Synthesis and antioxidant activity of long chain alkyl hydroxycinnamates

Long chain alkyl hydroxycinnamates (8e21) were synthesized from the corresponding half esters of malonic acid (5e7) and benzaldehyde derivatives by Knoevenagel condensation. The total antioxidant capacity of these hydroxycinnamyl esters was evaluated using DPPH and ABTS assays. The observed antioxidant activity was highest for esters of caffeic acid followed by sinapic esters and ferulic esters. The parameters for drug-likeness of these hydroxycinnamyl esters were also evaluated according to the Lipinski’s ‘rule-of-five’. All the ester derivatives were found to violate one of the Lipinski’s parameters (cLogP >5), even though they have been found to be soluble in protic solvents. The predictive topological polar surface area (TPSA) data allow concluding that they could have a good capacity for penetrating cell membranes. Therefore, one can propose these novel lipophilic compounds as potential antioxidants for tackling oxidative processes.info:eu-repo/semantics/publishedVersio

A simple two-step synthesis of avenanthramides, constituents of oats (Avena sativa L)

2074-2078A simple two-step general procedure has been developed to prepare naturally occurring and synthetic avenanthramides, constituents of oats (Avena sativa L). Reaction of anthranilic acid 1 with Meldrum’s acid 2 gives half amide of malonic acid 3 which on condensation with different benzaldehyde derivatives 4a-m gives avenanthramides 5a-m of which 5a-d are natural, 5e-g are their methyl ethers and 5h-m are synthetic

Synthesis of olivacene, a constituent of <i>Archilejeunea olivacea</i>

2662-2664A simple synthesis of olivacene 1, a naturally occurring sesquiterpenoid hydrocarbon isolated from Archilejeunea olivacea has been described

Facile syntheses of 4-hydroxy-7-methyl-1-indanone, isolated from cyanobacterium Nostoc commune

1597-1599Two different high yielding synthetic routes both starting with 6-methylcoumarin 2 have been described to prepare 4-hydroxy-7-methyl-1-indanone 1, a constituent of cyanobacterium Nostoc commune having antibacterial activity. In the first route, methylative lactone ring opening of the coumarin 2 followed by catalytic hydrogenation of the cinnamyl double bond and subsequent PPA cyclization gives the methyl ether 5 of 1 which on demethylation gives 1 in excellent yield. Alternatively, catalytic hydrogenation of 2 followed by fusion with anhydrous AlCl₃ gives high yield of 1 in just two steps

Unusual KMnO₄oxidation product of β-ionone

1038-1041KMnO₄ oxidation of β-ionone has been reinvestigated. The structure proposed for the hydroxyionolactone 3 obtained in this reaction is supported by MS, UV, IR, ¹H and ¹³C NMR data and further confirmed by single crystal X-ray diffraction studies of the bromolactone 8

Inulavosin and its benzo-derivatives, melanogenesis inhibitors, target the copper loading mechanism to the active site of tyrosinase

Tyrosinase, a melanosomal membrane protein containing copper, is a key enzyme for melanin synthesis in melanocytes. Inulavosin inhibits melanogenesis by enhancing a degradation of tyrosinase in lysosomes. However, the mechanism by which inulavosin redirects tyrosinase to lysosomes is yet unknown. The analyses of structure-activity relationship of inulavosin and its benzo-derivatives reveal that the hydroxyl and the methyl groups play a critical role in their inhibitory activity. Intriguingly, the docking studies to tyrosinase suggest that the compounds showing inhibitory activity bind through hydrophobic interactions to the cavity of tyrosinase below which the copper-binding sites are located. This cavity is proposed to be required for the association with a chaperon that assists in copper loading to tyrosinase in Streptomyces antibioticus. Inulavosin and its benzo-derivatives may compete with the copper chaperon and result in a lysosomal mistargeting of apo-tyrosinase that has a conformational defect