Kawakawa tea Intake and its anti-diabetic and anti-inflammatory effects: An integrative microRNA and mRNA analysis

Abstract

Purpose Piper excelsum (kawakawa), a vascular plant endemic to Aotearoa, New Zealand, is of cultural and medicinal importance to Māori. Presence of biologically active compounds in kawakawa may underpin its putative beneficial health properties, particularly its anti-inflammatory effects. However, no human studies on its anti-inflammatory effects exist. Method Blood samples from a crossover two-arm randomised controlled trial to assess the impact of ingesting kawakawa tea (4g leaves/250 mL hot-water) on postprandial plasma abundances of microRNAs (miRNA) involved in metabolic-related pathways and their respective gene and protein targets in healthy human volunteers (n = 26; Age; 33.6 ± 1.9 (yr) and BMI; 22.5 ± 0.4 (kg/m2)) compared to water control, were used for the analysis. Results Nine miRNAs showed significantly different abundances following the two interventions. The abundance of hsa-miR-17-5p, -21-5p, -320a-5p, let-7g-5p, -16-5p, -122-5p, and − 144-3p was upregulated in response to kawakawa intake compared to water and the expression of hsa-miR-221-3p and − 223-3p was downregulated in kawakawa intake compared to water over a120 min postprandial period. In-silico analysis indicated miRNA enrichment in metabolic-related pathways, such as apoptosis, cytokine signaling, MAPK signaling, and MTOR pathways. Furthermore, the postprandial expression of IL-8 (p = 0.03), IL-6 (p = 0.01) and PPAR-γ was significanly reduced following kawakawa consumption compared to water control. While as IL-6 cytokine was significantly increased at 120 min in the kawakawa intervention only compared to baseline. Conclusion These findings highlight the interconnected nature of metabolic regulation pathways and highlight the need for further intervention studies to explore the chronic anti-inflammatory effects of kawakawa. Clinical Trial Registration: The clinical trial is registered with Australian New Zealand Clinical Trials Registry ( ACTRN12621000311853).