Carvacrol/thymol derivatives as highly selective BuChE inhibitors with anti-inflammatory activities: Discovery and bio-evaluation

In this study, nine novel carvacrol/thymol derivatives incorporating carbamate groups were designed, synthesized, and evaluated as multifunctional anti-AD agents. These derivatives displayed superior BuChE inhibitory and anti-inflammatory characteristics compared to the parent compounds. While the derivatives exhibited AChE IC₅₀ values exceeding the detectable limit (>100 μM), they demonstrated high potency as BuChE inhibitors, with IC₅₀ values ranging from 0.05 to 9.62 μM. In an inflammation model of BV2 microglial cells induced by lipopolysaccharide (LPS), the derivatives effectively reduced the levels of the pro-inflammatory cytokine interleukin-1β (IL1β), with inhibition rates of IL1β exceeding 50 % at 10 μM. Notably, compound SXF3 ‌attained the highest BuChE inhibition efficacy (eqBuChE IC₅₀ = 0.05 ± 0.003 μM, hBuChE IC₅₀ = 0.04 ± 0.001 μM), the highest selectivity for BuChE (with a selectivity index, SI, exceeding 2000, calculated as the ratio of eeAChE IC₅₀ to eqBuChE IC₅₀) and high anti-inflammatory activity (inhibition of IL1β, IC₅₀ = 8.33 ± 0.08 μM). In a scopolamine-induced AD mouse model, SXF3 (15 mg/kg) significantly reduced the latency to the platform and attenuated memory deficits. Biochemical analysis confirmed that SXF3 significantly increased acetylcholine (ACh) levels in the mice hippocampus, primarily due to the inhibition of BuChE rather than AChE, and that SXF3 significantly reduced IL1β levels to normal, further confirming its anti-inflammatory activities. Hence, the selective BuChE inhibitory properties and anti-inflammatory attributes of SXF3 render it a promising candidate for further investigation in the treatment of AD.

Alzheimer's disease; Butyrylcholinesterase; Carvacrol; Inflammation; Thymol.