Limonoids from Carapa grandiflora (meliaceae)

✍ Scribed by J. Foyere Ayafor; Samuel F. Kimbu; Bonaventure T. Ngadjui; Thomas M. Akam; Etienne Dongo; B.Lucas Sondengam; Joseph D. Connolly; David S. Rycroft

• Book ID: 104203331
• Publisher: Elsevier Science
• Year: 1994
• Tongue: French
• Weight: 707 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)85511-3

✦ Synopsis

The seeds of Campa grandifloru sprsgue (Meliacex), popularly known in Cameroon as "engang", ate used in traditional medicine as a febrifuge and for the treatment of arthritis, general fatigue and skin diseases'. As part of our continuing search for plant fihuicides related to carapolide A 1, which had shown strong in virro activity against Onchocerca volvuZus microfilariae23, we have investigated the extract of the seeds of C. grundiflora and obtained eight. tetmnorni terpenoids, some of which am related to carapolide A 1, but not compound 1 itself. A preliminary communication' reporkd the structural elucidation of three of them, carapolide D 3, E 4, and F 5. The present paper reports the isolation and structure determination of four additional liionoids from the seeds and presents full experimental details concerning 3-5 and 13.

An acetone extract of the defatted seeds was subjected to repeated column chromatography, affording compounds 2, 3, 4, 5, 6, 7, 8, and 13 in yields of 0.002, 0.001, 023, 0.01, 0.02, 0.018, 0.002, and 0.3% respectively. Evodoulone 13, previously obtained from C. proceru ', was character&d by direct comparison (mmp, [al,, IR and NMR) with an authentic sample.

The structutes of carapolides C 26. D 3, and E 4 have already been reported'. They constitute further members of the rare group of teuanortriterpenoids with a C-9, C-10 cleaved carbon skeleton. Attempts were made to correlate chemically these three compounds. Thus treatment of carapolidc E 4 with p-toluene sulfonic acid yielded carapolide C 2, identical in all respects with the natural sample. Ffforts to convert campolide E 4 into carapolide D 3 through dehydration with thionyl chloride in dry pyridine at 0% were, however, unsuccessful and led to the formation of the chloride 9. The IR spectrum of 9 lacked a hydroxyl absorption band and, though its 'H NMR spectrum was very similar to that of 4, the hydroxyl proton resonance at 6 2.41 ppm in the spectrum of 4 was absent. As expected reaction of carapolide E 4 with acidic methanol yielded the methyl acetal 10. The 'H NMR spectral data of the acctal (experimental section) were consistent with structure 10. Paucity of material precluded attempts to transform 3 into 4 by hydration.