Aqueous Angophora floribunda extract as a source of phenolics and antioxidants with anti-pancreatic cancer and antimicrobial activity

OBJECTIVE: To elucidate the phytochemical, anticancer, antibacterial and antifungal properties of crude aqueous freeze-dried extract of Angophora floribunda leaves. METHODS: The phytochemical profile was studied by analyzing the total phenolic content (TPC), total flavonoid content (TFC), proanthocyanidins and antioxidant properties of the extract. The cytotoxicity of the extract against the MIA PaCa-2 pancreatic cancer cell line was evaluated using the Dojindo Cell Counting Kit-8 assay (CCK-8). The Muse caspase 3/7 assay was applied to evaluate the apoptotic profile of the cancer cells. The antimicrobial activity of the extract was elucidated against 2 pathogenic bacterial strains (Escherichia coli and Staphylococcus lugdunensis) and 2 fungal strains (Aspergillus brasiliensis and Candida albicans) using the 96 well plate-based method with resazurin dye. RESULTS: The TPC, TFC and proanthocyanidin values found were: 227.16 ± 14.62 mg of gallic acid equivalents per g, 91.42 ± 3.32 mg of rutin equivalents per g and 102.15 ± 4.57 mg of catechin equivalents per g, respectively. The antioxidant values expressed in mg trolox equivalents per g of extract (mg TE/g) were: ABTS = 657.53 ± 14.24 mg TE/g, DPPH = 758.21 ± 43.65 mg TE/g and CUPRAC= 834.52 ± 73.43 mg TE/g. The extract at 80 µg/mL inhibited the growth of MIA PaCa-2 cells by 59.71 ± 11.76%, with caspase 3/7 mediated apoptosis of cells observed after 24 h of treatment. In regards to the antimicrobial activity of the extract, minimum inhibitory concentration values were demonstrated to be: A. brasiliensis = 9.75 µg/mL, S. lugdunensis = 156.25 µg/mL, E. coli = 312.5 µg/mL and C. albicans = 2500 µg/mL. CONCLUSION These findings reveal the significance of the A. floribunda aqueous extract as a potential source of phenolics and antioxidants with anti-pancreatic cancer, antibacterial and antifungal properties.