The gastroprotective effect of red propolis extract from Northeastern Brazil and the role of its isolated compounds

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis has been used in folk medicine to treat gastric disorders for centuries. However, although studies have been conducted to validate the gastroprotective and anti-ulcer activity of some types of propolis, red propolis activity remains unknown.

AIM OF THE STUDY

The present study aimed to evaluate the gastroprotective effect of the hydroalcoholic extract of red propolis (HERP), its mode of action, and the main compounds involved in its activity, therefore contributing to validate the chemical and pharmacological potential of this product.

MATERIAL AND METHODS

The effect of HERP (30, 100 and 300 mg/kg p.o. and 30 mg/kg i.p.), and the isolated compounds vestitol (VS), neovestitol (NV), methylvestitol (MV), medicarpin (MD), and oblongifolin AB (OB) (10 mg/kg p.o.) were evaluated on gastric ulcers induced by 60% ethanol/0.3 M HCl (5 mL/kg, p.o.) in mice. Histological changes and mucin levels were assessed by HE and PAS, respectively. Moreover, oxidative stress parameters and myeloperoxidase activity were analyzed on ulcerated tissue. The effect of HERP on gastric acid secretion was evaluated by pyloric ligature model and the mechanisms involved in its gastroprotective effect were investigated by pretreating mice with L-NAME (a non-selective nitric oxide synthase inhibitor, 70 mg/kg, i.p.), NEM (a sulfhydryl group chelator, 10 mg/kg, i.p.), yohimbine (an alpha-adrenergic receptor antagonist, 2 mg/kg, i.p.) and indomethacin (a non-selective cyclooxygenase inhibitor, 10 mg/kg, i.p.).

RESULTS

HERP (300 mg/kg p.o. or 30 mg/kg i.p.), MV, and MD (10 mg/kg p.o.) protected gastric mucosa against the damage induced by ethanol/HCl. Histological changes were attenuated by the HERP, MV, and MD. Moreover, HERP and MV increased mucin levels. Besides, oxidative stress and MPO activity were reduced by the three treatments. HERP did not display anti-secretory action, but its effect was abolished by indomethacin treatment.

CONCLUSIONS

HERP displays gastroprotective property against ethanol/HCl-induced damage. Its effect is dependent on prostaglandins and mucin production. The compounds MV and MD may have an essential role in the activity of HERP. Our data contribute to validate the traditional use of propolis for gastric disorders.

Antitrypanosomal, antileishmanial and cytotoxic activities of Brazilian red propolis and plant resin of Dalbergia ecastaphyllum (L) Taub

The treatment for leishmaniasis and Chagas disease can be hard and painful, such that many patients give up on the treatment. In order to find an alternative path for the treatment of these diseases, researchers are using natural products to fight these parasites. The aim of this study was to evaluate the antiprotozoan and cytotoxic activities of red propolis samples collected from different Brazilian states and seasons whilst searching for possible activity differences. We also compared the red propolis results with the ones obtained for the plant resin extract collected from Dalbergia ecastaphyllum trees. The hydroethanolic red propolis extracts from Pernambuco and Alagoas, and the D. ecastaphyllum resin were evaluated regarding their antileishmanial, antitrypanosomal and cytotoxic activity. All extracts showed antiprotozoan and cytotoxic activity. RP-PER showed to be more cytotoxic against protozoan parasites and fibroblast cells. All propolis extracts showed a higher cytotoxic activity when compared to resin extracts. The propolis sample collected in Pernambuco during the rainy season killed the parasites with lower concentrations than the sample collected in the dry season. The IC₅₀ observed against the parasites could be used without high fibroblast cell damage.