Presenting Author University of Delhi South Campus
Background: Hypertension, which is described as chronically increased blood pressure above 140/90 mmHg, has emerged as a starring cause of mortality and morbidity worldwide. It is a leading risk factor for major cardiovascular events (such as heart attack and stroke), chronic kidney disease, heart failure, cognitive impairment and dementia. The dire consequences of uncontrolled hypertension indicate that controlling it will have a direct preventive effect on the vital organs. Despite the availability of a large number of classical anti-hypertensive drugs it still affects humans adversely and poses a global disease burden thus necessitating new drugs. A non-conventional target whose inhibition can regulate hypertension is Dopamine βeta hydroxylase (DBH). This enzyme, which plays a significant role in the catecholamine biosynthetic pathway, utilizes the body’s blood pressure (BP) lowering mechanism and thus can combat resistant hypertension.
Methodology: In the study, we have screened thousands of small molecules against the active site of DBH (PDB ID:4ZEL). Hits identified in silico were assessed for their inhibitory potential and strength of binding (Kd) in vitro. The ex vivo toxicity parameters were evaluated to get rid of toxic molecules before going for in vivostudies. Selected leads were screened in spontaneously hypertensive rats (SHRs) to evaluate their efficacy in reducing blood pressure as well as their ability to improve other cardiac parameters. Thereafter, acute as well as genotoxicity study was performed to minimize the rate of attrition in later phases of clinical development.
Results: Our best lead molecule “BPM4” inhibited DBH efficiently with an IC50 value of 18 μM and dissociation constant of 22 nM. BPM4 when administered through IP at a dose of 10 mg/kg BW significantly reduced BP with a p-value of 0.001 as compared to the untreated group. Additionally, a significant reduction was observed in IVSs, IVSd, LVPWs and LVPWd, whereas increment was observed in internal diameter in the case of end systole and diastole (LVIDs and LVIDd). A high oral lethal dose (LD50) gt; 2000 mg/kg was observed in the acute toxicity test. Ames test showed no positive mutagenic effect +-S9. No statistically significant decrease in % mitotic index nor any aberrant cells were observed in lymphocytes and bone marrow of rodents.
Conclusion: BPM4 (at 10 mg/kg BW) statistically reduced the BP as well as improved the left ventricular hypertrophy parameters in SHRS. The area of fibrosis was also decreased post treatment (cardiac fibrosis disrupts the normal myocardial structure and has a direct impact on heart function and survival). Subsequently, the compound successfully passed the three battery genotoxicity tests as it did not cause any structural damage to DNA nor did it induce any ploidy changes, holds scope for being a potent anti-hypertensive drug candidate.
