Synthesis of carvacrol derivatives and their potential as cardioprotective agents against doxorubicin-induces cardiotoxicity

Abstract

Cancer, a pervasive global threat, is killing millions of people each year, with over 10 million deaths in 2020. While cancer treatments have advanced over time, chemotherapy patients are at risk of developing cardiovascular disease due to the cardiotoxic effects of certain drugs, including doxorubicin (DOX). Carvacrol (CA) with an IUPAC name 5-isopropyl-2-methylphenol is a phenolic monoterpene known for its pharmacological benefits, particularly cardioprotective properties. Concurrently, phenolic acids (PA) have shown promising effects against DOX-induced cardiotoxicity (DIC). Thorough research on carvacrol phenolic acid hybrids (CPAH) in this present study is expected to supplement the potential drug candidates for combating the alarming DIC. Twenty-one CPAHs (1–21) were synthesized with moderate to high yield by covalently linking the scaffolds of CA and PA via acyl or alkyl linkers. The structures of CPAHs were characterized using nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS). Subsequently, the CPAH’s cardioprotective potential against DOX-induced H9c2 cell death was explored via MTT cell viability assay. The cardiomyocytes H9c2 cell viability was significantly reduced in the presence of 3 μM and 10 μM DOX. In contrast, the CPAHs and their parent compounds were non-toxic to cardiomyocytes. Interestingly, at 0.01 μg/mL, 1–6 protected H9c2 cells during DIC, better than CA and 3,4-dihydroxybenzoic acid; therefore, revealed that the CPAHs from the hybrids of CA and hydroxylated-benzoic acid demonstrated notable cardioprotective activity. The cardioprotective activity essentially necessitates the presence of a hydroxy group on the benzoic acid moiety of PA; however, the numbers and/or positions of substituted hydroxy groups on PA do not show any significant changes in its potency. Meanwhile, the CPAHs derived from CA and cinnamic acid analogs (7–10) revealed only 8, with p-hydroxycinnamic acid moiety, demonstrated positive cardioprotective activity at 0.01 μg/mL concentration against DOX-induced H9c2 cell damages. It was notable that diminishing the hydroxy group, replacing the hydroxy group with a chloro group, or substituting an additional hydroxy group on the cinnamic ring were proven to decrease the activity. Therefore, the presence of only one hydroxy substituent is vital for the protective effect of CPAH against DOX-induced cell death. Furthermore, the effect of different types of linkers (11–15) and an introduction of CH2OH group at the para position of CA (16–21) were explored. It is revealed that only 15 (10 μM), with an ether linkage containing four carbons possessed an optimal cardioprotective efficacy based on a notable increase in the percentage of viable cells compared to the DOX group (p<0.05). Conversely, 16–21, failed to attenuate DOX-induced cell damage based on notable toxicity, as evidenced by the reduced cell viability compared to the DOX-treated group. This suggested that the presence of CA represented as the pharmacophore scaffold with the most optimal SAR for cardioprotective activity. In conclusion, the synthesis of CPAHs introduces new chemical entities with potential cardioprotection against DIC and potentially improves the quality of life for cancer survivors.