Enhanced Anti-Tumor Effect of Folate-Targeted FA-AMA-hyd-DOX Conjugate in a Xenograft Model of Human Breast Cancer.

Folate-aminocaproic acid-doxorubicin (FA-AMA-hyd-DOX) was firstly synthesized by our group. It was indicated that FA-AMA-hyd-DOX was pH-responsive, and had strong cytotoxicity on a folate receptor overexpressing cell line (KB cells) in vitro. The aim of our study was to further explore the potential use of FA-AMA-hyd-DOX as a new therapeutic drug for breast cancer. The cellular uptake and the antiproliferative activity of the FA-AMA-hyd-DOX in MDA-MB-231 cells were measured. Compared with DOX, FA-AMA-hyd-DOX exhibited higher targeting ability and cytotoxicity to FR-positive tumor cells. Subsequently, the tissue distribution of FA-AMA-hyd-DOX was studied, and the result confirmed that DOX modified by FA can effectively increase the selectivity of drugs in vivo. After determining the maximum tolerated dose (MTD) of FA-AMA-hyd-DOX in MDA-MB-231 tumor-bearing nude mice, the antitumor effects and the in vivo safety of FA-AMA-hyd-DOX were systematically evaluated. The data showed that FA-AMA-hyd-DOX could effectively increase the dose of DOX tolerated by tumor-bearing nude mice and significantly inhibit MDA-MB-231 tumor growth in vivo. Furthermore, FA-AMA-hyd-DOX treatment resulted in almost no obvious damage to the mice. All the positive data suggest that FA-targeted FA-AMA-hyd-DOX is a promising tumor-targeted compound for breast cancer therapy.

pH-dependent, thermosensitive polymeric nanocarriers for drug delivery to solid tumors.

Polymeric micelles are promising carriers for anti-cancer agents due to their small size, ease of assembly, and versatility for functionalization. A current challenge in the use of polymeric micelles is the sensitive balance that must be achieved between stability during prolonged blood circulation and release of active drug at the tumor site. Stimuli-responsive materials provide a mechanism for triggered drug release in the acidic tumor and intracellular microenvironments. In this work, we synthesized a series of dual pH- and temperature-responsive block copolymers containing a poly(ε-caprolactone) (PCL) hydrophobic block with a poly(triethylene glycol) block that were copolymerized with an amino acid-functionalized monomer. The block copolymers formed micellar structures in aqueous solutions. An optimized polymer that was functionalized with 6-aminocaproic acid (ACA) possessed pH-sensitive phase transitions at mildly acidic pH and body temperature. Doxorubicin-loaded micelles formed from these polymers were stable at blood pH (~7.4) and showed increased drug release at acidic pH. In addition, these micelles displayed more potent anti-cancer activity than free doxorubicin when tested in a tumor xenograft model in mice.

Investigation of substituted 6-aminohexanoates as skin penetration enhancers.

Skin penetration enhancers are compounds used to facilitate the transdermal delivery of drugs that are otherwise not sufficiently permeable. Through a synthetic route implementing two series of esters, we generated transdermal penetration enhancers by a multi-step reaction with substituted 6-aminohexanoic acid. We present the synthesis of all newly prepared compounds here with structural confirmation accomplished by (1)H NMR, (13)C NMR, IR and mass spectroscopy (MS). The lipophilicity (logk) of all compounds was determined via RP-HPLC and their hydrophobicity (logP/ClogP) was also calculated using two commercially available programs. Ab initio calculations of geometry and molecular dynamic simulations were employed to investigate the 3-dimensional structures of selected compounds. The transdermal penetration-enhancing activity of all the synthesized esters were examined in vitro and demonstrated higher enhancement ratios than oleic acid. Compounds 2e (C(10) ester chain) and 2f (C(11) ester chain) exhibited the highest enhancement ratios. It can be concluded that the series non-substituted at the C((2)) position by a ω-lactam ring showed significantly higher activity than those with azepan-2-one. None of the prepared compounds penetrated through the skin. All of the investigated agents demonstrated minimal anti-proliferative activity using the SK-N-MC neuroepithelioma cell line (IC(50)>6.25µM), suggesting these analogs would have a low cytotoxic profile when administered in vivo as chemical penetration enhancers. The correlation between the chemical structure of the studied compounds and their lipophilicity is discussed in regards to transdermal penetration-enhancing activity.

Novel yellow compounds, dilysyldipyrrolones A and B, formed from xylose and lysine by the Maillard reaction.

When a solution containing xylose and L-lysine is heated under weakly acidic conditions, it turns brown by the Maillard reaction. We isolated here two novel yellow compounds from a heated solution containing xylose and lysine, and identified pyrrolyl-methylidene-pyrrolone derivatives named dilysyldipyrrolones A and B. Their chemical structures were elucidated by instrumental analyses as 6-[[1-[(S)-5-amino-1-carboxypentyl]-3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-methyl-1,2H-pyrrol-3-one-1-ly]-(S)-2-amino-hexanoic acid (dilysyldipyrrolone A) and 6-[[1-[(S)-5-amino-5-carboxypentyl]-3-hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-methyl-1,2H-pyrrol-3-one-1-yl]-(S)-2-amino-hexanoic acid (dilysyldipyrrolone B). These were the major pigments in the heated solution.

Synthesis and enhancing effect of transkarbam 12 on the transdermal delivery of theophylline, clotrimazole, flobufen, and griseofulvin.

PURPOSE: Dodecyl-6-aminohexanoate (DDEAC) is a transdermal permeation enhancer with excellent activity, low toxicity, and no dermal irritation. We hypothesized that DDEAC reacts with air CO2 to form a two-chain ammonium carbamate--Transkarbam 12 (T12)--which is responsible for the enhancing effect. METHODS: DDEAC and T12 were synthesized, their structures were confirmed by spectral methods, and their enhancing activity was studied using the Franz diffusion cell and human skin. A high-performance liquid chromatography method was developed for determination of T12, and its biodegradability was evaluated using porcine esterase. RESULTS: Only the carbamate salt T12 was responsible for the high enhancing activity; DDEAC tested under argon to avoid reaction with CO2 was inactive. T12 enhanced transdermal permeation of drugs covering a wide range of physicochemical properties, including theophylline (enhancement ratio up to 55.6), clotrimazole (7.7), flobufen (5.0), and griseofulvin (24). The activity was pH-dependent, further confirming the importance of the carbamate structure. The metabolization of T12 followed a second-order kinetics with t(1/2) = 31 min. CONCLUSION: Our results indicate that T12 is a promising biodegradable permeation enhancer for a wide range of drugs, and the structurally novel group of carbamate enhancers warrants further investigation.

Synthesis and characterization of fluorescent neutral lipid analogs containing N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-aminohexanoic acid.

The synthesis, identification and characterization of neutral lipid analogs containing N-(7-nitro-2,1,3-benzoxadiazoi-4-yl)-aminocaproic acid are reported. The acyl-imidazole derivative of the fluorescent fatty acid was used to esterify L-alpha-glycerophosphorylcholine. Fluorescent phosphatidylcholines were converted to the corresponding diacylglycerols by phospholipase C digestion. Triacylglycerols were formed by esterification with either fluorescent fatty acid-imidazole or non-fluorescent fatty acid anhydride. The 11 compounds synthesized were identified by a combination of thin layer chromatography, liquid secondary ion mass spectrometry and enzymatic digestion. A solvent system for identifying all eleven analogs by thin layer chromatography is presented. The fluorescence characteristics of these analogs are consistent with previously observed parameters of NBD-lipid analogs, including the density-dependent quenching of analogs containing multiple NBD fluorophores. These analogs mimic native lipids, as evidenced by digestions with the enzymes, porcine pancreatic lipase, phospholipase C and phospholipase A2.

epsilon-Aminocaproic acid esters as transdermal penetration enhancing agents.

The synthesis of epsilon-aminocaproic acid esters is described. Two representative members from a group of five of the 1-alkyl homologues synthetized as flexible analogues of 1-alkylazacyclohepatanone derivatives were evaluated in vitro for their effectiveness on the transport of theophylline through the excised human cadaver skin in comparison with Azone. The 1-octyl- and 1-dodecyl-epsilon-aminocaproic acid esters (OCEAC and DDEAC) show excellent penetration enhancement. Donor samples contained 2.5% theophylline and 1% enhancers tested in three different vehicles. Fluxes of theophylline were increased with OCEAC about 19 times from olive oil, 45 times from water, and about 38 times from water-propylene glycol (3:2) vehicle toward controls (with DDEAC about 17, 39, and 35 times, respectively) and they were markedly higher than Azone under the given conditions. Acute LD50's (i.p. in mice) of OCEAC (DDEAC) were 245 mg/kg (352 mg/kg), with a slightly lower toxicity than Azone. OCEAC and DDEAC did not exhibit acute dermal irritation in vivo on rabbits at a 5% concentration in white petrolatum.

The detection of an early advanced glycation product which co-elutes with the Amadori product on aminophenylboronate affinity chromatography.

The production of an antiserum recognizing an early advanced glycation product of glycated human serum albumin (HSA) is reported. The antiserum was produced with the intention of recognizing the Amadori product, i.e. the monofructosamine derivative, of any glycated protein. In retrospect, however, the immunogen appears to have been transformed in vivo which led to the production of antibodies to an early advanced glycation product. Two-site immunometric and competitive ELISAs showed that the affinity-purified antibodies recognized glycated HSA only after it had been stored for several months. This recognition, by the antibody, was more specific for the transformed product than for the original hapten (1-amino-1-deoxy-D-fructose-6-aminohexanoic acid) used for immunization by a factor of more than 1,000. These antibodies also detected immunoreactive material present in the elution fraction after in vivo glycated HSA had been chromatographed on an aminophenylboronate affinity column, indicating that an early advanced glycation product can co-elute with the Amadori product of glycated HSA on aminophenylboronate affinity chromatography. This suggests that the antiserum recognized an early advanced glycation product that also contained cis-diols as does the Amadori product, and may prove useful in the early detection of clinical complications in diabetic patients.

[The production of pharmacologically active acexamic acid derivatives. I. The production of acexamic acid and its zinc salt]. / Cercetari privind obtinerea unor derivati ai acidului acexamic farmacologic activi. (I). Obtinerea acidului acexamic si a sarii de zinc a acestuia.

In view of studying the pharmacological properties of zinc acexamath a simple and cheap method for the synthesis of acexamic acid by re-evaluating some indigenous raw materials is presented. The conversion of acexamic acid into the corresponding zinc salt is highly efficient by reacting this acid with zinc oxide or zinc carbonate.

Labeling of DNA probes with a photoactivatable hapten.

A photoactivatable reagent for introducing haptens onto DNA probes has been prepared using a commercially available bifunctional linker arm reagent and amino-derivatized 2,4-dinitrophenyl (DNP). The resulting compound (photo-DNP) couples efficiently to DNA using an ordinary sunlamp. Under optimum conditions, about 7-23 DNP molecules per 1000 bases are incorporated into the DNA. Hybridization experiments demonstrate that as little as 1.5 x 10(5) copies of target DNA can be detected by filter hybridization with a photo-DNP-labeled probe and immunochemical detection.

Nitrophenylated derivatives of epsilon-aminocaproic acid: synthesis and physico-chemical characterization.

Methods for the synthesis of the mono-, di- and tri-nitro derivatives of epsilon-aminocaproic acid are presented. Special attention is given to the purification procedure, as we have found that methods recommended in the literature do not produce a single product. Evidence is presented which shows that recrystallizing the haptens from hot ethanol produces a by-product which is the ethyl ester of the haptens. Characterization methods and physical properties of the nitro-phenylated derivates of epsilon-aminocaproic acid are summarized.