Nutraceutical efficacy in experimental animal models of inflammatory bowel disease: Echinacea angustifolia, Prunella vulgaris and Hypericum gentianoides

In this study, the anti-colitic potential of Prunella vulgaris , Hypericum gentianoides, and Echinacea angustifolia were determined in the mdr1a deficient (-/-) mouse model of spontaneous colitis or the chemically induced dextran sodium sulphate (DSS) mouse model of acute colitis. Extracts of E. angustifolia root or above ground sections of P. vulgaris or H. gentianoides were extracted using the Soxhlet method in 95% ethanol and were solubilized in a final concentration of 5% ethanol for use in studies.;In the DSS model of acute colitis, E. angustifolia was not found to be effective during the period of DSS treatment (in low dose 1.75% to high dose 2.5% DSS in male and female C57BL/6 mice), or during restitution. E. angustifolia was not found to be cytotoxic in vivo. Conversely, P. vulgaris was able to significantly (p < 0.05) decrease weight loss and improve macroscopic indicators of severe colitic wasting. The disparity between E. angustifolia and P. vulgaris efficacies in this acute model of colitis could be due to the difference in the constituent types found in these two extracts. E. angustifolia is composed mostly of phenolics and alkylamides, while P. vulgaris contains phenolics, flavonoids and triterpinoids. Certain types of phenols have been shown to have efficacy in low dose DSS colitis; however, flavonoids have efficacy in models of colitis as well, and in combination with phenols may be synergistic. Since flavonoids have recently proven very effective in ameliorating spontaneous colitis, P. vulgaris was also evaluated in the mdr1a-/- model of spontaneous colitis.;In the mdr1a-/- mouse model of spontaneous colitis, P. vulgaris extract treatment was compared to mdr1a-/- mice treated with 5% ethanol vehicle, metronidazole (an antibiotic and anti-colitic control) and FVBWT mice. It was discovered that P. vulgaris was able to delay onset of spontaneous colitis, significantly (p < 0.05) decrease macroscopic typhlocolitic and microscopic cecal disease scores, prevent cecal neutrophil influx, and downregulate nuclear factor-kappaB (NF-kappaB) related cytokines/chemokines and gene targets. The downregulation of innate immune signals and function is hypothesized to contribute to the observed decrease in cecal tonsil CD4+ helper and CD8 + cytotoxic T cells as well as germinal center B cells. Adaptive immune function was also altered. Loss of immune tolerance to the microflora is a characteristic of chronic colitis. Unlike mdr1a-/- vehicle treated mice, which displayed antibody production to microflora antigens, P. vulgaris treated mice displayed little to no Ab response to the same microflora antigens.;H. gentianoides contains flavonoids, phenolics and a unique antimicrobial compound called uliginosin A. As the mdr1a-/- mouse model of spontaneous colitis is driven by the host immune response to the microflora and Hypericum species are known to be immunomodulatory, this extract was of interest as a therapeutic anti-colitic in the mdr1a -/- model. Onset of spontaneous colitis was significantly delayed by H. gentianoides, but was not completely abolished. Macroscopic scores, microscopic scores, serum cytokine levels and myeloperoxidase production were all significantly (p < 0.05) reduced by H. gentianoides gavage. While H. gentianoides has immunosuppressant potential, a surprising increase in intestinal plasma cell infiltrate and an increase in serum IL-6 correlated with H. gentianoides gavage in mdr1a -/- mice. To date, anti-microbial functions have not been ruled out as a contributing factor in the efficacy of anti-colitic activity of this extract.;Together, these novel experiments have identified new candidates for anti-colitic therapy or therapeutic supplementation of current IBD treatment strategies. P. vulgaris, H. gentianoides and E. angustifolia merit further research as nutraceutical treatments of chronic inflammatory disorders, and these studies make it clear that synergy between phenolics, flavonoids and natural anti-bacterial compounds also warrant further research. (Abstract shortened by UMI.)...