this review. Moreover, experimental variables and readout parameters to determine skeletal muscle wasting and cachexia are methodologically evaluated to allow critical comparison of similar studies. Single- and multinutrient intervention studies including qualitative modulation of dietary protein, dietary fat, and supplementation with specific nutrients, such as carnitine and creatine, were reviewed for their efficacy to counteract muscle mass loss and its underlying mechanisms in experimental cancer cachexia. Numerous studies showed favorable effects on impaired protein turnover and related metabolic abnormalities of nutritional supplementation in parallel with a beneficial impact on cancer-induced muscle wasting. The combination of high quality nutrients in a multitargeted, multinutrient approach appears specifically promising, preferentially as a multimodal intervention, although more studies investigating the optimal quantity and combination of nutrients are needed. During the review process, a wide variation in timing, duration, dosing, and route of supplementation, as well as a wide variation in animal models were observed. Better standardization in dietary design, and the development of experimental models that better recapitulate the etiology of human cachexia, will further facilitate successful translation of experimentally-based multinutrient, multimodal interventions into clinical practice.

Consuming Genistein Improves Survival Rates in the Absence of Laxative in ΔF508-CF Female Mice

Genistein is a naturally occurring isoflavone found in soy. Genistein has been shown to increase the open probability of the most common cystic fibrosis (CF) disease-associated mutation, ∆F508-CFTR. Mice homozygous for the ∆F508 mutation are characterized with severe intestinal disease and require constant laxative treatment for survival. This pathology mimics the intestinal obstruction (meconium ileus) seen in some cystic fibrosis patients. This study tested whether dietary supplementation with genistein would reduce the dependence of the ∆F508 CF mouse model on laxatives for survival, thereby improving mortality rates. At weaning (21 days), homozygous ∆F508 mice were maintained on one of three diet regimens for a period of up to 65 days: normal diet, normal diet plus colyte, or genistein diet. Survival rates for males were as follows: standard diet (38%, n = 21), standard diet plus colyte (83%, n = 42) and genistein diet (60%, n = 15). Survival rates for females were as follows: standard diet (47%, n = 19), standard diet plus colyte (71%, n = 38), and genistein diet (87%, n = 15). Average weight of male mice fed genistein diet increased by ~2.5 g more (p = 0.006) compared to those with colyte treatment. Genistein diet did not change final body weight of females. Expression of intestinal SGLT-1 increased 2-fold (p = 0.0005) with genistein diet in females (no change in males, p = 0.722). Expression of GLUT2 and GLUT5 was comparable between all diet groups. Genistein diet reduced the number of goblet cells per micrometer of crypt depth in female (p = 0.0483), yet was without effect in males (p = 0.7267). The results from this study demonstrate that supplementation of diet with genistein for ~45 days increases the survival rate of female ∆F508-CF mice (precluding the requirement for laxatives), and genistein only improves weight gain in males.

Dietary supplementation with alkylresorcinols prevents muscle atrophy through a shift of energy supply

It has been reported that phytoextracts that contain alkylresorcinols (ARs) protect against severe myofibrillar degeneration found in isoproterenol-induced myocardial infarction. In this study, we examined the effect of dietary ARs derived from wheat bran extracts on muscle atrophy in denervated mice. The mice were divided into the following four groups: (1) sham-operated (control) mice fed with normal diet (S-ND), (2) denervated mice fed with normal diet (D-ND), (3) control mice fed with ARs-supplemented diet (S-AR) and (4) denervated mice fed with ARs-supplemented diet (D-AR). The intake of ARs prevented the denervation-induced reduction of the weight of the hind limb muscles and the myofiber size. However, the expression of ubiquitin ligases and autophagy-related genes, which is associated with muscle proteolysis, was slightly higher in D-AR than in D-ND. Moreover, the abundance of the autophagy marker p62 was significantly higher in D-AR than in D-ND. Muscle atrophy has been known to be associated with a disturbed energy metabolism. The expression of pyruvate dehydrogenase kinase 4 (PDK4), which is related to fatty acid metabolism, was decreased in D-ND as compared with that in S-ND. In contrast, dietary supplementation with ARs inhibited the decrease of PDK4 expression caused by denervation. Furthermore, the abnormal expression pattern of genes related to the abundance of lipid droplets-coated proteins that was induced by denervation was improved by ARs. These results raise the possibility that dietary supplementation with ARs modifies the disruption of fatty acid metabolism induced by lipid autophagy, resulting in the prevention of muscle atrophy.

Advances in extraction and analysis of phenolic compounds from plant materials

Phenolic compounds, the most abundant secondary metabolites in plants, have received more and more attention in recent years because of their distinct bioactivities. This review summarizes different types of phenolic compounds and their extraction and analytical methods used in the recent reports, involving 59 phenolic compounds from 52 kinds of plants. The extraction methods include solid-liquid extraction, ultrasound-assisted extractions, microwave-assisted extractions, supercritical fluid extraction, and other methods. The analysis methods include spectrophotometry, gas chromatography, liquid chromatography, thin-layer chromatography, capillary electrophoresis, and near-infrared spectroscopy. After illustrating the specific conditions of the analytical methods, the advantages and disadvantages of each method are also summarized, pointing out their respective suitability. This review provides valuable reference for identification and/or quantification of phenolic compounds from natural products.

Genistein diet does not modify crypt morphology in the ob/ob mouse jejunum: a comparison of cryostat and clearing techniques

INTRODUCTION

Diabetes is commonly associated with gastrointestinal dysfunction. We have previously shown that transepithelial short circuit current, I_sc (chloride secretion), is significantly reduced in the jejunum from ob/ob mice vs lean controls, and consumption of 600 mg genistein/kg of diet (600 G) for 4 weeks significantly rescues I_sc. We aimed to evaluate whether morphological changes in the jejunal crypts contribute to the rescue of I_sc.

METHODS

Male mice (ob/ob and lean controls) were fed either a genistein-free diet or genistein-containing diet (600 G). Comparisons of crypt morphology were made for crypt depth, length, and numbers of proliferative cells. Assessments of crypt measures using DAPI and 5-ethynyl-2'-deoxyuridine (EdU) were performed using traditional cryostat sectioning and an innovative 3D optical clearing method.

RESULTS

We found that crypt length in the ob/ob genistein-fed group was significantly greater when measured with cleared tissue (85.19±4.73 µm, P<0.05, n=8) compared to lengths measured with cryostat (65.42±3.48 µm, n=8). In addition, proliferative EdU+ counts were approximately fivefold greater with clearing, compared to counts obtained via single plane images from cryostat sections for all groups measured. The average length to EdU+ ratio was unchanged between groups.

CONCLUSION

Thus, we conclude that genistein diet does not affect overall cellular proliferation or crypt morphology, other than for the modest increased crypt length measured via clearing in the ob/ob genistein group. The increase in crypt length is likely indicative of the greater accuracy of the 3D measures compared to single plane. Genistein diet-induced increases in the intestinal I_sc are therefore likely not attributed to changes in intestinal crypt morphology.