In a recent review published in Nutrients, researchers reviewed existing data on the structure, extraction, health benefits, and mechanisms of Dendrobium officinale polysaccharides (DOPs).
Study: Structure, Health Benefits, Mechanisms, and Gut Microbiota of Dendrobium officinale Polysaccharides: A Review. Image Credit: bennie/Shutterstock.com
DOPs are active polysaccharides present in Dendrobium officinale, a traditional food ingredient or herbal medicine in China.
DOPs can alter the gut microbial composition and enzymatic degradation capability of symbiotic bacterial organisms, which may impact the efficiency of dietary treatments. Data on the association between DOPs and intestinal microbes are limited.
About the study
In the present study, researchers studied the structure, extraction, biological functions, underlying mechanisms, and associations of DOPs with gut microbes.
Structure and extraction of DOPs
Dendrobium officinale, a Chinese herbal medicine, has approximately 20% water-soluble, non-starchy, active polysaccharides (DOPs).
These polysaccharides are mostly heteropolysaccharides comprising mannose, glucose, xylose, galactose, rhamnose, and arabinose. Fresh DOPs are cleaned, dried, and powdered in low thermal conditions. Organic solvents are used to extract crude DOPs by eliminating low-molecular-weight compounds.
Ultrasound-aided extraction, hot water extraction (HWE), enzyme-aided extraction, microwave-aided extraction, mechanochemical-aided extraction, steam-aided flash extraction, and enzyme-aided extraction using eutectic solvents are common extraction procedures. Among the methods, hot water extraction is most commonly used due to its simplicity, ease, and safety.
Higher yields are obtained with ultrasonic-assisted hot water extraction and freeze-thaw cold pressing, whereas mechanochemical-assisted extraction enhances efficiency and reduces extraction time.
Deep eutectic solvent-based extraction is attractive due to its steady performance and fewer environmental issues, whereas enzyme-assisted extraction offers gentle reaction conditions and excellent efficiency.
Health benefits and underlying mechanisms
DOPs may help with metabolic problems such as obesity, type 2 diabetes, and inflammation. DOPs alleviated metabolic abnormalities in C57BL/6 murine animals fed a high-fat diet (HFD) for 11 weeks, including glutamine metabolism, fatty acid synthesis, Kreb cycle, butyrate metabolism, and glutathione metabolism. These effects may be partially transmitted by transplanting fecal microbes into high-fat diet-induced obese murine animals.
DOPs also ameliorate mitochondrial impairment by increasing phosphorylated AMP-stimulated protein kinase (p-AMPK) levels and boosting citric acid cycle functions.
They inhibit glucose metabolism and glycogen synthesis by activating the phosphoinositide-3-kinase-protein kinase (PI3K/Akt) signaling pathway, mediating the protein kinase A (PKA) and protein kinase/forkhead box O1 (Akt/FoxO1) signaling pathways to inhibit glycogen degradation, increase hepatic glycogen formation, inhibit hepatic gluconeogenesis, and regulate peroxisome proliferator-activated receptor (PPAR) levels to improve lipid metabolism.
In Wistar rats with type 2 diabetes induced by streptozotocin, a 28-day treatment with two naturally acetylated glucomannans and DOPs corrected metabolic disorders related to lipids and glucose levels.
DOPs performed excellently, were safe, and had no hazardous adverse effects in treating obese murine animals at one gram per kg per day over 11 weeks.
DOPs restore intestinal barrier function and preserve the mucosal barrier of the intestine. They boost the production of intestinal epithelial tight junction proteins, keep the mucosal barrier stable, minimize lipopolysaccharide translocation, and lower serum lipopolysaccharide (LPS) levels.
They stimulate the nuclear factor erythroid-2 related factor 2 (Nrf2)/heme oxygenase (HO-1) signaling pathway in injured cells at inflammatory locations, reducing oxidative damage and effectively controlling inflammation.
Associations of DOPs with the intestinal microbiome
Gut microbes process DOPs in the colon, producing short-chain fatty acids (SCFAs) and oligosaccharides that alter gut microbial composition and improve human health. DOPs have been shown to decrease harmful bacteria like Escherichia coli and Staphylococcus while promoting beneficial ones like Bifidobacterium.
DOPs alter the composition and diversity of the gut microbiome and enhance the synthesis of SCFAs such as acetate, propionate, and butyrate. This supplementation can restore gut microbial balance and improve microbial diversity in obese mice and model animals, bringing the gut microbiota closer to a healthy condition.
DOPs also affect alterations in the gut microbiota at the phylum level, with obesity linked to a drop in the Firmicutes/Bacteroidetes ratio. DOPs can break down DOPs and create SCFAs, promoting the development of Bifidobacterium and Lactobacillus microbial populations.
Common probiotic strains can also break down and consume DOPs, creating SCFAs, preventing pathogenic bacteria development, and reducing Akkermansia formation.
Based on the review findings, DOPs can boost gut health as probable prebiotics, offering health benefits like metabolism regulation, inflammation modulation, immunity moderation, and cancer intervention.
They can improve gut microbiome composition, offering new strategies for metabolic and inflammatory diseases. However, the association between DOPs and the intestinal microbiome is not fully understood.
Future research should focus on DOPs’ growth-promoting effect on probiotics and their role in cancer processes and immune activity.