Abstract Campomanesia lineatifolia (gabiroba) is a native edible species found in the Amazon Rainforest. Previous studies have demonstrated the flavonoid nature of ethanolic extract from the C. lineatifolia leaves, in addition to gastroprotective activity and TNF inhibition. However, the extraction process used was long and consumed a large amount of solvent. Therefore, the objective of this study was to obtain a bioactive extract rich in phenolics, in an extractive method of simpler, faster, and lower-cost execution. The C. lineatifolia leaves were dried and crushed, and the extractions were carried out in different solvents/mixtures (ethanol, methanol, ethyl acetate, and water) under ultrasonic bath (UB), electromagnetic stirring, and continuous reflux extraction (R). The extraction efficiency was evaluated by the flavonoid major compound concentration in the extracts, in a method developed by ultra-high performance liquid chromatography (UHPLC). Injection and pattern matching tests, and UHPLC analyses coupled to ultraviolet spectrometry were conducted to identify catechin and quercitrin. It has been demonstrated that the ethanolic extraction by R and the mixture of ethanol: water (8:2) by UB represented optimized methods in obtaining the flavonoid compounds identified. Thus, the results may contribute to chemical-biological extract standardization for gastric antiulcer activity evaluation.