Carvacrol Protect Hippocampal Neurons Against Hydroxychloroquine-induced Damage: in vitro Study

Abstract

The use of hydroxychloroquine, an antimalarial drug, in the treatment of Covid-19 disease, which has turned into a worldwide epidemic, was initially viewed positively. However, the lack of evidence for its use in treatment and even neuronal side effects caused hydroxychloroquine to be approached with suspicion. Carvacrol, on the other hand, is a very interesting ingredient with its anti-oxidant, anti-inflammatory, and anti-cancer properties. Primary neuron culture was prepared for our study. Carvacrol (10, 25, 50, and 100 mg/L), hydroxychloroquine (10,20,40, and 80µM), hydroxychloroquine+carvacrol groups (10µM+10mg/L, 20µM+25mg/L, 40µM+50mg/L, 80µM+100mg/L) were applied to neuron culture for 24 and 48 hours. After the application, results were obtained with MTT, TAS, TOS, Thiol analyses, and acetylcholinesterase (AChE), butyrylcholinesterase (BChE) activities. According to our MTT results, carvacrol (100mg/mL) increased neuronal viability by ~10% in the combined group compared to pure hydroxychloroquine (80µM). The same dose of carvacrol reduced the antioxidant level 1.3 times. Doses of carvacrol alone did not affect thiol levels but increased in combination with hydroxychloroquine(431µmol/L). It is now known that Covid-19 is associated with neurodegenerative diseases. Recent studies have shown that hydroxychloroquine, which is seen as a hope for the global epidemic, causes oxidative stress on neurons. In our study, we designed to both provide protection and prevent the occurrence of side effects by using carvacrol against the neurodegenerative effects of hydroxychloroquine.