In continuation of our studies on carbazole alkaloids of Rutaceae [1,2] we now report the structure and synthesis of a new carbazole alkaloid, mukonine (mp 198-200°) isolated from the stem bark of Murraya koenigii Spreng. Mukonine (1), C₁₅H₁₃NO₃, M⁺ 255, was homogeneous by TLC and MS. The IR spectrum of the compound showed the presence of -NH and ester carbonyl functions on an aromatic system. The UV spectrum of (1) was similar to that of 1-methoxycarbazole. On alkaline hydrolysis, (1) furnished a compound (2) (mp 242°) which was identical to mukoeic acid [3] based on its UV, IR and mixed melting point (mmp) data. Mukonine is the methyl (Me) ester of mukoeic acid and can be represented by structure (1). The mass spectrum (MS) of (1) also supports this conclusion; the peak at (M-59) was readily suggestive of the presence of a carbomethoxy group in mukonine. Other significant peaks are at m/e 224, 196 and 153, which could be represented by the following ionic species (3-6). The oxocompound (10) underwent Wolff-Kishner-Huang Minlon reduction in ethylene glycol followed by treatment with CH₂N₂ to produce 1-methoxy-3-carbomethoxy-5,6,7,8-tetrahydrocarbazole (11), C₁₇H₁₉NO₃, mp 172-173°. Compound (11) was then dehydrogenated with 10% Pd/C to yield a compound with mp 198-200°, which was identical to natural mukonine (1) in all respects (UV, IR, TLC and mmp). The occurrence of murrayanine, mukoeic acid and mukonine in M. koenigii shows that the aromatic C-Me group at C-3 of the carbazole nucleus is oxidized to a carboxylic acid group and methylated in the same plant to yield mukonine.