Ramlee, Nurul Izzati
(2015)
Synthesis, Characterization And
Analgesic Activity Of Mitragynine
Analogues.
Masters thesis, Perpustakaan Hamzah Sendut.
Abstract
Mitragyna speciosa contains many alkaloids and mitragynine (MG) is its
most abundant alkaloid and has received much attention due to its analgesic
property. In this work, a series of MG analogues, which includes 7-
hydroxymitragynine (7-0HMG), Na salts of 7-hydroxymitragynine (Na 7-0HMG),
K salts of 7-hydroxymitragynine (K 7-0HMG), reduced 7-hydroxymitragynine
(reduced 7-0HMG) and nicotinic ester 7-hydroxymitragynine (nicotinic ester 7-
OHMG) were synthesized, characterized and evaluated for their analgesic activity.
Various oxidants were used to produce 7-0HMG from MG. Oxidation reaction using
tert-butyl hydroperoxide (TBHP), hydrogen peroxide (H202) or metachloroperoxybenzoic
acid (MCPBA) was carried out in the presence of palladium
(Pd) as a catalyst while (bis(trifluoroacetoxy)iodo )benzene (PIFA) was used without
any catalyst. H202 was found to be the best oxidant, producing around 99% yield of
7-0HMG, followed by TBHP, MCPBA and PIFA. Na 7-0HMG and K 7-0HMG
were synthesized by neutralizing 7-0HMG with sodium hydroxide (NaOH) or
potassium hydroxide (KOH) and the best yield was observed when the molar ratio of
7-0HMG: NaOHIKOH at 1: l was used with the yield of 59 and 78% for Na 7-
OHMG and K 7-0HMG, respectively. The reduction of 7-0HMG using sodium
borohydride (NaBH4) successfully produced reduced 7-0HMG with 99% yield.
Whilst, the esterification of nicotinic acid to 7-0HMG in the presence of N,N'Dicyclohexy1carbodiimide
(DCC) and 4-Dimethylaminopyridine (DMAP) as a
coupling agent and catalyst, respectively has been carried out and produced around
94% yield of nicotinic ester 7-0HMG.
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