Gastroprotective activity of kaempferol glycosides from Malvaviscus arboreus Cav

ETHNOPHARMACOLOGICAL RELEVANCE

Malvaviscus arboreus is traditionally used in Mexico and Central America for culinary and medicinal purposes. Leaves and flowers of this species are commonly used for preparation of salads, herbal teas and herbal dyes. Panamanian, Guatemalan and Mexican healers use this medicinal plant for the management of fever, respiratory complications, dysentery, liver and gallbladder problems, stomachache and gastritis between other health troubles.

AIM OF THE STUDY

Considering the traditional use of M. arboreous as well as its content in flavonoids and other polyphenols, the objective of this work was to evaluate the gastroprotective effect of an aqueous extract and identify the potential bio-active principles from flowers of this species.

MATERIAL AND METHODS

Fresh flowers of Malvaviscus arboreus were collected, dried, and macerated with water. The aqueous extract (ExAq) was partitioned using an immiscible mixture of water and ethyl acetate, giving an aqueous (MaAq) and organic (MaEA) fractions. The gastroprotective effect was carried out using an ethanol-induced gastric ulcer experimental test in male rats. While tween 20 was used as a negative control, famotidine (10 mg/kg) and L-arginine (300 mg/kg) were used as positive controls. Compounds 1 and 2 were isolated by several chromatographic techniques and the chemical characterization was carried out by means of the analysis of the NMR spectra in one and two dimensions.

RESULTS

The integrate extract (ExAq) to 250, 500 and 750 mg/kg showed gastroprotective effect with high levels of 97.8%, 79.5% and 91.1% respectively. The organic fraction (MaEA) displayed a protection of 91.2%, 96.0% and 99.4% when it was evaluated at 125, 250 and 500 mg/kg respectively. Comparison of these results with famotidine at 10 mg/kg (83% of gastroprotection) indicated that ethyl acetate fraction showed a better gastroprotection. The bio-guided separation of this organic mixture, allowed obtaining the most active fraction (C1F4, 60 mg/kg) which was finally purified to obtain two glycosylated flavonols: kaempferol 3-O-D-sophoroside (1) and kaempferol 3-O-D-sambubioside (2). This mixture of flavonoids (40 y 60 mg/kg) showed 93.7 and 92% of gastroprotective activity respectively.

CONCLUSION

This study allowed demonstrating that an aqueous extract and its organic fraction (MaEA) from M. arboreous contain glycosylated flavonoids (1 and 2) which are responsible of the gastroprotective properties of M. arboreous. These results will be used in the future development of a standardized treatment useful in the therapeutic management of gastric ulcers.

Anti-inflammatory effect of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranosyl sitosterol] from Agave angustifolia on ear edema in mice

In Mexico Agave angustifolia has traditionally been used to treat inflammation. The aim of this study was to measure the anti-inflammatory effect of the extract of A. angustifolia, the isolation and identification of active compounds. From the acetone extract two active fractions were obtained, (AsF13 and AaF16). For the characterization of pharmacological activity, the acute inflammatory model of mouse ear edema induced with TPA was used. The tissue exposed to TPA and treatments were subjected to two analysis, cytokine quantification (IL-1β, IL-6, IL-10 and TNF-α) and histopathological evaluation. The active fraction (AaF16) consisted principally of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranpsyl] sitosterol. In AaF13 fraction was identified β-sitosteryl glucoside (2) and stigmasterol (3). The three treatments tested showed a concentration-dependent anti-inflammatory effect (AaAc Emax = 33.10%, EC50 = 0.126 mg/ear; AaF13 Emax = 54.22%, EC50 = 0.0524 mg/ear; AaF16 Emax = 61.01%, EC50 = 0.050 mg/ear). The application of TPA caused a significant increase on level of IL-1β, IL-6 and TNFα compared with basal condition, which was countered by any of the experimental treatments. Moreover, the experimental treatments induced a significant increase in the levels of IL-4 and IL-10, compared to the level observed when stimulated with TPA. Therefore, the anti-inflammatory effect of Agave angustifolia, is associated with the presence of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranosyl] sitosterol.

Scorpion antivenom effect of micropropagated Aristolochia elegans

Aristolochia elegans Mast. (Aristolochiaceae) has been used to treat scorpion envenoming in Mexican traditional medicine. In vitro studies of the pharmacological activity of raw extracts from A. elegans roots have shown activity against scorpion bite. The aim of the present study was to determine for the first time the antagonistic effect of hexane and methanol extracts of the aerial parts and roots from micropropagated A. elegans plants in a model of isolated guinea-pig ileum contracted by scorpion bite. Results showed that the methanol extracts of aerial organs (74%) and roots (65%) of micropropagated plants have a similar antitoxin activity against scorpion poisoning to hexane extracts of wild plants (65%). These results suggest that using methanol extracts from the micropropagated plant material instead of wild plant root extracts from A. elegans is an alternative for treatment against scorpion bite symptoms, and will contribute to the conservation of this medicinal species.