Annelies Breynaert

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.

Development and Validation of an in vitro Experimental GastroIntestinal Dialysis Model with Colon Phase to Study the Availability and Colonic Metabolisation of Polyphenolic Compounds

The biological effects of polyphenols depend on their mechanism of action in the body. This is affected by bioconversion by colon microbiota and absorption of colonic metabolites. We developed and validated an in vitro continuous flow dialysis model with colon phase (GastroIntestinal dialysis model with colon phase) to study the gastrointestinal metabolism and absorption of phenolic food constituents. Chlorogenic acid was used as model compound. The physiological conditions during gastrointestinal digestion were mimicked. A continuous flow dialysis system simulated the one-way absorption by passive diffusion from lumen to mucosa. The colon phase was developed using pooled faecal suspensions. Several methodological aspects including implementation of an anaerobic environment, adapted Wilkins Chalgren broth medium, 1.10(8) CFU/mL bacteria suspension as inoculum, pH adaptation to 5.8 and implementation of the dialysis system were conducted. Validation of the GastroIntestinal dialysis model with colon phase system showed a good recovery and precision (CV < 16 %). Availability of chlorogenic acid in the small intestinal phase (37 ± 3 %) of the GastroIntestinal dialysis model with colon phase is comparable with in vivo studies on ileostomy patients. In the colon phase, the human faecal microbiota deconjugated chlorogenic acid to caffeic acid, 3,4-dihydroxyphenyl propionic acid, 4-hydroxybenzoic acid, 3- or 4-hydroxyphenyl acetic acid, 2-methoxy-4-methylphenol and 3-phenylpropionic acid. The GastroIntestinal dialysis model with colon phase is a new, reliable gastrointestinal simulation system. It permits a fast and easy way to predict the availability of complex secondary metabolites, and to detect metabolites in an early stage after digestion. Isolation and identification of these metabolites may be used as references for in vivo bioavailability experiments and for investigating their bioactivity in in vitro experiments.

Investigation of the in vivo antioxidative activity of Cynara scolymus (artichoke) leaf extract in the streptozotocin‐induced diabetic rat

The in vivo antioxidant activity of a quantified leaf extract of Cynara scolymus (artichoke) was studied. The aqueous artichoke leaf extract (ALE), containing 1.5% caffeoylquinic acid with chlorogenic acid being most abundant (0.30%), and luteolin-7-O-glucoside as major flavonoid (0.15%), was investigated by evaluating the effect on different oxidative stress biomarkers, after 3 wk oral supplementation in the streptozotocin-induced diabetic rat model. Apart from two test groups (0.2 g ALE/kg BW/day and 1 g ALE/kg BW/day, where BW is body weight), a healthy control group, untreated oxidative stress group, and vitamin E treated group (positive control) were included. A 0.2 g/kg BW/day of ALE decreased oxidative stress: malondialdehyde and 8-hydroxydeoxyguanosine levels significantly diminished, whereas erythrocyte glutathione levels significantly increased. A 1.0 g/kg BW/day ALE did not show higher antioxidant activity.

In Vitro and In Vivo Study of the Gastrointestinal Absorption and Metabolisation of Hymenocardine, a Cyclopeptide Alkaloid

Hymenocardine is a cyclopeptide alkaloid present in the root bark of Hymenocardia acida. In traditional African medicine, the leaves and roots of this plant are used to treat malaria, and moderate in vitro antiplasmodial activity has been reported for hymenocardine. However, in view of its peptide-like nature, potential metabolisation after oral ingestion has to be taken into account when considering in vivo experiments. In this study, the stability and small intestinal absorption of hymenocardine was assessed using an in vitro gastrointestinal dialysis model. In addition, potential liver metabolisation was investigated in vitro by incubation with a human S9 fraction. Moreover, hymenocardine was administered to rats per os, and blood and urine samples were collected until 48 and 24 h after oral administration, respectively. All samples resulting from these three experiments were analyzed by LC-MS. Analysis of the dialysate and retentate, obtained from the gastrointestinal dialysis model, indicated that hymenocardine is absorbed unchanged from the gastrointestinal tract, at least in part. After S9 metabolisation, several metabolites of hymenocardine could be identified, the major ones being formed by the reduction and/or the loss of an N-methyl group. The in vivo study confirmed that hymenocardine is absorbed from the gastrointestinal tract unchanged, since it could be identified in both rat plasma and urine, together with hymenocardinol, its reduction product.

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

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.

Vegetable relishes, high in β-carotene, increase the iron, zinc and β-carotene nutritive values from cereal porridges

Abstract Iron, zinc and vitamin A deficiencies are serious public health problems in sub-Saharan Africa, which can be alleviated by dietary diversification. The effects of adding cowpea leaf (CL) and orange-fleshed sweet potato (OFSP) relishes to sorghum and maize porridges on iron, zinc and β-carotene contents and bioaccessibilities were determined. Despite the high iron content of the CL relish (14.59 mg/100 g), the vegetable relishes had little effect on the iron bioaccessibility from the cereal porridges. Importantly, the addition of the CL relish increased the percentage and amount of bioaccessible zinc 2- and 3-fold, respectively. Addition of CL and OFSP relishes resulted in β-carotene contents of 10–13 mg/100 g. The β-carotene from the OFSP relish meals was double as bioaccessible than that from the CL relish meals. Addition of the vegetable relishes has real potential to improve especially the vitamin A and zinc nutritive value of cereal diets.