**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 polyphenolic compounds characterized by a central three-carbon chain connecting two benzene rings (A and B rings), with various functional groups such as hydroxyl, methoxy, methyl, or isopentenyl groups. These compounds often exist in glycoside forms, bound to sugars. They are widely distributed in plants and exhibit a range of biological activities, including antioxidant, anti-inflammatory, and antitumor properties.
The objective of this study was to optimize the extraction process for total flavonoids from *Astragalus membranaceus* using ultraviolet spectrophotometry. The effects of key parameters—such as solvent type, extraction time, and number of extractions—were investigated to determine the most effective conditions for maximizing flavonoid yield.
The experimental design employed an orthogonal array (L9(3â´)) to evaluate the influence of three factors: solvent concentration (ethanol), extraction time, and number of extractions. A standard curve was prepared using baicalin as a reference compound. The absorbance was measured at 277.6 nm, which was identified as the maximum absorption wavelength through UV scanning between 190–500 nm. The calibration curve showed a strong linear relationship (Y = 66.878X – 0.003, R² = 0.9996), confirming the reliability of the method.
Results from the orthogonal experiments revealed that the most significant factor affecting flavonoid yield was the solvent dosage (C), followed by extraction time (A) and number of extractions (B). The optimal conditions were found to be: 30% ethanol as the solvent, with a dosage of 12, 10, and 10 times the sample weight, and extraction times of 2, 1, and 1 hour respectively. Under these conditions, the total flavonoid content reached 19.03%, 18.65%, and 19.48% in three separate trials, demonstrating high consistency and reproducibility.
This study provides a scientific basis for improving the extraction efficiency of total flavonoids from *Astragalus*. The proposed method is simple, accurate, and suitable for large-scale application in pharmaceutical production. It also highlights the importance of optimizing extraction parameters to enhance both yield and quality of bioactive compounds. Future work could explore the use of different solvents or advanced techniques such as microwave-assisted extraction to further improve the process.
**Key words**: Astragalus; Flavonoids; Extraction; Ultraviolet Spectrophotometry; **Aesthetic Instrument**; UV-1500PC
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