In vitro gastrointestinal biotransformation and characterization of a Desmodium adscendens decoction: the first step in unravelling its behaviour in the human body.

OBJECTIVES: The isolation and identification of the flavonoids present in a decoction of Desmodium adscendens was performed. In view of the oral use of the decoction, this work focused on the stability in gastrointestinal conditions and biotransformation by intestinal microflora in the colon of D-pinitol, vitexin and the flavonoid fraction of the decoction, as a first step in unravelling its behaviour in the human body. METHODS: The freeze-dried decoction was first subjected to column chromatography. Subsequently an enriched flavonoid fraction, was separated by repeated semi-preparative high-performance liquid chromatography (HPLC) or by HPLC-SPE. The isolated compounds were elucidated by NMR. Biotransformation experiments were carried in an in vitro gastrointestinal dialysis model. KEY FINDINGS: The major flavonoids of a decoction of D. adscendens were characterized as vicenin-2, isoschaftoside, schaftoside, 2″-O-xylosylvitexin, 2″-O-pentosyl-C-hexosyl apigenin and a O-hexosyl-C-hexosyl apigenin, tentatively identified as 2″-O-glucosyl-vitexin. During their passage in the gastrointestinal dialysis model, vitexin and C-glycosides thereof were found to be stable. Only the O-glycosidic bonds of O-glycosides of vitexin or isovitexin were hydrolysed during the colonic phase. CONCLUSIONS: A D. adscendens decoction was found to be rich in vitexin and isovitexin glycosides from which vitexin and the C-glycosides thereof were found to be stable in the simulated gastrointestinal tract.

Advantages of a validated UPLC-MS/MS standard addition method for the quantification of A-type dimeric and trimeric proanthocyanidins in cranberry extracts in comparison with well-known quantification methods.

The berries of Vaccinium macrocarpon, cranberry, are widely used for the prevention of urinary tract infections. This species contains A-type proanthocyanidins (PACs), which intervene in the initial phase of the development of urinary tract infections by preventing the adherence of Escherichia coli by their P-type fimbriae to uroepithelial cells. Unfortunately, the existing clinical studies used different cranberry preparations, which were poorly standardized. Because of this, the results were hard to compare, which led sometimes to conflicting results. Currently, PACs are quantified using the rather non-specific spectrophotometric 4-dimethylaminocinnamaldehyde (DMAC) method. In addition, a normal phase HPTLC-densitometric method, a HPLC-UV method and three LC-MS/MS methods for quantification of procyanidin A2 were recently published. All these methods contain some shortcomings and errors. Hence, the development and validation of a fast and sensitive standard addition LC-MS/MS method for the simultaneous quantification of A-type dimers and trimers in a cranberry dry extract was carried out. A linear calibration model could be adopted for dimers and, after logaritmic transformation, for trimers. The maximal interday and interconcentration precision was found to be 4.86% and 4.28% for procyanidin A2, and 5.61% and 7.65% for trimeric PACs, which are all acceptable values for an analytical method using LC-MS/MS. In addition, twelve different cranberry extracts were analyzed by means of the newly validated method and other widely used methods. There appeared to be an enormous variation in dimeric and trimeric PAC content. Comparison of these results with LC-MS/MS analysis without standard addition showed the presence of matrix effects for some of the extracts and proved the necessity of standard addition. A comparison of the well-known and widely used DMAC method, the butanol-HCl assay and this newly developed LC-MS/MS method clearly indicated the need for a reliable method able to quantify A-type PACs, which are considered to be the pharmacologically active constituents of cranberry, since neither the DMAC or butanol-HCl assays are capable of distinguishing between A and B-type PACs and therefore cannot detect adulterations with, for example, extracts with a high B-type PAC content. Hence, the combination of the DMAC method or butanol-HCl assay with this more specific LC-MS/MS assay could overcome these shortcomings.

Saponins and Flavonoids from an Infusion of Herniaria hirsuta.

Stone diseases present a major health problem in the Western society, since both urinary and biliary stones occur with a relatively high prevalence of 10-12 % and 10-20 %, respectively, and demonstrate a high recurrence rate. At the moment treatment is mainly based on interventional procedures, or prophylactic and dissolution therapy. However, many of the current drugs cause severe side effects, and therefore, there is an increasing interest in natural medicines. At the moment no registered herbal medicinal products are available for treatment of gallstones. Since an infusion of Herniaria hirsuta L. has a proven efficacy against urolithiasis and cholelithiasis, its phytochemical composition has been investigated. Two previously undescribed triterpene saponins, 28-O-{[ß-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)]-[ß-D-glucopyranosyl-(1-6)]-ß-D-glucopyranosyl}-medicagenic acid and 3-O-[α-L-rhamnopyranosyl-(1 → 3)-ß-D-glucuronopyranosyl]-28-O-{[ß-D-glucopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 4)]-[ß-D-apiofuranosyl-(1 → 3)]-α-L-rhamnopyranosyl-(1 → 2)-ß-D-fucopyranosyl}-medicagenic acid and three known flavonoids, quercetin-3-O-(2″-O-α-L-rhamnopyranosyl)-ß-D-glucuronopyranoside, rutin, and narcissin (isorhamnetin-3-O-rutinoside), were isolated using flash chromatography and successive semi-preparative HPLC and were well characterized by MS and 1D and 2D NMR spectroscopic techniques. These findings could contribute to the development of a standardized extract that can be used in prophylaxis and treatment of gall and kidney stones.

Cholesterol lowering effect in the gall bladder of dogs by a standardized infusion of Herniaria hirsuta L.

ETNOPHARMACOLOGICAL RELEVANCE: Infusions of Herniaria hirsuta L., Herniaria glabra L. and Herniaria fontanesii J.Gay are well known in Moroccon folk medicine for the treatment of biliary dyskinesia, (uro)lithiasis or as a diuretic. Herniariae Herba which can contain H. glabra and H. hirsuta is known in Europe as an urological drug. AIM OF THE STUDY: To investigate the efficacy of a standardized infusion of Herniaria hirsuta against choleltihiasis, and evaluation of its genotoxicity. METHODS AND MATERIALS: An analytical HPLC-UV method to quantify flavonoids and saponins present in the extract of H. hirsuta was developed and validated. An in vivo experiment to evaluate the cholesterol lowering effect of a infusion of H. hirsuta in the gall bladder of dogs was carried out. Dogs were divided into 3 groups i.e. control dogs (CG), dogs treated with ursodeoxycholic acid (UDCA) (2×7.35mg/kg body weight/day) and dogs treated with the standardized infusion (HG) (2×48.5mg/kg body weight/day). Dogs were fed a fatty diet during 120 days after which a diet without additional fat was introduced till day 180. Treatment started 30 days after introduction of the fatty diet and lasted till the end of the experiment. A bile and blood sample of each dog was collected every 30 days, after which the concentration of cholesterol was determined. An Ames test was performed according to the OECD-guidelines. RESULTS: The validated HPLC-UV method showed a linear calibration model and an acceptable precision for the total flavonoid content (total content 4.51%) as well as the total saponin content (12.74%). The in vivo experiments already showed a minor difference for bile cholesterol between CG and HG after 30 days of treatment with the infusion, and the difference was more pronounced after 90 days of treatment. Even 30 days after discontinuation of the cholesterol-rich diet a significant difference remained between CG and HG. There was no statistically significant difference in blood cholesterol. The Ames test showed that the infusion of H. hirsuta could be considered as being free from genotoxic risks. CONCLUSION: A method for the standardization of a infusion of Herniaria hirsuta was developed and validated. Prolonged use of this standardized H. hirsuta extract resulted in a cholesterol-lowering effect in the bile of dogs. Since this pharmacological effect prevents the formation of gallstones and can contribute to solving existing gallstones, a standardized infusion of H. hirsuta may have a positive effect in the treatment of gallstones in human patients.

Antihepatotoxic activity of a quantified Desmodium adscendens decoction and D-pinitol against chemically-induced liver damage in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The isolation of D-pinitol (or 3-O-methyl-D-chiro-inositol) from an aqueous decoction of Desmodium adscendens (Fabaceae) leaves and twigs is reported. The protective and curative effect of this decoction, in which d-pinitol was quantified, and of pure D-pinitol, against chemically-induced liver damage in rats has been evaluated. MATERIALS AND METHODS: Enzyme levels of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP), which are among the usual biomarkers for liver damage, were determined in serum samples of experimental animals. The protective effects against D-galactosamine-induced and ethanol-induced liver damage of a decoction of D. adscendens, quantified on its main constituent D-pinitol, was investigated in rats. In addition, the curative effects of pure D-pinitol and D. adscendens against chronic D-galactosamine-induced and acute acetaminophen-induced hepatotoxicity in rats was studied. Silymarin was used as positive control. RESULTS: In a first experiment evaluating the protective effect against acute D-galactosamine-induced liver damage in rats, a significant decrease of AST and ALT was observed for the D. adscendens decoction at a dose equivalent to 5 mg/kg/day and 20 mg/kg/day D-pinitol, as well as 20 mg/kg/day pure D-pinitol. With respect to chronic ethanol-induced liver damage in rats, the protective effects of D. adscendens at doses equivalent to 2 mg/kg/day and 10 mg/kg/day D-pinitol, were not observed for serum AST and ALT levels. However, with respect to reduced mortality of animals, statistical analysis showed a trend towards significance for the Desmodium group receiving a dose equivalent to 10 mg/kg/day D-pinitol, versus the untreated hepatotoxic animals. Additional experiments in rat models of acute acetaminophen-induced and chronic D-galactosamine-induced liver damage indicated that D. adscendens decoction and pure D-pinitol had no curative effect when given in a dose equivalent to 10 mg/kg/day D-pinitol, or up to 20 mg/kg/day as a pure compound daily, respectively. CONCLUSIONS: The aqueous decoction of D. adscendens showed a protective effect in rats against liver damage induced by D-galactosamine and ethanol, and this effect is at least in part due to the presence of D-pinitol. However, no curative effect of D. adscendens decoction or D-pinitol on liver damage induced by the tested chemicals could be demonstrated.