**4. Results and discussion**

The model of alloxan-induced diabetes has produced alterations in the activity of the three enzymes [55–57] involved in glucose metabolism homeostasis (**Figure 3**).

Moreover, the lipid profile was altered by the administration of the pancreatic toxic, registering statistically significant increases in total cholesterol, LDL cholesterol, and triglycerides, together with decreases in HDL cholesterol (**Figure 4**).

**Figure 3.** Variations of the activity of the enzymes involved in glucose metabolism in diabetic animals compared to nondiabetic animals.

**Figure 4.** Variation of plasma lipids in diabetic animals compared to nondiabetic animals \*\* p<0.01; \*\*\* p<0.001.

To what concern the effect of new compounds with possible affinity for beta-3 adrenergic receptors, seven of those (A1-βPhEA, 20 mg/kg weight; A3-βPhEA, 100 mg/kg weight; A4 βPhEA, 100 mg/kg weight; A6-βPhEA, 100 mg/kg weight; A8-βPhEA, 100 mg/kg weight; A9-


βPhEA, 100 mg/kg weight; A13-βPhEA, 100 mg/kg weight) have markedly reduced the values of total cholesterol (**Table 2**, **Figure 5**).

**Table 2.** The effect of new derivatives of beta-phenylethylamine on total cholesterol in rats with alloxan-induced diabetes \* p<0.05; \*\* p<0.01; \*\*\* p<0.001.

**Figure 3.** Variations of the activity of the enzymes involved in glucose metabolism in diabetic animals compared to

**Figure 4.** Variation of plasma lipids in diabetic animals compared to nondiabetic animals \*\* p<0.01; \*\*\* p<0.001.

To what concern the effect of new compounds with possible affinity for beta-3 adrenergic receptors, seven of those (A1-βPhEA, 20 mg/kg weight; A3-βPhEA, 100 mg/kg weight; A4 βPhEA, 100 mg/kg weight; A6-βPhEA, 100 mg/kg weight; A8-βPhEA, 100 mg/kg weight; A9-

nondiabetic animals.

228 Adiposity - Epidemiology and Treatment Modalities

**Figure 5.** Alterations of total cholesterol in diabetic animals treated with reference substance (BRL 37344) or newly synthesized derivatives of beta-phenyl ethylamine compared to diabetic control group \* p<0.05; \*\* p<0.01; \*\*\* p<0.001.

The majority of the tested compounds (**Table 3**) have markedly reduced the values of LDL cholesterol (**Figure 6**), the effect probably due to increased plasma clearance for this lipid fraction as total cholesterol serum concentration decreased. Smaller reductions, still statistically significant (**Table 3**) in values of LDL cholesterol, and comparable to those of the beta-3adrenergic agonist, BRL 37344, were produced by the compounds: A7-βPhEA, A10 βPhEA, A12-βPhEA, and A13-βPhEA (**Figure 6**).


**Table 3.** The effect of new derivatives of beta-phenylethylamine on LDL cholesterol values in alloxan-induced diabetic rats \*\* p<0.01; \*\*\* p<0.001.

**Figure 6.** Alterations of LDL cholesterol values in diabetic animals treated with reference substance (BRL 37344) or new derivatives of beta-phenylethylamine compared to diabetic control group \*\* p<0.01; \*\*\* p<0.001.

The results for lowered total cholesterol and LDL cholesterol are in line with other literature data showing that several beta-3adrenergic agonists have induced similar effects in mice with apolipoprotein E deficiency and in wild C57BL/6J strain animals. For such substances an increase in apolipoprotein A1 and PPARα and PPARγ receptors (peroxisome proliferatoractivated receptor) expression in liver was demonstrated [58].

The majority of the tested compounds (**Table 3**) have markedly reduced the values of LDL cholesterol (**Figure 6**), the effect probably due to increased plasma clearance for this lipid fraction as total cholesterol serum concentration decreased. Smaller reductions, still statistically significant (**Table 3**) in values of LDL cholesterol, and comparable to those of the beta-3adrenergic agonist, BRL 37344, were produced by the compounds: A7-βPhEA, A10-

**control** 

**Table 3.** The effect of new derivatives of beta-phenylethylamine on LDL cholesterol values in alloxan-induced diabetic

**Figure 6.** Alterations of LDL cholesterol values in diabetic animals treated with reference substance (BRL 37344) or

new derivatives of beta-phenylethylamine compared to diabetic control group \*\* p<0.01; \*\*\* p<0.001.

Nondiabetic control 51.07 ± 3.610 <0.0001\*\*\* <0.0001\*\*\* \*\*\*

BRL 37344 50 mg/kg 78.71 ± 4.940 ns \*\* A1-βPhEA 20 mg/kg 56.87 ± 1.887 ns \*\*\* A2-βPhEA 50 mg/kg 57.47 ± 2.831 ns \*\*\* A3-βPhEA 100 mg/kg 50.91 ± 1.205 ns \*\*\* A4-βPhEA 100 mg/kg 57.08 ± 2.302 ns \*\*\* A5-βPhEA 100 mg/kg 56.26 ± 2.134 ns \*\*\* A6-βPhEA 100 mg/kg 56.88 ± 2.496 ns \*\*\* A7-βPhEA 100 mg/kg 75.91 ± 6.447 \*\* \*\*\* A8-βPhEA 100 mg/kg 54.62 ± 2.458 ns \*\*\* A9-βPhEA 100 mg/kg 53.70 ± 2.128 ns \*\*\* A10-βPhEA 100 mg/kg 76.00 ± 7.567 \*\* \*\*\* A11-βPhEA 100 mg/kg 57.52 ± 3.112 ns \*\*\* A12-βPhEA 100 mg/kg 66.77 ± 7.334 ns \*\*\* A13-βPhEA 100 mg/kg 50.21 ± 1.188 ns \*\*\*

**ANOVA Dunnett posttest/D control** 

βPhEA, A12-βPhEA, and A13-βPhEA (**Figure 6**).

230 Adiposity - Epidemiology and Treatment Modalities

Diabetic Control 103.2 ± 7.899 \*\*\*

rats \*\* p<0.01; \*\*\* p<0.001.

**Group M ± SE ANOVA Dunnett posttest/ND**

Other trials showed that, due to effects on lipid metabolism but also to glycemia reduction, the β3 adrenergic agonist BRL 37344 has induced a reduction in the process of formation of atherosclerotic plaque in ApoE(-/-) mice [59].

A pivotal role in slowing down the process of atherosclerosis stands with HDL cholesterol, which is a small size alpha-lipoprotein, formed in liver or shed from chylomicrons dismemberment. These lipoproteins have a cholesterol-rich core with type 1 and 2 apolipoproteins at the surface, ensuring the reverse transport of cholesterol, from tissues to liver. The trial conducted by Shi et al. demonstrated the increases in mARN and apoA1 expression.


**Table 4.** The effect of new derivatives of beta-phenyl ethylamine on HDL cholesterol in rats with alloxan-induced diabetes \* p<0.05; \*\*\* p<0.001.

The results of the experimental research have shown that all tested compounds have induced statistically significant increases in HDL cholesterol, compared to diabetic control group (**Table 4**). A smaller effect of increase of the values for this lipid fraction was produced by the compounds A11-βPhEA and A12-βPhEA, still being similar to the one for beta3 adrenergic agonist BRL 37344 (**Figure 7**).

**Figure 7.** Alteration of HDL cholesterol in diabetic animals treated with reference substance (BRL 37344) or with derivatives of beta-phenylethylamine compared to diabetic control group \* p<0.05; \*\*\* p<0.001.


**Table 5.** The effect of new derivatives of beta-phenyl ethylamine on serum TG in rats with alloxan-induced diabetes \*\*\* p<0.001.

In Wistar rats alloxan has induced a high increase, statistically significant, of serum triglycerides (TG) (**Table 5**). Compared to diabetic control group, all the tested compounds have reduced the values of serum triglycerides with high statistical significance. These effects could be due to increased expression [58] of PPARα (liver, kidney, muscle, adipose tissue) and PPAR γ receptors (subtypes 1, 2, 3 in adipose tissue) resulting in increased expression of the gene for lipoprotein lipase.

#### **4.1. Effects on body weight**

**Figure 7.** Alteration of HDL cholesterol in diabetic animals treated with reference substance (BRL 37344) or with deriv-

**ANOVA Dunnett posttest/D control** 

**control** 

**Table 5.** The effect of new derivatives of beta-phenyl ethylamine on serum TG in rats with alloxan-induced diabetes \*\*\*

In Wistar rats alloxan has induced a high increase, statistically significant, of serum triglycerides (TG) (**Table 5**). Compared to diabetic control group, all the tested compounds have reduced the values of serum triglycerides with high statistical significance. These effects could

atives of beta-phenylethylamine compared to diabetic control group \* p<0.05; \*\*\* p<0.001.

Nondiabetic control 81.74 ± 2.261 0.0002\*\*\* <0.0001\*\*\* \*\*\*

BRL 37344 50 mg/kg 77.13 ± 3.639 ns \*\*\* A1-βPhEA 20 mg/kg 91.25 ± 4.573 ns \*\*\* A2-βPhEA 50 mg/kg 88.01 ± 4.158 ns \*\*\* A3-βPhEA 100 mg/kg 90.23 ± 4.643 ns \*\*\* A4-βPhEA 100 mg/kg 67.38 ± 8.630 ns \*\*\* A5-βPhEA 100 mg/kg 66.32 ± 5.682 ns \*\*\* A6-βPhEA 100 mg/kg 66.58 ± 9.860 ns \*\*\* A7-βPhEA 100 mg/kg 80.60 ± 3.113 ns \*\*\* A8-βPhEA 100 mg/kg 84.24 ± 2.831 ns \*\*\* A9-βPhEA 100 mg/kg 87.80 ± 4.384 ns \*\*\* A10-βPhEA 100 mg/kg 86.21 ± 2.935 ns \*\*\* A11-βPhEA 100 mg/kg 87.86 ± 5.032 ns \*\*\* A12-βPhEA 100 mg/kg 84.35 ± 3.656 ns \*\*\* A13-βPhEA 100 mg/kg 91.25 ± 6.193 ns \*\*\*

**Group M ± SE ANOVA Dunnett posttest/ND**

Diabetic control 166.3 ± 6.793 \*\*\*

232 Adiposity - Epidemiology and Treatment Modalities

p<0.001.

During the research, animals had free access to standard food and water. The body weight was determined initially, at 48 hours after alloxan administration and then in day 5, 10, and 14 of the experiment. For nondiabetic control group the same determination were performed as in the case of diabetic groups. The food was dispensed daily in same amounts and body weight was determined before the next feeding.

Throughout this determination it was apparent that alloxan-induced diabetes produces, in 48 hours from administration, a statistically nonsignificant reduction (**Figure 8**) of body weight in treated animals (203.4 ± 0.7004 vs. 205.9 ± 0.7078).

**Figure 8.** Body weight of animals initially and at 48 hours after alloxan administration \*\*\* p<0.001.

The research results showed that, for diabetic control group, animal body weight increases after alloxan administration, reaching a significant higher value in day 14 of the experiment (*p* = 0.0097\*\*). For the groups treated with reference substance, the body weight varied statistically nonsignificantly in all moments of determination (**Table 6**). The amount of consumed food increased for the diabetic control group, while for the treated groups, it remained constant. In the determinations of day 14, for nondiabetic control group it was registered an increase of 1.07% in body weight against the initial measurement, while for the diabetic control group the increase reached 5.65%. The variation in body weight at the end of the experiment against initial and compared to diabetic control group was calculated using the formulas:


**Table 6.** The effect of new derivatives of beta-phenylethylamine on body weight in rats with alloxan-induced diabetes \*\* p<0.01.

New Potential Beta-3 Adrenergic Agonists with Beta-Phenylethylamine Structure, Synthesized for the Treatment... http://dx.doi.org/10.5772/65328 235

$$\text{Effect } \% \frac{\text{BW}}{\text{basal}} = \frac{\text{BW basall} \left(\text{g}\right) - \text{BW day} 14 \left(\text{g}\right)}{\text{BW basall} \left(\text{g}\right)} \times 100 \tag{1}$$

$$\begin{array}{l}\text{Effect }\% \text{ BW} \\ \text{Dialbeit} \end{array} \begin{array}{l}\text{Diabetic} \begin{array}{l}\text{control} \end{array} = \text{Effect }\% \text{ BW} \\ \text{Diabetic control} \end{array} + \begin{array}{l}\text{Effect }\% \text{ BW} \\ \text{Substance} \end{array} \tag{2}$$

Taking into account that body weight increased for the animals in diabetic control group and that for all tested substances it has decreased against initial, the effect of the tested substances was determined compared to diabetic control group (**Figure 9**). It was therefore noted that newly synthesized derivatives of beta-phenyl ethylamine and the reference substance BRL 37344 had produced decreases in body weight between 5.89 and 7.76%, compared to diabetic control animals after 14 days of treatment.

**Figure 9.** Variation of body weight for animals treated with reference substance and tested substances compared to diabetic control group at day 14 determination.

#### **5. Conclusions**

**Group Parameter Body weight**

234 Adiposity - Epidemiology and Treatment Modalities

ANOVA/48 h 0.7341 ns

ANOVA/48 h after A 0.0097\*\*

ANOVA/48 h after A 0.6778 ns

ANOVA/48 h after A 0.7823 ns

ANOVA/48 h after A 0.9238 ns

ANOVA/48 h after A 0.6202 ns

ANOVA/48 h after A 0.4047 ns

ANOVA/48 h after A 0.6717 ns

ANOVA/48 h after A 0.7505 ns

ANOVA/48 h after A 0.7213 ns

ANOVA/48 h after A 0.9261 ns

ANOVA/48 h after A 0.3638 ns

ANOVA/48 h after A 0.7431 ns

ANOVA/48 h after A 0.7922 ns

ANOVA/48 h after A 0.7561 ns

ANOVA/48 h after A 0.6257 ns

ns, nonsignificant; A, alloxan.

\*\* p<0.01.

**BRL 37344** **basal**

**Body weight 48 h after alloxan**

**ND control** M ± SE 203.8 ± 3.301 200.2 ± 4.176 204.3 ± 2.894 205.5 ± 2.766 206.0 ± 2.733

**D control** M ± SE 203.2 ± 3.429 197.0 ± 3.967 206.5 ± 2.363 209.7 ± 2.305 214.7 ± 1.382\*\*

**A1-βPhEA** M ± SE 202.5 ± 2.872 197.2 ± 3.640 201.7 ± 2.836 200.8 ± 3.114 199.8 ± 3.092

**A2-βPhEA** M ± SE 200.2 ± 3.781 195.5 ± 4.123 198.5 ± 3.667 198.7 ± 3.556 199.0 ± 3.540

**A3-βPhEA** M ± SE 208.0 ± 2.206 201.8 ± 3.936 206.0 ± 2.145 205.5 ± 2.247 205.0 ± 2.556

**A4-βPhEA** M ± SE 204.8 ± 2.701 199.5 ± 3.805 202.8 ± 2.651 203.2 ± 2.151 202.0 ± 3.088

**A5-βPhEA** M ± SE 207.2 ± 2.868 201.1 ± 4.083 206.0 ± 3.044 204.7 ± 2.552 206.7 ± 3.232

**A6-βPhEA** M ± SE 205.0 ± 2.966 199.1 ± 3.973 203.2 ± 2.868 202.5 ± 2.754 202.0 ± 2.781

**A7 -βPhEA** M ± SE 206.7 ± 2.552 201.1 ± 3.989 204.8 ± 2.358 204.2 ± 2.167 203.7 ± 2.290

**A8-βPhEA** M ± SE 204.8 ± 1.990 201.7 ± 3.802 203.5 ± 1.586 202.7 ± 1.926 203.7 ± 2.290

**A9 -βPhEA** M ± SE 208.2 ± 1.249 202.1 ± 3.667 205.5 ± 0.7638 204.7 ± 1.022 203.8 ± 1.558

**A10-βPhEA** M ± SE 206.3 ± 2.741 200.8 ± 4.036 205.0 ± 2.477 204.8 ± 2.587 204.0 ± 2.671

**A11-βPhEA** M ± SE 208.0 ± 3.066 202.2 ± 4.401 206.2 ± 2.738 205.8 ± 2.713 205.7 ± 2.813

**A12-βPhEA** M ± SE 207.3 ± 2.894 201.7 ± 4.234 205.7 ± 2.565 205.3 ± 2.603 204.5 ± 2.320

**A13-βPhEA** M ± SE 209.3 ± 2.591 203.0 ± 4.244 206.7 ± 2.028 206.7 ± 2.390 205.0 ± 2.266

**Table 6.** The effect of new derivatives of beta-phenylethylamine on body weight in rats with alloxan-induced diabetes

M ± SE 204.3 ± 2.963 198.7 ± 3.920 203.8 ± 2.868 202.7 ± 2.246 201.5 ± 2.513

**Body weight Day 5**

**Body weight Day 10**

**Body weight Day 14**

> The results of this experimental research have demonstrated that newly synthesized derivatives of beta-phenylethylamine produce marked biological activity over lipid profile which is altered in diabetes induced by alloxan administration in rats.

> All tested compounds have markedly decreased the values of total cholesterol, LDL cholesterol, and triglycerides, the effect being more intense than with reference substance BRL 37344. They also have increased the values of antiatherogenic HDL cholesterol, significantly more

than the reference substance. Overall, the activity on body weight was of reduction even if the food consumption of the animals was not altered. These experimental data suggest that the tested new chemical entities have high therapeutical potential in the treatment of dislipidemias and/or obesity.
