**Study on the Extraction Process of Total Flavonoids from Astragalus Using Ultraviolet Spectrophotometry**
**Keywords**: Astragalus; Flavonoids; Extraction; Ultraviolet Spectrophotometry; Aesthetic Instrument; UV-1500PC
Flavonoids are a class of naturally occurring compounds characterized by two benzene rings (A and B) connected by a three-carbon chain, forming a central chroman or pyrone ring. These compounds often contain functional groups such as hydroxyl, methoxy, methyl, or isopentenyl groups, and they frequently occur in glycosidic forms when combined with sugars. Flavonoids are known for their wide range of biological activities, including antioxidant, anti-inflammatory, and antimicrobial properties. In traditional Chinese medicine, *Astragalus membranaceus* is widely used for its health benefits, particularly due to its high flavonoid content.
The objective of this study was to optimize the extraction process of total flavonoids from *Astragalus membranaceus* using ultraviolet spectrophotometry. The effects of three key factors—extraction solvent, extraction time, and number of extractions—were systematically investigated. By employing an orthogonal experimental design, the optimal conditions were determined to maximize the yield of total flavonoids.
The results indicated that 30% ethanol was the most effective solvent, with an optimal extraction protocol involving three steps: 12 times the solvent volume at 2 hours, followed by 10 times at 1 hour each. This method significantly improved the extraction efficiency compared to traditional water-based methods, which typically result in lower yields and longer processing times.
To validate the findings, a series of experiments were conducted, measuring the absorbance at 277.6 nm using a UV-1500PC spectrophotometer. A standard curve was established using baicalin as a reference, confirming a strong linear relationship between concentration and absorbance (R² = 0.9996). The stability of the reference solution over one hour also supported the reliability of the method without the need for additional color reagents.
This study provides a scientific basis for optimizing the extraction of total flavonoids from *Astragalus*, offering practical guidance for industrial applications. The developed method is not only efficient but also easy to scale up, making it suitable for large-scale production of flavonoid-rich extracts.
**Keywords**: Astragalus; Flavonoids; Extraction; Ultraviolet Spectrophotometry; Aesthetic Instrument; UV-1500PC
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