Resveratrol (RSV) is a natural polyphenol that has attracted considerable scientific interest in recent decades due to its wide range of biological effects, including antioxidant, antiinflammatory, antidiabetic, anticancer,cardioprotective, and neuroprotective activities. Despite promising results from preclinical and clinical studies, its clinical application remains limited, primarily due to its low bioavailability and rapid metabolism following oral administration. Consequently, RSV is more commonly used in the form of dietary supplements (DS), whose quality and efficacy are not always adequately controlled. Therefore, the aim of this master’s thesis was to evaluate the quality of RSV-containing DS, with a particular focus on their content and release properties in biorelevant media for predicting the behaviour of DS in the body.
Firstly, a review of key preclinical and clinical studies was conducted, focusing on the therapeutic effects of RSV in oncology, oxidative stress and inflammation, neurological, cardiovascular, and metabolic diseases, as well as its potential role in lifespan extension.
In the experimental part, seven commercially available RSV-containing DS were selected. The actual RSV content was determined using an appropriate extraction method followed by high performance liquid chromatography analysis and compared with the declared values provided by the manufacturers. In addition, the disintegration time of capsules was determined, which directly effects the release of active substance. Dissolution testing was performed using a paddle apparatus in accordance with the European Pharmacopoeia. The tests were conducted in media simulating physiological conditions, namely at pH 1.2 (fasted stomach conditions) and pH 6.8 (intestinal conditions). Due to the poor solubility of RSV, dissolution was also evaluated under “sink” conditions using the addition of surfactants. To better simulate the transit of the dosage form through the gastrointestinal tract, a dissolution method with medium change was also employed.
The results showed that the quality of RSV-containing DS is not consistent, as only 4 of the 7 analysed products complied with the declared content. Additionally, two products exceeded the permitted disintegration time (30 minutes), which may affect the release of active substance. RSV release under physiological conditions was limited (up to 26 % in pH 1.2 medium), whereas in the presence of surfactants it increased up to eightfold (from 4.3 % to 35.6 % in pH 6.8 medium). These findings highlight significant variability among products and raise concerns regarding their quality and effectiveness. Furthermore, they represent a basis for future research in the field of quality control and biopharmaceutical properties of DS.
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