Two New Coumarins from the Roots of Aegle marmelos Xiu Wei Yang 1, Masao Hattori 2 and Tsuneo Namba 2

Two new coumarins, named marminal (13) and 7' O methylmarmin (15), along with nineteen known compounds: ( sitosteryl pentadecanoate (1), 4 methoxy 1 methyl 2 quinolone (2), aurapten (3), 4 sitosten 3 one (4), lupeol (5), imperatorin (6), xanthotoxin (7), dictamnine (8), (+) epoxyaurapten (9), ( sitosterol (10), ( fagarine (11), skimmianine (12), scoparone (14), umbelliferone (16), scopoletin (17), decursinol (18), marmesin (19), marmin (20), and integriquinolone (21) were isolated from the methanolic extract of the roots of Aegle marmelos Corr. (family Rutaceae).

Oxalic acid catalyzed solvent-free one pot synthesis of coumarins

Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.

L-Proline as an efficient and reusable promoter for the synthesis of coumarins in ionic liquid

The effect of L-proline as a promoter on the condensation reaction of salicylaldehyde or its derivatives with ethyl acetoacetate in neutral ionic liquid [emim]BF4 was studied. All reactions were carried out under mild reaction conditions and achieved high yields. Moreover, the ionic liquid containing L-proline could be recycled and reused for several times without noticeably decreasing in productivity. The results show that the L-proline-[emim]BF4 system has a potential in contribution to the development of environmentally friendly and inexpensive processes in organic syntheses.

Anti-Alzheimer's disease potential of coumarins from Angelica decursiva and Artemisia capillaris and structure-activity analysis

Objective: To use structure-activity analysis to study the anti-Alzheimer's disease(anti-AD) activity of natural coumarins isolated from Angelica decursiva and Artemisia capillaries, along with one purchased coumarin(daphnetin). Methods: Umbelliferone, umbelliferone 6-carboxylic acid, scopoletin, isoscopoletin, 7-methoxy coumarin, scoparone, scopolin, and esculetin have been previously isolated; however 2'-isopropyl psoralene was isolated from Angelica decursiva for the first time to evaluate their inhibitory effects against acetylcholinesterase(ACh E), butyrylcholinesterase(BCh E), and β-site amyloid precursor protein cleaving enzyme 1(BACE1) enzyme activity. We scrutinized the potentials of coumarins as cholinesterase and BACE1 inhibitors via enzyme kinetics and molecular docking simulation. Results: Among the test compounds, umbelliferone 6-carboxylic acid, esculetin and daphnetin exhibited potent inhibitory activity against ACh E, BCh E and BACE1. Both esculetin and daphnetin have a catechol group and exhibit significant anti-AD activity against ACh E and BCh E. In contrast, presence of a sugar moiety and methoxylation markedly reduced the anti-AD activity of the coumarins investigated in this study. With respect to BACE1 inhibition, umbelliferone 6-carboxylic acid, esculetin and daphnetin contained carboxyl or catechol groups, which significantly contributed to their antiAD activities. To further investigate these results, we generated a 3D structure of BACE1 using Autodock 4.2 and simulated binding of umbelliferone 6-carboxylic acid, esculetin and daphnetin. Docking simulations showed that different residues of BACE1 interacted with hydroxyl and carboxylic groups, and the binding energies of umbelliferone 6-carboxylic acid, esculetin and daphnetin were negative(-4.58,-6.25 and-6.37 kcal/mol respectively). Conclusions: Taken together, our results suggest that umbelliferone 6-carboxylic acid, esculetin and daphnetin have anti-AD effects by inhibiting ACh E, BCh E and BACE1, which might be useful against AD.

NEW COUMARINS FROM PEUCEDANUM PRAERUPTORUM

Four new coumarins named qianhucoumarins A, B, C, D have been isolated from traditional Chinese medicine-the root of Peucedanum praeruptorum. Their structures were elucidated by chemical evidences and spectral analysis.

Silica triflate as an efficient reagent for the solvent-free synthesis of coumarins

Silica triflate, as a new silica-based reagent, can be used for the efficient synthesis of 4-substituted coumarins via a Pechmann reaction under solvent-free reaction conditions. All reactions were performed at 80 ℃ in good to high yields.

TWO NEW COUMARINS FROM ANGELICA PUBESCENS F.BISERRTA

Two new coumarins,4'-hydroxycolumbianetin named angelidiol(A)and 6- [(?)(R),2(S)-3-trihydroxy-3-methylbutyl]-7-methoxycoumarin named angelitriol(B),were isolated from the EtOAc-soluble fraction of the 80% EtOH extract and structurally eluciated on the basis of spectral analyses.

The Synthesis of a Series of Phosphoryl Coumarins

Different hydroxy substituted coumarins were successfully phosphorylated with diisopropylphophite （DIPPH） by the Atherton-Todd reaction in 76-89% yields. Moreover, the reaction activities of different hydroxys of the coumarins in the Atherton-Todd reaction were studied.

Silica-bonded S-sulfonic acid a recyclable catalyst for the synthesis of coumarins

Silica-bonded S-sulfonic acid （SBSSA） was prepared by the reaction of 3-mercaptopropylsilica （MPS） and chlorosulfonic acid in chloroform. This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols and β-keto- esters at 80 ℃ under solvent-free conditions.

The synthesis of tetracyclic coumarins via decarboxylative asymmetric[4+2]cycloadditions enabled by Pd(0)/Cu(I)synergistic catalysis

Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains challenging due to the inertness of coumarins as dienophiles.Herein,we de‐velop a decarboxylative asymmetric[4+2]cycloaddition of 3‐cyanocoumarins with vinyl benzoxa‐zinones,affording the coumarin‐derived condensed rings bearing three continuous stereocenters in high yields with excellent diastereoselectivities(>20/1 d.r.)and enantioselectivities(up to 99%ee).This direct enantioselective reaction was achieved by a Pd(0)/Cu(I)bimetallic catalytic system.The mechanism studies indicated that the synergistic activation effect,in which chiral Cu(I)as an availa‐ble Lewis acid catalyst activates 3‐cyanocoumarin and chiral Pd(0)complex activates benzoxazi‐none by the formation ofπ‐allyl‐palladium intermediate,plays an important role on the stereoselec‐tive control.The current work provides a new activation modes of Cu catalyst in the Pd/Cu bimetal‐lic catalytic system.

ABNORMAL CYCLIZATION IN PREPARATION OF SOME COUMARINS

This paper reports abnormal cyclization in the formation of some coumarins

A Semi-Vectorial Morphological Segmentation Multi-Component Images of Coumarins on Thin Layer Combined with Laser for Better Separation

In this work, we propose an approach for the separation of coumarins from thin-layer morphological segmentation based on the acquisition of multicomponent images integrating different types of coumarins. The first step is to make a segmentation by region, by thresholding, by contour, etc. of each component of the digital image. Then, we proceeded to the calculations of parameters of the regions such as the color standard deviation, the color entropy, the average color of the pixels, the eccentricity from an algorithm on the matlab software. The mean color values atR = 91.20 in red, atB = 213.21 in blue showed the presence of samidin in the extract. The color entropy values HG = 5.25 in green and HB = 4.04 in blue also show the presence of visnadine in the leaves of Desmodium adscendens. These values are used to consolidate the database of separation and discrimination of the types of coumarins. The relevance of our coumarin separation or coumarin recognition method has been highlighted compared to other methods, such as the one based on the calculation of frontal ratios which cannot discriminate between two coumarins having the same frontal ratio. The robustness of our method is proven with respect to the separation and identification of some coumarins, in particular samidin and anglicine.

Two New O-terpenoidal Coumarins, Excavacoumarin A and B from Clausena excavata

Two new O-terpenoidal coumarins named excavacoumarin A (2): B (3), and a known one 1 were isolated from the leaves of Clausena excavata Burm. f. (Rutaceae) collected in Xishuangbanna, Yunnan, Structure elucidation and unambiguous NMR assignments for the title compounds were carried out on the basis of 1D and 2D NMR experiments.

Three New Coumarins from Micromelum integerrimum

Three derivatives of micromelin, named hydramicromelins A-C (1-3), were isolated from the aerial part of Micromelum integerrimum (Buch.-Ham) Roem., respectively. Hydramicromelins A-C (1-3) were epimers which possessed the same plane structure and molecular formula. Their structures were elucidated based on MS and NMR data. The relative configurations of 1-3 were established by NOE analysis.

Prenylated Coumarins from Heracleum stenopterum,Peucedanum praeruptorum,Clausena lansium,and Murraya paniculata

Four hitherto unknown prenylated coumarins,namely 600-O-b-D-apiofuranosylapterin(1),40-O-isobutyroylpeguangxienin(2),6-(3-methyl-2-oxobutyroyl)-7-methoxycoumarin(3),and 6-hydroxycoumurrayin(4),were isolated from the ethanol extract of Heracleum stenopterum,Peucedanum praeruptorum,Clausena lansium,and Murraya paniculata,respectively.Their chemical structures were established on the basis of extensive spectroscopic analysis.Compound 2 exhibited in vitro cytotoxic activity against five human cancer cell lines(HL-60,A-549,SMMC-7721,MCF-7,and SW-480)with IC50 values ranging from 15.9 to 23.2μM.

Microwave promoted one-pot synthesis of 3-(2′-amino-3′-cyano-4′-arylpyrid-6′-yl)coumarins

A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR, ^1H NMR, and mass spectral data.

Syntheses of Coumarins in Environmentally Friendly Ionics Liquids

Syntheses of 3-substituted coumarins by the condensation reaction of salicylaldehyde with activated methylene compounds （ethyl cyanoacetate, malonic acid） are discussed in media of ionic liquids--（2-hydroxyethyl）ammonium carboxylates （formates, acetates, lactates） without utilization of any other catalysts. The dependence of yields of the reaction product is investigated on the structure of ionic liquids （their cations, anions, total polarity and pseudo-pH values）. 3-Substituted coumarins are prepared in high yields in media of these environmentally friendly ionic liquids which serve simultaneously as reaction media and as catalysts. The mentioned ionic liquids are prepared by reactions of corresponding hydroxyethyl-amines with carboxylic acids, and their quantitative analyses being made by potentiometric titration of ionic liquids with perchloric acid in 100% acetic acid.

¹³C-NMR Data from Coumarins from Moraceae Family

Species from Moraceae family stand out in popular medicine and phytotherapy, have been for example used as expectorants, bronchodilators, anthelmintics and treatment of skin diseases, such as vitiligo, due to the presence of compounds with proven biological activity, as the coumarins. Coumarins are lactones with 1,2-benzopyrone basic structure, and are widely distributed in the plant kingdom, both in free form, and in glycosylated form. This work reports a literature review, describing the data of 13C NMR from 53 coumarins isolated from the family Moraceae, and data comparison between genera who presented photochemical studies, in order to contribute to the chemotaxonomy of this family.

Synthesis and Biological Evaluation of Cyclic Imides with Coumarins and Azacoumarins

A series of new N-substituted cyclic imides of coumarins and azacoumarins have been synthesized. All the compounds were screened for their antibacterial and antifungal activities. α-Amylase enzyme inhibition activities of some N-substituted phthalimide derivatives have been explored. All the compounds were characterized by IR, 1H-NMR, and GC-MS.

A review of research on coumarins from Radix Glehniae

Radix Glehniae,with a wide range of chemical components of various pharmacological effects,is widely used in the prevention and treatment of various diseases in clinical practice.It has a broad prospect of development and application.Coumarin,as one of its major active components,also displays good biological activities for analgesia and sedation,antibacteria,antivirus,anti HIV,anti-inflammation,anti-tumor,anti mutation,tyrosinase inhibition,vasodilation and blood pressure reduction.The aim of the present review is to discuss the studies on coumarin components,content determination,pharmacological activities,processing methods and provide a guide for the further development and utilization of Radix Glehniae.