Spd 15c

Total flavonoid content was determined according to the method of Jin et al. [6 (link)]. In brief, the dry AR sample (0.1 g) was soaked in 10 mL of 70% ethanol, heated at 60 °C for 3 h, and filtered with a filter paper. The filtrate was used to determine the total flavonoid content via the aluminum nitrate colorimetric method at 510 nm using a spectrophotometer; rutin was used as the standard. The result was expressed as the equivalent of rutin per gram of the DW sample.
The method of Zhang et al. [42 (link)] was used to determine the contents of rutin, quercetin, and kaempferide using high-performance liquid chromatography with a C₁₅ column (4.6 × 250 mm, 5 μm, Thermo Scientific, Waltham, MA, USA) and ultraviolet–visible detector (SPD-15C, Shimadzu Co., Kyoto, Japan). The mobile phases were methanol (A) and 0.1% phosphorus solution (B). Gradient elution was performed as follows: 55% B for 0−15 min and 20% B for 15−30 min. The flow rate was 0.8 mL/min. rutin, quercetin, and kaempferide were detected at 366 nm (Figure 8). Standards of rutin (purity > 98%), quercetin (purity > 98%), and kaempferide (purity > 98%) were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China).

Films were examined for drug dissolution using a USP basket dissolution apparatus (RCZ-8-B, Shanghai, China) at a rotating speed of 100 rpm. The dissolution medium was 300 mL of pH 6.8-simulated saliva fluid maintained at 37.0 ± 0.5 °C. The specified aliquots were withdrawn at preset time intervals [28 (link)]. The supernatant was obtained by centrifugation of the sample at 10,000 rpm for 10 min. The Shimadzu HPLC system was then analyzed (model SPD-15c, Shimadzu Corporation, Kyoto, Japan) equipped with a UV-detector. A CST column (4.6 × 250 mm², 5 μm) was applied as a stationary phase. The mobile phase was composed of 0.5% (v/v) triethylamine and acetonitrile (85:15, v/v, respectively). The mobile phase’s flow rate was set to 1.5 mL·min⁻¹ with a column temperature set to 40 °C and a detection wavelength of 260 nm.