ABC | Volume 114, Nº6, June 2020

Original Article Yurre et al. Evaluation of the cardiac effects of WSMoL Arq Bras Cardiol. 2020; 114(6):1029-1037 Results The 21-day treatment withWSMoL did not induce changes (p > 0.05) in blood glucose levels (Figure 1A) or body weight (Figure 1B) in comparison with CNTRL group. In addition, the HW/BW (Figure 1C) and HW/TL (Figure 1D) ratios were similar (p > 0.05) in both groups, indicating that no cardiac hypertrophy was developed. The treatment also did not modify glucose tolerance (Figure 1E) or insulin resistance (Figure 1F) in comparison with untreated mice (p > 0.05), revealing absence of alterations in carbohydrate metabolism. Figure 2 shows the ECG parameters at day 21 of treatment. The PR, RR, QRS, and QJ intervals (Figure 2C–F) were not significantly different (p > 0.05) between the WSMoL and CNTRL groups. The APD 30 and APD 90 were similar (p > 0.05) between untreated and treated mice (Figure 2G–J). Thus, the data obtained here consistently demonstrated that WSMoL treatment was safe for the electrical behavior of mouse heart. Since some antibiotics have been shown to be able to impair left ventricular function and structure, we studied the left ventricular function in detail by ECHO (Figure 3). The mice from both CNTRL and WSMoL groups showed preserved left ventricular structure and function, as indicated by the absence of significant differences (p > 0.05) in the following parameters: ejection fraction (Figure 3A), fractional area change (Figure 3B), stroke volume (Figure 3C), end-diastolic volume (Figure 3D), end-systolic volume (Figure 3E), and left ventricular mass (Figure 3F). Taken together, these data show that WSMoL treatment did not impair left ventricular function. Finally, in order to verify whether WSMoL interferes in the physiology of heart mitochondrial function, we performed experimental approaches to analyze two important mitochondrial functions: oxidative phosphorylation and reactive oxygen species production. The 21-day treatment with WSMoL did not induce alterations in the mitochondrial oxygen consumption, as can be observed in Figure 4A–E. In addition, the treatment did not interfere in the rate of H 2 O 2 production in the presence of different substrates, inhibitors, and uncouplers (Figure 4F), nor did it alter electron leakage (Figure 4G) when compared to the CNTRL group. Discussion The high toxicity of some drugs currently used for treatment of several diseases is a major concern in health systems. For example, several classes of antibiotics are cardiotoxic. 18-20 In this scenario, natural compounds have been increasingly studied due to their potential for drug discovery and development. 36 However, it is also important to evaluate the safety of natural compounds used for food and medical purposes. Previous studies by our group demonstrated the antibacterial and immunomodulatory activities of WSMoL, 8-10 which is also a coagulant protein from M. oleifera seeds. In this study, we evaluated possible cardiotoxic effects of orally administrated WSMoL on mice. Safety studies are imperative, even when lectins are administered orally, since it has been reported that some proteins of this class can cross the intestinal barrier and be found systemically. 37 Figure 1 – WSMoL treatment for 21 days did not induce metabolic alterations. (A) Blood glucose levels after 21 days of treatment with saline (CNTRL) or WSMoL(WSMoL) solution (CNTRL n = 14 mice and WSMoL n = 11 mice), (B) body weight of CNTRL and WSMoL groups (CNTRL n = 14 mice and WSMoL n = 11 mice), (C) heart weight/ body weight ratio (CNTRL n = 8 mice and WSMoL n = 7 mice) and (D) heart weight/tibia length ratio, showing that the treatment with 5mg/kg body weight of WSMoL preserves cardiac structure (CNTRL n = 8 mice and WSMoL n = 7 mice), (D) intraperitoneal glucose tolerance test and (E) intraperitoneal insulin tolerance test with their correspondentAUC graphs on inset (CNTRL n = 9 mice and WSMoL n = 7 mice). Each dot represents individual values and lines represent mean values. ○: CNTRL mice; ●: WSMoL mice. Comparisons between groups were performed using unpaired Student’s t test. The results are shown as mean ± SD. CNTRL WsMoL CNTRL WsMoL CNTRL WsMoL CNTRL WsMoL CNTRL Time (minutes) Blood glucose levels (mg/dL) Blood glucose levels (mg/dL) Body weight (g) HW/BW (mg/g) HW/TL (mg/g) Blood glucose levels (mg/dL) AUC AUC Time (minutes) WsMoL CNTRL WsMoL 150 50 0 100 40 20 10 0 60000 40000 20000 0 30000 400 300 200 100 50 100 150 0 150 50 100 0 0 50 100 150 0 20000 10000 0 30 10 4 2 0 8 6 10 4 2 0 8 6 A C D B E F 1032