Targeted delivery of atorvastatin via asialoglycoprotein receptor (ASGPR).

Targeted drug delivery platforms can increase the concentration of drugs in specific cell populations, reduce adverse effects, and hence improve the therapeutic effect of drugs. Herein, we designed two conjugates by installing the targeting ligand GalNAc (N-acetylgalactosamine) onto atorvastatin (AT). Compared to the parent drug, these two conjugates, termed G2-AT and G2-K-AT, showed increased hepatic cellular uptake. Moreover, both conjugates were able to release atorvastatin, and consequently showed dramatic inhibition of ß-hydroxy-ß-methylglutaryl-CoA (HMG-CoA) reductase and increased LDL receptors on cell surface.

Atorvastatin-loaded lipid nanoparticles: antitumor activity studies on MCF-7 breast cancer cells.

Atorvastatin is a synthetic statin commonly used in the treatment of hypercholesterolemia. Apart from this, statins appear to have pleiotropic effects, including modulation of cell growth, apoptosis. Through modulation of these pathways, statins have the potential to influence a wide range of disease processes, including cancer. However, poor aqueous solubility (0.1 mg/mL) and poor oral bioavailability has limited therapeutic application of atorvastatin. Present work is an attempt to improve tumor targeting of atorvastatin by incorporating in nanostructured lipid carriers (NLCs) and studying its anticancer activity on MCF-7 cell lines. NLCs of atorvastatin were formulated by high-speed homogenization followed by probe sonication method. The optimized batch of NLCs had a mean size of 130.02 ± 3.1 nm and entrapment efficiency of 90.42 ± 3.7%. The in vitro drug release study by dialysis method indicated that drug entrapped in the NLCs remains entrapped at acidic pH as well as in phosphate buffer of pH 7.4 for a prolonged period of time as compared to plain drug. In vitro cytotoxicity studies on MCF-7 (mammary adenocarcinoma human cell lines) cell lines showed that concentration of drug required for total growth inhibition (TGI) and 50% growth inhibition (GI50) of MCF-7 cells was found to be 27.4 µg/mL and <10 µg/mL respectively, in case of atorvastatin- NLCs which is less than that required in case of plain atorvastatin and almost similar to that of adriamycin. All these findings reinforce the fact that atorvastatin loaded NLCs are promising novel delivery system for treating breast cancer.

α-Unsubstituted Pyrroles by NHC-Catalyzed Three-Component Coupling: Direct Synthesis of a Versatile Atorvastatin Derivative.

A practical one-pot cascade reaction protocol provides direct access to valuable 1,2,4-trisubstituted pyrroles. The process involves an N-heterocyclic carbene (NHC)-catalyzed Stetter-type hydroformylation using glycolaldehyde dimer as a novel C1 building-block, followed by a Paal-Knorr condensation with primary amines. The reaction makes use of simple and commercially available starting-materials and catalyst, an important feature regarding applicability and utility. Low catalyst loading under mild reaction conditions afforded a variety of 1,2,4-substituted pyrroles in a transition-metal-free reaction with high step economy and good yields. This methodology is applied in the synthesis of a versatile Atorvastatin precursor, in which a variety of modifications at the pyrrole core structure are possible.

Enhancing the biocatalytic manufacture of the key intermediate of atorvastatin by focused directed evolution of halohydrin dehalogenase.

Halohydrin dehalogenases (HHDHs) are biocatalytically interesting enzymes due to their ability to form C-C, C-N, C-O, and C-S bonds. One of most important application of HHDH was the protein engineering of HheC (halohydrin dehalogenase from Agrobacterium radiobacter AD1) for the industrial manufacturing of ethyl (R)-4-cyano-3-hydroxybutanoate (HN), a key chiral synthon of a cholesterol-lowering drug of atorvastatin. During our development of an alternative, more efficient and economic route for chemo-enzymatic preparation of the intermediate of atorvastatin, we found that the HheC2360 previously reported for HN manufacture, had insufficient activity for the cyanolysis production of tert-butyl (3 R,5 S)-6-cyano-3,5-dihydroxyhexanoate (A7). Herein, we present the focused directed evolution of HheC2360 with higher activity and enhanced biocatalytic performance using active site mutagenesis. Through docking of the product, A7, into the crystal structure of HheC2360, 6 residues was selected for combined active sites testing (CASTing). After library screening, the variant V84G/W86F was identified to have a 15- fold increase in activity. Time course analysis of the cyanolysis reaction catalyzed by this variant, showed 2- fold increase in space time productivity compared with HheC2360. These results demonstrate the applicability of the variant V84G/W86F as a biocatalyst for the efficient and practical production of atorvastatin intermediate.

Combinatorial synthesis of deuterium-enriched atorvastatin.

It becomes more and more difficult to discover a new drug by existing models. The concept of deuteration has gained attention due to its advantages in the study of clinical pharmacokinetics and metabolic profiles. Herein we built a library of deuterated atorvastatins using combinatorial chemistry, and all 16 D-compounds were characterized by 1H NMR, 13C NMR, MS, and elemental analysis.

Synthesis and evaluation of atorvastatin esters as prodrugs metabolically activated by human carboxylesterases.

We synthesized 11 kinds of prodrug with an esterified carboxylic acid moiety of atorvastatin in moderate to high yields. We discovered that they underwent metabolic activation specifically by the human carboxylesterase 1 (CES1) isozyme. The results suggested that these ester compounds of atorvastatin have the potential to act as prodrugs in vivo.

The total synthesis of calcium atorvastatin.

A practical and convergent asymmetric route to calcium atorvastatin (1) is reported. The synthesis of calcium atorvastatin (1) was performed using the remote 1,5-anti asymmetric induction in the boron-mediated aldol reaction of ß-alkoxy methylketone (4) with pyrrolic aldehyde (3) as a key step. Calcium atorvastatin was obtained from aldehyde (3) after 6 steps, with a 41% overall yield.

Rh(II)-catalyzed [3+2] cycloaddition of 2 H-azirines with N-sulfonyl-1,2,3-triazoles.

Rh(II)-catalyzed intermolecular [3+2] cycloaddition of 2 H-azirines with N-sulfonyl-1,2,3-triazoles is disclosed, in which a series of fully functionalized pyrroles is produced via rhodium azavinyl carbene intermediates. A distinct feature of this reaction is that the azavinyl carbene serves as a [2 C] equivalent, instead of as [1 C] or aza-[3 C] synthons, which have been reported previously in cyclopropanations and [3+n] cycloadditions. Moreover, this methodology has also been successfully applied in the total synthesis of URB447 as well as the formal synthesis of Atorvastatin (Lipitor).