In Vitro and In Vivo Inhibition of Intestinal Glucose Transport by Guava (Psidium Guajava) Extracts |
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| Authors: | Ulrike Müller Flora Stübl Bettina Schwarzinger Georg Sandner Marcus Iken Markus Himmelsbach Clemens Schwarzinger Nicole Ollinger Verena Stadlbauer Otmar Höglinger Tobias Kühne Peter Lanzerstorfer Julian Weghuber |
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| Affiliation: | 1. University of Applied Sciences Upper Austria, Wels, Austria;2. Austrian Competence Center for Feed and Food Quality, Safety and Innovation, Wels, Austria;3. PM International AG, Schengen, Luxembourg;4. Johannes Kepler University, Institute for Analytical Chemistry, Linz, Austria;5. Johannes Kepler University, Institute for Chemical Technology of Organic Materials, Linz, Austria |
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| Abstract: | 1 Scope Known pharmacological activities of guava (Psidium guajava) include modulation of blood glucose levels. However, mechanistic details remain unclear in many cases. 2 Methods and results This study investigated the effects of different guava leaf and fruit extracts on intestinal glucose transport in vitro and on postprandial glucose levels in vivo. Substantial dose‐ and time‐dependent glucose transport inhibition (up to 80%) was observed for both guava fruit and leaf extracts, at conceivable physiological concentrations in Caco‐2 cells. Using sodium‐containing (both glucose transporters, sodium‐dependent glucose transporter 1 SGLT1] and glucose transporter 2 GLUT2], are active) and sodium‐free (only GLUT2 is active) conditions, we show that inhibition of GLUT2 was greater than that of SGLT1. Inhibitory properties of guava extracts also remained stable after digestive juice treatment, indicating a good chemical stability of the active substances. Furthermore, we could unequivocally show that guava extracts significantly reduced blood glucose levels (≈fourfold reduction) in a time‐dependent manner in vivo (C57BL/6N mice). Extracts were characterized with respect to their main putative bioactive compounds (polyphenols) using HPLC and LC‐MS. 3 Conclusion The data demonstrated that guava leaf and fruit extracts can potentially contribute to the regulation of blood glucose levels. |
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| Keywords: | GLUT2 guava extract intestinal glucose transport postprandial blood glucose SGLT1
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