The stability of medicinal plant microRNAs in herb preparation process

Herbal medicine is now globally accepted as a valid alternative system of pharmaceutical therapies. Various studies around the world have been initiated to develop scientific evidence-based herbal therapies. Recently, microRNAs (miRNAs) have been indicated as new bioactive ingredients in medicinal plants [1]. However, the stability of miRNAs during herbal preparation process remains unclear. This study evaluated the stability of mistletoe miRNAs in different mistletoe preparations. Fresh mistletoe leaves and prepacked dried leaves were powdered, extracted at room temperature, 80 °C or 100 °C with or without mechanical treatment, to mimic the clinical medicinal use as well as folk medicinal use of mistletoe. The total RNA was isolated from these extracts and the miRNAs including miR166a-3 p, miR159a, miR831-5 p, val-miR218 and val-miR11 were quantified by stem-loop qRT-PCR. As a result, the miRNAs showed the highest level in fresh plants. A significant decrease of miRNAs was observed in the extracts made from fresh plants, and mechanical treatment increased miRNA damage. Unexpectedly, a relatively high number of tested miRNAs were found in prepackaged dried mistletoe plants, indicating that these miRNAs could survive air-drying and storage process. Only miR166a-3 p and miR159a with relatively low levels were determined in the mimicked mistletoe tea preparation (soak dried mistletoe in hot water for 10 min). The Ct values of tested miRNAs in mistletoe decoction (boiled in water for 30 min) were below the limit of detection. These data suggested that the miRNA could survive some preparation process, and indicated our consumption that medicinal plants preparations might introduce miRNAs into mammals [2].

• References

• 1 Xie W, Weng A, Melzig MF. MicroRNAs as New Bioactive Components in Medicinal Plants. Planta Med 2016; 83: 1153-1162
• 2 Xie W, Adolf J, Melzig MF. Identification of Viscum album L. miRNAs and prediction of their medicinal values. PLoS One. 2017; 12: e0187776