RESUMO
Objective: To optimize the ultrasonication method for efficient extraction of β-sitosterol and lupeol from the roots of Astragalus atropilosus using Box-Behnken design of response surface methodology (RSM), and its validation by high performance thin layer chromatography (HPTLC) method.Methods: Ultrasonication method was used to extract β-sitosterol and lupeol from Astragalus atropilosus (roots). RSM was used to optimize the different extraction parameters viz. liquid to solid ratio (10–14 mL/g), temperature (60-80 ℃) and time (40–60 min) to maximize the yield of β-sitosterol and lupeol. The quantitative estimation of β-sitosterol and lupeol was done in chloroform extract of Astragalus atropilosus by validated HPTLC method on 10 cm × 20 cm glass-backed silica gel 60F254 plate using hexane and ethyl acetate (8:2, v/v) as mobile phase. Results: A quadratic polynomial model was found to be most appropriate with regard to R1 (yield of total extraction; R2/％ CV = 0.9948/0.28), R2 (β-sitosterol yield; R2/％ CV = 0.9923/0.39) and R3 (lupeol yield; R2/％ CV = 0.9942/0.97). The values of adjusted R2/predicted R2/signal to noise ratio for R1, R2, and R3 were 0.9782/0.9551/48.77, 0.9904/0.9110/31.33, and 0.9927/0.9401/36.08, respectively, indicating a high degree of correlation and adequate signal. The linear correlation plot between the predicted and experimental values for R1, R2, and R3 showed high values of R2 ranging from 0.9905-0.9973. β-sitosterol and lupeol in chloroform extract of Astragalus atropilosus were detected at Rf values of 0.22 and 0.34, respectively, at λ max = 518 nm. The optimized ultrasonic extraction produced 8.462％ w/w of R1, 0.451％ w/w of R2 and 0.172％ w/w of R3 at 13.5 mL/g liquid to solid ratio,78 ℃ of temperature and 60 min of time.Conclusions: The experimental findings of RSM optimized extraction and HPTLC analysis can be further applied for the efficient extraction of β-sitosterol and lupeol in other species of Astragalus.