10-Benzoyl-1,8-dihydroxy-9(10H)-anthracenones: Synthesis and biological properties

Phosphoric Acid-Catalyzed Enantioselective Synthesis of Axially Chiral Anthrone-based Compounds

Anthrones and analogues are structural cores shared by diverse pharmacologically active natural and synthetic compounds. The sp² -rich nature imposes inherent obstruction to introduce stereogenic element onto the tricyclic aromatic backbone. In our pursuit to expand the chemical space of axial chirality, a novel type of axially chiral anthrone-derived skeleton was discovered. This work establishes oxime ether as suitable functionality to furnish axial chirality on symmetric anthrone skeletons through stereoselective condensation of the carbonyl entity with long-range chirality control. The enantioenriched anthrones could be elaborated into dibenzo-fused seven-membered N-heterocycles containing well-defined stereogenic center via Beckmann rearrangement with axial-to-point chirality conversion.

A facile synthesis of 10-arylmethylene anthracenones under microwave irradiation

10-Arylmethylene anthracenones were synthesised by the condensation of aromatic aldehydes with anthracenone using sodium hydroxide as catalyst under microwave irradiation in good yields.

Design, synthesis and in vitro degradation of a novel co-drug for the treatment of psoriasis

Psoriasis is a common, chronic and relapsing inflammatory skin disease. It affects approximately 2% of the western population and has no cure. Combination therapy for psoriasis often proves more efficacious and better tolerated than monotherapy with a single drug. Combination therapy could be administered in the form of a co-drug, where two or more therapeutic compounds active against the same condition are linked by a cleavable covalent bond. Similar to the pro-drug approach, the liberation of parent moieties post-administration, by enzymatic and/or chemical mechanisms, is a pre-requisite for effective treatment. In this study, a series of co-drugs incorporating dithranol in combination with one of several non-steroidal anti-inflammatory drugs, both useful for the treatment of psoriasis, were designed, synthesized and evaluated. An ester co-drug comprising dithranol and naproxen in a 1:1 stoichiometric ratio was determined to possess the optimal physicochemical properties for topical delivery. The co-drug was fully hydrolyzed in vitro by porcine liver esterase within four hours. When incubated with homogenized porcine skin, 9.5% of the parent compounds were liberated after 24 h, suggesting in situ esterase-mediated cleavage of the co-drug would occur within the skin. The kinetics of the reaction revealed first order kinetics, Vmax = 10.3 μM·min-1 and Km = 65.1 μM. The co-drug contains a modified dithranol chromophore that was just 37% of the absorbance of dithranol at 375 nm and suggests reduced skin/clothes staining. Overall, these findings suggest that the dithranol-naproxen co-drug offers an attractive, novel approach for the treatment of psoriasis.

Redermination of 9,9'-bianthracene-10,10'(9H,9'H)-dione

The crystal structure of the title compound, C₂₈H₁₈O₂, was originally determined by Ehrenberg [(1967 ▶). Acta Cryst. 22, 482–487] using intensity data obtained from Weissenberg photographs. The current determination provides a crystal and mol­ecular structure with a significantly higher precision and presents standard uncertainties on geometric parameters which are not available from the original work. The mol­ecule lies on a crystallographic twofold rotation axis which bis­ects the C—C bond [1.603 (3) Å] which joins the two anthracen-9(10H)-one units.

2-Arylalkyl-substituted anthracenones as inhibitors of 12-lipoxygenase enzymes. 2. Structure-activity relationships of the linker chain

A series of 2-arylalkyl-substituted anthracenones were tested as inhibitors of three types of 12-lipoxygenase isoforms in epidermal homogenate of mice, bovine platelets and porcine leukocytes. Their inhibitory activities were compared with those to inhibit the 5-lipoxygenase enzyme in bovine leukocytes. The compounds were synthesised by Marschalk, Wittig or Horner-Emmons reaction at the anthracenedione stage and then reduced to the anthracenones. Structure-activity relationship for the chain linking the anthracenone nucleus and the phenyl ring terminus was investigated. The 2-phenylethyl analogues were among the most potent inhibitors, and 3,4-dimethoxy-substituted 10f was identified as a selective inhibitor of the 12-LO enzymes over 5-LO. Selectivity for 12-LO isoforms was observed with an increase in the overall lipophilicity of the inhibitors. However, none of the linker chains of the 2-substituted anthracenones provided inhibitors that were able to discriminate between the 12-LO isoforms.

10-Phenylbutyryl-substituted anthracenones as inhibitors of keratinocyte growth and LTB(4) biosynthesis

A recent observation that phenylbutyryl anthracenone 2, an analogue of the antipsoriatic anthralin, is a potent inhibitor of leukotriene B(4) (LTB(4)) biosynthesis has prompted a search of other anthracenones with improved antiproliferative activity. In that direction, a limited number of analogues related to 2 have been prepared and evaluated in the HaCaT keratinocytes proliferation and in the polymorphonuclear leukocyte LTB(4) assay. The 4-methoxy analogue 2a and the side chain methylated 2l retain the full inhibitory activity of 1 against LTB(4) biosynthesis while their antiproliferative activity is markedly enhanced and comparable to that of the antipsoriatic anthralin. In contrast to anthralin, cytotoxic effects against cell membranes are strongly reduced as documented by the LDH activity released from cytoplasm of keratinocytes.

Anti-inflammatory profile of N-phenylpyrazole arylhydrazone derivatives in rats

A series of synthetic N-phenylpyrazole arylhydrazone compounds, rationally designed as mixed-hybrid isosteres of two known inhibitors of prostaglandin synthase and 5-lipoxygenase enzymes, BW-755c and CBS-1108, has been investigated for anti-inflammatory activity in the carrageenan-induced pleurisy model in rats. The compounds have different oxygenated substituent groups in the aryl group of the hydrazone framework to ensure a different range of redox properties. A new arylhydrazone derivative, 2,6-di-tert-butyl-4-(4-nitro-3-methyl-N-phenylpyrazol-5-yl-hydr azonomethyl)phenol, was also synthesized and tested for anti-inflammatory activity. Although all the compounds significantly inhibited (by 30-90%) neutrophil accumulation in the pleural cavity, there was great variability in the anti-oedematogenic effect of the compounds (3-96%). 5-(4'-Hydroxy-3'-methoxybenzylidene)hydrazone-3-methyl-4-nitrop henylpyrazole was the most active compound in this series; it had a remarkable antiinflammatory profile, almost blocking both assays. In contrast, the compound with a 2,6-di-tert-butylated hydroxybenzene ring on the hydrazone group inhibited neutrophil migration only. These results will be useful for further structure-activity relationship studies devoted to improving the dual prostaglandin synthase-5-lipoxygenase activity of these derivatives and determining the minimum structural requirements necessary for this activity.

10-omega-phenylalkyl-9(10H)-anthracenones as inhibitors of keratinocyte growth with reduced membrane damaging properties

Work aimed at further improving the benefit to risk ratio of the antipsoriatic agent anthralin has led to 10-omega-phenylalkyl-9(10H)-anthracenones, members of which are equally potent as inhibitors of the growth of HaCaT keratinocytes. In contrast to anthralin, induction of membrane injury is strongly reduced as documented by the release of LDH activity from cytoplasm of keratinocytes.