Natural Potent NAAA Inhibitor Atractylodin Counteracts LPS-Induced Microglial Activation

Abstract

N-acylethanolamine-hydrolyzing acid amidase (NAAA) is a lysosomal enzyme that inhibits the degradation of palmitoylethanolamide (PEA), an endogenous lipid that induces analgesic, anti-inflammation, and anti-multiple sclerosis through PPARa activation. Only a few potent NAAA inhibitors have been reported to date, which is mainly due to the restricted substrate-binding site of NAAA. Here, we established a high-throughput fluorescence-based assay for NAAA inhibitor screening. Several new classes of NAAA inhibitors were discovered from a small library of natural products. One of these is atractylodin, a polyethylene alkyne compound from the root of Atractylodes lancea (Thunb) DC., which significantly inhibits NAAA activity and has an IC 50 of 2.81 µM. Kinetic analyses and dialysis assays suggested that atractylodin engages in competitive inhibition via reversible reaction to the enzyme. Docking assays revealed that atractylodin occupies the catalytic cavity of NAAA, where the atractylodin furan head group has a hydrophobic-related interaction with the backbone of the Trp181 and Leu152 residues of human NAAA. Further investigation indicated that atractylodin significantly increases PEA and OEA levels and dose-dependently inhibits LPS-induced nitrate, TNF-a, IL-1b, and IL-6 pro-inflammatory cytokine release in BV-2 microglia. Our results show that atractylodin elevates cellular PEA levels and inhibits microglial activation by inhibiting NAAA activity, which in turn could contribute to NAAA functional research.

Palmitoylethanolamide: A Nutritional Approach to Keep Neuroinflammation within Physiological Boundaries—A Systematic Review

“…In line with this view, inhibition of PEA catabolic enzyme in experimental systemic inflammation results in a significant elevation in the endogenous PEA levels in the brain and an associated decrease of brain inflammatory mediators [ 69 ]. Likewise, increasing the levels of PEA in LPS-challenged microglial cells through the inhibition of its hydrolysis significantly reduces microglial activation [ 70 ]. On the other hand, administration of PEA significantly relieves neuroinflammatory-associated disorders [ 32 ], and counteracts neuroinflammation at the cellular level, provided the compound is formulated in bioavailable forms [ 71 ].…”

Micronized Palmitoylethanolamide Ameliorates Methionine- and Choline-Deficient Diet–Induced Nonalcoholic Steatohepatitis via Inhibiting Inflammation and Restoring Autophagy

“…As an endogenous bioactive lipid, PEA can be degraded by NAAA and FAAH (Piomelli et al, 2020;Rankin and Fowler, 2020). Thus, increasing intracellular PEA accumulation through pharmacological inhibition of NAAA or FAAH could also be an efficient therapy in the modulation of various diseases (Wortley et al, 2017;Yang et al, 2020). Our previous reports have indicated that NAAA is an excellent target for anti-inflammatory and analgesic therapy (Yang et al, 2015;Jin W. et al, 2020).…”

Atrachinenynes A–D, four diacetylenic derivatives with unprecedented skeletons from the rhizomes of Atractylodes chinensis

“…[15][16][17][18] Among them, atractylodin, a major diacetylene in A. chinensis, may be considered as a marker to distinguish other species in the Atractylodes genus 19 and showed a variety of biological activities such as anti-cholangiocarcinoma, anti-inflammatory, insecticidal, and repellent activities. [20][21][22][23] In our previous investigations of A. chinensis, three bioactive meroterpenoids with novel C 27 skeletons were identified from the rhizomes of A. chinensis. 24 Our ongoing efforts on the phytochemical investigations of A. chinensis led to the discovery of four diacetylenic derivatives with three novel scaffolds, named atrachinenynes A-D (1-4) (Fig.…”

“…15–18 Among them, atractylodin, a major diacetylene in A. chinensis , may be considered as a marker to distinguish other species in the Atractylodes genus 19 and showed a variety of biological activities such as anti-cholangiocarcinoma, anti-inflammatory, insecticidal, and repellent activities. 20–23…”