Bicyclo[3.2.1]octane and 6-Oxabicyclo[3.2.2]nonane Type Neolignans from Magnolia denudata.

Abstract

From the ethyl acetate soluble fraction of twigs of Magnolia denudata (Magnoliaceae), seven new neolignan derivatives, 1-7, were isolated along with eighteen known lignan and neolignan derivatives, 8-25. The structures of the new neolignans were elucidated by means of spectral methods, especially by 1H-NMR and 13C-NMR spectra, and two dimensional NMR methods such as 1H-detected heteronuculear multiple bond connectivity1 (HMBC), 1H-detected multiple quantum coherence (HMQC) and 1H-1H-correlation spectroscopy (COSY). Compounds 1-4 have novel structures possessing a 6-oxabicyclo[3.2.2]nonane skeleton and compounds 5-8 also have novel structures possessing a bicyclo[3.2.1]octane skeleton. The anti-platelet-activating factor (PAF) activity of these compounds was tested by measurement of inhibition activity against acetyl transferase to lyso-PAF.

Lignan and Neolignan Derivatives from Magnolia denudata

“…The Table 1, and thus its structure was estimated to be a novel compound constructed with a sixmember ring, four-member ring, and three-member ring, that is, the plane structure for 1 was represented as 6-allyl-7-(3,4-dimethoxyphenyl)-2,3-dimethoxy-8-methyl-tricyclo[4.2.0.0 2,8 ]oct-3-en-5-one. Moreover, nuclear Overhauser effect enhancement spectroscopy (NOESY, Fig.…”

“…5) Iida et al found denudatins A and B and denudatone, burchellin, veraguensin, and futoenone isolated from the leaves of M. denudata. 6) In connection with our studies on the genera Magnoliaceae that has diverse biological activities, we have surveyed the constituents of the flower buds of M. denudata to isolate the new neolignan 6-allyl-7-(3,4-dimethoxyphenyl)-2,3-dimethoxy-8-methyl-tricyclo[4.2.0.0 2,8 ]oct-3-en-5-one (1), together with 15 known tetrahydrofuran-type and bis-tetrahydrofuran-type lignans and neolignans. The known lignans and neolignans were identified as veragensin (2), 2) galgravin (3), 7) a lignan (4), 8) fargesone B (5), 9) lariciresinol (6), 10) a lignan (7), 11) fargesin (8), 12) (Ϫ)-methylpiperitol (9), 13) magnolone (10), 14) (Ϫ)-galbacin (11), 15) licarin B (12), 16) acuminatin (13), 2) hancinone (14), 2) burcellin (15), 2) and a neolignan (16) 2) by analysis of their 1 H-and 13 C-NMR spectra and comparison with published data.…”

New Cytotoxic Phenolic Derivatives from Matured Fruits ofMagnolia denudata

“…Measurement of the cytotoxic activities of denudalide (1) and denudaquinol (2). SFME cells were presented by Dr. S. Shirahata (Kyushu University, Fukuoka, Japan), and r/mHM-SFME-1 cells were from our own cell stock.…”

“…[1][2][3][4] However, the chemical constituents of the matured fruits of this plant material have not been studied. This paper reports the isolation of two new phenolic derivatives, named as denudalide (1) and denudaquinol (2), from the matured fruits of M. denudata, as well as a known neolignan (denudatin A, 3). The structural elucidation of 1 and 2 was based on spectral evidence.…”

Machilin G and Four Neolignans from Young Fruits ofMagnolia denudataShow Various Degrees of Inhibitory Activity on Nitric Oxide (NO) Production

“…The chemical constituents of the bark, leaves, and flower buds of M. denudata have been investigated, and it has been established that M. denudata contains many terpenoids, lignans, and neolignans. [1][2][3][4] However, the chemical constituents of the fruits of this plant and their biological activities have not been studied in detail.…”