| Nerve growth factor(NGF) was first found and best known among the neurotrophic factors(NFs). NGF plays an important role in neuronal survival, growth, differentiation, maturation, and promotion of neurite outgrowth. NGF shows potential in the treatment of nervous system diseases that were caused by neuronal degeneration and injury. NGF, as a large protein, has the disadvantage of structural instability, short half-life, weak permeability to cross the blood brain barrier, so it can't be applied to cure nervous system diseases in the large scale. The researchers started to search for the neurotrophic molecules similar to NGF, or the active compounds that were associated with NGF. Rat pheochromocytoma(PC-12) cells response to NGF and serve as a model system for primary neuronal cells. There are two types of receptors on the membrane in PC-12 cells responsible to NGF, namely TrkA and p75 NTR receptors. NGF binds to TrkA receptor, activates several signaling pathways and influences the effects to promote or inhibit neurite outgrowth in NGF-mediated PC-12 cells.In the present study, we explored the neurotrophic activity of sixteen novel 19-OH acylated sarcodoninG analogues G-1~16 and striatoids A-F for the first time. In the absence of NGF, G-1~16 and striatoids A-F were unable to promote neurite outgrowth in PC-12 cells. G-5 showed the highest activity to promote neurite outgrowth and G-15 showed the strongest activity to inhibit neurite outgrowth in NGF-mediated PC-12 cells. Fluoro-substituted benzoyl analogues exhibited the stronger ability to influence neurite outgrowth in NGF-mediated PC-12 cells. Striatoids A-F dose-dependently enhanced NGF-mediated neurite outgrowth in PC-12 cells. The results indicated that the structure and concentration of compounds were related to the neurotrophic activity. In the presence of NGF, G-1~16 showed no cytotoxic activity against PC-12 cells at the concentrations ranging from 1?M to 10?M. However, striatoids A-F were cytotoxic to NGF-mediated PC-12 cells at the concentrations between 10?M and 40?M.The primary mechanism on neurotrophic action of G-5 and G-15 were investigated in NGF-mediated PC-12 cells using the methods described as western blot, treatment with specific inhibitors and determination the level of intracellular Ca2+. G-5 and G-15 regulated phosphorylation of tyrosine kinase A(TrkA), and inhibition of TrkA with pharmacological inhibitor K252 a effectively attenuated the neurite outgrowth induced by G-5 and G-15 in NGF-mediated PC-12 cells. The effects on neurite outgrowth of G-5 and G-15 were mediated by Ca2+ signaling in NGF-induced PC-12 cells. G-5 and G-15 regulated phosphorylation of protein kinase C-??(PKC-??) and extracellular signal-regulated protein kinase 1/2(ERK1/2). Consistent with activation of the two signaling molecules, neurite outgrowth induced by G-5 and G-15 was effectively attenuated by the MAPK/ERK kinase inhibitors PD98059 and U0126, and the protein kinase C inhibitors GF109203 X and Enzastaurin. G-5 and G-15 also induced phosphorylation of cAMP response element-binding protein(CREB) that was markedly attenuated by GF109203 X. Taken together, the results indicated that G-5 and G-15 induced neurite outgrowth in NGF-mediated PC-12 cells and suggested that regulation of intracellular Ca2+, activation of PKC and ERK signaling pathways may be involved in this process. Moreover, activation of CREB may play a crucial role for G-5, G-15-induced neurite outgrowth in NGF-mediated PC12 cells.One new meroterpenoid, named hericenone K(11), along with 10 known compounds(1–10), ergosterol peroxide(1), cerevisterol(2), 3b,5a,9a-trihydroxy-ergosta-7,22-dien-6-one(3), inoterpene A(4), astradoric acid C(5), betulin(6), oleanolic acid(7), ursolic acid(8), hemisceramide(9), and 3,4-dihydro-5-methoxy-2-methyl-2-(40-methyl-20-oxo-30-pentenyl)-9(7H)-oxo-2H-furo[3,4-h]benzopyran(10), was isolated from the fruiting bodies of the mushroom Hericium erinaceus. Their structures were characterized on the basis of spectroscopic methods, as well as through comparison with previously reported data. Compounds 3–6, 8, and 9 were isolated from Hericium species for the first time. Compounds 10 and 11 was suggested to be racemic by the CD spectrum data and specific rotations, which ware resolved by chiral HPLC into respective enantiomers. Compounds 1–3,(±)-10,(-)-10 and(+)-10 in the presence of NGF(20 ng/mL) exerted a significant increase in neurite-bearing cells.The methanol extract of the mycelium of the mushroom Hericium erinaceus showed to promote neurite outgrowth in NGF-mediated PC12 cells. Chemical studies of its methanol extract resulted in the isolation of two new compounds, 3-(hydroxymethyl)-2-furaldehyde(13) and 5-acetyl-1,6-dihydro-3-pyridinecarboxylic acid(17), together with six known compounds, 4-chloro-3,5-dimethoxybenzoic methyl ester(12), erinacine A(14), herierin III(15), herierin IV(16), erinacerin G(18), and uridine(19). The structures of new compounds 2 and 6 were characterized using HR-MS, 1D and 2D NMR spectroscopic data. 4-chloro-3,5-dimethoxy benzoic methyl ester(1) and erinacine A(3) were found not only to significantly enhance nerve growth factor(NGF)-mediated neurite outgrowth in PC12 cells but also to significantly prevent the death of NGF-differentiated PC12 cells after removal of NGF. 4-chloro-3,5-dimethoxy benzoic methyl ester(1) and erinacine A(3) were found to significantly enhance the level of phospho-TrkA(p-TrkA) in nerve growth factor(NGF)-mediated PC12 cells. In addition, erinacine A could stimulate neurite outgrowth in primary cultured rat cortex neurons. |
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