The activity of mate saponins (Ilex paraguariensis) in intra-abdominal and epididymal fat, and glucose oxidation in male Wistar rats

Ethnopharmacological relevance: Ilex paraguariensis A. St. Hilaire (mate) has traditionally been used in several South American countries to prepare tea-like beverages having stimulant effects on the CNS and appetite. In recent years, however, mate preparations have been recommended putatively as an appetite suppressant and slimming remedy. Moreover, studies carried out on either normal or diet-induced obese rats treated with mate extracts revealed anti-obesity and satiety effects, thus refuting ethnopharmacological data. In this work, the effect of mate on the intra-abdominal and epididymal fat, and glucose oxidation levels after oral administration in male Wistar rats, was studied using crude extract from leaves, unripe fruits, and a chemically well-defined purified saponin fraction (MSF). Material and methods: Saponin, polyphenol and methylxanthine contents in MSF were analyzed by HPLC-PDA and UPLC/Q-TOF-MS. Crude extracts from mate leaves (LAE) and unripe fruits (FHE) were assayed for comparison purposes. Male Wistar rats fed with standard diet and water ad libitum were used as the control group. Results: The fat weight and both liver and adipose glucose oxidation were reduced significantly by MSF (35, 90 and 60%, respectively), while LAE and FHE were less active. Also, a significant lowering of the blood triglycerides level was observed in rats treated with MSF and LAE. All creatinine, urea, and transaminase plasma levels remained unaffected no matter what mate preparation was considered. It is also worth pointing out that the glucose blood level was increased after treatment with FHE. This finding did not correlate either with the content of methylxanthines, polyphenols or saponins. Conclusion: A reduction in both visceral fat weight and glucose oxidation of hepatic and adipose tissue in healthy rats fed with a standard diet could be ascribed to a purified mate saponin fraction from unripe fruits. These findings agree with former studies carried out with crude mate extracts and also suggest their potential use as an anti-obesity preparation. Nonetheless, further in vivo experiments are still required to corroborate its effect on human beings. (C) 2012 Elsevier Ireland Ltd. All rights reserved.