There are about 100 trillion bacteria in the human gut, of which more than 99% belong to Firmicutes, Bacteroides, Actinomycetes and Proteobacteria, especially Firmicutes and Bacteroidetes, accounting for about 64% each and 23%. Other bacteria such as Archaea, Ferrobacterium, Clostridium, Spirochet, Verrucous Microbacteria, and Black Narcissus accounted for less than 1%. According to the relationship between intestinal bacteria and hosts, the large number of bacteria can be roughly divided into three categories: (1) beneficial bacteria, such as Bifidobacteria, Lactobacillus and Ackermansi; (2) Pathogens: such as Vibrio desulfurization, Clostridium difficile in Clostridium spp., Clostridium perfringens and Staphylococcus aureus in Staphylococcus spp.; (3) Conditionally pathogenic bacteria: such as Escherichia coli in Escherichia spp., Enterococci spp., Bacteroides fragilis in Bacteroides spp., and Acinetobacter baumannii in Acinetobacter spp.
The gut microbiota can produce a variety of enzymes, mainly α-rhamnosidase, β-glucosidase, β-galactosidase, nitroreductase, 7α-hydroxylase, protease, and a variety of carbohydrate-active enzymes，CAZymes. TCM components can be biotransformed through the various enzymes mentioned above to produce active metabolites with higher bioavailability. In addition, the gut microbiota can also alter the properties of the toxic components of natural products, which in turn can have different effects on host health.
1. The intestinal flora metabolizes the active ingredients of traditional Chinese medicine, enhances absorption, and improves drug efficacy
Under the action of intestinal flora, the components of traditional Chinese medicine will undergo hydrolysis, oxidation and reduction reactions, so that the components of traditional Chinese medicine are easier to absorb, metabolize and even produce new active substances, and the efficacy of traditional Chinese medicine will be enhanced by activity.
(1) Alkaloids. Berberine is insoluble in water, and can be converted into dihydroberberine by nitroreductase produced by 14 kinds of intestinal bacteria such as Staphylococcus aureus, Enterococcus faecium, and Acinetobacter baumannii, and the absorption can be increased by 5 times. Dihydroberberine is absorbed by the gastrointestinal tract and can be oxidized into berberine into the bloodstream, thereby enhancing the bioavailability of berberine. In addition, studies have also found that Lactobacillus acidophilus and Escherichia coli can convert berberine to oxyberberine, which also exhibits good anti-inflammatory, antiarrhythmic, and antifungal activities.
(2) Flavonoids. Most flavonoids undergo hydrolysis, reduction, dehydroxylation and other reactions through the action of intestinal flora and are converted into simple phenolic acids, which are easily absorbed by the body and thus exert significant efficacy. Catechins are a class of flavonoids with strong antioxidant activity, but the bioavailability is not high, and catechins are metabolized to γ-penterolactone under the action of intestinal bacteria and Eggertella. Compared with catechins, γ-penterolactone, which is metabolized by the gut microbiota, exhibits significant antioxidant activity. Baicalin cannot be absorbed directly, and can only be converted into baicalin through the action of intestinal flora to enter the blood circulation and improve bioavailability. Studies have found that Escherichia coli and Lactobacillus breve can hydrolyze baicalin into baicalein and melaleucin A, and the active products metabolized by the microflora have anti-tumor and intestinal inflammation effects. Apigenin can be metabolized by Bacillus circularis into small molecule acidic substances and exhibits superior antiviral effects than the prototype. Citrus flavonoids are converted into active aglycones by the intestinal flora, such as hesperidin by Pseudosmall-chain Bifidobacterium to hesperetin, which is more easily absorbed by the intestine due to the lack of glycoside moiety and thus exerts neuroprotective effects.
(3) Saponin...
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