Inhibitory activities of baicalin against renin and angiotensin-converting enzyme

Figures & data

Figure 1.  Renin inhibitory phenomena of baicalin (0.1 mg/mL) observed by fluorescence spectrometry assay.

Figure 2.  Plot of percentage inhibition of renin activity versus concentration of baicalin. The IC₅₀ for baicalin is 120.36 µM.

Figure 3.  Fluorescence emission spectra of renin (appoximately 40 μg/mL) excited at 280 nm showing the quench effect of increasing concentration of baicalin (0, 1.57, 3.08, 4.53, 5.93, 7.27, 8.87 μΜ).

Figure 4.  Fluorescence emission spectra of angiotensin-I-converting enzyme excited at 295 nm showing the quench effect of baicalin alone (A) and baicalin in the presence of angiotensin I (B).

Table 1.  Stern−Volmer constant and coefficient for the interaction of baicalin with renin and angiotensin-I converting enzyme (ACE).

	Linear equations	Linear coefficient R^2	Ksv (×10^3M^−1)	Kq (M^−1S^−1)
Renin	Y = 0.06x + 1	0.9565	60.0	6 × 10^12
ACE	Y = 0.0171x + 1	0.9509	17.1	1.71 × 10^12

Table 2.  The binding constants, number of binding sites of complex, and Gibbs free energy for the interaction of baicalin with renin and angiotensin-I-converting enzyme (ACE).

	Linear equations	Linear coefficient R^2	Kb (M^−1)	ΔG (KJ/M)	Binding sites (N)
Renin	Y = 15.901 + 2.9291x	0.9946	796.15 × 10^13	-94.38	2.9
ACE	Y = 5.8352 + 1.4349x	0.9766	6.8 × 10^5	-34.64	1.4