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At present, more and more people are suffering from various diseases and it is particularly important to find a suitable biological model to evaluate the prevention and treatment effects of various drugs and active ingredients on diseases. In all biological models, Caenorhabditis elegans is a kind of organism that is easy to observe and cultivate, has a clear genetic background and a high degree of signal pathway conservation with humans. A variety of active ingredients such as polyphenols, polysaccharides, polypeptides, and vitamins exist from natural products, which has extremely high physiological functions and medicinal values. It is highly reliable to evaluate the trophic and functional properties of the active ingredients from natural products in C. elegans. The functional properties of the active ingredients from natural products such as antiaging, anti-oxidation, regulating lipid metabolism, preventing and treating Alzheimer's disease in C. elegans were clarified in this review. At the same time, its possible pathways were summarized. The literature revealed that it had great effect to evaluate the nutrition and functionality of the active ingredients from natural products in C. elegans. Finally, the shortcomings in this field and suggestions for further improvement in this field have been emphasized.

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Summary In the food industry, yeast was used to regulate food flavour and produce fermented products. In recent years, research has found that yeast contains amino acids, peptides and other active substances, but there was little research on its improvement of health benefits. In this study, the antioxidant and anti‐ageing activities of nucleotide‐rich yeast hydrolysates (NYH) were explored in Caenorhabditis elegans nematode model system, it was found that the lifespan, anti‐heat stress and anti‐acute oxidative stress were enhanced in C. elegans supplemented with NYH by up‐regulating the activity of antioxidant enzymes and down‐regulating the level of MDA and ROS. The mRNA expression level such as age‐1 and daf‐2 was significantly down‐regulated. In addition, the antioxidant and anti‐ageing activities of NYH were exerted mainly through tyrosine metabolism, glycerophospholipid metabolism and glutathione metabolism metabolic pathways. These results showed that NYH had the potential of antioxidation and anti‐ageing, which provided a possibility for the development of yeast products as a functional food in food science.

Lentinus edodes (L. edodes) was a fungus plant, which was widely grown and eaten as food in China. As an antioxidant, the polysaccharide of L. edodes has been widely studied in terms of antioxidant activity, however, the effect of action and underlying mechanism of L. edodes ethanol extracts (LEEE) in antioxidant aspects were largely unknown. In this study, the antioxidant activity of LEEE was investigated in vitro. In addition, the antioxidant activity of LEEE was estimated in vivo through Caenorhabditis elegans model. It was found that LEEE had excellent antioxidant activity in vitro by scavenging DPPH, ABTS and hydroxyl radicals. At the same time, the anti-heat stress abilities of C. elegans were enhanced after supplementation with different concentrations of LEEE. The activities of antioxidant enzymes such as T-SOD, GSH-PX and CAT were significantly enhanced and the levels of MDA and ROS were significantly down-regulated. However, the level of apoptosis of C. elegans could not be improved after supplementation with LEEE. In the study of LEEE antioxidant-related signaling pathways through q-PCR experiments, it was found that LEEE exerted antioxidant activity in C. elegans by up-regulating MTL-1, DAF-16 and SOD-3 mRNA expression and down-regulating DAF-2 mRNA expression. This provided a solid foundation for the active substances of Lentinus edodes in improving oxidation-related diseases.

Kudzu-resistant starch was prepared by pullulanase debranching recrystallization. Based on single factor experiments, the response surface optimization method was used to analyze the optimal conditions for the preparation of kudzu-resistant starch. The results showed that the highest yield of 90.46% was obtained at the enzymatic reaction time of 4 h, temperature of 56°C, and amount of enzyme being 57 U/g. After debranching, the content of the resistant starch was higher than native starch. The crystal structure of the debranched starch changed from A-type to a mixture of B+V-type. The results of scanning electron microscope showed that the surface of the native starch granule was smooth and varied in size, showing a spherical or irregular polyhedral shape, while the debranched starch granule was irregular in shape and size and the surface was rough and gully. The granule morphology of the modified starch granule was also changed.