Table 1.

Stability of astilbin and neoastilbin in plasma (1 μg/mL) under different store conditions. (n = 3).

Conditions	Stability	Relative Recovery (%) 1
		Astilbin	Neoastilbin
Short-time (Ambient Atmosphere)	2 h	106.16 ± 2.76	92.38 ± 1.04 *
	4 h	98.02 ± 3.48	89.38 ± 1.73 *
	6 h	101.10 ± 5.71	89.23 ± 4.48 *
	8 h	95.60 ± 5.28	96.30 ± 6.03
Long-time (−80 °C)	7 days	86.34 ± 2.17	87.78 ± 8.01
	14 days	91.52 ± 2.48	92.40 ± 4.46
	21 days	89.04 ± 8.91	89.57 ± 9.25
	28 days	86.65 ± 3.35	86.87 ± 6.60
Freeze/Thaw	Three freeze/thaw	97.15 ± 7.45	93.29 ± 10.32

¹ The astilbin/neoastilbin concentration in plasma was calculated through the calibration curve in Table 2. * means significant difference (p < 0.05) between astilbin and neoastilbin.