Research on the hydrolysis process and antioxidant activity of polysaccharides from American cockroaches
The American cockroach (Periplaneta Americana L.) is one of the largest insects in the cockroach genus. The medicinal value of cockroaches has long been recorded in the “Shennong Bencao Jing” and the Ming Dynasty’s “Compendium of Materia Medica”. Since the 1980s, researchers led by Professor Li Shunan have been dedicated to the medicinal research of American cockroaches. Ethanol extracts of artificially raised American cockroaches are taken orally or topically for the treatment of ulcers, cancer, and other conditions. Research has found that the chemical composition of American cockroaches includes proteins, amino acids, peptides, sugars, fatty acids, pheromones, and others, with biological activities such as anti-tumor, anti liver fibrosis, antibacterial, antiviral, and antioxidant effects.

Carbohydrates are the most abundant organic compounds on Earth, accounting for three-quarters of the total biomass, while polysaccharides make up approximately 90% of the total. The biological activities of polysaccharides mainly include anti-tumor, hypoglycemic, anti-aging, enhancing bone marrow hematopoietic function, regulating immunity, etc., and they are basically non-toxic and have no side effects. Therefore, they have received widespread attention and have great application prospects in the field of medicine. Its activity is related to its relative molecular weight, chemical composition, glycosidic bond configuration, connection mode, and spatial configuration. To understand the characteristics of American cockroach polysaccharides, hydrolysis reaction can be used to analyze the changes in monosaccharide composition and content, providing a basis for quality control of American cockroach polysaccharides. The experiment used American cockroach polysaccharides as the experimental object. Based on single factor experiments, the total peak area of monosaccharides in high-performance liquid chromatography was used as the indicator to optimize the hydrolysis process of American cockroach polysaccharides using response surface methodology to obtain the highest monosaccharide content. In addition, the antioxidant activity of American cockroach polysaccharides was studied, providing reference for the structural identification and subsequent development and utilization of American cockroach polysaccharides.

This study used a combination of single factor experiments and response surface experiments to optimize the extraction process conditions of polysaccharides from American cockroaches and preliminarily evaluate their antioxidant capacity. The optimal process conditions for the hydrolysis of American cockroach polysaccharides are: hydrolysis time of 1 hour, hydrolysis temperature of 120 ℃, TFA dosage of 3.5 mL, and total peak area of 4740.15. The results of antioxidant activity assay showed that the polysaccharides from American cockroaches have good antioxidant activity, and they have good scavenging ability against DPPH, OH, and ABTS free radicals, with IC50 values of 0.028, 0.78, and 0.07 mg/mL, respectively, and have certain reducing ability. Zhang et al. found a certain positive correlation between the ratio of galactose and arabinose in Bawanghua polysaccharides and their IC50 for clearing ABTS free radicals. Shang et al. conducted Pearson correlation analysis between the chemical composition and monosaccharide composition of five edible fungal polysaccharides and their antioxidant activity (IC50), and found that the content of fucose, mannose, and galactose had an impact on the ABTS free radical scavenging activity of polysaccharides; The content of glucose and mannose has a significant impact on the OH radical scavenging activity of polysaccharides, while the content of fucoidan is positively correlated with the IC50 value of superoxide anions in polysaccharides. Ai found that mannose, xylose, galactose, and arabinose have a significant impact on the antioxidant activity of tea polysaccharides. Relevant literature indicates that the antioxidant activity of polysaccharides is closely related to their monosaccharide composition and the content of each monosaccharide. The experiment found that the polysaccharides of American cockroaches have good scavenging ability against DPPH, OH, and ABTS free radicals. HPLC test results showed that their hydrolysate contains mannose, glucosamine hydrochloride, rhamnose, glucose, galactose, xylose, arabinose, and fucose, with a molar ratio of 17.0:13.2:9.6:53.4:21.8:1.0:4.6:1.3. The antioxidant activity of American cockroach polysaccharides may be related to their monosaccharide composition, and whether the antioxidant activity of hydrolyzed American cockroach polysaccharides can be maintained or increased remains to be further studied in experiments.