Laxative effects and mechanism of action of Brazilian green propolis

Mamoru Kakino,Hideaki Hara,Yoko Araki,Masamitsu Shimazawa,Hiroshi Izuta,Kenji Ichihara,Kazuhiro Tsuruma

doi:10.1186/1472-6882-12-192

Abstract

BackgroundBrazilian green propolis is reported to have wide range of biological properties including antibacterial, anti-inflammatory, anti-influenza, and antioxidant activities. In the digestive system, a protective effect of propolis on gastric ulcer has been reported, but a laxative effect has not yet been reported. We investigated the effect and the mechanism of action of water and ethanol extracts of Brazilian green propolis.MethodsWe examined the laxative effect of propolis on stool frequency by administering orally an ethanol extract of propolis (EEP) or a water extract of propolis (WEP) at 10, 50, 100, or 500 mg/kg to normal mice. We then investigated the effects of propolis using constipation model mice induced by two types of drugs, loperamide (a μ opioid receptor agonist) and clonidine (an α-2 adrenergic receptor agonist). We also investigated the effects of WEP on gastrointestinal transit and contractional tension of the ileum to uncover the mechanism of action of WEP.ResultsTreatment with WEP, but not with EEP, significantly increased the weight of stools (p<0.01 at 500 mg/kg). WEP treatment significantly restored stool frequency and stool weight in clonidine-induced constipation model mice, but not in loperamide-induced constipation model mice. WEP treatment did not affect gastro-intestinal transit, but significantly increased the contractional tension of the isolated ileum of guinea pigs. This increase was inhibited by an acetylcholine receptor antagonist (atropine), but not by a 5-HT receptor antagonist (GR113808).ConclusionThese findings indicate that WEP has laxative effects both in normal mice and in clonidine-induced constipation model mice. The laxative effects of WEP might be mediated by increased contractional tension of the ileum exerted at least in part via activation of an acetylcholine receptor.

Highlights

Brazilian green propolis is reported to have wide range of biological properties including antibacterial, anti-inflammatory, anti-influenza, and antioxidant activities
Effects of water extract of propolis (WEP) and ethanol extract of propolis (EEP) in normal mice When WEP (10, 50, 100, and 500 mg/kg, n=6) was orally administered to normal mice, the wet weight of stools was significantly increased from 171.7 ± 18.7 to 306.0 ± 49.5 g at the 500 mg/kg administration dose (Figure 1A)
Neither WEP nor EEP affected GI transit (Figure 3A). These findings indicate that WEP, but not EEP, had a laxative effect, and indicated that the main constituents found in WEP, but not in EEP, may be responsible for the laxative effect of propolis

Summary

Introduction

Brazilian green propolis is reported to have wide range of biological properties including antibacterial, anti-inflammatory, anti-influenza, and antioxidant activities. We investigated the effect and the mechanism of action of water and ethanol extracts of Brazilian green propolis. Brazilian “green” propolis is made when honeybees mix their own saliva and very small pieces of plant material that they gather from fresh tops of Baccharis dracunculifolia [8,9,10,11]. Brazilian green propolis contains various constituents and the ethanol extract of propolis (EEP) is reported to have a wide range of biological properties, such as anti-bacterial [12], anti-inflammatory [13], anti-hypertensive [14,15,16], anti-tumor [17], antihyperlipidemic [18], and antioxidant [19] activities

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