A new ursane triterpenoic acid and other potential anti-inflammatory and anti-arthritic constituents from EtOAc extracts of Vitellaria paradoxa stem bark

OBJECTIVE

Vitellaria paradoxa (shea tree) is used in traditional medicine for the treatment of various ailments, including, inflammation and fever. Therefore the present research investigates the anti-inflammatory and anti-rheumatic effects of V. paradoxa stem bark extracts in rats and the isolation and characterization of its active constituents.

METHODS

The anti-inflammatory activity of ethyl acetate extract of V. Paradoxa (VPEE) was evaluated by use of the carrageenan-induced paw oedema model in rats. Moreover, rheumatoid arthritis (RA) was induced by injection of Freund's Completed Adjuvant (FCA) into the subplantar surface of the hind paw of the male Wistar rats. Paw volume was measured plethysmometrically. Joint swelling was measured using electronic vernier caliper. Hot plate test was used to assess the effect of VPEE on hyperalgesia while open field was used to assess the locomotors activity. The relative weight of spleen, liver and thymus was obtained as well as some haematological parameters. Tibiotarsal joint was extracted for histopathology under light microscope. Chemical analysis was carried out by high resolution mass spectrometry and one and two-dimensional NMR techniques.

RESULTS

LC-MS analysis of the EtOAc extract revealed the presence of a new triterpenoid and several known compounds. The structure of the novel compound was elucidated by means of LC-MS and selected 1D and 2D-NMR experiments. The biological effects of ethyl acetate (VPEE), methanol (VPME) and water extracts (VPAE) of V. paradoxa were tested on carrageenan model of acute inflammation and FCA-induced rheumatoid arthritis animal model. In the carrageenan-induced inflammation, VPEE (150 mg/kg) significant (66.67%) inhibited the first (after 1h) and the second phase (4-6h) of edema formation. On the Complete Freund's adjuvant-induced rheumatoid arthritis, VPEE at the same dose showed a significantly protective effect. On days 19-28th of treatment, the maximum inflammatory percentage was between 9.60 and 8.91% for the VPEE compared to 30.91-24.29% for the controls. All the extracts significantly reduced the score of arthritis but the maximal reduction was obtained with the VPEE on day 24th of the experimentation. The altered haematological parameters in the arthritic rats were significantly recovered to near normal by the treatment with VPEE at the dose of 150 mg/kg. Further histological studies revealed the anti-arthritic activity by preventing cartilage destruction of the arthritic joints of adjuvant arthritic rats. The spleen hypertrophy induced by the FCA was also significantly inhibited.

CONCLUSION

These findings provide pharmacological basis for the application of the VPEE in inflammatory disorders.

Maternal and developmental toxicity evaluation of Acanthus montanus leaves extract administered orally to Wistar pregnant rats during organogenesis

Acanthus montanus is a plant used in Cameroon to treat pains and threatened abortion. The aim of this study was to evaluate the influence of methanol/methylene chlorides leaves extract from Acanthus montanus on Wistar pregnant rats and identify the substance(s) essential for these actions. Dams were treated orally from days 6 to 15 of the pregnancy at the dose levels of 0, 250, 500 and 1000 mg/(kgday). They were sacrificed on day 20 or allowed to deliver and wean. Various parameters were assessed. The F(1) generation offsprings were allowed to give birth to F(2) generation and a number of parameters assessed. The results showed that there was no maternal or organs toxicity. Embryotoxicity was observed during organogenesis manifested by reduction in foetal body weight, crown-rump and tail lengths and reduced ossification of extremities bones. However after delivery, these signs of growth retardation were seen before day 5, and henceforth, the treated pups regained all their parameters to normality. All others parameters for F(1) and F(2) generations were insignificant. beta-Sitosterol was the major chemical component of the extract and its role on these results could not be ignored. The MeOH/CH(2)Cl(2) extract of this plant is embryotoxic peri-natally at high doses but this failed to manifest after 5 days of post-natal survival. beta-Sitosterol may be central in the observed effects of the extract. This extract can be tolerated by pregnant patients.

Vasorelaxant effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on isolated rat vascular smooth muscle

Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/methanol leaves extracts of Brillantaisia nitens were tested for their relaxing ability in vitro. Strips of rat aorta, with or without intact endothelium, were mounted in tissue baths, contracted with KCl (60mM) or norepinephrine (10(-4)M), and then exposed to the plant extracts. These extracts exhibited concentration-dependent vasorelaxations of norepinephrine-induced contractions of intact aortic strips. The EC(50) were 0.42+/-0.01mg/ml (aqueous extract), 0.63+/-0.02mg/ml (methylene chloride extract), 0.73+/-0.02mg/ml (methanol extract) and 0.36+/-0.02mg/ml (methylene chloride/methanol extract). The methylene chloride/methanol (CH(2)Cl(2)/CH(3)OH) extract was the most potent relaxing extract. It caused a concentration-dependent and endothelium-independent relaxation of the rat aortic strips contracted by KCl or norepinephrine. On the NE-induced contraction, its maximal relaxant activity (109%) due to the dose of 1.5mg/ml, was not significantly modified by the pretreatment of aortic strips with indomethacin (89%, P>0.05) or with l-NAME (103%, P>0.05). This suggests that the vasorelaxation elicited by CH(2)Cl(2)/CH(3)OH extract was not mediated via endothelium-derived prostacyclin or nitric oxide. In contrast, this relaxation was markedly reduced by tetraethylammonium, a blocker of non-selective K(+) channels and glibenclamide, a blocker of ATP-sensitive K(+) channels. The CH(2)Cl(2)/CH(3)OH extract significantly inhibited Ca(2+)-induced concentration-contraction and the Ca(2+) influx in aortic strips incubated with 60mM KCl. These results indicate that the vasorelaxant effect of the CH(2)Cl(2)/CH(3)OH extract of Brillantaisia nitens is due to an inhibition of Ca(2+) influx, possibly via the activation of ATP-sensitive K(+) channels.

Anti-diabetic activity of methanol/methylene chloride stem bark extracts of Terminalia superba and Canarium schweinfurthii on streptozotocin-induced diabetic rats

Stem bark extracts of Terminalia superba Engl. and Diels and Canarium schweinfurthii Engl. are used in Africa for the treatment of various ailments, including diabetes mellitus. The anti-diabetic effects of the methanol/methylene chloride extracts of the stem barks on streptozotocin (STZ)-induced diabetes were evaluated on male rats. Through the subcutaneous route, diabetes was induced using 60 mg/mL of streptozotocin. After 2 days, the rats received, by gavage, 150 mg/kg and 300 mg/kg of extract daily for 14 days. At 300 mg/kg, the two extracts (Terminalia superba and Canarium schweinfurthii), significantly showed at least 67.1% and 69.9% reduction in blood glucose level, respectively, while insulin (three units) given subcutaneously and once daily, had 76.8% reduction compared to diabetic untreated control rats. Similarly, the weight gains were 6.6% and 4.9%, respectively, and were comparable to the normal rats, whereas, diabetic untreated rats lost 14.1% body weight. Still with the same dose, there was 68.5% and 58.5% (p < 0.001) significant decrease in food consumption and 79.7% and 64.0% (p < 0.001) in fluid intake by diabetic rats treated with the respective plant extracts. The insulin-treated rats showed 56.4% and 75.8% decrease in food and fluid intake compared to an augmentation for diabetic control rats, 43.0% and 383.8%, respectively, at the end of the second week of experimentation. These results showed that the plant extracts can reverse hyperglycemia, polyphagia and polydipsia provoked by streptozotocin, and thus, they have anti-diabetic properties.

Antiinflammatory, lack of central analgesia and antipyretic properties of Acanthus montanus (Ness) T. Anderson

Aqueous leaves extract of Acanthus montanus (Nees) T. Anderson (Acanthaceae) were tested for antiinflammatory, analgesic and antipyretic properties. This was done using standard methodologies following oral administration of the extract. The results showed that the extract significantly reduced the oedema induced by carrageenan within 30 min with 200 mg/kg being the most potent. On the analgesia front, acetic acid writhing test was significant. The extract reduced only the number of paw licks of phase 2 and not phase 1 of formalin test. The results on hotplate and tail immersion tests excluded central acting analgesic properties of the extract. In overall, the analgesic tests conducted revealed that the extract had only peripheral analgesic properties. Its effect on pyresis was also observed to be appreciable. It significantly reduced fever at doses greater than 100 mg/kg within 6 h.

Analgesic and antiinflammatory activities of Erigeron floribundus

This study was intended to evaluate the analgesic and antiinflammatory activities of an aqueous extract of Erigeron floribundus (H.B. & K) or (syn": Conyza sumatrensis (Retz) E.K. Walker) (Asteraceae). Phytochemical analysis was carried out using standard methodologies. The analgesic investigations were carried out against two types of noxious stimuli, chemical (formalin-induced pain and acetic acid-induced writhing) and thermal (hotplate and tail immersion tests). The effects following aspirin and naloxone pretreatments were also studied. For the antiinflammatory activities, the carrageenan-induced oedema of the hindpaw of rats was used and the paw volume measured plethysmometrically from 0 to 24 h after injection. This was compared to a standard drug indomethacin (10 mg/kg). The results were subjected to statistical analysis. The plant had saponins, flavonoids, glycosides, alkaloids, oils, phenols and tannins and significantly increased the reaction time of hotplate and immersion tests. It decreased the writhings of acetic acid-induced abdominal contractions and lickings of formalin-induced pain. Aspirin had no effect on hotplate and tail immersion tests but showed an effect on writhing test. These results showed that the plant had both central and peripheral acting effects and this was confirmed by its effect on both phases of formalin-induced pain. The extract also significantly decreased the rat paw oedema volume at 50 mg/kg and above. In conclusion, Erigeron floribundus has central and peripheral analgesic properties as well as antiinflammatory activities.