Limonoids from the Stem Bark of <i>Khaya senegalensis</i>

Abstract

Six new limonoids with modified furan ring, khaysenelide A-F (1-6), together with six known limonoids (7-12) were isolated from the stem bark of Khaya senegalensis. The basic skeletons of these new limonoids belong to mexicanolide (1, 2) and rearrangement phragmalin (3-6), which were elucidated on the basis of spectroscopic methods including high resolution-electrospray ionization (HR-ESI)-MS, one and two dimensional (1D and 2D)-NMR and confirmed by single-crystal X-ray crystallography using CuKα radiation of 1 and 3. Their absolute configurations were determined by the X-ray crystallography data and comparison of their electronic circular dichroism spectra. The inhibitory effect on nitric oxide (NO) production in lipopolysaccaride-activated RAW264.7 macrophages of new compounds was also tested.

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“…Phytochemical screening carried out on the Khaya senegalensis barks has detected the presence of alkaloids, saponins, tannins and flavonoids 10 , and as for the extracts of Melia azedarach we have detected in MMFM (methanol extract from Melia azedarach leaves) polyphenol, flavonoids, tannins alkaloids and saponins, MAFM (ethyl acetate extract from Melia azedarach leaves) sterols and polyterpenes, MDFM (dichloromethane extract from Melia azedarach leaves) alkaloids, and MCFM (cyclohexane extract from Melia azedarach leaves) sterols, polyterpenes, and alkaloids. Phytochemical studies on Khaya senegalensis leaves, bark and seeds have isolated limonoid, triterpenoid, α-tocopherol, khayanolide and khayanone -type molecules 11,12,13,14,15,16,17,18,19 . Table 2 lists the results of the antiplasmodial activity of the extracts of Melia azedarach and Khaya sengalensis, as regards Table 3 and 4, those of the cytotoxicity and the selectivity index (SI) of the extracts respectively for the strain 3D7 and W2 of Plasmodium falcipaum.…”

Cipadessains A–K, eleven limonoids from the fruits ofCipadessa cinerascens

“…Its IR absorption bands at 3460 and 1728 cm À1 showed the presence of hydroxyl and carbonyl functionalities. The NMR data (Table 1) 14,16 These aforementioned data strongly suggested 1 was a B,D-seco mexicanolide-type limonoid, 7,19 typical constituent of Cipadessa genus.…”

“…On the contrary, those mexicanolides bearing complete furan moiety or hydroxybutenolide furan moiety were inactive (1,2,5,(8)(9)(10)(11). According to the continuing study, [14][15][16] the modied furan moiety may play important role on the bioactivity of these limonoids.…”

Triterpenoids

“…Khaysenelides A 476-F 481 are modied furan derivatives from the stem bark of Khaya senegalensis. 154 The structures of khaysenelides A 476 and C 478 were conrmed by X-ray crystallographic analyses. Khaysenelide F 481 shows neuroprotective activity.…”