Quassinoids structure

QUASSINOIDS STRUCTURAL DIVERSITY, BIOLOGICAL ACTIVITY AND SYNTHETIC... 

Curcino Vieira IJ, Braz-Filho R (2006) Quassinoids structural diversity, biological activity and synthetic studies. In Atta-ur-Rahman FRS (ed) Bioactive natural products. Elsevier, Amsterdam, p 433... 

Polonsky J, Varenne J, Prange T, Pascard C 1980 Antileukaemic quassinoids Structure (X-ray analysis) of bruceine C and revised structure of bruceantinol. Tetra Lett 21 1853-1856... 

Polonsky, J., J. Varenne, T. Prange, and C. Pascard Antileukaemic Quassinoids Structure (X-Ray Analysis) of Bruceine C and Revised Structure of Bruceantinol. Tetrahedron Lett. 21, 1853 (1980). 

For a recent structure-activity relationship correlation of quassinoids as antitumor agents see M. Okano, F. Narihiko, K. Tagahara, H. Tokuda, A. Iwashima, H. Nishino and K-H. Lee, Cancer Lett. 1995, 94, 139. 

Quassinoids.—The structure of soulameolide (108), a new C25 quassinoid from Soulamea tomentosa, has been established by X-ray analysis.The search for biologically active compounds continues. Undulatone (109) from Hannoa undulata, 6a-tigloyloxychapparinone (110) from Ailanthus integrifoliaj and 6a-senecioylchapparinone (111) from Simaba multiflora have antileukaemic... 

Quassinoids.— The full paper on the structural elucidation of picrasins A—G has been published. Two new compounds, nigakihemiacetals E (79) and F (80), have been isolated from Picrasma ailanthoides. 

Quassinoids.—Soulameamuelleri (Simaroubaceae) has yielded soulameanone (120), 1,12-di-O-acetylsoulameanone (121), and A2-picrasin B (122). The structure of (120) was established by X-ray analysis. Treatment of (122) with diazomethane afforded quassin.70 Other new quassinoid natural products reported this year are soularubinone (123), an antileukaemic compound from S. tomentosa,71 13,18-... 

Grieco and his co-workers have completed a most notable total synthesis of /-quassin (130) (Scheme 3).1 The synthesis of the hydroxy-lactone (127) was outlined last year (see Vol. 11, p. 121). The conditions developed for the conversion of the bis-(a-hydroxy-ketone) (128) into the bis-(O-methyldiosphenol) (129) also achieved the crucial inversion of configuration at C-9.74 The close proximity of the C-7 oxygen atom to the C-ll carbon atom in the 9-epiquassin skeleton is evident from a series of reactions in which intramolecular participation occurs. Thus, for example, treatment of the epoxide (131) with lithium aluminium hydride gave the ether (132) whose structure and stereochemistry were established by A -ray analysis.75 Synthesis of the tetracyclic (133), a possible intermediate for quassinoid synthesis, involved the intramolecular cycloaddition of a quinonedimethane as the key step.78... 

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... 

The alkylating-cyclization method may be extended to the enantioselective introduction of an alkyl chain, if a chiral alcohol is used as starting material. The tributyltin hydride mediated radical cyclization of the bromoacetal of 18,19-bisnor-9/i-podocarp-l 3-en-12-one gives a tetracyclic d-lactone, the characteristic structural feature of quassinoids, a complex family of degraded triterpenes82. The hydrogen abstraction in the last step of the reaction has to occur stereoselectively, because only two C-16 diastereomers are formed during the reaction. 

Quassinoids.—2 -AcetylgIaucarubine (98) and a new antineoplastic quassinoid, 13,18-dehydroglaucarubinone (99), have been isolated from Simarouba amara. The related 13,18-dehydroglaucarubol-15-isovalerate (100) has been reported from Ailanthus excelsa. The details of the crystal structural analyses of samaderin 7A (101), from Samadera indica, and 6-hydroxypicrasin B (102), from Soulamea species, have appeared. 

The review containing structural data, biological activities and chemical modifications of quassinoids was published last decade with references up to September 1984 by Polonsky [1]. According to Simao et al. [2] more than two hundred quassinoids were isolated and identified until December 1984. 

Support for this biogenetic picture has also come from the isolation of compounds representing the various stages and structural variations among quassinoids. 

Seven quassinoids were isolated from Ailanthus altissima Swingle, ailantinol A-F (44-49) [26-28], and their structures were elucidated from spectral data. The ailantinol E (47) and F (48) were evaluated for its antitumor promoting effects against Epstein-Barr virus through early antigen activation introduced by 12-0-... 

Six quassinoids, named vilmorinine A-F (57-62) were isolated from the cortex of Ailanthus vilmoriniana. The structures were elucidated by various spectroscopic methods, X-ray analysis, and computational chemical methods. Vilmorinines did not show cytotoxic activity (IC50 > 100 (ig/mL) [33-34]. 

Three quassinoids named yadanziolides A (90), B (91), and C (92), and four quassinoids glycosides named yadanziosides F (93), I (94), J (95), and L (96) were isolated from water-soluble fraction methanol extract of seeds of Bruceci javanica Merr., and their structures were determined by spectral and chemical means [44]. 

Javanicin (101) an unusual quassinoid with seco ring A had its structure and relative configuration established unequivocally by single crystal X-ray analysis [47],... 

The structure of a new bitter-tasting quassinoid, named peninsularinone (111) isolated from the roots of Castela peninsularis... 

A new quassinoid, 11 -<9-iram-/ -coumaroyl amarolide (112) isolated from Castela texana and the structure was elucidated by spectroscopic analysis. Compound (112) is the first coumaroyl quassinoid derivative to be isolated from nature [50], Testing in the antimalarial bioassay showed that (112) possessed moderate antimalarial activity without potent cytotoxicity. 

Soulamea amara Lam., is a Simaroubaceae indigenous to Vanuatu (New-Hebrides). The new quassinoid 15-O-benzoylbrucein (204) was isolated from the aerial parts, and the structure has been established from spectral data and by single-crystal X-ray [84],... 

Problems associated with construction of C(8), C(ll) bridged hemiketal structural array, which is common to numerous naturally occurring quassinoids. To follow is described the synthesis of pentacyclic alcohol (243) which features a protocol for elaboration of ring C functionality found in chaparrinone and related quassinoids A facile five-step sequence commencing with picrasane derivative (237) has been developed for elaboration of the sensitive ring C hemiketal unit chaparrinone (226) (c.f. pentacyclic alcohol 243) [118],... 

Amarolide (267) is one of the representative quassinoid, and was first isolated from Ailanthus glcmdulosa [127] and A. altissima [128] being its structure established as (267). 

The 5(R)- and 5(,S)-polyandranes (33 and 29), Zus-lactones, were isolated from Castela texana and Castela polyandra [17], respectively, and have been shown by single-crystal X-ray analysis to possess the novel carbon skeleton. In view of the structural similarity between the polyandranes and the C20 quassinoids, it has been suggested that (33) and (29) are derived biogenetically from chaparrinone (226) [134]. 

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