Supercritical fluid extraction (SFE) is an innovative green technology for the extraction of phytochemicals from plants. Therefore, this study aimed to evaluate the application of SFE and to optimize the extraction conditions of the Thai herbal formula, Kleeb Bua Daeng (KBD). A Box–Behnken design (BBD) with response surface methodology (RMS) was used to determine the effect of the extraction time (30–90 min), temperature (30–60 °C), and pressure (200–300 bar) on response variables including the extraction yield, total phenolic content (TPC), total flavonoid content (TFC), total carotenoid content (TCC), and total anthocyanin content (TAC) of the KBD formula. The highest percentage extraction yield (3.81%) was achieved at 60 °C, 300 bar, and 60 min of the extraction time. The highest TPC (464.56 mg gallic acid equivalents/g extract), TFC (217.19 mg quercetin equivalents/g extract), and TCC (22.26 mg β-carotene equivalents/g extract) were all achieved at 60 °C, 250 bar, and 90 min of the extraction time. On the contrary, it was not possible to quantify the total anthocyanin content as anthocyanins were not extracted by this method. The results indicated that SFE-CO2 is a suitable method of extraction for a green recovery of phytochemicals with low and moderate polarity from the KBD formula.
