BACKGROUND: Phenolic compounds, antioxidant activity, and antimicrobial properties of unripe and ripe mastic tree (Pistacia lentiscus L.) fruits and their oils were investigated. RESULTS: A total of 20 phenolic compounds were identified by using liquid chromatography-diode array detection and electrospray ionization tandem mass spectrometry, among which phenolic acids were predominant. The main phenolic compound was catechin in the unripe fruit and trigalloylquinic acid in the unripe fruit oil, whereas galloylquinic acid was dominant in the ripe fruit and its oil. Unripe fruits had the highest amount of total phenolic content (TPC
2771.4 mg kg CONCLUSION: The fruits and their oils exhibited significant alterations in phenolic composition, antioxidant activity, and antimicrobial effects during ripening. These findings highlight the impact of ripeness on the bioactive properties of mastic tree fruits and their potential applications in the food and pharmaceutical industries. © 2025 Society of Chemical Industry.