Boon-ek Yingyongnarongkul

Diarylheptanoids, new phytoestrogens from the rhizomes of Curcuma comosa: Isolation, chemical modification and estrogenic activity evaluation.

Three new diarylheptanoids, a 1:2 mixture of (3S)- and (3R)-1-(4-methoxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol (13a and 13b) and 1-(4-hydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-one (15), together with two synthetically known diarylheptanoids 1,7-diphenyl-(1E,3E,5E)-1,3,5-triene (9) and 1-(4-hydroxyphenyl)-7-phenyl-(4E,6E)-4,6-heptadien-3-one (16), and nine known diarylheptanoids, 2, 8, 10-12, 14, a 3:1 mixture of 17a and 17b, and 18, were isolated from the rhizomes of Curcuma comosa Roxb. The absolute stereochemistry of the isolated compounds has also been determined using the modified Moshers method. The isolated compounds and the chemically modified analogues were evaluated for their estrogenic-like transcriptional activity using RT-PCR in HeLa cell line. Some of the isolated diarylheptanoids and their modified analogues exhibited estrogenic activity comparable to or higher than that of the phytoestrogen genistein. Based on the transcriptional activation of both estrogenic targets, Bcl-xL and ERbeta gene expression, the structural features for a diarylheptanoid to exhibit high estrogenic activity are the presence of an olefinic function conjugated with the aromatic ring at the 7-position, a keto group at the 3-position, and a phenolic hydroxyl group at the p-position of the aromatic ring attached to the 1-position of the heptyl chain.

Solid-phase construction: high efficiency dendrimer synthesis using AB3 isocyanate-type monomers

Solid-phase synthesis is an ideal tool for reactions that require high concentrations and excess reagents and forcing chemical conditions. One such chemistry is that required for dendrimer construction. In this paper the synthesis of a series of symmetrical AB(3) isocyanate-type monomers is reported and used for the preparation of tri-branched dendrimers on the solid-phase. This method not only allows isolable dendrimer but can generate high-loading supports and devices for multivalent presentation.

Parallel and multiplexed bead-based assays and encoding strategies.

Advances in high throughput screening (HTS), together with the rapid progress in combinatorial chemistry, genomic and proteomic sciences have dramatically stimulated the development of a variety tools to enable the drug discovery process to become more efficient. Major future challenges in HTS include obtaining high density and good quality data based on assays that are rapid, reliable, inexpensive, sensitive, simple and miniaturised. This paper reviews the development and role of bead-based assays for HTS including DNA and single nucleotide polymorphism (SNP) assays, particularly from a multiplex perspective and evaluating the recent advances in bead-based arrays. The encoding strategies that are commonly used in bead-based assays are highlighted, while the importance of magnetic beads in genomic and proteomic purifications is discussed. In conclusion, bead-based assays offer a powerful promising approach for many aspects of drug discovery.

High transfection efficiency and low toxicity cationic lipids with aminoglycerol-diamine conjugate.

The solid phase synthesis of a library of aminoglycerol-diamine conjugate-based transfection agents having urea linkage between diverse length of diamines and various lengths of hydrophobic tails is described. These compounds were characterized and structure-activity relationships were determined for DNA binding and transfection ability when formulated as cationic liposomes. Cationic lipids with short spacer length and short hydrophobic tails bound to DNA and delivered DNA into HEK293 cells more efficient than those with longer ones. Transfection efficiency of some of the cationic liposomes was superior to that of the commercial transfection agents, Effectene, DOTAP and DC-Chol. The lipids 6Ab and 6Bb did not require the helper lipid DOPE to produce high-efficiency transfection of human cells while displaying minimal cytotoxicity. This suggests that these newly described aminoglycerol-based lipids should be very promising in liposome-mediated gene delivery and illustrate the potential of solid phase synthesis method for non-viral vector discovery.

Synthesis and biological activity of 2-deoxy-20-hydroxyecdysone and derivatives

Abstract The naturally occurring ecdysteroids 2-deoxy-20-hydroxyecdysone (2-D-20-ECD, 2-deoxycrustecdysone), 2-D-20-ECD 3-acetate (2-deoxyecdysterone 3-acetate), 2-D-20-ECD 22-acetate and 2-D-20-ECD 22-benzoate have been partially synthesized from 20-hydroxyecdysone. Moulting hormone activity of these ecdysteroids has been studied using the Musca bioassay.

Asymmetric dihydroxylation of stachysterone C: stereoselective synthesis of 24-epi-abutasterone

Abstract Stachysterone C was synthesized from 20-hydroxyecdysone (20-ECD). Sharpless asymmetric dihydroxylation of this rare ecdysteroid using osmium tetroxide and a chiral ligand afforded 24- epi -abutasterone, another rare ecdysteroid, and its C-24 epimer, abutasterone. High diastereomeric excess of the former ecdysteroid was obtained when the chiral ligands dihydroquinidine 1,4-phthalazinediyl diether and dihydroquinidine 2,5-diphenyl-4,6-pyrimidinediyl diether were employed. The two C-24 epimeric ecdysteroids exhibited similar moulting hormone activity in the Musca bioassay. However, they were significantly less active than 20-ECD.

Regioselective synthesis of 24-epi-pterosterone

Abstract In order to have compounds available for structure-activity relationship studies, the ecdysteroid 24- epi -pterosterone was synthesized from 20-hydroxyecdysone and pterosterone was obtained from Vitex glabrata stem bark. The former was approximately 7-fold less active than the latter in the Musca bioassay for moulting hormone activity.

Synthesis and moulting hormone activity of 3-epi-2-deoxy-20-hydroxyecdysone and analogues

The minor ecdysteroid 3-epi-2-deoxy-20-hydroxyecdysone (3-epi-2-D-20-ECD) has been partially synthesized from 20-hydroxyecdysone. 2-D-5α-20-ECD and the 3-dehydro analogues, 3-dehydro-2-D-20-ECD and 3-dehydro-2-D-5α-20-ECD, have also been synthesized. Moulting hormone activity of these compounds has been studied using the Musca bioassay.

Synthesis and in vitro transfection efficiency of spermine-based cationic lipids with different central core structures and lipophilic tails

Twelve spermine-based cationic lipids with four different central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) and three hydrophobic tails (lauric acid, myristic acid and palmitic acid) were synthesized. The liposomes containing lipids and DOPE showed moderate to good in vitro DNA delivery into HeLa cells. GFP expression experiments revealed that liposomes composed of lipids with 3-amino-1,2-dioxypropyl as a central core structure exhibited highest transfection efficiency under serum-free condition. Whereas, lipid with 2-amino-1,3-dioxypropyl core structure showed highest transfection under 10% serum condition. Moreover, the liposomes and lipoplexes composted of these cationic lipids exhibited low cytotoxicity.

The metabolism of 20-hydroxyecdysone in mice: Relevance to pharmacological effects and gene switch applications of ecdysteroids

Ecdysteroids exert many pharmacological effects in mammals (including humans), most of which appear beneficial, but their mechanism of action is far from understood. Whether they act directly and/or after the formation of metabolites is still an open question. The need to investigate this question has gained extra impetus because of the recent development of ecdysteroid-based gene-therapy systems for mammals. In order to investigate the metabolic fate of ecdysteroids in mice, [1α,2α-(3)H]20-hydroxyecdysone was prepared and injected intraperitoneally to mice. Their excretory products (urine+faeces) were collected and the different tritiated metabolites were isolated and identified. The pattern of ecdysteroid metabolites is very complex, but no conjugates were found, in contrast to the classical fate of the (less polar) endogenous vertebrate steroid hormones. Primary reactions involve dehydroxylation at C-14 and side-chain cleavage between C-20 and C-22, thereby yielding 14-deoxy-20-hydroxyecdysone, poststerone and 14-deoxypoststerone. These metabolites then undergo several reactions of reduction involving, in particular, the 6-keto-group. A novel major metabolite has been identified as 2β,3β,6α,22R,25-pentahydroxy-5β-cholest-8(14)-ene. The formation of this and the other major metabolites is discussed in relation to the various effects of ecdysteroids already demonstrated on vertebrates.