Buddleoside: Bioavailability and Metabolism by Intestinal Microbiota

Chrysanthemum indicum is used in traditional Chinese medicine to treat headache, influenza, and hepatic and eye diseases. Its major flavonoid constituent is buddleoside, also known as linarin, which is reported to have antihypertensive, antioxidative, anti-inflammatory, and antimicrobial effects. Tao et al. (2016) posit that human intestinal microbiota may have an important role to play in buddleoside metabolism and its bioavailability.¹

The researchers purchased buddleoside as a single-agent substance. They also obtained 4 g of fresh human feces from a healthy female, which they mixed with saline, homogenized and then incubated under anaerobic conditions at 37°C for 72 hours. Tao et al. isolated about 100 different bacterial colonies. The researchers took 0.1 mM aquilots of bacteria from the incubated feces and added 0.9 mL of Gifu Anaerobic Broth containing 0.1 mM buddleoside, before incubating again at 37°C for 72 hours.

Tao et al. performed chromatographic separations using an ultra performance liquid chromatography (UPLC) system with a quaternary Accela 600 pump and Accela autosampler (both Thermo Scientific). They coupled the UPLC system to a linear ion trap and LTQ Orbitrap hybrid mass spectrometer equipped with a heated electrospray ionization probe (both Thermo Scientific).

They identified eight Escherichia, 16 Enterococcus, and 16 Bacillus strains of bacteria in the human feces sample and found that all of the isolated bacterial colonies had metabolic capacity for buddleoside. Four bacteria had particularly powerful effects: Escherichia sp. 4, Escherichia sp. 34, Enterococcus sp. 45 and Bacillus sp. 46. They also detected six buddleoside metabolites: acacetin-7-glucoside (M1), acacetin (M2), methylated acacetin (M3), acetylated acacetin (M4), hydroxylated acacetin (M5) and hydrogenated acacetin (M6).

Tao et al. posit that their technique of combining UPLC and LTQ Orbitrap mass spectrometry indicate that buddleoside can be converted by four major metabolic routes: deglycosylation, acetylation, methylation and hydroxylation, which may increase absorption and bioavailiabilty.

Reference
1. Tao, J.H., et al. (2016) “Biotransformation and metabolic profile of buddleoside with human intestinal microflora by ultrahigh-performance liquid chromatography coupled to hybrid linear ion trap/orbitrap mass spectrometer,” Journal of Chromatography B, 1025 (pp. 7–15).