Production of unnatural glucosides of curcumin with drastically enhanced water solubility by cell suspension cultures of Catharanthus roseus

Catharanthus roseus cell suspension cultures converted exogenously supplied curcumin to a series of glucosides, none of which has been found in nature so far. The efficiency of glucosylation was dependent on culture stage of the cells and medium sucrose concentration. Methyl jasmonate and salicylic acid enhanced the glucoside formation only when they were added to the cultures prior to the addition of curcumin. The glucoside yield was 2.5 micromol/g fresh weight of the cells at an optimal culture condition. The water solubility of curcumin-4',4"-O-beta-D-digentiobioside was 0.65 mmol/ml, which was 20 million-fold higher than that of curcumin.     

Synthesis and preclinical characterization of a paclitaxel prodrug with improved antitumor activity and water solubility

The development of novel chemotherapy strategies based on prodrugs remains a major challenge for effective treatment of malignancies. We tested the hypothesis that this can be achieved by a prodrug of paclitaxel where one biologically active center, represented by the C7 hydroxyl group, was blocked by a dihydroxypropyl side chain which can be hydrolytically cleaved by a pH-dependent, slow-release mechanism. The prodrug was synthesized by condensation of solketal chloroformate with the C7 hydroxyl group of paclitaxel followed by a ring-opening reaction to the dihydroxyl derivative. The cytotoxicity of the prodrug was similar to paclitaxel, when tested in vitro against a variety of human tumor cell lines. In vitro cell cycle analysis indicated that concentrations within the micromolar range of both drug and prodrug are required to induce sufficient G2M arrest. The hydrophilic paclitaxel prodrug proved to be more than 50-fold more water soluble than the parental drug and effectively converted to paclitaxel by pH dependent hydrolysis. Importantly, the prodrug could be used at a 3-fold higher maximum tolerated dose (MTD) and revealed a markedly improved antitumor activity in mice compared to paclitaxel. Taken together, our results demonstrate, that a hydrolytically activated paclitaxel prodrug exhibits greater water solubility and superior antitumor activity than the parental drug.     

Design and synthesis of benzopyran-based inhibitors of the hypoxia-inducible factor-1 pathway with improved water solubility

While progress has been made in treating cancer, cytotoxic chemotherapeutic agents are still the most widely used drugs and are associated with severe side-effects. Drugs that target unique molecular signalling pathways are needed for treating cancer with low or no intrinsic toxicity to normal cells. Our goal is to target hypoxic tumours and specifically the hypoxia inducible factor (HIF) pathway for the development of new cancer therapies. To this end, we have previously developed benzopyran-based HIF-1 inhibitors such as arylsulfonamide KCN1. However, KCN1 and its earlier analogs have poor water solubility, which hamper their applications. Herein, we describe a series of KCN1 analogs that incorporate a morpholine moiety at various positions. We found that replacing the benzopyran group of KCN1 with a phenyl group with a morpholinomethyl moiety at the para positions had minimal effect on potency and improved the water solubility of two new compounds by more than 10-fold compared to KCN1, the lead compound.     

Chitosan-based delivery systems for curcumin: A review of pharmacodynamic and pharmacokinetic aspects

Effective drug delivery is one of the most important issues associated with the administration of therapeutic agents that have low oral bioavailability. Curcumin is an active ingredient in the turmeric plant, which has low oral bioavailability due to its poor aqueous solubility. One strategy that has been considered for enhancing the aqueous solubility, and, thus, its oral bioavailability, is the use of chitosan as a carrier for curcumin. Chitosan is a biodegradable and biocompatible polymer that is relatively water-soluble. Therefore, various studies have sought to improve the aqueous solubility of chitosan. The use of different pharmaceutical excipients and formulation strategies has the potential to improve aqueous solubility, formulation processing, and the overall delivery of hydrophobic drugs. This review focuses on various methods utilized for chitosan-based delivery of curcumin.     

Low Mw sulfated curdlan with improved water solubility forms macromolecular complexes with polycytidylic acid

The water solubility of curdlan was enhanced by partial sulfation at O-6. Circular dichroism measurements suggest that the sulfated curdlan with the degree of substitution (DS) from 0 to 8.7 mol% forms macromolecular complexes with polycytidylic acid (poly(C)). Although the thermal stability of the complexes decreased with increase in DS, this could be overlapped by addition of NaCl in the concentration above that of serum. The results clearly indicate that the drawback arising from the electrostatic repulsion between the anionic charges can be partially compensated by the presence of salt. Furthermore, the polynucleotide chain complexed with the sulfated curdlan was protected from the enzymatic hydrolysis, corroborating the assumption that the sulfated curdlan has an ability to bind poly(C).     

Design and synthesis of dimethylaminomethyl-substituted curcumin derivatives/analogues: Potent antitumor and antioxidant activity,improved stability and aqueous solubility compared with curcumin

A series of dimethylaminomethyl-substituted curcumin derivatives/analogues were designed and synthesized. All compounds effectively inhibited HepG2, SGC-7901, A549 and HCT-116 tumor cell lines proliferation in MTT assay. Particularly, compounds 2a and 3d showed much better activity than curcumin against all of the four tumor cell lines. Antioxidant test revealed that these compounds had higher free radical scavenging activity than curcumin towards both DPPH and galvinoxyl radicals. Furthermore, the aqueous solubility and stability of the target compounds were also significantly improved compared with curcumin.     

Influence of capsaicin,curcumin and ferulic acid in rats fed high fat diets

Three compounds capsaicin, curcumin and ferulic acid showing hypolipidemic activity have been tested in adult Wistar rats fed high fat diets. Capsaicin (0.20 mg%) fed to female rats along with a 30% saturated fat diet lowered the rate of weight gain, liver and serum triglycerides. In male rats it lowered only the liver and serum total and very low density and low density lipoprotein triglycerides whether fed continuously for 13 or 8 weeks after interchanging the control and test diets from the 5th week onwards. Capsaicin fed to female rats in 30% mixed fat diet increased the rate of weight gain, lowered liver and serum triglycerides, lowered adipose tissue lipoprotein lipase, elevated the hormone sensitive lipase and serum free fatty acids. Capsaicin in 30% saturated fat diet lowered both the enzyme activities to a much lesser extent. Curcumin and ferulic acid (both at 25 mg%) in 30% saturated fat diet tended to lower the rate of weight gain, liver total lipids and serum triglycerides. It is of significance that a common dietary compound ‘capsaicin’ in the range of human intake triggers lipid lowering action in rats fed high fat diets. This paper was presented at the 55th Annual Meeting of the Society of Biological Chemists (India) held at Trivandrum during December 15–17th, 1986.     

Amino acid contribution to protein solubility: Asp, Glu, and Ser contribute more favorably than the other hydrophilic amino acids in RNase Sa

Poor protein solubility is a common problem in high-resolution structural studies, formulation of protein pharmaceuticals, and biochemical characterization of proteins. One popular strategy to improve protein solubility is to use site-directed mutagenesis to make hydrophobic to hydrophilic mutations on the protein surface. However, a systematic investigation of the relative contributions of all 20 amino acids to protein solubility has not been done. Here, 20 variants at the completely solvent-exposed position 76 of ribonuclease (RNase) Sa are made to compare the contributions of each amino acid. Stability measurements were also made for these variants, which occur at the i+1 position of a type II beta-turn. Solubility measurements in ammonium sulfate solutions were made at high positive net charge, low net charge, and high negative net charge. Surprisingly, there was a wide range of contributions to protein solubility even among the hydrophilic amino acids. The results suggest that aspartic acid, glutamic acid, and serine contribute significantly more favorably than the other hydrophilic amino acids especially at high net charge. Therefore, to increase protein solubility, asparagine, glutamine, or threonine should be replaced with aspartic acid, glutamic acid or serine.     

耐受微酸性次氯酸水乳酸菌的分离鉴定、耐受特性及益生特性

【背景】次氯酸水具有杀菌性,当其作为饮用水可能会对畜禽肠道内有益菌造成负面影响。【目的】筛选出具有耐受微酸性次氯酸水(slightly acidic hypochlorous acid water, SAHW)能力的乳酸菌并研究其益生特性。【方法】从内蒙古地区传统自然发酵制品中分离筛选出8株乳酸菌菌株,经16SrRNA基因测序进行鉴定。进一步通过耐受SAHW、耐酸、耐胆盐、疏水性及自凝聚能力试验进行耐受特性和益生特性研究。【结果】菌株MBH3-2为副干酪乳杆菌,其经过质量浓度为20mg/L的SAHW处理2h,菌落对数值仅下降0.3lg(CFU/mL),存活率为50.10%;而且在酸性(pH 2.0、2.5和3.0)、胆盐环境下均可存活;疏水率达62.12%,属于高度疏水性;自凝聚能力在2 h达到97.29%。【结论】最终确定一株具有优良耐受SAHW及基本满足作为微生态制剂要求的菌株,MBH3-2具有作为新型微生态制剂菌株的潜力。     

Lipase-catalyzed acidolysis of menhaden oil with conjugated linoleic acid: effect of water content

The effect of the water content on the lipase-catalyzed (Candida rugosa) interesterification (acidolysis) of menhaden oil with conjugated linoleic acid was studied for amounts of added water ranging from 0-4% (w/w). The rate of the acidolysis reaction increased with increasing water content, but the corresponding percentage of n-3 fatty acids liberated also increased. The implications of water content for minimization of the release of n-3 fatty acid residues while maximizing incorporation of CLA are discussed.     

The complexation of aqueous metal ions relevant to biological applications. 1. Poorly soluble zinc salts and enhanced solubility with added amino acid

Abstract

The effect of added amino acid (glycine, alanine and serine) on the solubility of zinc citrate, zinc succinate and zinc oxalate was investigated. Equilibrated solutions were prepared and titrated to endpoint at pH 5.5 with Na₂EDTA using Xylenol Orange indicator. In every case, a significant enhancement in solubility was seen as the amino acid increased from 1 to 50 molar excess. The increase was non-linear, and, with zinc succinate, showed saturation effects. In these cases, solution composition may be more complicated than initially thought, including mixed-ligand complexes and increasing percent free metal ion as the proportion of amino acid increases.     

Evaluation of improved zirconyl hematoxylin compared to the classical pH 2.5 Alcian blue method for demonstrating acid mucins

Abstract

Acid mucins have diagnostic significance for many pathological conditions, especially in certain tumors. We compared the classical pH 2.5 Alcian blue method to a new, improved zirconyl hematoxylin (IZH) method for demonstrating acid mucins using two fixatives: Bouin`s solution and 10% neutral buffered formalin (NBF). We used rabbit small intestine, large intestine and trachea. Specimens were fixed in Bouin`s solution and NBF. A total of 160 paraffin sections were prepared and stained with pH 2.5 Alcian blue and IZH. The stained acid mucins were assessed using digital image analysis software. Stained mucins were quantified for each staining procedure and fixative. No important differences were observed in acid mucin staining by either method after either fixative. The IZH method provides results as good as pH 2.5 Alcian blue and can be used to obtain reliable staining for acid mucins.     

Esters of betulin and betulinic acid with amino acids have improved water solubility and are selectively cytotoxic toward cancer cells

Betulin and betulinic acid are naturally occurring pentacyclic triterpenes showing cytotoxicity towards a number of cancer cell lines. Unfortunately they are practically insoluble in aqueous media and therefore their overall absorption index is not satisfactory. We have modified structures of both compounds by simple transformation to mono- and disubstituted esters of l-amino acids. This allowed us to achieve better water solubility without loss of the observed earlier anticancer properties. Comet assay on various cancer cell lines demonstrate that these compounds act via an apoptotic mechanism.     

The synthesis and activity evaluation of N‐acylated analogs of echinocandin B with improved solubility and lower toxicity

Presently, echinocandins have been recommended as the first‐line drugs for the treatment of invasive candidiasis. However, low oral bioavailability and solubility limit their application. To improve this situation, this study chose amino acid and fatty acid as raw materials to modify the nucleus of echinocandin B. Six N‐acylated analogs were screened from the derivatives that possessed potent antifungal activity and good water solubility. Based on antifungal susceptibility and hemolytic toxicity, compound 5 as the candidate had good antifungal activity and no hemolytic effect. Moreover, compared with anidulafungin, compound 5 showed a comparable fungicidal effect, much higher solubility, and lower toxicity. In conclusion, compound 5 has the potential for further research and development on account of reserved antifungal activity, high solubility, and low toxicity.     

Conversion of puerarin into its 7-O-glycoside derivatives by Microbacterium oxydans (CGMCC 1788) to improve its water solubility and pharmacokinetic properties

Microbacterium oxydans strain NJ 6 isolated from soil samples converted puerarin into two novel compounds, puerarin-7-O-glucoside and puerarin-7-O-isomaltoside, via an unreported O-glycosylation of the phenolic hydroxyl group at the 7-position of puerarin. Sucrose, maltotriose, and maltose could be used as glucosyl donors for glycosylation of puerarin, but uridine-diphosphate glucose, glucose, fructose, lactose, cyclodextrin, and starch could not. Regardless of the position of B-ring in the (iso)flavonoids core structure, the glycosylation of the phenolic hydroxyl group at the 7-position of (iso)flavonoids was governed by the presence or absence of a glucosyl residue at 8-C. The apparent solubility of puerarin-7-O-glucoside and puerarin-7-O-isomaltoside was approximately 18 and 100 times that of natural puerarin, respectively. Like parent puerarin, puerarin-7-O-glucoside maintained its physiological ability to relax the contractions of isolated rat thoracic aortic rings in vitro induced by phenylephrine. However, puerarin-7-O-glucoside was able to maintain higher plasma concentrations and have a longer mean residence time in the blood than the parent puerarin.     

Curcumin‐galactomannosides mitigate alcohol‐induced liver damage by inhibiting oxidative stress,hepatic inflammation,and enhance bioavailability on TLR4/MMP events compared to curcumin

Alcoholic liver diseases are classified as one of the major reasons for worldwide morbidity and mortality. Curcuminoids exhibit a wide range of pharmacological activities that are beneficial for health, including hepatoprotective effects, but its clinical significance is limited due to poor oral bioavailability. In the present study, a novel formulation of curcumin as curcumin‐galactomannosides (CGM) with enhanced oral bioavailability alleviated alcohol‐induced liver damage in wistar rats with an increased potency compared to the unformulated natural curcuminoids (CM). Ethanol administration significantly elevated liver toxicity markers, lipid peroxidation and inflammatory markers with a simultaneous reduction in antioxidant defenses. Supplementation of CGM reversed all of the pathological effects of alcohol administration, almost close to the normal level, when compared with CM. Histopathology of liver tissue also confirmed the better protective effect of CGM, indicating the enhancement in antioxidant and anti‐inflammatory effects as a function of bioavailability.