Koenigine

Synthesis of 1,1'- and 2,2'-Bicarbazole Alkaloids by Iron(III)-Catalyzed Oxidative Coupling of 2- and 1-Hydroxycarbazoles.[Pubmed:29024097]

Chemistry. 2018 Jan 9;24(2):458-470.

We describe the synthesis of 1,1'- and 2,2'-bicarbazoles by oxidative homocoupling of 2- and 1-hydroxycarbazoles. The oxidative coupling using catalytic amounts of F16 PcFe can be applied to both groups of substrates. Although F16 PcFe generally provides the best yields for the synthesis of 1,1'-bicarbazoles, di-tert-butyl peroxide affords better results for the 2,2'-bicarbazoles. In our study, we have achieved the first syntheses of the biscarbalexines A-C, bisglybomine B, 2,2'-dihydroxy-7,7'-dimethoxy-3,3'-dimethyl-1,1'-bicarbazole, bispyrayafoline C, and bisisomahanine. The iron-catalyzed coupling of Koenigine led to an improved synthesis of 8,8''-bisKoenigine and afforded an unprecedented decacylic product. Oxidative coupling of 1-hydroxycarbazoles led to bisclausenol, and to the first total syntheses of bismurrayafoline B and D.

Pyranocarbazoles from Murraya koenigii (L.) Spreng. as antimicrobial agents.[Pubmed:28368664]

Nat Prod Res. 2018 Feb;32(4):430-434.

The bioassay guided fractionation of methanolic extract of Murraya koenigii (L.) Spreng. leaves resulted in the isolation of seven pyranocarbazoles. These were evaluated against four bacterial strains and ten Candida sp. including two matched pair of fluconazole sensitive/resistant clinical isolates. Out of seven, three i.e. Koenine (mk279), Koenigine (mk309) and Mahanine (mk347) exhibited significant antibacterial activity MIC90 3.12-12.5 mug/mL against bacterial strains Streptococcus aureus and Klebsiella pneumonia compared with standard drug Kanamycin MIC90 12.5 mug/mL. However, only mk309 was found active against variety of Candida species MIC90 12.5-100 mug/mL. It was observed that hydroxylation at C-6 and C-7 positions in the studied pyranocarbazoles activate the bioactivity. Simultaneously, decrease in Log P value compares with -H and -O-CH3 substituted derivatives. The study is focused on selective antifungal and antibacterial activity of pyranocarbazoles on bacterial strains S. aureus, K. pneumonia and variety of Candida species with structure activity relationship observations.

Two new carbazole alkaloids from Murraya koenigii.[Pubmed:12662104]

J Nat Prod. 2003 Mar;66(3):416-8.

Two new carbazole alkaloids named murrayanine (1) and 8,8' '-bisKoenigine (2) were isolated from Murraya koenigii. The structure elucidations for 1 and 2 were carried out on the basis of 1D and 2D NMR experiments. Compound 1 was a novel carbazole alkaloid with a rare phenylpropanyl substitution. Compound 2 was a symmetrical dimer of the carbazole alkaloid Koenigine and showed antiosteoporotic activity in the CAT-B model with IC(50) 1.3 microg/mL. The synthesis of 2 from Koenigine was carried out through oxidative coupling using a solid state reaction.

[Study on carbazole alkaloids of Murraya microphylla].[Pubmed:12571921]

Zhong Yao Cai. 1999 Sep;22(9):458-60.

Four carbazole alkaloids were isolated from the methanol extract of Murraya microphylla. Their structures were identified by spectral analysis and chemical evidence, which were identified as Koenigine, bis-6-hydroxy-7-methoxygirinimbine, girinimbine and mukonicine. All the compounds were discovered from this plant for the first time, and bis-6-hydroxy-7-methoxygirinimbine was a new compound.