Real-Time Polymerase Chain Reaction (PCR) Analysis
To determine the effect of A. princeps extract on gene expression, a real-time PCR assay was performed. The subminimal inhibitory concentration (1–4 mg/mL) of A. princeps extract was used to treat and culture MRSA for 24 h. Total RNA was isolated from S. mutans by using Trizol reagent (Gibco-BRL) according to the manufacturer's instructions. Then, cDNA was synthesized using a reverse transcriptase reaction (Superscript; Gibco-BRL). The DNA amplifications were carried out using an ABI-Prism 7,000 Sequence Detection System with Absolute QPCR SYBR Green Mixes (Applied Bio systems Inc., Foster City, CA, USA). The primer pairs that were used in this study were described by previous report [17–20] and are listed in Table 1. 16S rRNA was used as an internal control.