Synthesis and Biological Evaluation of Dihydrobenzofuran Lignans and Related Compounds as Potential Antitumor Agents that Inhibit Tubulin Polymerization

Pieters, Luc; Dyck, Stefaan Van; Gao, Ming; Bai, Ruoli; Hamel, Ernest; Vlietinck, A. J.; Lemière, Guy L. F.

doi:10.1021/jm990251m

Cited by 192 publications

(164 citation statements)

References 20 publications

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“…Whilst dehydration occurs by loss of the benzylic hydroxyl group in the β-O-4 unit, 25b,26b deformylation could occur in the β-O-4 unit as well as the β-5 unit in AB1. Compounds A 15 and B 16 were used to investigate this issue further.…”

Section: Product Formation Profiles and Reaction Intermediates Using mentioning

confidence: 99%

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

et al. 2016

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ABSTRACT:The development of fundamentally new approaches for lignin depolymerization is challenged by the complexity of this aromatic biopolymer. While overly simplified model compounds often lack relevance to the chemistry of lignin, the use of lignin streams directly, poses significant analytical challenges to methodology development. Ideally, new methods should be tested on model compounds that are complex enough to mirror the structural diversity in lignin, but still of sufficiently low molecular weight to enable facile analysis. In this contribution we present a new class of advanced (β-O-4)-(β-5) dilinkage models that are highly realistic representations of a lignin fragment. Together with selected β-O-4, β-5 and β-β structures, these compounds provide a detailed understanding of the reactivity of various types of lignin linkages in acid catalysis in conjunction with stabilization of reactive intermediates using ethylene glycol. The use of these new models has allowed for identification of novel reaction pathways and intermediates and led to the characterization of new dimeric products in subsequent lignin depolymerization studies. The excellent correlation between model and lignin experiments highlights the relevance of this new class of model compounds for broader use in catalysis studies. Only by understanding the reactivity of the linkages in lignin at this level of detail can fully optimized lignin depolymerization strategies be developed.

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Section: Product Formation Profiles and Reaction Intermediates Using mentioning

confidence: 99%

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

et al. 2016

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“…In addition, b-sitosterol glucoside (daucosterol), and b-sitosterol 22) from the hexane fraction and caffeic acid 23,24) and its methyl ester 25) from the EtOAc fraction were isolated and identified by comparison of their physical and spectral data with those previously reported.…”

mentioning

confidence: 99%

Triterpenoid Saponins from the Seeds of Pharbitis nil

Jung

Lee

et al. 2008

CHEMICAL & PHARMACEUTICAL BULLETIN

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Pharbitis nil CHOISY [ϭIpomoea nil (L.) ROTH] is found throughout Southeast Asia. The seeds and the resin extracted from the plant are medicinal. The main use is as a purgative.1) The Japanese morning glory has been domesticated as an ornamental plant in Japan. There have been several reports on the isolation of resin glycosides, 2-4) a diterpenoid, pharbitic acid, 5) flavonoids, caffeic acid, and chlorogenic acid derivatives, 6) and anthocyanins 7-10) from the seeds and flowers of this plant but there has been no report on the chemical investigation of the saponins in the seeds. In continuation of our studies on phytochemical studies on naturally occurring bioactive glycosides, [11][12][13][14] we became interested in the saponin content of the seeds of the plant. This paper describes the structural determination of the two new saponins isolated from the MeOH extract of the seeds.The powdered seeds of P. nil were sonicated with MeOH and partitioned as described in the Experimental. b-Sitosterol and its glucoside and caffeic acid and its methyl ester were isolated by successive chromatography using silica gel and reverse-phase C 18 from the hexane and EtOAc fractions, respectively. The BuOH-soluble fraction after repeated chromatographic purification over MCI gel and reverse-phase C 18 afforded two compounds designated pharbitosides A (1) and B (2).Pharbitoside A (1) was obtained as colorless crystalline needles. High-resolution (HR) FAB-MS gave the composition C 48 H 78 O 18 . An inspection of the 1 H-and 13 C-NMR spectra of the compound readily indicated the presence of three monosaccharide units through easily identifiable signals for anomeric protons and carbons. Acid hydrolysis of 1 afforded glucose (Glc) and rhamnose (Rha) as the sugar components identified on TLC analysis by comparison with authentic samples. The absolute configurations of sugars were determined to be the L-form for Rha and D-form for Glc, respectively, which were identified by GLC analysis of the thiazolidine derivatives.15) The negative-ion mode FAB mass spectrum of 1 exhibited an [MϪH] Ϫ ion at m/z 941, which is consistent with a trisaccharide glycoside carrying two Glc, one Rha, and an aglycon with a molecular mass of 472. Ϫ showed the presence of a linear sugar chain, and the sugar sequence appeared to be that of Glc-Glc-Rha.16) The spectroscopic data of the aglycon moiety of 1 were closely related to those of oleanolic acid 17) ; however, the molecular formula of the aglycon moiety was higher by one oxygen atom than that of oleanolic acid, implying the presence of one more hydroxyl group in addition to the C-3 hydroxyl group. The oxygenated methylene protons at

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“…These compounds were synthesized employing previously procedures reported with modifications. [24][25][26] All the structures were confirmed on the basis of NMR, EI-MS and IR data and comparison with the literature.…”

Section: Synthesis Of Dihydrobenzofuran Neolignans 1-8mentioning

confidence: 70%

“…11,12 Dihydrobenzofuran neolignans (DBN) are compounds derived from the coupling of two phenylpropanoids (C 6 C 3 units) linked specifically by 7.O.4' and 8.5' positions. 13,14 Various biological activities have been reported for DBN, such as anti-inflammatory, 15 antileishmanial, 16 antitumor, 17 antioxidant, and cytotoxic. 18 DBNs have been also reported to display interesting antifungal activities.…”

Section: Introductionmentioning

confidence: 99%