Synthesis and biological evaluation of stilbene derivatives coupled to NO donors as potential antidiabetic agents

Figures & data

Scheme 1. General synthetic route to NO-donor compounds 3a–3e and 7a–7c. Reagents and conditions: (a) dibromo alkane, K₂CO₃, acetone, reflux, 6 h; (b) AgNO₃, acetonitrile, 80 °C, 2 h; (c) ethyl bromoacetate, K₂CO₃, acetone; (d) KOH, methanol; (e) dibromo alkane, Et₃N, acetone, reflux, 24 h.

Table 1. Biological evaluation in vitro.

		IC50 value (μM)
Products	NO releasing activity (%)^a	α-Glucosidase inhibitory activity^b	AGEs inhibitory activity^c	ALR2 inhibitory activity^d
DMSO
Pterostilbene		>1000	1.99 ± 0.51**	>1000
Resveratrol		241.53 ± 16.98**	0.83 ± 0.21**	17.02 ± 0.31
3a	1.029 ± 0.009**	>1000	2.90 ± 0.09**	>1000
3b	1.359 ± 0.034**	>1000	2.39 ± 0.11**	>1000
3c	1.391 ± 0.050**	83.12 ± 16.21**	1.49 ± 0.20**	299.25 ± 22.62**
3d	0.896 ± 0.004**	>1000	1.39 ± 0.16**	10.03 ± 0.15
3e	0.900 ± 0.006**	178.74 ± 5.76**	1.05 ± 0.25**	8.18 ± 0.33
7a	0.922 ± 0.020**	>1000	1.29 ± 0.04**	>1000
7b	1.000 ± 0.004**	>1000	0.97 ± 0.16**	>1000
7c	1.056 ± 0.023**	163.40 ± 14.20**	0.68 ± 0.07**	121.13 ± 13.28**
SNP	6.825 ± 0.187
Acarbose		0.05 ± 0.003
AG			282.81 ± 8.52
Quercetin				3.71 ± 0.29

Each value represents the mean ± SD (n = 3).

^a Percentage of NO released relative to a theoretical maximum release of 1 mol NO/mol of test compound; determined by Griess reagent in the presence of 5 mM l-cysteine, at pH 7.4.

^b The concentration required for a 50% inhibition in the optical density of PNP (p-nitrophenol) at 405 nm relative to DMSO. IC₅₀ values were calculated from the dose inhibition curve.

^c The concentration required for a 50% inhibition of the fluorescence intensity of AGE relative to 0.1% DMSO, IC₅₀ values were calculated from the dose inhibition curve.

^d The concentration required for a 50% inhibition of the decrease in the optical density of NADPH at 340 nm relative to DMSO. IC₅₀ values were calculated from the dose inhibition curve.

** p < .01 significantly different ANOVA followed by Dunnett’s t-test for comparison with standard.

Figure 1. Acute effect of compounds 3c, 3e, and 7c on blood glucose levels in STZ-diabetics mice. Each value is the mean ± SEM for six mice in each group. *p < .05 significantly different ANOVA followed by Dunnett’s t-test for comparison with respect to initial levels in each group.

Table 2. Acute effect of compounds 3c, 3e, and 7c on blood glucose levels in STZ-diabetics mice.

Test samples	Blood glucose concentration (mM)
	Dose (per os) mg/kg of bw	0 h	1.5 h	3 h	5 h	7 h	9 h
Control (vehicle)	–	20.3 ± 10.1	19.0 ± 5.6 (–6.16)	18.2 ± 5.2 (–10.36)	16.4 ± 6.4 (–19.00)	11.5 ± 5.5 (–43.17)	11.5 ± 6.4 (–43.17)
Glibenclamide	10	20.2 ± 5.4	11.6 ± 4.9 (–42.63)	7.6 ± 3.9* (–62.32)	6.1 ± 3.6* (–69.58)	5.7 ± 3.6* (–71.84)	5.6 ± 3.6* (–72.11)
Pterostilbene	40	17.2 ± 7.0	12.1 ± 6.4 (–29.91)	10.2 ± 6.2* (–40.89)	8.4 ± 5.6* (–51.42)	7.7 ± 5.3* (–55.36)	6.9 ± 4.3* (–59.82)
Resveratrol	40	20.0 ± 2.6	16.3 ± 2.9 (–18.42)	14.0 ± 2.0 (–29.83)	12.4 ± 2.1 (–38.08)	11.2 ± 1.8 (–44.25)	10.7 ± 1.4* (–46.33)
3c	10	22.6 ± 7.0	18.1 ± 7.3 (–20.13)	17.0 ± 6.6 (–24.78)	16.8 ± 6.1 (–25.66)	15.7 ± 4.3 (–30.53)	13.2 ± 3.5 (–41.59)
3c	40	21.7 ± 5.7	17.2 ± 5.6 (–20.74)	16.3 ± 7.5 (–25.04)	15.7 ± 6.4 (–27.57)	14.3 ± 9.6 (–34.02)	9.9 ± 4.6* (–54.30)
3c	100	18.6 ± 1.9	15.9 ± 3.6 (–14.34)	15.2 ± 3.0 (–18.28)	15.1 ± 3.7 (–19.00)	13.4 ± 4.7 (–28.23)	11.1 ± 3.0 (–40.32)
3e	10	21.8 ± 6.3	18.8 ± 5.2 (–13.84)	17.8 ± 4.8 (–18.35)	18.6 ± 7.3 (–14.53)	15.6 ± 6.0 (–28.59)	11.5 ± 4.4* (–47.48)
3e	40	20.8 ± 7.6	16.9 ± 5.6 (–18.67)	16.5 ± 9.1 (–20.83)	15.0 ± 8.7 (–28.04)	13.3 ± 9.4 (–36.22)	11.0 ± 8.0 (–47.20)
3e	100	22.5 ± 5.6	15.7 ± 7.7 (–30.37)	16.0 ± 6.8 (–29.04)	15.4 ± 9.6 (–31.78)	12.9 ± 6.4 (–42.81)	10.9 ± 4.5 (–51.48)
7c	10	22.0 ± 5.2	17.0 ± 7.4 (–22.65)	16.9 ± 10.6 (–23.18)	16.1 ± 7.7 (–26.82)	15.7 ± 8.3 (–28.56)	13.3 ± 5.7 (–39.70)
7c	40	20.1 ± 1.9	13.2 ± 2.8 (–34.33)	11.0 ± 3.6* (–45.11)	8.7 ± 2.5* (–56.80)	8.2 ± 1.8* (–59.37)	7.1 ± 1.2* (–64.76)
7c	100	20.2 ± 2.0	13.7 ± 4.0 (–32.43)	11.1 ± 3.0* (–44.88)	9.9 ± 2.5* (–50.83)	8.2 ± 1.9* (–59.49)	6.9 ± 1.4* (–66.01)

Each value is the mean ± SEM for six mice in each group.

* p < .05 significantly different ANOVA followed by Dunnett’s t-test for comparison with respect to initial levels in each group.

% Variation of glycaemia is in parentheses.

Table 3. The amount and order of each reactant of α-glucosidase inhibition test.

Reagents	Volume (μL)
	Blank group	Control group	Sample blank group	Sample group
PBS	20	10	20	10
Compounds/Inhibitors	0	0	10	10
PNPG	20	20	20	20
Water	10	10	0	0
Mix well and incubate at 37 °C for 10 minutes
α-Glucosidase	0	10	0	10
Mix well and react at 37 °C for 20 minutes
Na2CO3	70	70	70	70