Antiproliferative effects of Australian native plums against the MCF7 breast adenocarcinoma cells and UPLC-qTOF-IM-MS-driven identification of key metabolites

The rich and unique phytochemical profiles of Australian native fruits are attributed to the intense climatic conditions of the island. Of these native fruits, the Kakadu plum (KP; Terminalia ferdinandiana), Illawarra plum (IP; Podocarpus elatus), and Davidson's plum (DP; Davidsonia pruriens) have been increasingly used in the food industry. However, their phytochemical profiles and bioactivity are not well explored. This study examined the antiproliferative activity of water and ethanol extracts of KP, IP and DP against the MCF7 breast adenocarcinoma cells using the Alamar blue assay. The potential induction of apoptosis and reactive oxygen species (ROS) generation in the MCF7 cells by the active extracts was examined. The most potent extracts were analysed using biochemometric and liquid chromatography-mass spectrometry (LC-MS) driven metabolomic identification. A dose-dependent antiproliferative activity of KP-water (IC50 = 239.9 μg/mL), KP-ethanol (IC50 = 254.7 μg/mL), and IP-ethanol (IC50 = 521.7 μg/mL) was observed. All other extracts (IP-water, DP-water, DP-ethanol) showed IC50 values > 3000 μg/mL. The three potent extracts at 3000 μg/mL induced apoptosis (P < 0.05) but did not increase the production of ROS in the MCF7 cells. The metabolomic identification revealed an abundance of tannin, flavonoids, and triterpenoid compounds as potential anticancer metabolites in the KP extracts. Further mechanistic investigations are warranted to formulate Australian plum-based dietary interventions.