Investigation of Antioxidant, Anticancer, and Chemopreventive Properties of Hawaiian Grown Māmaki tea (Pipturus albidus)

Abstract

Objective Māmaki tea ( Pipturus albidus) is a native Hawaiian plant species that is best known for its medicinal uses. It is endemic and only grows on the Hawaiian Islands. We evaluated different extraction methods and investigated antioxidant, anticancer, and/or chemopreventive potential of Māmaki tea. Materials and Methods Fresh Māmaki tea leaves were purchased from Hilo Farmers Market on Big Island. The Ferric Reducing Antioxidant Power (FRAP) assay was used to evaluate the antioxidant activities of selected Hawaii-grown teas, fruits, and vegetables. In addition, chemopreventive assays against tumor necrosis factor (TNF)-α-induced nuclear factor kappa B (NF-κB) and nitric oxide (NO) were performed for these Māmaki tea extracts. Cytotoxicity testing was done using in vitro sulforhodamine B (SRB) assay against lung (LU-1) and breast (MCF-7) cancer cell lines. Results Locally grown red vine Māmaki tea exhibited the highest level (40.0 µM/µg) of antioxidants among the tested locally grown fruits, vegetables, and tea. In addition, when tested at 20 µg/mL, the dehydrated Māmaki tea powders (AS-18), brewed from boiling water, showed the highest NF-κB inhibition (75.0%); and the freeze-dried Māmaki leaf powder (AS-1) brewed using room temperature water had the highest inhibitory activity with 55.5% in the nitrite assay. Furthermore, AS-25, the 100% ethanol extract from dehydrated Māmaki tea leaves exhibited the best anticancer activity with the lowest 71.3% survival of breast cancer cells. Conclusions This work stimulates further studies on the biological properties and medicinal uses of Māmaki tea, and raises community and public awareness to promote Māmaki tea.