Inhibitory effect of doxycycline conjugated with deoxycholic acid and polyethylenimine conjugate on nasal fibroblast differentiation and extracellular production.

BACKGROUND: Chronic rhinosinusitis (CRS) is an inflammatory disease affecting the sinuses or nose. Persistent inflammatory responses can lead to tissue remodeling, which is a pathological characteristics of CRS. Activation of fibroblasts in the nasal mucosal stroma, differentiation and collagen deposition, and subepithelial fibrosis have been associated with CRS. OBJECTIVES: We aimed to assess the inhibitory effects of doxycycline and deoxycholic acid-polyethyleneimine conjugate (DA3-Doxy) on myofibroblast differentiation and extracellular matrix (ECM) production in nasal fibroblasts stimulated with TGF-ß1. METHODS: To enhance efficacy, we prepared DA3-Doxy using a conjugate of low-molecular-weight polyethyleneimine (PEI) (MW 1800) and deoxycholic acid (DA) and Doxy. The synthesis of the DA3-Doxy polymer was confirmed using nuclear magnetic resonance, and the critical micelle concentration required for cationic micelle formation through self-assembly was determined. Subsequently, the Doxy loading efficiency of DA3 was assessed. The cytotoxicity of Doxy, DA3, PEI, and DA-Doxy in nasal fibroblasts was evaluated using the WST-1 assay. The anti-tissue remodeling and anti-inflammatory effects of DA3-Doxy and DA3 were examined using real-time polymerase chain reaction (Real-time PCR), immunocytochemistry, western blot, and Sircol assay. RESULTS: Both DA3 and DA3-Doxy exhibited cytotoxicity at 10 µg/ml in nasal fibroblasts. Doxy partially inhibited α-smooth muscle actin, collagen types I and III, and fibronectin. However, DA3-Doxy significantly inhibited α-SMA, collagen types I and III, and fibronectin at 5 µg/ml. DA3-Doxy also modulated TGF-ß1-induced changes in the expression of MMP 1, 2, and 9. Nonetheless, TGF-ß1-induced expression of MMP3 was further increased by DA3-Doxy. The expression of TIMP 1 and 2 was partially reduced with 5 µg/ml DA3-Doxy. CONCLUSIONS: Although initially developed for the delivery of genetic materials or drugs, DA3 exhibits inhibitory effects on myofibroblast differentiation and ECM production. Therefore, it holds therapeutic potential for CRS, and a synergistic effect can be expected when loaded with CRS treatment drugs.

Immune modulation of the liver metastatic colorectal cancer microenvironment via the oral CAPOX-mediated cGAS-STING pathway.

We evaluated modulation of the immunosuppressive tumor microenvironment in both local and liver metastatic colorectal cancer (LMCC), focusing on tumor-associated macrophages, which are the predominant immunosuppressive cells in LMCC. We developed an orally administered metronomic chemotherapy regimen, oral CAPOX. This regimen combines capecitabine and a nano-micelle encapsulated, lysine-linked deoxycholate and oxaliplatin complex (OPt/LDC-NM). The treatment effectively modulated immune cells within the tumor microenvironment by activating the cGAS-STING pathway and inducing immunogenic cell death. This therapy modulated immune cells more effectively than did capecitabine monotherapy, the current standard maintenance chemotherapy for colorectal cancer. The macrophage-modifying effect of oral CAPOX was mediated via the cGAS-STING pathway. This is a newly identified mode of immune cell activation induced by metronomic chemotherapy. Moreover, oral CAPOX synergized with anti-PD-1 antibody (αPD-1) to enhance the T-cell-mediated antitumor immune response. In the CT26. CL25 subcutaneous model, combination therapy achieved a 91 % complete response rate with a confirmed memory effect against the tumor. This combination also altered the immunosuppressive tumor microenvironment in LMCC, which αPD-1 monotherapy could not achieve. Oral CAPOX and αPD-1 combination therapy outperformed the maximum tolerated dose for treating LMCC, suggesting metronomic therapy as a promising strategy.

Development of porcine skeletal muscle extracellular matrix-derived hydrogels with improved properties and low immunogenicity.

Hydrogels derived from decellularized extracellular matrices (ECM) of animal origin show immense potential for regenerative applications due to their excellent cytocompatibility and biomimetic properties. Despite these benefits, the impact of decellularization protocols on the properties and immunogenicity of these hydrogels remains relatively unexplored. In this study, porcine skeletal muscle ECM (smECM) underwent decellularization using mechanical disruption (MD) and two commonly employed decellularization detergents, sodium deoxycholate (SDC) or Triton X-100. To mitigate immunogenicity associated with animal-derived ECM, all decellularized tissues were enzymatically treated with α-galactosidase to cleave the primary xenoantigen-the α-Gal antigen. Subsequently, the impact of the different decellularization protocols on the resultant hydrogels was thoroughly investigated. All methods significantly reduced total DNA content in hydrogels. Moreover, α-galactosidase treatment was crucial for cleaving α-Gal antigens, suggesting that conventional decellularization methods alone are insufficient. MD preserved total protein, collagen, sulfated glycosaminoglycan, laminin, fibronectin, and growth factors more efficiently than other protocols. The decellularization method impacted hydrogel gelation kinetics and ultrastructure, as confirmed by turbidimetric and scanning electron microscopy analyses. MD hydrogels demonstrated high cytocompatibility, supporting satellite stem cell recruitment, growth, and differentiation into multinucleated myofibers. In contrast, the SDC and Triton X-100 protocols exhibited cytotoxicity. Comprehensive in vivo immunogenicity assessments in a subcutaneous xenotransplantation model revealed MD hydrogels' biocompatibility and low immunogenicity. These findings highlight the significant influence of the decellularization protocol on hydrogel properties. Our results suggest that combining MD with α-galactosidase treatment is an efficient method for preparing low-immunogenic smECM-derived hydrogels with enhanced properties for skeletal muscle regenerative engineering and clinical applications.

Insight into the Effect of Submicellar Concentrations of Sodium Deoxycholate on the Structure, Stability, and Activity of Bovine and Human Serum Albumin: An Interesting Comparison between Single and Double Tryptophan Proteins.

The progressive escalation in the applications of bile salts in diverse fields has triggered research on their interaction with various biological macromolecules, especially with proteins. A proper understanding of the interaction process of bile salts, particularly in the lower concentrations range, with the serum albumin seems important since the normal serum concentration of bile salts is approximately in the micromolar range. The current study deals with a comprehensive and comparative analysis of the interaction of submicellar concentrations of sodium deoxycholate (NaDC) with two homologous transport proteins: bovine serum albumin (BSA) and human serum albumin (HSA). HSA and BSA with one and two tryptophans, respectively, provide the opportunity for an interesting comparison of tryptophan fluorescence behavior on interaction with NaDC. The study suggests a sequential interaction of NaDC in three discrete stages with the two proteins. A detailed study using warfarin and ibuprofen as site markers provides information about the sites of interaction, which is further confirmed by inclusive molecular dynamics simulation analysis. Moreover, the comparison of the thermodynamics and stability of the NaDC-serum albumin complexes confirms the stronger interaction of NaDC with BSA as compared to that with HSA. The differential interaction between the bile salt and the two serum albumins is further established from the difference in the extent of decrease in the esterase-like activity assay of the proteins in the presence of NaDC. Therefore, the present study provides important insight into the effect of submicellar concentrations of NaDC on the structure, stability, and activity of the two homologous serum albumins and thus can contribute not only to the general understanding of the complex nature of serum albumin-bile salt interactions but also to the design of more effective pharmaceutical formulations in the field of drug delivery and biomedical research.

Development of Sustained Release Formulations Based on Lipid-Liquid Crystal to Control the Release of Deoxycholate: In Vitro and In Vivo Assessment.

Subcutaneous injections of phosphatidylcholine (PC), sodium deoxycholate (NADC), and a mixture of them were found to be an effective option for treating cellulite. However, it is noteworthy that the injection of NADC may result in inflammation as well as necrosis in the injection area. The preparation of a sustained release formulation based on lipid-liquid crystal that controls the release of NADC could be a potential solution to address the issue of inflammation and necrosis at the site of injection. To present a practical and validated approach for accurately determining the concentration of NADC in LLC formulations, spectrofluorimetry was used based on the International Council for Harmonization (ICH) Q2 guidelines. Based on the validation results, the fluorometric technique has been confirmed as a reliable, efficient, and economical analytical method for quantifying NADC concentrations. The method demonstrated favorable attributes of linearity, precision, and accuracy, with an r2 value of 0.999. Furthermore, it exhibited excellent interday and intraday repeatability, with RSD values below 4%. The recovery percentages ranged from 97 to 100%, indicating the method's ability to accurately measure NADC concentrations. The subcutaneous injection of the LLC-NADC demonstrated a reduction in inflammation and tissue necrosis in skin tissue, along with an increase in fat lysis within 30 days, when compared to the administration of only NADC solution. Moreover, the histopathological assessment confirmed that the use of the LLC formulation did not result in any detrimental side effects for kidney or heart tissue.

Interactions in Aqueous Mixtures of Cationic Hydroxyethyl Cellulose and Different Anionic Bile Salts.

It is known that the reduction of blood cholesterol can be accomplished through foods containing a large number of dietary fibers; this process is partially related to the binding of bile salt to fibers. To gain new insights into the interactions between dietary fibers and bile salts, this study investigates the interactions between cationic hydroxyethyl cellulose (catHEC) and sodium deoxycholate (NaDC) or sodium cholate (NaC), which have a similar structure. Turbidity measurements reveal strong interactions between catHEC and NaDC, and under some conditions, macroscopic phase separation occurs. In contrast, the interactions with NaC are weak. At a catHEC concentration of 2 wt %, incipient phase separation is approached at concentrations of NaC and NaDC of 32.5 and 19.3 mM, respectively. The rheological results show strong interactions and a prominent viscosification effect for the catHEC/NaDC system but only moderate interactions for the catHEC/NaC system. Both cryogenic transmission electron microscopy and small-angle X-ray scattering results display fundamental structural differences between the two systems, which may explain the stronger interactions in the presence of NaDC. The surmise is that the extended structures formed in the presence of NaDC can easily form connections and entanglements in the network.

Enhanced Oral Absorption and Liver Distribution of Polymeric Nanoparticles through Traveling the Enterohepatic Circulation Pathways of Bile Acid.

The intestinal epithelium is known to be a main hindrance to oral delivery of nanoparticles. Even though surface ligand modification can enhance cellular uptake of nanoparticles, the "easy entry and hard across" was frequently observed for many active targeting nanoparticles. Here, we fabricated polymeric nanoparticles relayed by bile acid transporters with monomethoxy poly(ethylene glycol)-poly(D,l-lactide) and deoxycholic acid-conjugated poly(2-ethyl-2-oxazoline)-poly(D,l-lactide) based on structural characteristics of intestine epithelium and the absorption characteristics of endogenous substances. As anticipated, deoxycholic acid-modified polymeric nanoparticles featuring good stability in simulated gastrointestinal fluid could notably promote the internalization of their payload by Caco-2 cells through mediation of apical sodium-dependent bile acid transporter (ASBT) and transmembrane transport of the nanoparticles across Caco-2 cell monolayers via relay-guide of ASBT, ileal bile acid-binding protein, and the heteromeric organic solute transporter (OSTα-OSTß) along with multidrug resistance-associated protein 3 (MRP3) evidenced by competitive inhibition and fluorescence immunoassay, which was further visually confirmed by the stronger fluorescence from C6-labeled nanoparticles inside enterocytes and the basal side of the intestinal epithelium of mice. The transcellular transport of deoxycholic acid-modified nanoparticles in an intact form was mediated by caveolin/lipid rafts and clathrin with intracellular trafficking trace of endosome-lysosome-ER-Golgi apparatus and bile acid transport route. Furthermore, the increased uptake by HepG2 cells compared with unmodified nanoparticles evidenced the target ability of deoxycholic acid-modified nanoparticles to the liver, which was further supported by ex vivo imaging of excised major organs of mice. Thus, this study provided a feasible and potential strategy to further enhance transepithelial transport efficiency and liver-targeted ability of nanoparticles by means of the specific enterohepatic circulation pathways of bile acid.

Formulation Optimization and Stability of Polymyxin B Based on Sodium Deoxycholate Sulfate Micelles.

Polymyxin B (PMB) and sodium deoxycholate sulfate (SDCS) ratios were optimized. The self-assembly of PMB-SDCS was characterized using dynamic light scattering. Five different mole ratios of SDCS to PMB (5:1, 10:1, 15:1, 30:1, and 45:1) were prepared after optimization. FTIR and 1H-NMR were employed to characterize PMB formulations. The chemical stability of PMB was quantified with tandem mass spectrometry. Both PMB and SDCS formed micelles at 14 and 8 µg/ml, respectively. At the critical micelle concentration (CMC), the hydrodynamic diameter of 213 nm was obtained. PMB had a positive charge (+6 mV) while SDCS had a negative charge (‒33 mV). Increasing in SDCS content decreased the charges from ‒6 to ‒25 mV. FTIR revealed H-bonding between PMB and SDCS. The NMR spectra confirmed that chemical shifts of PMB and SDCS did not change. The hydrodynamic size of PMB-SDCS was from 193 to 318 d.nm. Our results suggest that the lower mole ratios of SDCS (< 15:1) were able to stabilize PMB and released PMB within 30 min. Moreover, 5:1 mole ratio maintained the antimicrobial activity against Pseudomonas aeruginosa (MBC = 2 µg/ml). PMB-SDCS micelles of particular mole ratio is able to provide physical and chemical stability of PMB.

Increased selectivity of sodium deoxycholate to around Tryptophan213 in bovine serum albumin upon micellization as revealed by singular value decomposition for excitation emission matrix.

In the present study, we investigated the effect of bile salts (sodium deoxycholate, NaDC) on the conformation of a globular protein (bovine serum albumin, BSA). The two Tryptophan (Trp) residues of BSA and the fluorescence energy of NaDC are in a three-way relationship, and singular value decomposition (SVD) was used to separate each element in the fluorescence spectra. SVD was used to separate the elements in the fluorescence spectra. SVD showed that NaDC had a particularly large effect on the microenvironment around Trp213 and that micellar NaDC enhanced the selectivity for Trp213. In addition, the Stern-Volmer plots of the warfarin (WAR) specific domain (domain I) and ketoprofen (KP) specific domain (domain II) in the presence and absence of NaDC showed that the effect of NaDC was selective for domain II, where Trp213 is located. These results indicate that NaDC induces a localized and selective conformational change in BSA, and that the selectivity varies depending on the aggregation state of NaDC.

Synthesis and Biological Investigation of Bile Acid-Paclitaxel Hybrids.

Chenodeoxycholic acid and ursodeoxycholic acid (CDCA and UDCA, respectively) have been conjugated with paclitaxel (PTX) anticancer drugs through a high-yield condensation reaction. Bile acid-PTX hybrids (BA-PTX) have been investigated for their pro-apoptotic activity towards a selection of cancer cell lines as well as healthy fibroblast cells. Chenodeoxycholic-PTX hybrid (CDC-PTX) displayed cytotoxicity and cytoselectivity similar to PTX, whereas ursodeoxycholic-PTX hybrid (UDC-PTX) displayed some anticancer activity only towards HCT116 colon carcinoma cells. Pacific Blue (PB) conjugated derivatives of CDC-PTX and UDC-PTX (CDC-PTX-PB and UDC-PTX-PB, respectively) were also prepared via a multistep synthesis for evaluating their ability to enter tumor cells. CDC-PTX-PB and UDC-PTX-PB flow cytometry clearly showed that both CDCA and UDCA conjugation to PTX improved its incoming into HCT116 cells, allowing the derivatives to enter the cells up to 99.9%, respect to 35% in the case of PTX. Mean fluorescence intensity analysis of cell populations treated with CDC-PTX-PB and UDC-PTX-PB also suggested that CDC-PTX-PB could have a greater ability to pass the plasmatic membrane than UDC-PTX-PB. Both hybrids showed significant lower toxicity with respect to PTX on the NIH-3T3 cell line.

The human bile salt sodium deoxycholate induces metabolic and cell envelope changes in Salmonella Typhi leading to bile resistance.

Introduction. Salmonella enterica serovar Typhi (S. Typhi) is the etiological agent of typhoid fever. To establish an infection in the human host, this pathogen must survive the presence of bile salts in the gut and gallbladder.Hypothesis. S. Typhi uses multiple genetic elements to resist the presence of human bile.Aims. To determine the genetic elements that S. Typhi utilizes to tolerate the human bile salt sodium deoxycholate.Methodology. A collection of S. Typhi mutant strains was evaluated for their ability to growth in the presence of sodium deoxycholate and ox-bile. Additionally, transcriptomic and proteomic responses elicited by sodium deoxycholate on S. Typhi cultures were also analysed.Results. Multiple transcriptional factors and some of their dependent genes involved in central metabolism, as well as in cell envelope, are required for deoxycholate resistance.Conclusion. These findings suggest that metabolic adaptation to bile is focused on enhancing energy production to sustain synthesis of cell envelope components exposed to damage by bile salts.

Using Nuclear Magnetic Resonance Spectroscopy to Probe Hydrogels Formed by Sodium Deoxycholate.

Hydrogels of bile acids and their salts are promising materials for drug delivery, cellular immobilization, and other applications. However, these hydrogels are poorly understood at the molecular level, and further study is needed to allow improved materials to be created by design. We have used NMR spectroscopy to probe hydrogels formed from mixtures of formic acid and sodium deoxycholate (NaDC), a common bile acid salt. By assaying the ratio of deoxycholate molecules that are immobilized as part of the fibrillar network of the hydrogels and those that can diffuse, we have found that 65% remain free under typical conditions. The network appears to be composed of both the acid and salt forms of deoxycholate, possibly because a degree of charge inhibits excessive aggregation and precipitation of the fibrils. Spin-spin relaxation times provided a molecular-level estimate of the temperature of gel-sol transition (42 °C), which is virtually the same as the value determined by analyzing macroscopic parameters. Saturation transfer difference (STD) NMR spectroscopy established that formic acid, which is present mainly as formate, is not immobilized as part of the gelating network. In contrast, HDO interacts with the network, which presumably has a surface with exposed hydrophilic groups that form hydrogen bonds with water. Moreover, the STD NMR experiments revealed that the network is a dynamic entity, with molecules of deoxycholate associating and dissociating reversibly. This exchange appears to occur preferentially by contact of the hydrophobic edges or faces of free molecules of deoxycholate with those of molecules immobilized as components of the network. In addition, DOSY experiments revealed that gelation has little effect on the diffusion of free NaDC and HDO.

Self-assembling, supramolecular chemistry and pharmacology of amphotericin B: Poly-aggregates, oligomers and monomers.

Antifungal drugs such as amphotericin B (AmB) interact with lipids and phospholipids located on fungal cell membranes to disrupt them and create pores, leading to cell apoptosis and therefore efficacy. At the same time, the interaction can also take place with cell components from mammalian cells, leading to toxicity. AmB was selected as a model antifungal drug due to the complexity of its supramolecular chemical structure which can self-assemble in three different aggregation states in aqueous media: monomer, oligomer (also known as dimer) and poly-aggregate. The interplay between AmB self-assembly and its efficacy or toxicity against fungal or mammalian cells is not yet fully understood. To the best of our knowledge, this is the first report that investigates the role of excipients in the supramolecular chemistry of AmB and the impact on its biological activity and toxicity. The monomeric state was obtained by complexation with cyclodextrins resulting in the most toxic state, which was attributed to the greater production of highly reactive oxygen species upon disruption of mammalian cell membranes, a less specific mechanism of action compared to the binding to the ergosterol located in fungal cell membranes. The interaction between AmB and sodium deoxycholate resulted in the oligomeric and poly-aggregated forms which bound more selectively to the ergosterol of fungal cell membranes. NMR combined with XRD studies elucidated the interaction between drug and excipient to achieve the AmB aggregation states, and ultimately, their diffusivity across membranes. A linear correlation between particle size and the efficacy/toxicity ratio was established allowing to modulate the biological effect of the drug and hence, to improve pharmacological regimens. However, particle size is not the only factor modulating the biological response but also the equilibrium of each state which dictates the fraction of free monomeric form available. Tuning the aggregation state of AmB formulations is a promising strategy to trigger a more selective response against fungal cells and to reduce the toxicity in mammalian cells.

Metronomic delivery of orally available pemetrexed-incorporated colloidal dispersions for boosting tumor-specific immunity.

In this study, we developed oral pemetrexed (PMX) for metronomic dosing to enhance antitumor immunity. PMX was electrostatically complexed with positively charged lysine-linked deoxycholic acid (DL) as an intestinal permeation enhancer, forming PMX/DL, to enhance its intestinal permeability. PMX/DL was also incorporated into a colloidal dispersion (CD) comprised of the block copolymer of poly(ethylene oxide) and poly(propylene oxide), and caprylocaproyl macrogol-8 glycerides (PMX/DL-CD). CD-containing PMX/DL complex in a 1:1 molar ratio [PMX/DL(1:1)-CD] showed 4.66- and 7.19-fold greater permeability than free PMX through the Caco-2 cell monolayer and rat intestine, respectively. This resulted in a 282% improvement in oral bioavailability in rats. In addition, low-dose metronomic PMX led to more immunogenic cell death in CT26.CL25 cells compared to high PMX concentrations at the maximum tolerated dose. In CT26.CL25 tumor-bearing mice, oral metronomic PMX/DL-CD elicited greater antitumor immunity not only by enhancing the number of tumor-infiltrating lymphocytes but also by suppressing T cell functions. Oral PMX/DL-CD substantially increased programmed cell death protein ligand-1 (PD-L1) expression on tumor cells compared to the control and PMX-IV groups. This increased antitumor efficacy in combination with anti-programmed cell death protein-1 (aPD-1) antibody in terms of tumor rejection and immunological memory compared to the combination of PMX-IV and aPD-1. These results suggest that oral metronomic scheduling of PMX/DL-CD in combination with immunotherapy has synergistic antitumor effects.

Deoxycholic acid induces proinflammatory cytokine production by model oesophageal cells via lipid rafts.

The bile acid component of gastric refluxate has been implicated in inflammation of the oesophagus including conditions such as gastro-oesophageal reflux disease (GORD) and Barrett's Oesophagus (BO). Here we demonstrate that the hydrophobic bile acid, deoxycholic acid (DCA), stimulated the production of IL-6 and IL-8 mRNA and protein in Het-1A, a model of normal oesophageal cells. DCA-induced production of IL-6 and IL-8 was attenuated by pharmacologic inhibition of the Protein Kinase C (PKC), MAP kinase, tyrosine kinase pathways, by the cholesterol sequestering agent, methyl-beta-cyclodextrin (MCD) and by the hydrophilic bile acid, ursodeoxycholic acid (UDCA). The cholesterol-interacting agent, nystatin, which binds cholesterol without removing it from the membrane, synergized with DCA to induce IL-6 and IL-8. This was inhibited by the tyrosine kinase inhibitor genistein. DCA stimulated the phosphorylation of lipid raft component Src tyrosine kinase (Src). while knockdown of caveolin-1 expression using siRNA resulted in a decreased level of IL-8 production in response to DCA. Taken together, these results demonstrate that DCA stimulates IL-6 and IL-8 production in oesophageal cells via lipid raft-associated signaling. Inhibition of this process using cyclodextrins represents a novel therapeutic approach to the treatment of inflammatory diseases of the oesophagus including GORD and BO.

The novel nanocomplexes containing deoxycholic acid-grafted chitosan and oleanolic acid displays the hepatoprotective effect against CCl4-induced liver injury in vivo.

Chemical liver injury threatens seriously human health, along with the shortage of efficiency and low-toxicity drugs. Herein, the novel oral nanocomplexes composed of deoxycholic acid-grafted chitosan and oleanolic acid were constructed to reverse the CCl4-induced acute liver damage in mice. Results indicated core-shell nanocomplexes, maintained by the hydrophobic interaction between deoxycholic acid and oleanolic acid, could be dissociated in the intestine. Notably, the nanocomplexes possessed superior hepatoprotective effect in vivo, possibly due to the synergistic effect between grafted chitosan and oleanolic acid. Mechanism investigations suggested that nanocomplexes reversed CCl4-induced liver injury through improving hepatic antioxidant capacity via NrF2/Keap1 pathway and regulating inflammation response via NF-κB signaling pathway. The novel oral nanocomplexes represent an effective strategy for chemical liver injury therapy.

Synthesis and Biological Activity of New Brassinosteroid Analogs of Type 24-Nor-5ß-Cholane and 23-Benzoate Function in the Side Chain.

Brassinosteroids are polyhydroxysteroids that are involved in different plants' biological functions, such as growth, development and resistance to biotic and external stresses. Because of its low abundance in plants, much effort has been dedicated to the synthesis and characterization of brassinosteroids analogs. Herein, we report the synthesis of brassinosteroid 24-nor-5ß-cholane type analogs with 23-benzoate function and 22,23-benzoate groups. The synthesis was accomplished with high reaction yields in a four-step synthesis route and using hyodeoxycholic acid as starting material. All synthesized analogs were tested using the rice lamina inclination test to assess their growth-promoting activity and compare it with those obtained for brassinolide, which was used as a positive control. The results indicate that the diasteroisomeric mixture of monobenzoylated derivatives exhibit the highest activity at the lowest tested concentrations (1 × 10-8 and 1 × 10-7 M), being even more active than brassinolide. Therefore, a simple synthetic procedure with high reaction yields that use a very accessible starting material provides brassinosteroid synthetic analogs with promising effects on plant growth. This exploratory study suggests that brassinosteroid analogs with similar chemical structures could be a good alternative to natural brassinosteroids.

Structure and properties of corn starch synthesized by using sulfobetaine and deoxycholic acid.

Novel starch polymers (sulfobetaine-starch-deoxycholic acid) were first synthesized by grafting zwitterionic sulfobetaine and deoxycholic acid onto corn starch molecules. In order to explore the mechanism of modified starch, the chemical structure, morphological properties, thermal stability, and self-assembly performance of modified corn starch were determined. Preliminary structural characterization, using NMR, demonstrated that the glucose carbon C6 was the main etherification grafting site and C2 and C3 were the esterification grafting sites. This was confirmed using FT-IR to detect the presence of a new carbonyl signal around 1739 cm-1. XRD, SEM, and PLM micrographs showed structural losses in the starch granule. Thermogravimetric analysis showed an increase in thermal stability with etherification and esterification in nature. Self-assembly performance analysis demonstrated that the polymer formed more thermodynamically stable micelles under highly diluted conditions. This work will help expand the space for starch application.

A graph theoretic model to understand the behavioral difference of PPCA among its paralogs towards recognition of DXCA.

Among all the proteins of Periplasmic C type Cytochrome family obtained from cytochrome C7 found in Geobacter sulfurreducens, only the Periplasmic C type Cytochrome A (PPCA) protein can recognize the deoxycholate (DXCA), while its other paralogs do not, as observed from the crystal structures. Though some existing works have used graph-theoretic approaches to realize the 3-D structural properties of proteins, its usage in the rationalisation of the physiochemical behavior of proteins has been very limited. To understand the driving force towards the recognition of DXCA exclusively by PPCA among its paralogs, in this work, we propose two graph theoretic models based on the combinatorial properties, namely, base-pair-type and impact, of the nucleotide bases and the amino acid residues, respectively. Combinatorial analysis of the binding sequences using the proposed base-pair type based graph theoretic model reveals the differential behaviour of PPCA among its other paralogs. Further, to investigate the underlying chemical phenomenon, another graph theoretic model has been developed based on impact. Analysis of the results obtained from impact-based model clearly indicates towards the helix formation of PPCA which is essential for the recognition of DXCA, making PPCA a completely different entity from its paralogs.

In Vitro Metabolism of E2, G2: Novel Bile Acid-Coupling Camptothecin Analogues, in Rat Liver Microsomes.

BACKGROUND: E2 (Camptothecin - 20 (S) - O- glycine - deoxycholic acid), and G2 (Camptothecin - 20 (S) - O - acetate - deoxycholic acid) are two novel bile acid-derived camptothecin analogues, modified deoxycholic acid at 20-position of CPT(camptothecin) with greater anticancer activity and lower systematic toxicity in vivo. OBJECTIVE: We aimed to investigate the metabolism of E2 and G2 by Rat Liver Microsomes (RLM). METHODS: Phase I and Phase II metabolism of E2 and G2 in rat liver microsomes were performed, respectively, and the mixed incubation of phase I and phase II metabolism of E2 and G2 was also processed. Metabolites were identified by liquid chromatographic/mass spectrometry. RESULTS: The results showed that phase I metabolism was the major biotransformation route for both E2 and G2. The isoenzyme involved in their metabolism had some difference. The intrinsic clearance of G2 was 174.7 mL/min. mg protein, more than three times that of E2 (51.3 mL/min . mg protein), indicating a greater metabolism stability of E2. 10 metabolites of E2 and 14 metabolites of G2 were detected, including phase I metabolites (mainly via hydroxylations and hydrolysis) and their further glucuronidation products. CONCLUSION: These findings suggested that E2 and G2 have similar biotransformation pathways except for some differences in the hydrolysis ability of the ester bond and amino bond from the parent compounds, which may result in the diversity of their metabolism stability and responsible CYPs(Cytochrome P450 proteins).