Author: novelconjugates

Novel derivatives of abietic and dehydroabietic acid

Abietic and dehydroabietic acid are interesting diterpenes with a highly diverse repertoire of associated bioactivities. They have, among others, shown antibacterial and antifungal activity, potentially valuable in the struggle against the increasing antimicrobial resistance and imminent antibiotic shortage. In this paper, we describe the synthesis of a set of 9 abietic and dehydroabietic acid derivatives containing amino acid side chains and their in vitro antimicrobial profiling against a panel of human pathogenic microbial strains. Furthermore, their in vitro cytotoxicity against mammalian cells was evaluated. The experimental results showed that the most promising compound was 10 [methyl N-(abiet-8,11,13-trien-18-yl)-d-serinate], with an MIC90 of 60 μg/mL against Staphylococcus aureus ATCC 25923, and 8 μg/mL against methicillin-resistant S. aureusStaphylococcus epidermidis and Streptococcus mitis. The IC50 value for compound 10 against Balb/c 3T3 cells was 45 μg/mL. ( 2017 Jan 1;25(1):132-137.)

Galloyl-RGD as a new cosmetic ingredient

Background

The cosmetics market has rapidly increased over the last years. For example, in 2011 it reached 242.8 billion US dollars, which was a 3.9% increase compared to 2010. There have been many recent trials aimed at finding the functional ingredients for new cosmetics. Gallic acid is a phytochemical derived from various herbs, and has anti-fungal, anti-viral, and antioxidant properties. Although phytochemicals are useful as cosmetic ingredients, they have a number of drawbacks, such as thermal stability, residence time in the skin, and permeability through the dermal layer. To overcome these problems, we considered conjugation of gallic acid with a peptide.

Results

We synthesized galloyl-RGD, which represents a conjugate of gallic acid and the peptide RGD, purified it by HPLC and characterized by MALDI-TOF with the aim of using it as a new cosmetic ingredient. Thermal stability of galloyl-RGD was tested at alternating temperatures (consecutive 4°C, 20°C, or 40°C for 8 h each) on days 2, 21, 41, and 61. Galloyl-RGD was relatively safe to HaCaT keratinocytes, as their viability after 48 h incubation with 500 ppm galloyl-RGD was 93.53%. In the group treated with 50 ppm galloyl-RGD, 85.0% of free radicals were removed, whereas 1000 ppm galloyl-RGD suppressed not only L-DOPA formation (43.8%) but also L-DOPA oxidation (54.4%).

Conclusions

Galloyl-RGD is a promising candidate for a cosmetic ingredient. (. 2014; 15: 18.)

Novel 3-phenylcoumarin-lipoic acid conjugates as multi-functional agents for potential treatment of Alzheimer’s disease

New series of triazole-containing 3-phenylcoumarin-lipoic acid conjugates were designed as multi-functional agents for treatment of Alzheimer’s disease. The target compounds 4a-o were synthesized via the azide-alkyne cycloaddition reaction and their biological activities were primarily evaluated in terms of neuroprotection against H2O2-induced cell death in PC12 cells and AChE/BuChE inhibition. The promising compounds 4j and 4i containing four carbons spacer were selected for further biological evaluations. Based on the obtained results, the benzocoumarin derivative 4j with IC50 value of 7.3 µM was the most potent AChE inhibitor and displayed good inhibition toward intracellular reactive oxygen species (ROS). This compound with antioxidant and metal chelating ability showed also protective effect on cell injury induced by Aβ1-42 in SH-SY5Y cells. Although the 8-methoxycoumarin analog 4i was slightly less active than 4j against AChE, but displayed higher protection ability against H2O2-induced cell death in PC12 and could significantly block Aβ-aggregation. The results suggested that the prototype compounds 4i and 4j might be promising multi-functional agents for the further development of the disease-modifying treatments of Alzheimer’s disease. ( 2018 Sep;79:223-234.)

Traversal of the Blood–Brain Barrier by Cleavable l-Lysine Conjugates of Apigenin

Apigenin, a flavone abundant in parsley and celery, is known to act on several CNS receptors, but its very poor water solubility (<0.001 mg/mL) impedes its absorption in vivo and prevents clinical use. Herein, apigenin was directly conjugated with glycine, l-phenylalanine, and l-lysine to give the corresponding carbamate derivatives, all of which were much more soluble than apigenin itself (0.017, 0.018, and 0.13 mg/mL, respectively). The Lys-apigenin carbamate 10 had a temporary sedative effect on the mice within 5 min of intraperitoneal administration (single dose of 0.4 mg/g) and could be detected in the mice brain tissues at a concentration of 0.82 μg/g of intact Lys-apigenin carbamate 10 and 0.42 ug/g of apigenin at 1.5 h. This study accomplished the delivery of apigenin across the BBB in a manner that might be applicable to other congeners, which should inform the future development of BBB-crossing flavonoids.(J. Agric. Food Chem., 2018, 66 (30), pp 8124–8131)

Hyaluronic Acid Conjugates as Vectors for the Active Targeting of Drugs, Genes and Nanocomposites in Cancer Treatment

Hyaluronic acid is a high molecular weight (106 –107 Da) glycosaminoglycan polymer composed of repeating disaccharides: 𝛽1,3 N-acetyl glucosaminyl-𝛽 1,4 glucuronide. HA is ubiquitous, being the main component of extracellular matrix, and is essential for proper cell growth, structural stability of organs, and tissue organization. From the pharmaceutical standpoint, HA is a promising component, because it is biodegradable, biocompatible, nontoxic, hydrophilic, and nonimmunogenic. HA contains several chemical groups to which other components can be conjugated. The carboxylate on the glucuronic acid, the N-acetylglucosamine hydroxyl, and the reducing termination, have all been successfully utilized in conjugation reactions with drugs. The acetyl group may be enzymatically removed from the N-acetylglucosamine, and is thus also a potential site for drug conjugation. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.
Cancer is a leading cause of death worldwide, accounting for 7.6 million deaths (around 13% of all deaths) in 2008. Deaths from cancer worldwide are projected to continue rising, with an estimated 13.1 million deaths in 2030. Lung, stomach, liver, colon and breast cancers cause the most cancer deaths each year.Conjugation of cytotoxic drugs with macromolecules improves their pharmacokinetic profile, prolonging the distribution and elimination phases. Furthermore, the slow release of active drug from the carrier may result in sustained high intratumoral drug levels and lower plasma concentrations of the active drug. In order to achieve this combined effect, a macromolecule-drug conjugate should preferentially release the active drug within the tumor tissue. The following components are essential to reach this goal: a biodegradable linkage, a suitable spacer, and a potent bioactive anticancer agent. Among the most widely studied macromolecules are N-(2-hydroxypropyl) methacrylamide (HPMA), polyglutamate, human serum albumin, dextrans, heparin, chitosan, dendrimers, multi-arm polyethylene glycol (PEG), and hyaluronic acid.The molecular weight of native HA has a wide range. In water, high molecular weight HA self-aggregates to form a viscous solution in which each molecule forms a sponge-like matrix with a radius of about 100 nanometers; this makes it a suitable candidate for passive tumor accumulation. In addition, HA plays an important physiological role in the tumorigenesis process, and consequently HA receptors are overexpressed on many types of tumor cells. This feature could be exploited in drug delivery, by using the receptor as an anchor to attach prodrugs or nanomedicine-based delivery systems, through a ligand, so as to increase the efficiency of anticancer drugs. (Molecules 2014, 19(3), 3193-3230.)

Biomacromolecules as carriers in drug delivery and tissue engineering

Natural biomacromolecules have attracted increased attention as carriers in biomedicine in recent years because of their inherent biochemical and biophysical properties including renewability, nontoxicity, biocompatibility, biodegradability, long blood circulation time and targeting ability. Recent advances in our understanding of the biological functions of natural-origin biomacromolecules and the progress in the study of biological drug carriers indicate that such carriers may have advantages over synthetic material-based carriers in terms of half-life, stability, safety and ease of manufacture. In this review, we give a brief introduction to the biochemical properties of the widely used biomacromolecule-based carriers such as albumin, lipoproteins and polysaccharides. Then examples from the clinic and in recent laboratory development are summarized. Finally the current challenges and future prospects of present biological carriers are discussed.
Natural-origin biomacromolecules perform a diverse set of functions in their native setting. For example, polysaccharides function in membranes, intracellular communication and as storage sites, whereas proteins function as structural materials, transport vehicles, nutrients and catalysts. Transport proteins as carriers for delivery of nutrients and other necessary molecules are of special interest. Inspired by such natural processes in organisms, scientists started to utilize natural and biological macromolecules, including proteins, polysaccharides, and lipoproteins, for the delivery of drugs and tissue engineering. Biomacromolecule-based drug carriers are nontoxic, non-immunogenic and have high drug loading content, good biocompatibility and targeting ability. Meanwhile, they are also capable of controlled and sustained drug release. Many meaningful designs have been reported using biological carriers, some of which are already approved for clinical use. Biomacromolecules used as carriers include proteins (albumin, transferrin, lipoproteins, silk fibroin, collagen, keratin) and polysaccharides (chitosan, cyclodextrin, hyaluronic acid, heparin and pectin). The structural diagrams of these carriers are shown in Fig. 1. These biomacromolecules can be naturally obtained from animals and plants in abundant amounts and are renewable resources. They have good affinity to organisms and weak immune rejection, and can be degraded by in vivo enzymes; the metabolites also have low toxicity to organisms. Biomacromolecule-based carriers have been reported in the form of prodrugs, drug conjugates, nanoparticles, microcapsules, hydrogels and tissue engineering scaffolds. The use of biomacromolecule-based carriers has been shown to improve the pharmacokinetics of the payloads and to reduce systemic toxicity and immunogenicity. Furthermore, the hydroxyl, amine and carboxyl groups on the chains of these biomacromolecules can be utilized for chemical modification, making them of great significance in biomedical field.(Acta Pharm Sin B. 2018 Jan; 8(1): 34–50.)

Novel Spermine-Derivative Cationic Lipids as an Effective Gene Carrier In Vitro

In the present study, nonionic surfactant vesicles (niosomes) formulated with Span 20, cholesterol, and novel synthesized spermine-based cationic lipids with four hydrocarbon tails in a molar ratio of 2.5:2.5:1 were investigated as a gene carrier. The effects of the structure of the cationic lipids, such as differences in the acyl chain length (C14, C16, and C18) of the hydrophobic tails, as well as the weight ratio of niosomes to DNA on transfection efficiency and cell viability were evaluated in a human cervical carcinoma cell line (HeLa cells) using pDNA encoding green fluorescent protein (pEGFP-C2). The niosomes were characterized both in terms of morphology and of size and charge measurement. The formation of complexes between niosomes and DNA was verified with a gel retardation assay. The transfection efficiency of these cationic niosomes was in the following order: spermine-C18 > spermine-C16 > spermine-C14. The highest transfection efficiency was obtained for transfection with spermine-C18 niosomes at a weight ratio of 10. Additionally, no serum effect on transfection efficiency was observed. The results from a cytotoxicity and hemolytic study showed that the cationic niosomes were safe in vitro. In addition, the cationic niosomes showed good physical stability for at least 1 month at 4°C. Therefore, the cationic niosomes offer an excellent prospect as an alternative gene carrier.(Gene therapy has been widely endorsed as a promising therapeutic approach for many incurable diseases related to gene function, such as genetic diseases, cancer, cardiovascular diseases, and autoimmune diseases. Successful gene therapy requires not only therapeutically suitable genes but also a safe and efficient gene carrier. To avoid severe side effects resulting from viral vectors, such as immunogenicity, mutagenesis, and carcinogenesis, nonviral vectors offer an attractive alternative. Cationic liposomes, a vesicular system widely investigated as effective gene carriers, are one of the preferred nonviral vectors. In addition, several studies have reported on the use of another vesicular system, nonionic surfactant vesicles (niosomes), as a gene carrier that can potentially be substituted for liposomes.Niosomes are nonionic surfactant vesicles formed by the self-assembly of nonionic amphiphiles into a bilayer structure in an aqueous medium. The nonionic surfactants preferably used to prepare niosomes include alkyl ethers and alkyl glyceryl ethers (Brij), sorbitan fatty acid esters (Span), and polyoxyethylenefatty acid esters (Tween). However, niosomes have several advantages over liposomes, including low production costs, high purity, uniform content, greater stability, and the ease of storing nonionic surfactants. Cationic niosomes used as gene carriers are usually composed of nonionic surfactants (i.e., Tween and Span), cholesterol, and cationic lipids. One of the major factors affecting gene transfection mediated by cationic niosomes is niosome composition, including the types of surfactants and cationic lipids used.
The cationic lipids used as transfection reagents usually contain three parts: a hydrophobic group, a linker group, and a positively charged head group that can interact with DNA and cause DNA condensation. The polyamines furnish one of the most effective cationic lipid head groups. Among the polyamines, spermine, a well-known polyamine consisting of a tetraamine with two primary and two secondary amino groups, plays an important role as a gene carrier. Spermine-derivative cationic lipids commercially available for gene delivery applications include dioctadecylamidoglycylspermine (DOGS) and dipalmitoylphosphatidyl ethanolamidospermine (DPPES). In the present study, cationic niosomes formulated with Span, cholesterol, and novel synthesized spermine-based cationic lipids with four hydrocarbon tails, namely, Tetra-(N1,N1,N14,N14-myristeroyloxyethyl)-spermine (spermine-C14), Tetra-(N1,N1,N14,N14-palmitoyloxyethyl)-spermine (spermine-C16), and Tetra-(N1,N1,N14,N14-steroyloxyethyl)-spermine (spermine-C18), in a molar ratio of 2.5:2.5:1 were investigated as gene carriers. Factors affecting transfection efficiency and cell viability, including cationic lipid structure (i.e., differences in the acyl chain length (C14, C16, and C18) of the hydrophobic tails as well as the weight ratio of niosomes to DNA) were evaluated in a human cervical carcinoma cell line (HeLa cells) using pDNA-encoded green fluorescent protein (pEGFP-C2). The morphology, size, and charge of these niosomes/DNA complexes were characterized, and agarose gel electrophoresis was performed. Moreover, the physical stability of these cationic niosomes was evaluated with size and charge measurements.) (AAPS PharmSciTech. 2014 Jun; 15(3): 722–730.)

Reduction Sensitive Lipid Conjugates of Tenofovir: Synthesis, Stability, and Antiviral Activity

The therapeutic value of numerous small molecules hinges on their ability to permeate the plasma membrane. This is particularly true for tenofovir (TFV), adefovir, and other antiviral nucleosides that demonstrate potent antiviral activity but poor bioavailability. Using TFV as a model substrate, we hybridized two disparate prodrug strategies to afford novel reduction-sensitive lipid conjugates of TFV that exhibit subnanomolar activity toward HIV-1 and are stable in human plasma for more than 24 h with a therapeutic index approaching 30000. These compounds significantly rival the clinically approved formulation of TFV and revitalize the potential of disulfide-bearing prodrugs which have seen limited in vitro and in vivo success since their debut over 20 years ago. We further demonstrate the utility of these conjugates as a tool to indirectly probe the enzymatic hydrolysis of phosphonomonoesters that may further advance the development of other prodrug strategies for nucleosides, peptides, and beyond.
We sought to design disulfide-linked lipid conjugates that readily permeate the plasma membrane and rapidly releases the nucleoside within the target cell without the need for enzymatic activation. In contrast to other prodrug strategies, our design relies on the reduction-sensitive nature of the S–S bond that selectively bows to the universal glutathione redox potential that exists at the plasma membrane between the extra- and intracellular milieu.Glutathione, often referred to as GSH, is a tripeptide typically stockpiled in millimolar concentrations (2–10 mM) within the cytosol that participates in a multitude of biological functions to promote the reduction of disulfides, detoxification of xenobiotics, mediate immunoregulation, and curb oxidative stress32 among others. GSH is seldom found in the extracellular space and thus creates a gradient that fosters intracellular reduction of disulfides and simultaneously promotes an oxidative environment to support S–S formation in the surrounding media. (J Med Chem. 2016 Aug 11; 59(15): 7097–7110.)