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Spectral studies on coumarins and the determination of …

Apart from the above works, the present review focuses on the recent research done on coumarins, which basically incudes the synthesis of therapeutically useful coumarins alongwith the SAR, so as to give an overview of essential structural features required for therapeutic activities. 3

First-generation hydroxycoumarins were introduced as rodenticides in the late 1940s.

A series of coumarin–triazine hybrids, reported as novel non-nucleoside reverse transcriptase inhibitors (NNRTIs), has been explored against different strains of HIV, that is HIV-1 (III-B), HIV-2 (ROD), and double RT mutant HIV-1 (K103N and Y181C). Compound 41 is the most potent with IC50 value of 1 lg/ml against all strains whereas compounds 58-61 display selective activity against HIV-163. Coumarin–chalcone hybrids are inactive against both HIV-1 and HIV-2 strains 64.

Knoevenagel Reaction in MMImMSO4: Synthesis of Coumarins

Fais A. e al resynthesized coumarin- resveratrol hybrids by a traditional Perkin reaction carried out in refluxing dimethylsulfoxide (DMSO) between o-hydroxybenzaldehyde (or their methoxy substituted derivatives) and the corresponding aryl acetic acids, using dicyclohexylcarbodiimide (DCC) as dehydrating agent to investigate the structure activity relationship. Tyrosinase activity assays were performed with L-DOPA as substrate with slight modifications and activity of mushroom tyrosinase was determined by sectrophotometric technique. IC 50 values of these compounds were measured. The result showed that these compounds (figure 62) exhibited tyrosinase inhibitory activity. 3-(3’,4’,5’-trihydroxyphenyl - 6, 8 - dihydroxy coumarin was found to be the most potent compound (0.27mM) more than umbelliferone (0.42mM) used as a reference compound. The kinetic studies revealed that these compounds non-competitive tyrosine kinase inhibition and the number and the position of free hydroxyl groups play an important role in determining the activity.

The development of coumarin anticoagulants occurred during the Second World War and they were introduced as effective antithrombotic agents for treatment of thromboembolic disease in humans.

Studies on the mode of action of coumarins (coumarin, …

A recent study by Tsay et al. reports that direct hinging of benzimidazole nucleus with coumarin (Fig. 54-56) affords better antiviral profile (IC50 value of 3.0 lM) in comparison to compounds 52 (IC50 value of 10 lM). It is attributed to methylenethio linker in 52, which discourages intra-molecular H-bond between benzimidazole and coumarin. Compounds 54-60 exhibited potent anti-HCV activity with IC50 values of 3.0, 5.5 and 20 lM, respectively. SAR studies have revealed that attachment of methyl group(s) to benzimidazole (Fig. 54, 55) lead to remarkable increase in the activity. Appendage of methyl, bromo or methoxy substituent on coumarin nucleus reduces cytotoxicity and anti-HCV activity whereas fusion of benzene ring (8) increases the activity. Incorporation of b-D-ribofuranose 40 also leads to potent compounds 62.

Macrocyclic molecules have attracted much attention because of their potential use in a variety of chemical processes, complexation ability, selective complexing agents for metal ions, and photo-induced electron transfer since its discovery by Pedersen. 4- aminomethyl coumarin crown ether derivatives (Fig.63) have been studied for their antifungal activity. The complexation selectivity of coumarin fused crown ethers has often been explained in terms of the size-fit concept which states that crown ether forms a more stable complex with the cation which is more suitable in size for the crown ether cavity 65.

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The chemotaxonomic significance of these isolated coumarins ..

Viral and Human immunodeficiency viral (HIV) infections have no complete and effective remedy, and hence are posing the greatest threats to human health. The classical treatment involves use of drugs that have serious side effects. Owing to the urgent need for new drugs, compounds having multiple functional scaffolds are synthesized 60. Heteronuclei such as imidazopyridine (Fig. 49), purine (Fig. 50), benzoxazole (Fig. 51), benzothiazole (Fig. 52) and benzimidazole (Fig. 53) and its nucleoside have been linked to the coumarin nucleus via methylenethio linker, and evaluated for antiviral activity on HUH 5–2 cells.

Labanos / Raphanus sativus / radish: Philippine …

SAR study suggested that while coumarin is an essential scaffold for the activity, the potency decreased in the order of purine conjugates (figure 50, EC50 values of 2.0 lM), imidazopyridine conjugates (figure 49, EC50 values of 6.8 lM) and benzoxazole conjugates (Fig. 51, EC50 values of 12 lM). Further, presence of a bromo or methoxy substituent on coumarin nucleus increases the activity of the conjugates. Incorporation of an arene moiety on benzimidazole does not improve the activity whereas peracetyl 2-deoxyb- D-glucose increases the Hepatitis C virus (HCV) inhibition by 8.2-fold compared to unsubstituted benzimidazole conjugates 61.

Makahiya (Mimosa pudica) bashful mimosa, sensitive …

Cytochrome P450 (CYP) is a large family of hemoproteins present in most forms of life (plants, bacteria, and mammals). They are concerned with metabolism in vital processes and many of them with the ability to activate carcinogens have been implicated as risk factors for cancers Coumarin-linked imidazoles (Fig. 48) have been proved to be most promising compounds as CYP450 inhibitors. It (48) has been shown to display stronger CYP19 inhibitory activity (IC50 = 47 nM) than the standard drug fadrozole (IC50=52 nM) with excellent selectivity over CYP11B1 and CYP11B2 59.

Rhodium-Catalyzed Asymmetric 1,4-Addition and Its …

The most promising inhibitor, coumarin linked piperazine (Fig. 47) has been also crystallized in complex with CK2, and the experimental binding mode has been used to derive a linear interaction energy (LIE) model. In the last few years, intensive screening program has been performed, using both conventional and in silico approaches, with the aim of discovering novel potent and selective CK2 inhibitors 58.

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