Optimization of Tropane Alkaloids Extraction from <i>Anisodus luridus</i> Utilizing Response Surface Methodology and Quality Assessment through UPLC Fingerprinting

<i>Anisodus luridus</i>, a medicinal plant, is abundant in tropane alkaloids (e.g., hyoscyamine and scopolamine) within its roots. This species exhibits higher biomass and alkaloid content compared to traditional medicinal plants such as <i>Atropa belladonna</i> and <i>Datura stramonium</i>. Given the significant bioactivity of natural tropane alkaloids and the plant's commercial potential, this study optimized their extraction process using response surface methodology. The optimal conditions were determined as 78% ethanol concentration, 68 °C extraction temperature, and 20 min extraction time. The actual tropane alkaloid yield (6.211 mg/g) closely aligned with the predicted value (6.194 mg/g), validating the model's accuracy. Furthermore, a UPLC-PDA-based quantitative method was developed for analyzing chemical components of <i>Anisodus luridus</i> and subsequently applied to construct its UPLC fingerprint for quality assessment. The method demonstrated linearity for hyoscyamine in the range of 20.00-2000.00 μg/mL, scopolamine from 2.00 to 256.00 μg/mL, and anisodamine 1 and 2 in the ranges of 1.08-69.12 and 0.92-58.88 μg/mL, respectively. Average relative recoveries for these compounds were 98.91, 99.73, 100.05, and 97.01%, respectively. The alkaloid content in the tested batch samples ranged from 3.2044 to 22.0037 mg/g with significant differences. Based on experimental data and practical production requirements, the alkaloid content in medicinal materials meeting regulatory standards should not be lower than 0.05%. Additionally, the Technique for Order Preference by Similarity to an Ideal Solution scoring prediction indicated that the relative closeness of the August harvest to the optimal scheme was 0.882, the highest score recorded. This suggests that early August may be the most suitable period for harvesting to ensure optimal medicinal quality. These findings provide crucial references for the quality evaluation and industrial application of this plant.