Determination of guava (Psidium guajava L.) leaf phenolic compounds using HPLC-DAD-QTOF-MS

Markets of different countries have proposed guava tea infusions as a drink that can modulate the glycaemic index in blood. This property has been attributed to the phenolic compounds contained in guava leaves. However, phenolic profile of guava leaves is still not well-known. Based on this information, different ethanol/water mixtures were used to extract the phenolic compounds in guava leaves. Phenolic identification was carried out by HPLC-ESI-QTOF-MS in guava leaves from pomifera and pyrifera varieties; moreover, the antioxidant activities of the ethanolic extracts were determined by TEAC and FRAP methods. To sum up, seventy-two phenolic compounds were identified. To our knowledge, twelve of them were determined for the first time in guava leaves. The highest amount of phenolic compounds was found in EtOH/H2O 80:20 (v/v) mixture. Furthermore, pyrifera var. showed higher concentration of phenolic compounds than pomifera var. (113.34 vs. 86.12 mg/g leaf d.w.) and also greater antioxidant capacity.