Comparative In vitro metabolism of purified mogrosides derived from monk fruit extracts.

Mogrosides are the primary components responsible for the sweet taste of Monk fruit which is derived from Siraitia grosvenorii (Swingle), a herbaceous plant native to southern China. Many mogrosides have been identified from Monk fruit extract, but the major sweetness component of Monk fruit by mass is mogroside V, comprising up to 0.5% of the dried fruit weight. Recent pharmacokinetic studies indicate that the parent mogrosides undergo minimal systemic absorption following ingestion and hydrolysis by digestive enzymes and/or intestinal flora and are excreted as mogrol (i.e., the aglycone) and its mono- and diglucosides. The objective of this study was to demonstrate whether individual mogrosides, are metabolized to a common and terminal deglycosylated metabolite, mogrol. An in vitro assay was conducted with pooled human male and female intestinal fecal homogenates (HFH) using mogrosides IIIe, mogroside V, siamenoside I, and isomogroside V at two concentrations over a 48 h period. The results show that various mogrosides that differ in the linkages and number of glucose units attached to a common cucurbitane backbone, share a common metabolic fate, and are metabolized within 24 h to mogrol. Aside from an apparent difference in the initial rate of deglycosylation between mogrosides at higher concentrations, no apparent difference in the rate of deglycosylation was observed between the male and female HFH. Given the similar structures of these mogrosides and a shared metabolic fate to mogrol, the study provides support for a reasonably conservative approach to assess safety based on bridging safety data from an individual mogroside (i.e., Mogroside V) to other mogrosides, and the establishment of a group Acceptable Daily Intake (ADI), rather than individual ADI's for mogrosides.

In vitro metabolism of rebaudioside E under anaerobic conditions: Comparison with rebaudioside A.

The hydrolysis of the steviol glycosides rebaudioside (Reb) A and E, as well as steviolbioside (a metabolic intermediate) to steviol was evaluated in vitro using human fecal homogenates from healthy Caucasian and Asian donors. Incubation of each of the Rebs in both groups resulted in a rapid hydrolysis to steviol. Metabolism of 0.2mg/mL sample was complete within 24h, with the majority occurring within the first 16 h. There were no clear differences in the rate or extent of metabolism of Reb E relative to the comparative control Reb A. The hydrolysis of samples containing 2.0mg/mL of steviol glycosides Reb A and Reb E tended to take slightly longer than 0.2mg/mL samples. Herein, we report for the first time that there were no apparent gender or ethnicity differences in the rate of metabolism of any of the Rebs, regardless of the concentrations tested. Steviolbioside, an intermediate in the hydrolysis of Reb E to steviol was also found to be rapidly degraded to steviol. These results demonstrate Reb E is metabolized to steviol in the same manner as Reb A. These data support the use of toxicology data available on steviol, and on steviol glycosides metabolized to steviol (i.e., Reb A) to underpin the safety of Reb E.

In vitro metabolism of rebaudioside B, D, and M under anaerobic conditions: comparison with rebaudioside A.

The hydrolysis of the steviol glycosides rebaudioside A, B, D, and M, as well as of steviolbioside (a metabolic intermediate) to steviol was evaluated in vitro using human fecal homogenates from healthy donors under anaerobic conditions. Incubation of each of the rebaudiosides resulted in rapid hydrolysis to steviol. Metabolism was complete within 24h, with the majority occurring within the first 8h. There were no clear differences in the rate or extent of metabolism of rebaudioside B, D, or M, relative to the comparative control rebaudioside A. The hydrolysis of samples containing 2.0mg/mL of each rebaudioside tended to take slightly longer than solutions containing 0.2mg/mL. There was no apparent gender differences in the amount of metabolism of any of the rebaudiosides, regardless of the concentrations tested. An intermediate in the hydrolysis of rebaudioside M to steviol, steviolbioside, was also found to be rapidly degraded to steviol. The results demonstrate that rebaudiosides B, D, and M are metabolized to steviol in the same manner as rebaudioside A. These data support the use of toxicology data available on steviol, and on steviol glycosides metabolized to steviol (i.e., rebaudioside A) to substantiate the safety of rebaudiosides B, D, and M.

Cacao usage by the earliest Maya civilization.

The Maya archaeological site at Colha in northern Belize, Central America, has yielded several spouted ceramic vessels that contain residues from the preparation of food and beverages. Here we analyse dry residue samples by using high-performance liquid chromatography coupled to atmospheric-pressure chemical-ionization mass spectrometry, and show that chocolate (Theobroma cacao) was consumed by the Preclassic Maya as early as 600 bc, pushing back the earliest chemical evidence of cacao use by some 1,000 years. Our application of this new and highly sensitive analytical technique could be extended to the identification of other ancient foods and beverages.