Abstract:
Gastric hyperacidity and peptic ulcer are very common causes of human suffering in this era
of globalization. Treatment of peptic ulcer is targeted at either counteracting aggressive
factors or stimulating the mucosal defenses. Natural products from bees and plants are
recently becoming the focus of attention as preventive medicine in providing protection
against acute and chronic gastric lesions. In the present study, the gastroprotective effects of
ethanol extract of propolis (EEP) from Ethiopian central high land was evaluated against
ethanol and indomethacin-induced gastric ulcers in mice. Half kilogram of propolis was
soaked in 70% ethyl alcohol for two weeks at room temperature with intermittent shaking
twice a day. After evaporating the alcohol and lyophilizing the residue to dryness, a gummy
consistent crude propolis extract of 35.35g yield was obtained. The phytochemical screening
with thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC/MS)
showed that the major phyto-constituents of the extract were amryn type triterpenic alcohols
(26.2%), sugars (24.9%) and fatty acids (7.5%), with significant amount of aromatic acids,
esters and other alcohols including diterpenic alcohol. Swiss albino mice of 24-32g body
weight were fasted for 24hours and pretreated with varying doses of EEP or standard drugs
(omeprazole or cimetidine) fifty minutes before ulcer induction either with alcohol or
indomethacin. In alcohol-induced ulcers, EEP at doses of 25, 50 and 100mg/kg significantly
reduced lesion index and number of the total lesions (P<0.05) in the glandular area of the
stomach. In indomethacin-induced ulcers, the same dose of EEP as for alcohol- induced ulcers
also significantly decreased ulcer index and number of the total lesions (P<0.05) in the
glandular region of the stomach compared to the control. In both cases, the extract was shown
to reduce gastric lesions in a dose-dependent manner. The intraperitoneal (i.p) pretreatment
with indomethacin one hour before the extract did not affect the gastroprotective effects of the
EEP on alcohol-induced ulcers. The histological observations in the glandular area of the
stomach also revealed that severe hemorrhagic patchy lesions occurred covering most parts in
the absence of EEP. Mucosal epithelial damage was confirmed by microscopic observation of
the Hematoxylin-eosin fixed tissue taken from the same glandular area of the stomach. The
gastroprotective mechanism of EEP could be due to its antioxidant effects, and/or its film
forming properties. Further investigation on the chemical composition and the biological
activities of Ethiopian propolis from different agro-ecological zones are recommende
Keywords: Gastroprotective, propolis, EEP, ulcer index, alcohol, indomethacin, gastric
lesion