The activation of microglial NADPH oxidase (NOX2) induced by α-synuclein has been implicated in Parkinson's disease (PD) and other synucleinopathies. However, how α-synuclein activates NOX2 remains unclear. Previous study revealed that both toll-like receptor 2 (TLR2) and integrin play important roles in α-synuclein-induced microglial activation. In this study, we found that blocking CD11b, the α chain of integrin αMβ2, but not TLR2 attenuated α-synuclein-induced NOX2 activation in microglia. The involvement of CD11b in α-synuclein-induced activation of NOX2 was further confirmed in CD11b-/- microglia by showing reduced membrane translocation of NOX2 cytosolic subunit p47phox and superoxide production. Mechanistically, α-synuclein bound to CD11b and subsequently activated Rho signaling pathway. α-Synuclein induced activation of RhoA and downstream ROCK but not Rac1 in a CD11b-dependent manner. Moreover, siRNA-mediated knockdown of RhoA impeded NOX2 activation in response to α-synuclein. Furthermore, we found that inhibition of NOX2 failed to interfere with the activation of RhoA signaling and interactions between α-synuclein and CD11b, further confirming that NOX2 was the downstream target of CD11b. Finally, we found that genetic deletion of CD11b abrogated α-synuclein-induced NOX2 activatoin in vivo. Taken together, our results indicated that integrin CD11b mediates α-synuclein-induced NOX2 activation through a RhoA-dependent pathway, providing not only a novel mechanistic insight but also a new potential therapeutic target for synucleinopathies.

Nine new sesquiterpenoids (1-9), five new polyacetylenes (10-14), and six known compounds were isolated from the rhizomes of Atractylodes lancea. These new chemical structures were established using NMR, MS, and ECD data. Notably, compounds 3-5, the aglycone of which possesses two stereogenic centers (C-5 and C-7), exhibited similar ECD spectra to compounds 1 and 2, the aglycone of which possesses one stereogenic center (C-7). Such a difference was supported by the experimental and calculated ECD data and single-crystallographic analyses of 3a. In addition, compound 3 inhibited lipopolysaccharide-induced NO production in BV2 cells with an IC50 value of 11.39 μM (positive control curcumin, IC50 = 4.77 μM); compound 4 showed better hepatoprotective activity against N-acetyl-p-aminophenol-induced HepG2 cell injury than the positive drug (bicyclol) at a concentration of 10 μM (p < 0.001).

A cultured endophytic fungus, Guignardia mangiferae, isolated from the toxic plant Gelsemium elegans yielded five new sesquiterpenes (1−5), two new polyketones (6 and 7), and two known terpene polyketones (8 and 9). Their structures were elucidated using spectroscopic methods. On the basis of circular dichroism, the absolute configurations of the new compounds were determined. Compounds 1, 3, 4, and 9 inhibited lipopolysaccharide-induced NO production in BV2 cells with IC 50 values of 15.2, 6.4, 4.2, and 4.5 μM, respectively (positive control curcumin, IC 50 = 3.9 μM). M icroglia are a type of glial cell that are the resident macrophages of the central nervous system (CNS). Activation of microglia plays a critical role in the neural inflammatory process by releasing a variety of inflammatory mediators including nitric oxide (NO). 1,2 Thus, secondary metabolites that inhibit NO production may have antineuroinflammatory effects.Gelsemium elegans Benth., historically used in traditional Chinese medicine as an analgesic and antispasmodic and as a remedy for certain kinds of skin ulcers, 3 can be lethal to humans and livestock due to its toxic alkaloid content. 4 We have previously discovered some bisindole alkaloids with potential antineuroinflammatory activity by suppressing lipopolysaccharide (LPS)-induced NO production in BV2 microglial cells from G. elegans. 2 We have continued this research program on the discovery of bioactive secondary metabolites with NO production inhibition from endophytic fungi associated with the toxic plant G. elegans.Guignardia mangiferae is an endophytic fungus isolated from the leaves of G. elegans. A series of bioactive secondary metabolites including the cytotoxic tricycloalternarenes, 5,6 the cytotoxic vermistatin derivatives, 7 and the phytotoxic dioxolanone-type secondary metabolites 8 have been reported from Guignardia fungi. In our study, five new eremophilane sesquiterpenes named guignarderemophilanes A−E (1−5), two new benzyl derivatives named guignardene A (6) and guignarlactone A (7), and two known metabolites (8 and 9) were isolated from G. mangiferae. The compounds obtained were assayed for their inhibitory activity on NO production. Compounds 1, 3, 4, and 9 inhibited LPS-induced NO production in BV2 cells with IC 50 values of 15.2, 6.4, 4.2, and 4.5 μM, respectively (positive control curcumin, IC 50 = 3.9 μM). None of the compounds were active against the HCT-8, HCT-116, Bel-7402, BGC-823, A549, and A2780 cell lines. Herein, we report the structural elucidation and bioactivity of 1−9. ■ RESULTS AND DISCUSSIONThe fungus G. mangiferae was cultured in potato dextrose agar (PDA) medium (100 L). The filtrate of the culture was loaded onto a macroporous resin column and eluted with water and 95% alcohol, respectively. The alcohol elution, after concentration, was fractionated by chromatography, and compounds were purified by preparative HPLC, to afford compounds 1−9.

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