1.The biosynthetic origin of irregular monoterpenes in Lavandula: isolation and biochemical characterization of a novel cis-prenyl diphosphate synthase gene, lavandulyl diphosphate synthase.
Demissie ZA1, Erland LA, Rheault MR, Mahmoud SS. J Biol Chem. 2013 Mar 1;288(9):6333-41. doi: 10.1074/jbc.M112.431171. Epub 2013 Jan 10.
Lavender essential oils are constituted predominantly of regular monoterpenes, for example linalool, 1,8-cineole, and camphor. However, they also contain irregular monoterpenes including lavandulol and lavandulyl acetate. Although the majority of genes responsible for the production of regular monoterpenes in lavenders are now known, enzymes (including lavandulyl diphosphate synthase (LPPS)) catalyzing the biosynthesis of irregular monoterpenes in these plants have not been described. Here, we report the isolation and functional characterization of a novel cis-prenyl diphosphate synthase cDNA, termed Lavandula x intermedia lavandulyl diphosphate synthase (LiLPPS), through a homology-based cloning strategy. The LiLPPS ORF, encoding for a 305-amino acid long protein, was expressed in Escherichia coli, and the recombinant protein was purified by nickel-nitrilotriacetic acid affinity chromatography. The approximately 34.5-kDa bacterially produced protein specifically catalyzed the head-to-middle condensation of two dimethylallyl diphosphate units to LPP in vitro with apparent Km and kcat values of 208 ± 12 μm and 0.
2.Identification of PDE6D as a molecular target of anecortave acetate via a methotrexate-anchored yeast three-hybrid screen.
Shepard AR1, Conrow RE, Pang IH, Jacobson N, Rezwan M, Rutschmann K, Auerbach D, Sriramaratnam R, Cornish VW. ACS Chem Biol. 2013 Mar 15;8(3):549-58. doi: 10.1021/cb300296m. Epub 2013 Jan 9.
Glaucoma and age-related macular degeneration are ocular diseases targeted clinically by anecortave acetate (AA). AA and its deacetylated metabolite, anecortave desacetate (AdesA), are intraocular pressure (IOP)-lowering and angiostatic cortisenes devoid of glucocorticoid activity but with an unknown mechanism of action. We used a methotrexate-anchored yeast three-hybrid (Y3H) technology to search for binding targets for AA in human trabecular meshwork (TM) cells, the target cell type that controls IOP, a major risk factor in glaucoma. Y3H hits were filtered by competitive Y3H screens and coimmunoprecipitation experiments and verified by surface plasmon resonance analysis to yield a single target, phosphodiesterase 6-delta (PDE6D). PDE6D is a prenyl-binding protein with additional function outside the PDE6 phototransduction system. Overexpression of PDE6D in mouse eyes caused elevated IOP, and this elevation was reversed by topical ocular application of either AA or AdesA.
3.β-Keto-dioxinones and β,δ-diketo-dioxinones in biomimetic resorcylate total synthesis.
Cookson R1, Barrett TN1, Barrett AG1. Acc Chem Res. 2015 Mar 17;48(3):628-42. doi: 10.1021/ar5004169. Epub 2015 Feb 17.
Resorcylates are a large group of bioactive natural products that are biosynthesized from acetate and malonate units via the intermediacy of polyketides. These polyketides undergo cyclization reactions to introduce the aromatic core. The bioactivities of the resorcylates including resorcylate macrocyclic lactones include anticancer, antimalarial, mycotoxicity, antifungal, and antibiotic properties, and several compounds in the series are already in use in medicine. Examples are prodrugs derived from mycophenolic acid as immunosuppressants and the Hsp-90 inhibitor, AT13387, which is in phase-II clinical trials for the treatment of small cell lung cancer and melanoma. In consequence of these biological activities, methods for the concise synthesis of diverse resorcylates are of considerable importance. In natural product chemistry, biomimetic total synthesis can have significant advantages including functional group tolerance in key steps, the minimization of the use of protection and deprotection reactions and the shortening of the total number of synthetic steps.
4.Screening baccharin analogs as selective inhibitors against type 5 17β-hydroxysteroid dehydrogenase (AKR1C3).
Zang T1, Verma K2, Chen M1, Jin Y1, Trippier PC3, Penning TM4. Chem Biol Interact. 2015 Jun 5;234:339-48. doi: 10.1016/j.cbi.2014.12.015. Epub 2014 Dec 31.
Aldo-keto reductase 1C3 (AKR1C3), also known as type 5 17β-hydroxysteroid dehydrogenase, is a downstream steroidogenic enzyme and converts androgen precursors to the potent androgen receptor ligands: testosterone and 5α-dihydrotestosterone. Studies have shown that AKR1C3 is involved in the development of castration resistant prostate cancer (CRPC) and that it is a rational drug target for the treatment of CRPC. Baccharin, a component of Brazilian propolis, has been observed to exhibit a high inhibitory potency and selectivity for AKR1C3 over other AKR1C isoforms and is a promising lead compound for developing more potent and selective inhibitors. Here, we report the screening of fifteen baccharin analogs as selective inhibitors against AKR1C3 versus AKR1C2 (type 3 3α-hydroxysteroid dehydrogenase). Among these analogs, the inhibitory activity and selectivity of thirteen compounds were evaluated for the first time. The substitution of the 4-dihydrocinnamoyloxy group of baccharin by an acetate group displayed nanomolar inhibitory potency (IC50: 440 nM) and a 102-fold selectivity over AKR1C2.