The antibacterial and antiproliferative ability of kanuka, Kunzea ericoides, leaf extracts obtained by subcritical water extraction

BACKGROUND Subcritical water kanuka leaf extracts contain high levels of polyphenols. However, whether these extracts can serve as natural antimicrobial and chemopreventive agents is still a question. This study aimed to evaluate the antibacterial and antiproliferative efficacy of SWE kanuka leaf extracts. Subcritical water extraction (SWE) was used to obtain natural extracts from kanuka leaves potentially rich in biologically active compounds. The antibacterial and antiproliferative capacities were assessed by broth microdilution assay and MTT-assay, respectively. The assessed properties were compared to extraction from ethanol extraction (EE). Results The screening results for antibacterial properties demonstrated that subcritical water kanuka leaf extracts were active against Escherichia coli (minimum conc. 0.8 mg/mL) and Staphylococcus aureus (minimum conc. 3.8 mg/mL). These extracts also exerted dose-dependent antiproliferative effects on the viability of cancerous human cervical cell lines (Hep-2 and RD cells) and mouse cell lines (L cells). The extraction temperature had significantly affected the extract's activities by enhancing neoformed compounds with beneficial effects. CONCLUSIONS Subcritical water extracts of kanuka demonstrated a better efficacy against bacterial growth and malignant cells viability in comparison to extracts obtained using conventional ethanol extraction. This SWE kanuka leaf product could be used in a range of applications where antimicrobial and antiproliferative properties are required. Further studies are needed to examine the mechanism and markers of these properties. (c) 2020 Society of Chemical Industry