| Uncaria rhynchophylla (Uncariae Ramulus cum Uncis) is a traditional Chinese herb. People just know a little about the effect of Uncaria rhynchophylla on cardiovascular disease. My research team extracted total alkaloids (KHR98) from Uncaria rhynchophylla using distinct technologic method. KHR98 has obvious effect on long-term depress blood pressure, and also protecting target organ by anti-myocardial ischemia, reducing infact size, inhibting fibrocyte proliferation, anti-fibrotic tissue and organ, restraining vascular smooth muscle cell prolideration, depressing vessel wall hypertrophy, antioxidation, radical scavenging, inhibting renal fibrocyte and/or glomeruli of kidney proliferation.(Chinese patent 200610116517.2)In this study, I gained Hirsutine isolated from KHR98 by high performance liquid chromatography (HPLC). Based on this, using model of hypoxic neonatal rat cardiomyocytes, we conduct an exploratory investigation about protective effects of novel single compound, Hirsutine on hypoxic neonatal rat cardiomyocytes. The research included methylthiazol tetrazoium (MTT) assay for cell viability, lactate dehydrogenase (LDH) release as an index of cytotoxicity and malondialdehyde (MDA) content indicating lipid peroxidation were measured, the apoptosis proteins and signaling molecules using RT-PCR and Western blot, Hoechst staining observing apoptotic pathomorphological change. The results showed that Hirsutine can enhance the viability of myocytes injuried by hypoxia, reduce the leakage of LDH, increase the vitality of antioxidant enzymes, and inhibit myocyte apoptosis. The action mechanisms of Hirsutine in hypoxic neonatal rat cardiomyocytes may be related to its anti-oxidant and anti-apoptotic properties. This research may open an avenue for developing novel candidate compounds with cardioprotective effects from unique Chinese plant.Hirsutine is one of the corynanthe-type alkaloids of the "pseudo" sub-type, possessing the characteristic C(3)-Hβ, C(15)-H a, C(20)-Hβrelative stereochemical configuration. In the 1980s, the Racemic Total Synthesis and Enantioselective Synthesis of Hirsutine were reported by Wenker,Lounasmaand Tietze. There were some flawes in these synthenic routes, such as too many steps, the low production rate and expensive raw materials and chiral catalyst. This research took trypamine as starting materials, and obtained intermediate product 3 by Pictet-Spengler condensation. Boc-protected and Cbz-protected intermediate product 5 was reduced to aldehyde intermediate product 6 by DIBALH. Intermediate product 8 was got by domino Knoevenagel-hetero-Diels-Alder and hydroenization reaction with Meldrum acid and enol ether with intermediate product 6. At last, we got Hirsutine racemate by condensation with methyl formate and methylation with diazomethane and deprotection of Boc-group. We took L/D tryptophane as starting materials, and got diastereomers 1A/1B by Pictet-Spengler condensation. Because the thermodynamic of trans isomer is more stable,2A trans/2B trans could be exclusively obtained by epimerization of a mixture of the cis and trans isomers of the Nb-benzylated moieties 2A/2B under acidic conditions. Then we obtained pivotal enantiomer 3A/3B by removing C3 side chain and N-benzyl of intermediate product 2A trans/2B trans. At last, we can gain intermediate product 8a/8b by Boc-protected, Cbz-protected, reduced to intermediate product 3A/3B. At last, we can gain Hirsutine enantiomer and dihydrocorynantheine enantiomer by domino Knoevenagel-hetero-Diels-Alder and hydroenization reaction with intermediate product 8a/8b with Meldrum acid and enol ether. In this study, we finished racemic total synthesis of Hirsutine using trypamine as starting materials, and explored enantioselective total synthesis of Hirsutine using L/D tryptophan as starting materials by means of epimerization for the first time. The successful building of these synthetic routes has great meaning for the further research in pharmacodynamics of Hirsutine. |
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