Use of Callistemon citrinus as a gastroprotective and anti-inflammatory agent on indomethacin-induced gastric ulcers in obese rats.

Background: Obesity leads to an elevated risk of developing gastrointestinal disease such as gastric ulcers. Callistemon citrinus leaf extract has shown antioxidant, antimicrobial, hepatoprotective, and chemoprotective effects against colon cancer. The aim of this study is to evaluate the gastroprotective effect of C. citrinus leaf extract on indomethacin-induced gastric ulcers in obese rats. Methods: Gastric ulcers were induced in female obese Wistar rats using a single oral dose of indomethacin (IND). In the first stage, the rats were fed with a high fat sugar diet (HFSD) for 15 weeks to induce obesity and, at the same time, the diet of the other group of animals included daily administration of ethanolic C. citrinus leaf extract (250 mg/kg) in addition to HFSD. In the second stage, gastric ulcers were induced with IND (30 mg/kg). The gastroprotective activity of C. citrinus, the inflammatory enzyme activities, and cytokines in the stomach were determined. Results: C. citrinus produced a reduction of gastric lesions caused by IND. Myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), and 5-lipoxygenase (5-LOX) activities also decreased. Although inflammatory biomarkers such as TNFα, IL-6, AOPP, and leptin were significantly decreased by C. citrinus, adiponectin levels increased. Moreover, C. citrinus decreased weight gain and morphological and biochemical parameters. Conclusion: The use of indomethacin in rats fed with a high fat-sugar diet increased gastric ulcers. Gastroprotective effect of C. citrinus in obese rats is attributed to the reduction of pro-inflammatory cytokines and the inflammatory enzymes.

Investigation of the Antibacterial Activity and Subacute Toxicity of a Quercus crassifolia Polyphenolic Bark Extract for its Potential Use in Functional Foods.

Oak wood is used in barrels for wine aging. During aging, polyphenols are transferred from the barrels to the liquid. Although the bioactivity of oak polyphenols in wines has been extensively studied, no investigation exists on their toxicological properties, which limits their use as functional safe ingredients for other products. In this work, the chemical composition of a polyphenolic extract of Quercus crassifolia bark (QCBe) was studied by GC-MS. Its antibacterial properties on probiotic and pathogenic bacteria and its subacute-oral toxicity were determined as a way to understand the potential impact from its addition to fermented food as a functional ingredient. QCBe shows a selective inhibition of Escherichia coli compared with Lactobacillus bulgaricus and Streptococcus thermophylus. According to the toxicity evaluation, the subacute no-observed-adverse-effect-level was achieved at 11 mg/kg bw/day, whereas the subacute lowest-observed-adverse-effect-level for kidney damage was at 33 mg/kg bw/day. These results suggest that, given the fact an adverse effect was observed after subacute administration of this extract, further longer term toxicological studies are needed to provide sufficient safety evidence for its use in humans. PRACTICAL APPLICATION: Mexico's yogurt market is growing which creates opportunities for the development of some yogurt products as functional foods. As a first step to evaluate its potential use in yogurt formulation, the antibacterial effect of a Quercus crassifolia polyphenolic extract (QCBe) on probiotic bacteria and its subacute-oral toxicity in rats were studied. A low inhibition on probiotic bacteria growth was observed after QCBe addition to Lactobacillus bulgaricus and Streptococcus thermophylus cultures. Exposure to QCBe for a subacute duration resulted in renal injury in rats at dosages greater than or equal to 33 mg/kg/bw/day. This adverse effect indicates the importance of performing further long-term toxicological assessments prior to the addition of QCBe to a food like yogurt, which is regularly eaten by consumers.

Chemopreventive effect of Callistemon citrinus (Curtis) Skeels against colon cancer induced by 1,2-dimethylhydrazine in rats.

PURPOSE: Callistemon citrinus (Curtis) Skeels is a shrub native of Australia. In spite of containing an important number of bioactive compounds (1,8-cineole, limonene and α-terpineol) recognized as a potential chemotherapeutic agents, it is only used as an ornamental plant in Mexico. This study investigated the chemopreventive effect of C. citrinus leaves extract on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. METHODS: Twenty-four rats were divided into 3 groups of eight rats. Group 1 served as negative control, groups 2 and 3 were given subcutaneous injections of DMH (65 mg/kg b.w.) twice a week the first 2 weeks, and then one the third week. In addition, group 3 was administrated with leaves extracts (250 mg/kg b.w., orally daily) during the 22 weeks of the experiment. Animals were killed and the presence of colon tumors and aberrant crypt foci (ACF) were scored for number and distribution pattern along the colon. The activity of two-phase II enzymes quinone reductase (QR) and glutathione S-transferase (GST) was determined in the liver and three segments of the colon: proximal, middle and distal. RESULTS: The results show that rats feed with C. citrinus leaves extract significantly reduced the size of tumors, the number of ACF and the crypt multiplicity. Additionally, C. citrinus leaves extract increased or maintained the activity of QR and GST in the different tissues as compared with DHM-treated group (p > 0.05). CONCLUSION: This study demonstrates that Callistemon citrinus extract could have a chemopreventive effect against colon carcinogenesis.