- Biomimetic in vitro oxidation of lapachol: A model to predict and analyse the in vivo phase i metabolism of bioactive compounds
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The bioactive naphtoquinone lapachol was studied in vitro by a biomimetic model with Jacobsen catalyst (manganese(III) salen) and iodosylbenzene as oxidizing agent. Eleven oxidation derivatives were thus identified and two competitive oxidation pathways postulated. Similar to Mn(III) porphyrins, Jacobsen catalyst mainly induced the formation of para-naphtoquinone derivatives of lapachol, but also of two ortho-derivatives. The oxidation products were used to develop a GC-MS (SIM mode) method for the identification of potential phase I metabolites in vivo. Plasma analysis of Wistar rats orally administered with lapachol revealed two metabolites, α-lapachone and dehydro-α-lapachone. Hence, the biomimetic model with a manganese salen complex has evidenced its use as a valuable tool to predict and elucidate the in vivo phase I metabolism of lapachol and possibly also of other bioactive natural compounds.
- Niehues, Michael,Barros, Valeria Priscila,Emery, Flavio Da Silva,Dias-Baruffi, Marcelo,Assis, Marilda Das Dores,Lopes, Norberto Peporine
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experimental part
p. 804 - 812
(2012/09/10)
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- Chemistry of lapachol - Syntheses of some new biogenetically related naphthoquinones, naphthoquinone dimers, naphthaquinoxaline and naphtha-azaquinoxaline derivatives from lapachol
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The present short review focus on chemical transformations of lapachol to a large number of biogenetically related lapachol conegeners, dimers and heterocyclic analogues that have been achieved in our laboratory during more than two decades. Conversion of lapachol to stenocarpoquinone-B, rhinacanthin-A, β-(l-hydroxyisopropanyl)-dihydrofurano-1,2-naphthoquinone, stenocarpoquinone-A, dehydro-α-lapachone and dehydro-β-lapachone by the reaction with m-chloroperbenzoic acid; dehydroiso-α-lapachone, dehydroiso-β-lapachone, dehydro-α-lapachone, α-lapachone and β-lapachone by the reaction with aqueous NaNO2 and glacial AcOH; adenophyllone, quadrllone and dehydro-α-lapachone by the reaction with boiling pyridine; naphthaquinoxaline and naphtha-azaquinoxaline derivatives by the reaction with 1,2-diamines and dialkyltin dilapacholates by the reaction with dialkyltin diisopropoxides have been accomplished. Notably the syntheses of rhinacanthin-A, β-(1-hydroxyisopropanyl)-dihydrofurano-1,2-naphthoquinone, dehydroiso-α-lapachone, dehydroiso-β-lapachone, adenophyllone and quadrllone have been reported for the first time from our group starting from lapachol. The synthesis of novel naphthaquinoxaline and azaquinoxaline derivatives from lapachol has been additional interesting results of this investigation.
- Singh, Pahup,Krishna, Vivek,Khandelwal, Poonam,Sharma, Kuldeep K.,Sharma
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experimental part
p. 85 - 95
(2011/07/30)
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- Conversion of lapachol to array of furano and pyranonaphthoquinone congeners
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Chemical conversion of lapachol to α-lapachone, β-lapachone, dehydro-α-lapachone, dehydroiso-α-lapachone and dehydroiso-β- lapachone by reaction with aqueous NaNO2 and glacial AcOH; rhinacanthin-A, stenocarpoquinone-A, stenocarpoquinone-B and its isomer by reaction with meta-chloroperbenzoic acid at 0° for 30 min and dehydro-α-lapachone and dehydro-β-lapachone at 25° for 4 h respectively and di- and tribromo derivatives by reaction with Br2 in chloroform has been reviewed. In most of these reactions prenyl chain cyclises into an oxygen function to give a number of furano and pyrano-naphthoquinone derivatives. Some of these naphthoquinones co-occur with lapachol in the same plant species.
- Krishna, Vivek,Lamba, Jyoti,Singh, Pahup
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p. 1039 - 1044
(2007/10/03)
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- Chemical transformation of lapachol to dehydroiso-α-lapachone and related quinones
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Chemical transformation of lapachol to dehydroiso-α-lapachone, dehydroiso-β-lapachone, α-lapachone, β-lapachone and dehydro-α-lapachone in a single step synthesis by reaction with aqueous NaNO2 and glacial AcOH and to di- and tri-bromo derivatives by reaction with Br2 in CHCl3 has been achieved. Notably dehydroiso-α-lapachone and dehydroiso-β-lapachone have been obtained from lapachol for the first time.
- Singh,Jain,Krishna
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