Định lượng flavonoid toàn phần trong cao đặc từ ngũ sắc và một số dược liệu bằng quang phổ UV-Vis

Traditional medicinal plants, including a combination of Ageratum conyzoides (Ngũ sắc), honeysuckle, Eclipta alba, Angelica dahurica, and Ligusticum striatum, are widely used in Vietnamese traditional medicine, particularly for conditions like rhinosinusitis. These herbs are known to be rich in bioactive compounds, especially total flavonoids, which possess significant antibacterial, anti-inflammatory, and antioxidant properties. Despite their recognized therapeutic potential and widespread use, there is a notable lack of standardized and validated analytical methods for accurately quantifying these crucial compounds in complex concentrated extracts. This study addresses this gap by aiming to develop and validate a reliable and cost-effective method for the quantitative determination of total flavonoids in such herbal extracts using UV-Vis spectroscopy, expressed as quercetin equivalents, thereby enhancing quality control and scientific understanding of these traditional remedies.

Researchers in pharmaceutical analysis, medicinal chemistry, quality control of herbal products, traditional medicine practitioners, and regulatory bodies overseeing botanical drug development.

This research focused on establishing a robust and validated analytical method for quantifying total flavonoids in complex concentrated extracts derived from a synergistic blend of five traditional Vietnamese medicinal plants (Ageratum conyzoides, honeysuckle, Eclipta alba, Angelica dahurica, and Ligusticum striatum). The methodology employed was UV-Vis spectroscopy, utilizing a colorimetric reaction with AlCl3 reagent. The study meticulously optimized critical experimental parameters, including the maximum absorption wavelength at 430 nm, the optimal AlCl3 reagent concentration at 5%, and a reaction time of 45 minutes to ensure stable complex formation. Subsequent validation, adhering strictly to AOAC guidelines, demonstrated the method's high performance across several key analytical characteristics. The results confirmed excellent accuracy, with average recoveries ranging from 99.44% to 100.37% (RSD ≤ 2%), alongside commendable precision as evidenced by a system suitability RSD of ≤ 2% and an overall inter-day precision (RSDR) of ≤ 4%. Furthermore, the method exhibited strong linearity with a correlation coefficient (R) greater than 0.995 within the established concentration range. The total flavonoid content in the analyzed concentrated herbal extract was determined to be 3.04% (RSD = 0.7%), expressed as quercetin equivalents. This successfully developed and validated UV-Vis spectroscopy method offers a simple, cost-effective, and reliable tool for the quantitative analysis and quality control of total flavonoids in traditional herbal concentrated extracts. Its application will significantly contribute to standardizing the assessment of active compounds in such botanical formulations, providing a scientific basis for their efficacy and safety, and supporting further research and development in natural product chemistry and traditional medicine.