A rapid simultaneous determination of methylxanthines and proanthocyanidins in Brazilian guaraná (Paullinia cupana Kunth.)

- The developed RP-HPLC-UV/PDA method simultaneously quantifies 7 chemical markers.
- Caffeine is the major compound and all other, including tannins, are minor compounds.
- The new and validated method was sensitive, convenient, low-cost, fast, and reliable.
- A simple and low-cost extraction method is developed.
- This method could strengthen the quality control of guarana in food and medicines.

Paullinia cupana is a plant native to Brazil that is widely used in traditional medicine as a physical and mental stimulant. It is also used worldwide to produce soft drinks. A method for the simultaneous quantitation of seven markers in guaraná by HPLC-PDA was developed, and extraction methods for the determination of methylxanthines and tannins were investigated. Quantified substances were theobromine, theophylline, caffeine, catechin, epicatechin, procyanidins A2 and B2. Results confirmed the satisfactory selectivity and linearity (r2 ≥ 0.99) within the mass ranges. Repeatability (RSD ≤ 2.80%), intermediate precision (RSD ≤ 4.47%), accuracy (recoveries from 90.59%-104.67%), and robustness were demonstrated. Extract 1 presented the contents: 0.0177% (±1.02%) for theobromine, 0.0131% (±1.14%) for theophylline, 2.9429% (±1.27%) for caffeine, 0.4563% (±1.02%) for catechin, 0.5515% (±1.05%) for epicatechin, 0.0607% (±2.80%) for A2 and 0.1035% (±1.39%) for B2. The method for simultaneous quantitation of seven chemical markers in guaraná proved to be reliable using a simple and convenient HPLC setup.