Effect of O-methylated and glucuronosylated flavonoids from Tamarix gallica on α-glucosidase inhibitory activity: structure–activity relationship and synergistic potential

Figures & data

Table 1. α-Glucosidase inhibition activity, inhibition mode and specificity for sugar-based substrates using mammalian enzyme.

Substances	α-Glucosidase inhibition (%)						Inhibition mode^a
	Sucrase activity			Maltase activity
	1 μM	10 μM	100 μM	1 μM	10 μM	100 μM
1	0.2 ± 1.1	15.7 ± 1.3	21.8 ± 0.5	3.7 ± 1.1	16.9 ± 0.3	20.2 ± 1.5	Mixed
2	0.0 ± 2.8	24.9 ± 1.3	29.5 ± 0.5	8.5 ± 1.5	16.5 ± 2.3	23.7 ± 1.2	Mixed
3	0.1 ± 0.5	10.7 ± 1.9	17.5 ± 0.4	5.1 ± 0.2	17.0 ± 1.9	19.6 ± 1.7	Mixed
4	0.0 ± 1.8	12.9 ± 2.3	20.9 ± 1.2	7.5 ± 2.3	13.5 ± 1.3	20.7 ± 0.2	Mixed
5	1.0 ± 1.2	4.6 ± 2.5	9.2 ± 0.5	4.6 ± 0.3	12.0 ± 1.6	19.1 ± 0.5	Mixed
6	2.4 ± 2.5	20.0 ± 2.8	27.8 ± 0.5	4.1 ± 1.0	1.5 ± 1.6	62.0 ± 0.1	Non-competitive
7	2.2 ± 1.8	28.6 ± 0.1	30.9 ± 2.2	8.3 ± 1.5	18.9 ± 1.6	75.3 ± 0.5	Non-competitive
8	1.8 ± 0.5	3.0 ± 2.5	11.2 ± 1.5	4.9 ± 0.4	21.4 ± 0.9	31.7 ± 1.1	Non-competitive
9	2.5 ± 1.0	11.7 ± 2.6	16.7 ± 1.3	8.4 ± 1.3	15.2 ± 0.6	33.5 ± 1.1	Non-competitive
Acarbose	32.8 ± 1.5	33.3 ± 1.8	56.1 ± 0.6	6.1 ± 1.4	23.9 ± 0.9	62.5 ± 0.5	–

^a The mode of inhibition was measured with increasing concentrations of p-nitrophenol α-D-glucopyranoside.

Fig. 1 Structures of flavonoids 1–9.

Fig. 2 The combined effects of acarbose and flavonoids 1–9 on intestinal maltase inhibition (A) and intestinal sucrase inhibition (B).

Note: The results expressed as means ± S.E.M.; n = 3. *p < 0.05; **p < 0.01; *** p < 0.001 compared with acarbose.