Nigakilactone

Picrasma quassioides (D. Don) Benn. P quassioides (D. Don) Benn. f. dasycarpa Kitag. Ku Shu (stem bark) 2.4- dichloro-6-aminopyridine, 4.5- dimethoxycanthin-6-one, 2.6- dimethoxy-p-benzo-quinone, methyl nigakinone, picrasmin, nigakihemiacetal A, nigakilactone A, nigakinone, quassin.50 Treat fever, stomachache. 

Quassin (= Nigakilactone Ailanthus altissima, Picrasma spp., Bitter... 

Quassinoids.—Simarolide (136) had previously been the only substance providing a structural link between limonoids and quassinoids. The related picrasin A (137) has now been isolated from Picrasma quassioides P. ailan-thoides). It was accompanied in the extract by picrasin B (138) which was converted to quassin (139) by bismuth oxide oxidation and methylation. A series of closely related quassin derivatives, nigakilactones A (140), B (141), C (142), E (143), and F (144) occur with quassin in P. ailanthoides. - The structure of amarolide has been revised to (145). Observation of a large coupling between H-9 and H-11 in the n.m.r. spectrum makes the previous... 

QuassMoids). A group of structurally complex tri-terpenes with various tetra- and pentacyclic C -, C -, C20-, and C25-skeleton. The C2o picra ane system is the most widely distributed. Q. occur principally in the wood of the tree Quassia amara indigenous to Brazil and Surinam as well as the Caribbean Picrasma ex-celsa (Simaroubaceae). They have antifeedant effects on insects and taste very bitter. The most important representative of the Q. is quassia (2,12-dimethoxy-picrasa-2,12-diene-1,11,16-trione, nigakilactone D) C22H28O6, Mr 388.46, mp. 221-222 °C, [aJo +34.5° (CHCI3) - a partially hydrogenated phenanthiene derivative. 

Investigation of the minor bitter constituents of Picrasma ailanthoides Planchon led to the isolation and structural elucidation of the following new quassinoids Nigakilactone K (8), L (9), M (10) and N (11) (62). Quite recently two quassinoids hemiacetals, picrasinol-A (12) and -B (13) have been isolated from the bark of the same plant (77) they all have a methyl group at C-8. 

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