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    Inhibition of colon cancer in mice by microencapsulated probiotic
    (2016) Odun-Ayo, Frederick Oluwasheyi; Reddy, Lalini; Mellem, John Jason
    Colon cancer is the third most common cancer worldwide with a high morbidity and mortality rate. Therapies are less effective during metastasis, therefore prevention and earlier detection is key to reducing the risk of colon cancer. Increased dietary fibre and probiotic intake is known to lower the risk of colon cancer. Probiotics are defined as “live microorganisms which when administered orally in an adequate amount confer a health benefit on the host”. The International Dairy Federation recommends a viable minimum level of 6–7 log10cfu/g in a probiotic product being consumed. Different biopolymer matrices have been used for encapsulation of probiotics; however, loss of viability is still a major challenge. Citrus pectin is a dietary fibre polysaccharide broken down into smaller fragments to form modified citrus pectin (MCP). The unique bioactivity of MCP against carcinogenesisis is linked to its sugar β-galactose inhibiting the cell signalling protein marker, galectin-3 (gal-3), which is intimately involved in endothelial cell morphogenesis. The vascular endothelial growth factor (VEGF) signalling, which invariably drives angiogenesis can be activated when gal-3 binds to integrins. The bioactivity and uptake of MCP may be improved through a novel approach if conjoined with a supplement for example probiotic. Therefore, the synergistic inhibitory effect of modified citrus pectin alginate (MCPA) probiotic microbeads on gal-3 and VEGF in an azoxymethane (AOM) induced colon carcinogenesis Balb/c mouse model was investigated. A microencapsulation process was used to produce a MCPA microbead containing probiotic, Lactobacillus acidophilus ATCC 4356. Efficiency of the microbead was evaluated in vitro (simulated conditions) and in vivo (Balb/c mouse model). Genomic identification of faecal lactobacilli samples from the treated mice was analyzed. Optimization of AOM dose-time with 10 and 15 mg/kg AOM intraperitoneal (ip) administered to Balb/c mice for 2 and 4 weeks were performed. The optimal AOM dose was initiated prior to intake of MCPA, AP (alginate calcium) probiotic microbeads and MCP in Balb/c mice for 16 weeks; samples were analyzed for colon histopathology and immunohistochemistry. The MCPA probiotic microbeads significantly enhanced the viability of L. acidophilus ATCC 4356 compared to the AP microbeads in vitro (p< 0.05). Exposure of the MCPA probiotic microbeads to 3 h of simulated gastric juice (SGJ) resulted in 82.7% survival of L. acidophilus ATCC 4356. Also, the faecal lactobacilli count in the MCPA probiotic treated mice significantly increased after 28 days by 10.2% compared to the AP probiotic, MCP treated and control mice (p< 0.0001). A total of 4DNA encoding 16S rRNA gene closest to the genera namely Lactobacillus, Bacillus, Enterococcus and Bifidobacterium were identified from faecal samples of the colon cancer-induced Balb/c mice. Azoxymethane at 15 mg/kg for 4 weeks induced optimal gal-3 and VEGF immunoexpression. Furthermore, MCPA probiotic treatment significantly reduced gal-3 immunoexpression in the colon of AOM induced cancer Balb/c mice compared to the control mice (p< 0.0001). The immunoexpresion of VEGF in the MCPA and AP probiotic treated groups was weakly positive and significantly reduced when compared to the control group (p<0.05), while the MCP treated group was barely positive (p< 0.001). Modified citrus pectin alginate is a novel effective means of oral delivery of bacterial cells and bioactive compounds. It has a good biodegradability, inexpensive, non-toxic, proven efficiency, and stability at low temperatures warranting its use as a drug carrier by pharmaceuticals. Modified citrus pectin alginate probiotic microbeads increase bioactivity and chemoprevention against colon pre-cancerous lesions and adenocarcinoma through inhibition of gal-3 and VEGF in the mouse model. Modified citrus pectin alginate can be used in probiotic therapy, which may improve the prevention of colon cancer.
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    Dietary modulation of the human colonic microbiota through plant-derived prebiotic compounds
    (2007) Kassim, Muhammad Arshad
    The human gut microbiota play a major role in host health, and attempts are being made to manipulate the composition of the gut microbiota-increase the composition of bacterial groups, such as lactobacilli and bifidobacteria that are perceived as exerting health promoting properties. These bacteria defined as food supplements (probiotics) beneficially affect the host by improving the intestinal microbial balance, and have been used to change the composition of the colonic microbiota. However, such changes may be transient, and the implantation of exogenous bacteria therefore becomes limited. In contrast, prebiotics are naturally occurring carbohydrates that are classified as non-digestible oligosaccharides present in edible plants. These carbohydrates enter the colon as intact compounds, elicit systemic physiological functions and act as fermentable substrates for colonic microflora-influencing the species composition and metabolic characteristics of intestinal microflora providing important health attributes. Currently, a widely marketed prebiotic, inulin is extracted from plants of the family Asteraceae. There are many unexploited plants that are regularly consumed and that may have a prebiotic effect or can have very high levels of inulin which could make them commercially viable. In this study, we investigated prebiotic compounds, especially inulin from locally growing, non-commercialised leafy plants. The aqueous extracts of 22 plants from the families Asparagaceae, Alliaceae, Asteraceae, Solanaceae, Cucurbitaceae, Amaranthaceae, Acanthaceae, Polygonaceae, Portulaceae, Fabaceae, Chenopodiaceae, Pedaliaceae and Apiaceae from Kwa-Zulu Natal were investigated for a prebiotic effect using a modified batch-culture technique with Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus reuteri and Bifidobacterium longum, four common probiotics and the inulin content of the plants was determined using high performance liquid chromatography. Of the 22 plants studied, Solanum nigrum, Amaranthus spinosus, Amaranthus hybridus, Asystasia gangetica, Senna occidentalis, Cerathoteca triloba, Asparagus sprengeri, Tulbaghia violacea, Sonchus oleraceus and Taraxacum officinale exhibited a prebiotic effect. The prebiotic effect of the Taraxacum officinale, Sonchus oleraceus and Asparagus sprengeri extracts on L. lactis and L. reuteri was higher than or equivalent to inulin-a commercial prebiotic. In this study, Sonchus oleraceus exhibited the best prebiotic effect-was the only plant to stimulate all the probiotics including B. longum. Of all the plants analysed, Asparagus sprengeri tuber contained the highest amount of inulin (3.55%).