Synthesis, chiral chromatographic separation, and biological activities of the enantiomers of 10,10-dimethylhuperzine A

Rational design and synthesis of highly potent anti-acetylcholinesterase activity huperzine A derivatives

By targeting multi-active sites of acetylcholinesterase (AChE), a series of huperzine A (Hup A) derivatives with various aromatic ring groups were designed and synthesized by Schiff reaction. They were evaluated as AChE and butyrylcholinesterase (BChE) inhibitors. Results showed very significant specificity that the group of imine derivatives could inhibit TcAChE and hAChE, but no inhibitory effect on hBChE was detected. The experiment was explained by a docking study. In the docking model, we confirmed that aromatic ring of Hup A derivatives played the pi-pi stacking against aminophenol residues of AChE, and the structure-activity relationship (SAR) was discussed.

Huperzine A from Huperzia species--an ethnopharmacolgical review

Huperzine A (HupA), isolated originally from a traditional Chinese medicine Qiang Ceng Ta, whole plant of Huperzia serrata (Thunb. ex Murray) Trev., a member of the Huperziaceae family, has attracted intense attention since its marked anticholinesterase activity was discovered by Chinese scientists. Several members of the Huperziaceae (Huperzia and Phlegmariurus species) have been used as medicines in China for contusions, strains, swellings, schizophrenia, myasthenia gravis and organophosphate poisoning. HupA has been marketed in China as a new drug for Alzheimer's disease (AD) treatment and its derivative ZT-1 is being developed as anti-AD new drug candidate both in China and in Europe. A review of the chemistry, bioactivities, toxicology, clinical trials and natural resources of HupA source plants is presented.

Quantification of huperzine A in Huperzia serrata by HPLC-UV and identification of the major constituents in its alkaloid extracts by HPLC-DAD-MS-MS

A rapid, simple and reliable high performance liquid chromatography (HPLC) method has been established for the analysis of the major alkaloids in Huperzia serrata, a traditional Chinese medicine (TCM) herb. After chromatographic separation on a reversed-phase C18 column with methanol-ammonium acetate (pH 6.0; 80 mM, 30/70, v/v) as the mobile phase, nine alkaloid compounds in the alkaloid extracts of H. serrata were identified by online diode array detection-MS and by comparing with data from literature and standard samples. One compound in the extract, huperzine A, is a drug for treating Alzheimer's disease. Its content was quantified by HPLC coupled with UV-vis. The method was the validated. The recovery rates were 96.8-97.7% with R.S.D <2.44%. The intra- and inter-day precisions, expressed as R.S.D., ranged from 0.53% to 1.51%. Good linear regression was observed in the concentration range of 5-100 microg/ml (r = 0.9997). The results demonstrate that this method is simple, selective, and suitable for the quality control of this TCM herb.

Stereoselectivities of enantiomers of huperzine A in protection against beta-amyloid(25-35)-induced injury in PC12 and NG108-15 cells and cholinesterase inhibition in mice

Recently, the potent cholinesterase inhibitor (-)-huperzine A (HupA) was demonstrated to protect neuronal and glial cells against the cytotoxicity of beta-amyloid (Abeta). Since the unnatural (+)-HupA is a much less potent inhibitor, it was of interest to examine the stereoselectivity of cellular protection by the two isomers. In the present study, effects of (+)- and (-)-HupA on Abeta(25-35)-induced injury were compared in PC12 and NG108-15 neuroblastoma cell lines. Following a 24 h exposure to 1 microM Abeta(25-35), cell survival was markedly reduced, but preincubation with (+)-HupA or (-)-HupA (0.1-10 microM) enhanced survival significantly. The potency of (-)-HupA and (+)-HupA in protecting against Abeta toxicity was similar. This result contrasted with the stereoselectivity of cholinesterase inhibition in vitro and in vivo, in which (-)-HupA is about 50-fold more potent than (+)-HupA. It is concluded that the neuroprotective properties of HupA enantiomers have no relation to anti-cholinesterase activity.

Role of stereochemistry in N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) nephrotoxicity

The nephrotoxicity induced by the agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is mediated through oxidative metabolites of NDPS. Oxidation of the succinimide ring in NDPS yields the nephrotoxic metabolites N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and its hydrolysis product N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA). The oxidation of NDPS on the succinimide ring also introduces an asymmetric carbon atom into these NDPS metabolites, so that R- and S- enantiomers of NDHS and 2-NDHSA are possible. The purpose of this study was to begin to explore the importance of the stereochemical orientation at the asymmetric carbon atom for the nephrotoxicity induced by NDPS metabolites. Male Fischer 344 rats were administered a single intraperitoneal (ip) injection of R-(+)- or S-(-)-2-NDHSA (0.05, 0.1 or 2.0 mmol/kg) or vehicle, and renal function was monitored for 48 h. R-2-NDHSA (0.1 mmol/kg) administration had little effect on renal function. R-2-NDHSA (0.2 mmol/kg) treatment induced mild diuresis on day 1, increased proteinuria, and a small increase in blood urea nitrogen (BUN) concentration, but no change in kidney weight or glucosuria. S-2-NDHSA (0.1 mmol/kg) induced marked nephrotoxicity as evidenced by diuresis on both post-treatment days, increased proteinuria, glucosuria, and increased kidney weight and BUN concentration. No evidence of hepatotoxicity was obtained in any treated group. Thus, the S-isomer of 2-NDHSA is a more potent nephrotoxicant than the R-isomer, and stereochemistry may play a role in NDPS metabolite-induced nephrotoxicity.