lignans and galgravin

The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Brønsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Brønsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, S factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Brønsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.

Topics: Alcohols; Catalysis; Density Functional Theory; Furans; Kinetics; Lignans; Models, Chemical; Naphthols; Stereoisomerism

Chagas disease and leishmaniasis are neglected tropical diseases (NTDs) endemic in developing countries. Although there are drugs available for their treatment, efforts on finding new efficacious therapies are continuous. The natural lignans grandisin (1) and veraguensin (2) show activity against trypomastigote T. cruzi and their scaffold has been used as inspiration to design new derivatives with improved potency and chemical properties. We describe here the planning and microwave-irradiated synthesis of 26 isoxazole derivatives based on the structure of the lignans 1 and 2. In addition, the in vitro evaluation against culture trypomastigotes and intracellular amastigotes of T. cruzi and intracellular amastigotes of L. amazonensis and L. infantum is reported. Among the synthesized derivatives, compounds 17 (IC

Topics: Animals; Antiprotozoal Agents; Drug Design; Furans; Isoxazoles; Leishmania infantum; Leishmania mexicana; Leishmaniasis; Lignans; Molecular Structure; NADH, NADPH Oxidoreductases; Parasitic Sensitivity Tests; Structure-Activity Relationship; Trypanosoma cruzi

Sixteen 1,4-diaryl-1,2,3-triazole compounds 4-19 derived from the tetrahydrofuran neolignans veraguensin 1, grandisin 2, and machilin G 3 were tested against Leishmania (Leishmania) amazonensis intracellular amastigotes. Triazole compounds 4-19 were synthetized via Click Chemistry strategy by 1,3-dipolar cycloaddition between terminal acetylenes and aryl azides containing methoxy and methylenedioxy groups as substituents. Our results suggest that most derivatives were active against intracellular amastigotes, with IC50 values ranging from 4.4 to 32.7 µM. The index of molecular hydrophobicity (ClogP) ranged from 2.8 to 3.4, reflecting a lipophilicity/hydrosolubility rate suitable for transport across membranes, which may have resulted in the potent antileishmanial activity observed. Regarding structure-activity relationship (SAR), compounds 14 and 19, containing a trimethoxy group, were the most active (IC50 values of 5.6 and 4.4 µM, respectively), with low cytotoxicity on mammalian cells (SI = 14.1 and 10.6). These compounds induced nitric oxide production by the host macrophage cells, which could be suggested as the mechanism involved in the intracellular killing of parasites. These results would be useful for the planning of new derivatives with higher antileishmanial activities.

Topics: Animals; Antiprotozoal Agents; Furans; Humans; Leishmania; Leishmaniasis; Lignans; Macrophages; Nitric Oxide; Structure-Activity Relationship

The enantioselective synthesis of three structurally distinct classes of lignan from a single, aza-Claisen-derived, chiral morpholine amide is reported. The class of lignan formed is dependent on the substitution pattern in the aryl rings and choice of protecting group on a key benzylic hydroxyl group. The methodology has been used to asymmetrically synthesize and determine the absolute stereochemistry of lignans (+)-cyclogalgravin 3, (-)-pycnanthulignene A 4, (-)-pycnanthulignene B 5, and (-)-kadangustin J 8.

Topics: Furans; Lignans; Molecular Structure; Stereoisomerism

( - )-Talaumidin (1) and ( - )-galbelgin (2) have been synthesized via 4-pentenoic acid as a starting material with the overall yield of about 17.8 and 16.9%, respectively. The key steps include Evans asymmetry anti-aldol reaction, TBS protection, hydroboration, oxidation, Friedel-Crafts arylation, etc.

Topics: Aldehydes; Fatty Acids, Monounsaturated; Furans; Lignans; Molecular Structure; Stereoisomerism

The dichloromethane fraction of the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae) significantly protected primary cultures of rat cortical cells exposed to the excitotoxic amino acid, L-glutamate. Through the activity-guided isolation from the CH(2)Cl(2) fraction, (+)-9'-hydroxygalbelgin (1), isogalcatin B (2), (7S,8S,8'R)-3',4'-dimethoxy-3,4,-methylenedioxylignan-7-ol (3), 1-hydroxy-7-hydroxymethyl-6-methoxyxanthone (4), 5,7-dimethoxy-3',4'-methylenedioxyflavan-3-ol (5), (+)-(3S,4S,6R)-3,6-dihydroxypiperitone (6), protocatechuic acid methyl ester (7) and tyrosol (8) were obtained. All of them had significant neuroprotective activities against glutamate-induced neurotoxicity in primary cultures of rat cortical cells at concentrations ranging from 0.1 microM to 10.0 microM and were comparable to MK-801, a well-known inhibitor of glutamate receptor.

Topics: Animals; Cells, Cultured; Cerebellar Cortex; Circular Dichroism; Female; Furans; Glutamic Acid; Lauraceae; Lignans; Molecular Structure; Neurons; Neuroprotective Agents; Plant Bark; Plants, Medicinal; Rats; Rats, Sprague-Dawley

To study the chemical constituents in the stems of Schisandra propinqua and evaluate their effects on proliferation of vascular smooth muscle cells (VSMCs) in vitro by MTT assay.. The compounds were isolated and purified by various column chromatographic techniques and their structures were elucidated on the basis of spectral analysis (ESI-MS, 1H-NMR, 13C-NMR).. Five compounds were isolated and identified as galgravin (1), veraguensin (2), octadecanoic acid 2, 3-dihydroxypropyl ester (3), hexadecanoic acid 2, 3-dihydroxypropy ester (4), tetracosanoic acid 2, 3-dihydroxypropyl ester (5).. All the compounds were isolated for the first time from the plant. 1, 2, 5 showed inhibiting effects on vascular smooth muscle cell (VSMCs) proliferation in vitro.

Topics: Furans; Lignans; Magnetic Resonance Spectroscopy; Plant Stems; Plants, Medicinal; Schisandra; Spectrometry, Mass, Electrospray Ionization

Biotransformation of the 7,7'-epoxylignans, (+)-veraguensin, (+)-galbelgin and galgravin by Aspergillus niger has been investigated. These lignans were converted to their corresponding 4,4'-O-demethyl derivatives, (+)-verrucosin, (+)-fragransin A2 and nectandrin B.

Topics: Aspergillus niger; Biotransformation; Furans; Gas Chromatography-Mass Spectrometry; Lignans; Magnetic Resonance Spectroscopy; Methylation

Besides the known components kadsurenone, futoquinol and futoxide, three anti-platelet activating factor principles have been found from the stem part of Piper futokadsura (Piperaceae), the Chinese drug haifengteng. They were separated and identified as galgravin, galbelgin and veraguensin on the basis of HPLC and spectral analysis. The natural existence of these three anti-PAF constituents in haifengteng is reported for the first time.

Topics: Drugs, Chinese Herbal; Furans; Lignans; Platelet Activating Factor