Development and validation of an analytical method by HPLC-DAD for determination of caffeine in products based on guarana extracts (Paullinia cupana)

Abstract Guarana (Paullinia cupana) is a native plant from the Amazon whose seeds contain a high concentration of caffeine. Aqueous extract of guarana is widely used in the world. In this study, the objective was to develop and validate a High-Performance Liquid Chromatography method for the determination of caffeine in extracts and commercial beverages based on guarana. A sensitive, simple, and viable high performance liquid chromatographic method without the need of an analyte extraction procedure was developed and validated according to Brazilian and international requirements. The method presented high performance, fulfilling Brazilian and international requirements, in addition to allowing product compliance tests. Results confirmed high selectivity and linearity (>0.999) between 5 to 135 ug/mL, with no significant matrix effect. Detection and quantification limits were 0.02 µg/mL and 2 µg/mL, respectively. Precision was less than 4 %, and accuracy varied from 99.9-120 %. Applicability of the method was demonstrated by conducting a limited evaluation in products containing caffeine. Commercial extracts showed quite different caffeine levels, while carbonated drinks follow Brazilian and American recommendations. Our results indicate that the developed method can be used to evaluate the quality of the guarana extract and of products containing caffeine

Phytochemistry profile of rosella and jambolan extracts and the therapeutic effects on obesity.

Hibiscus sabdariffa extract (HSE) and Syzygium cumini extract (SCE) have been used in traditional medicine due to their hypoglycemic, antidiabetic, anti-obesity and antioxidant activities. This study aimed to evaluate the anti-obesity effects of these extracts, as well as to evaluate their toxicities. The phytochemical profiles were obtained by HPLC-DAD-ESI-MS/MS analyses. Pharmacological screening, motor activity, motor coordination and acute toxicity were evaluated by administering HSE or SCE (oral or intraperitoneal routes) at different doses to mice. The anti-obesity effects were examined by assessing the decrease in food intake and body weight loss in Wistar albino rats and by gastrointestinal transit in Swiss albino mice. Sibutramine was used as the positive control. Both extracts showed no toxic effects. At the end of 7 days of treatment, we observed that SCE and HSE reduced the weight gain and food intake of the treated rats in relation to the controls. Sub-chronic treatment revealed that HSE, SCE and sibutramine had the best effect 7 and 14 days after starting treatment. After 28 days, the SCE group showed less weight gain and reduced food consumption compared to the HSE group and controls. In addition, intestinal transit was increased in the HSE group, which is probably due to the high fiber content of the extract and may explain its anti-obesity properties. Myricetin glycosides were found in high levels in SCE and low levels in HSE, which may be the main compounds associated with the anti-obesity effect found in SCE. It is not possible to suggest an effective dose without conducting a preclinical toxicology study. We recommend clinical studies that evaluate the efficacy and safety, as well as the effect of discontinuing the extracts.