Comprehensive microRNA analysis toward exploring a new functional component in Matcha green tea

Matcha, a traditional Japanese green tea, has health-promoting effects. However, little is known about its bioactive components, except for polyphenols, caffeine, and amino acids. Here, we revealed the presence of diverse miRNAs, a type of functional RNAs, as new components of Matcha, using next-generation sequencing. Quantitative reverse-transcription PCR analysis of 10 different Matcha showed that miRNA levels varied depending on the cultivar and harvest season. As extraction methods of miRNAs, we found that soaking at 95 °C significantly enhanced total RNA and miRNA yields. Furthermore, a positive correlation was observed between total RNA and miRNA yields extracted from 27 plant-based dried powders. Notably, Matcha exhibited the highest levels of four representative miRNAs: lja-miR166-3p, csn-miR396d-5p, gma-miR396e, and csn-miRn409. The miRNA yields in Matcha were correlated with the major Matcha components. These results highlight Matcha as a source of miRNAs and candidate bioactive components. These findings provide new insights into the functionality of Matcha.