Design, synthesis and biological evaluation of bakuchiol derivatives as multi-target agents for the treatment of Alzheimer's disease.

The concept of multi-target-directed ligands offers fresh perspectives for the creation of brand-new Alzheimer's disease medications. To explore their potential as multi-targeted anti-Alzheimer's drugs, eighteen new bakuchiol derivatives were designed, synthesized, and evaluated. The structures of the new compounds were elucidated by IR, NMR, and HRMS. Eighteen compounds were assayed for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in vitro using Ellman's method. It was shown that most of the compounds inhibited AChE and BuChE to varying degrees, but the inhibitory effect on AChE was relatively strong, with fourteen compounds showing inhibition of >50% at the concentration of 200 µM. Among them, compound 3g (IC50 = 32.07 ± 2.00 µM) and compound 3n (IC50 = 34.78 ± 0.34 µM) showed potent AChE inhibitory activities. Molecular docking studies and molecular dynamics simulation showed that compound 3g interacts with key amino acids at the catalytically active site (CAS) and peripheral anionic site (PAS) of acetylcholinesterase and binds stably to acetylcholinesterase. On the other hand, compounds 3n and 3q significantly reduced the pro-inflammatory cytokines TNF-α and IL-6 released from LPS-induced RAW 264.7 macrophages. Compound 3n possessed both anti-acetylcholinesterase activity and anti-inflammatory properties. Therefore, an in-depth study of compound 3n is expected to be a multi-targeted anti-AD drug.

Discovery of Potent and Fast-Acting Antimalarial Bis-1,2,4-triazines.

Novel 3,3'-disubstituted-5,5'-bi(1,2,4-triazine) compounds with potent in vitro activity against Plasmodium falciparum parasites were recently discovered. To improve the pharmacokinetic properties of the triazine derivatives, a new structure-activity relationship (SAR) investigation was initiated with a focus on enhancing the metabolic stability of lead compounds. These efforts led to the identification of second-generation highly potent antimalarial bis-triazines, exemplified by triazine 23, which exhibited significantly improved in vitro metabolic stability (8 and 42 µL/min/mg protein in human and mouse liver microsomes). The disubstituted triazine dimer 23 was also observed to suppress parasitemia in the Peters 4-day test with a mean ED50 value of 1.85 mg/kg/day and exhibited a fast-killing profile, revealing a new class of orally available antimalarial compounds of considerable interest.

3,3'-Disubstituted 5,5'-Bi(1,2,4-triazine) Derivatives with Potent in Vitro and in Vivo Antimalarial Activity.

A series of 3,3'-disubstituted 5,5'-bi(1,2,4-triazine) derivatives was synthesized and screened against the erythrocytic stage of Plasmodium falciparum 3D7 line. The most potent dimer, 6k, with an IC50 (50% inhibitory concentration) of 0.008 µM, had high in vitro potency against P. falciparum lines resistant to chloroquine (W2, IC50 = 0.0047 ± 0.0011 µM) and artemisinin (MRA1240, IC50 = 0.0086 ± 0.0010 µM). Excellent ex vivo potency of 6k was shown against clinical field isolates of both P. falciparum (IC50 = 0.022-0.034 µM) and Plasmodium vivax (IC50 = 0.0093-0.031 µM) from the blood of outpatients with uncomplicated malaria. Despite 6k being cleared relatively rapidly in mice, it suppressed parasitemia in the Peters 4-day test, with a mean ED50 value (50% effective dose) of 1.47 mg kg-1 day-1 following oral administration. The disubstituted triazine dimer 6k represents a new class of orally available antimalarial compounds of considerable interest for further development.

Design, synthesis and molecular modeling of aloe-emodin derivatives as potent xanthine oxidase inhibitors.

A series of aloe-emodin derivatives were synthesized and evaluated as xanthine oxidase inhibitors. Among them, four aloe-emodin derivatives showed significant inhibitory activities against xanthine oxidase. The compound 4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carbaldehyde (A1) possessed the best xanthine oxidase inhibitory activity with IC50 of 2.79 µM. Lineweaver-Burk plot analysis revealed that A1 acted as a mixed-type inhibitor for xanthine oxidase. The docking study revealed that the molecule A1 had strong interactions with the active site of xanthine oxidase and this result was in agreement with kinetic study. Consequently, compound A1 is a new-type candidate for further development for the treatment of gout.

Acetylcholinesterase inhibition effects of marine fungi.

CONTEXT: To this day, there are no reports that marine compounds isolated from microorganisms of the Lianyungang area of China have been used for the treatment of Alzheimer's disease. OBJECTIVE: The present study was to isolate fungi from the sea sediment of the Lianyungang area and screen for acetylcholineseterase inhibition activities of ethyl acetate extracts. MATERIALS AND METHODS: Fungi were isolated from the sea sediment and fermented. After centrifugation, the supernate was extracted with ethyl acetate. The ethyl acetate extract was then fractionated into five fractions. Acetylcholinesterase inhibition activities of the ethyl acetate extracts and five sub-fractions were tested at a concentration of 500 µg/mL with the Ellman's method. RESULTS: Forty-three marine fungi were isolated; 15 extracts inhibited acetylcholinestrease >50% and 3 extracts inhibited the acetylcholinesterase >80% at the concentration of 500 µg/mL. The 3 extracts (L1705, S1101, SH0701) inhibited AChE dose-dependently with IC50 values of 11.3 ± 1.2, 72.1 ± 2.3, and 7.8 ± 2.8 µg/mL, respectively. After the extract of SH0701 was fractionated into five fractions, the ethyl acetate fraction possessed the highest acetylcholinesterase inhibitory activity with an inhibition rate of 71.55% at the concentration of 10 µg/mL. The fungus SH0701 was identified as Aspergillus ochraceus SH0701 according to morphology and molecular identification. DISCUSSION AND CONCLUSION: The present results indicates that some ethyl acetate extracts of marine fungi isolated from Lianyungang area of China could inhibit AChE potently. Therefore, some novel AChE inhibitors might exist in those extracts.

Synthesis, biological evaluation and molecular modeling of aloe-emodin derivatives as new acetylcholinesterase inhibitors.

A series of aloe-emodin derivatives were designed, synthesized and evaluated as acetylcholinesterase inhibitors. Most of the new prepared compounds showed remarkable acetylcholinesterase inhibitory activities. Among them, the compound 1-((4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracen-2-yl) methyl) pyridin-1-ium chloride (C3) which has a pyridinium substituent possessed the best inhibitory activity of acetylcholinesterase (IC(50)=0.09 µM). The docking study performed with AUTODOCK demonstrated that C3 could interact with the catalytic active site (CAS) and the peripheral anionic site (PAS) of acetylcholinesterase.

A novel 7-O-modified genistein derivative with acetylcholinesterase inhibitory effect, estrogenic activity and neuroprotective effect.

To find the multi-target-directed compounds for the treatment of Alzheimer's disease (AD), we synthesized 7-(4-(diethylamino)butoxy)-5-hydroxy-3-(4-hydroxyphenyl)-4H-chromen-4-one, a novel 7-O-modified genistein derivative (GS-14), and investigated its acetylcholinesterase (AChE) inhibitory effect, estrogenic activity and neuroprotective effect. GS-14 acted as a selective AChE inhibitor in vitro, with an IC50 value of 0.17 µM and showed no inhibition activity against butyrylcholinesterase (BuChE). The Lineweaver-Burk plot revealed that GS-14 was a non-competitive AChE inhibitor with a K(i) value of 0.23 µM and the molecular docking model indicated that GS-14 interacted with the peripheral anionic site (PAS) of AChE. The MCF-7 proliferation assay demonstrated that GS-14 possessed estrogenic activity and GS-14 exhibited a high specificity for estrogen receptor ß (ERß) with a dissociation constant (K(i)) of 2.86 nM compared with that of 1.01 µM for estrogen receptor α (ERα) in the molecular docking study. GS-14 also possessed a neuroprotective effect and showed the best protective effect against the ß-amyloid protein-induced injury on SH-SY5Y cells at a concentration of 1 nM. Considering its AChE-inhibition activity, estrogenic activity and neuroprotective effect, GS-14 may be a potential multi-target agent for the treatment of AD.

The therapeutic effects of tectorigenin on chemically induced liver fibrosis in rats and an associated metabonomic investigation.

The aim of this study was to investigate the effects of tectorigenin on chemically induced liver fibrosis in rats. Liver fibrosis was induced in rats with carbon tetrachloride, a diet high in fat, cholesterol and alcohol in the drinking water. Our results indicate that tectorigenin treatment significantly inhibited the increases in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the increases in the serum levels of hyaluronate (HA), laminin (LN) and procollagen III N-terminal peptide (PIIIP); tectorigenin treatment also significantly inhibited the increases in the amount of collagen in the livers of the fibrogenic rats. Chemically induced liver fibrosis caused a drop in the serum albumin concentration and a decrease in the ratio of albumin to globulin (A/G). Tectorigenin caused a remarkable increase at a dose of 30 mg/kg, but only a slight increase at the lower doses. Tectorigenin was also able to inhibit the increase in the liver lipid peroxidation (LPO), as well as the decrease in the activities of liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), caused by liver fibrosis. In addition, we present a related metabolic profile determined, using a (1)H NMR spectroscopy and multivariate pattern recognition techniques. The results were consistent with the pathological examination, liver function analysis and liver fibrosis marker analysis. Furthermore, tectorigenin does not cause acute toxicity.

Pro-apoptotic effects of tectorigenin on human hepatocellular carcinoma HepG2 cells.

AIM: To investigate the effects of tectorigenin on human hepatocellular carcinoma (HCC) HepG2 cells. METHODS: Tectorigenin, one of the main components of rhizome of Iris tectorum, was prepared by simple methods, such as extraction, filtration, concentration, precipitation and recrystallization. HepG2 cells were incubated with tectorigenin at different concentrations, and their viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was detected by morphological observation of nuclear change, agarose gel electrophoresis of DNA ladder, and flow cytometry with Hoechst 33342, Annexin V-EGFP and propidium iodide staining. Generation of reactive oxygen species was quantified using DCFH-DA. Intracellular Ca(2+) was monitored by Fura 2-AM. Mitochondrial membrane potential was monitored using Rhodamine 123. Release of cytochrome c from mitochondria to cytosol was detected by Western blotting. Activities of caspase-3, -8 and -9 were investigated by Caspase Activity Assay Kit. RESULTS: The viability of HepG2 cells treated by tectorigenin decreased in a concentration- and time-dependent manner. The concentration that reduced the number of viable HepG2 cells by 50% (IC(50)) after 12, 24 and 48 h of incubation was 35.72 mg/L, 21.19 mg/L and 11.06 mg/L, respectively. However, treatment with tectorigenin at 20 mg/L resulted in a very slight cytotoxicity to L02 cells after incubation for 12, 24 or 48 h. Tectorigenin at a concentration of 20 mg/L greatly inhibited the viability of HepG2 cells and induced the condensation of chromatin and fragmentation of nuclei. Tectorigenin induced apoptosis of HepG2 cells in a time- and dose-dependent manner. Compared with the viability rate, induction of apoptosis was the main mechanism of the anti-proliferation effect of tectorigenin in HepG2 cells. Furthermore, tectorigenin-induced apoptosis of HepG2 cells was associated with the generation of reactive oxygen species, increased intracellular [Ca(2+)](i), loss of mitochondrial membrane potential, translocation of cytochrome c, and activation of caspase-9 and -3. CONCLUSION: Tectorigenin induces apoptosis of HepG2 cells mainly via mitochondrial-mediated pathway, and produces a slight cytotoxicity to L02 cells.

Inhibition of urease by extracts derived from 15 Chinese medicinal herbs.

CONTEXT: Helicobacter pylori is a major causative factor in gastritis-like disorders, and urease plays a key role in Helicobacter pylori colonizing and persisting in the mucous layer of the human stomach. In China, a variety of Chinese medicinal herbs have been prescribed to attenuate or eradicate gastritis-like disorders. However, little is known about the urease inhibition of Chinese medicinal herbs. OBJECTIVE: The present study was conducted to investigate the urease inhibition activities of the ethanol and water extracts of 15 Chinese medicinal herbs. MATERIALS AND METHODS: The ethanol and water extracts derived from 15 medicinal herbs, traditionally used for the treatment of gastritis-like disorders in China, were tested for urease-inhibition activity using the phenol red method. RESULTS: Screened at 10 µg/mL, 14 ethanol extracts and 10 water extracts showed urease inhibition. The ethanol extracts of Magnolia officinalis Rehd. et Wils. (Magnoliaceae) and Cassia obtusifolia L. (Leguminosae) possessed inhibition rates higher than 50% with IC50 values of 6.5 and 12.3 µg/mL, respectively. After fractionating successively, the petroleum ether fraction of the ethanol extracts of Magnolia officinalis showed the best activity with 90.8% urease inhibition at a concentration of 10 µg/mL. The bioautography of the petroleum ether fraction indicated the existence of the urease inhibitors in the herb. DISCUSSION AND CONCLUSION: The present results indicated that some Chinese medicinal herbs might treat gastritis-like disorders via the inhibition of Helicobacter pylori urease and the further possibility for discovering useful novel urease inhibitors from the Chinese medicinal herbs.

Synthesis, structures, and urease inhibitory activities of three copper(II) and zinc(II) complexes with 2-{[2-(2-hydroxyethylamino)ethylimino]methyl}-4-nitrophenol.

In order to explore novel urease inhibitors, three new mononuclear complexes of Cu(II) and Zn(II) with Schiff base 2-{[2-(2-hydroxyethylamino)ethylimino]methyl}-4-nitrophenol have been prepared and structurally characterized by X-ray crystallography. Among the three complexes, two Cu(II) complexes show strong urease inhibitory activities with the IC(50) values being much lower than that of the acetohydroxamic acid, while the Zn(II) complex shows no activity at the concentration of 100 microM.

4-Hydr-oxy-N'-(4-methoxy-benzyl-idene)benzohydrazide.

The title compound, C(15)H(14)N(2)O(3), was synthesized by the reaction of 4-methoxy-benzaldehyde with 4-hydroxy-benzohydrazide in methanol. The mol-ecule adopts an E configuration about the C=N bond. The two benzene rings make a dihedral angle of 46.6 (2)°. In the crystal structure, mol-ecules are linked into a two-dimensional network parallel to (001) through O-H⋯O and N-H⋯O hydrogen bonds.

Protective effect of hopeahainol A, a novel acetylcholinesterase inhibitor, on hydrogen peroxide-induced injury in PC12 cells.

In this study, we evaluated the effects of hopeahainol A, a novel acetylcholinesterase inhibitor (AChEI) from Hopea hainanensis, on H(2)O(2)-induced cytotoxicity in PC12 cells and the possible mechanism. Exposure of PC12 cells to 200µM H(2)O(2) caused cell apoptosis, reduction in cell viability and antioxidant enzyme activities, increment in malondialdehyde (MDA) level, and leakage of lactate dehydrogenase (LDH). Pretreatment of the cells with hopeahainol A at 0.1-10µM before H(2)O(2) exposure significantly attenuated those changes in a dose-dependent manner. Moreover, hopeahainol A could mitigate intracellular accumulation of reactive oxygen species (ROS) and Ca(2+), the loss of mitochondrial membrane potential (MMP), and the increase of caspase-3, -8 and -9 activities induced by H(2)O(2). These results show that hopeahainol A protects PC12 cells from H(2)O(2) injury by modulating endogenous antioxidant enzymes, scavenging ROS and prevention of apoptosis. There was potential for hopeahainol A to be used in treating Alzheimer's disease (AD) that involved acetylcholinesterase, free radical, oxidative damage and cell apoptosis.

Inhibition of soluble epoxide hydrolase by extracts derived from inflammation-treating Chinese medicinal herbs.

Soluble epoxide hydrolase (sEH) has been proved to be a key enzyme involved in inflammation progression, and inhibition of sEH is therefore very helpful or crucial for the treatment of inflammation-related diseases. In order to uncover new clues suggesting the presence of phytochemical-based sEH inhibitors, and to rationalize the utility of the inflammation-treating Chinese medicinal herbs, the ethanol extracts derived from 46 medicinal herbs, traditionally used for the treatment of inflammation-associated diseases in China, were tested for sEH-inhibition activity using a recently developed sensitive fluorescence-based assay. Screened at 10 microg/mL, four extracts showed substantial inhibitions of sEH (inhibition rates >50%). The ethanol extract of Sophora flavescens root (Fabaceae) possessed the strongest inhibitory activity against sEH (IC(50): 2.07 microg/mL). These preliminary findings highlighted the presence of sEH inhibitor(s) in the plant kingdom, and the possibility that the inflammation-treating herbal medicines could be an untapped reservoir for sEH-inhibition agents.

Schiff base transition metal complexes as novel inhibitors of xanthine oxidase.

Twenty transition metal complexes with Schiff bases were evaluated for their inhibitory activities on xanthine oxidase (XO), of which 11 were newly synthesized and characterized by X-ray single crystal diffraction. It was found that 9 of the 20 complexes showed potent inhibitory activities against XO near to the standard inhibitor allopurinol. The cadmium(II) complex (8) had the most potent inhibitory activity with the IC(50) value of 2.16 microM. Relationships between the structures and the activities showed that the ligands and the metal ions influenced the inhibitory activities. The XO inhibition of the Schiff base metal complexes most probably resulted from their direct interactions with the enzymes "in the whole complex form". These results demonstrated that the Schiff base transition metal complexes could be potential selective XO inhibitors.

Hopeahainol A: an acetylcholinesterase inhibitor from Hopea hainanensis.

A phytochemical study of Hopea hainanensis has led to the isolation of three new polyphenols and one known compound. The most important of these compounds are hopeahainols A (2) and B (3), which contain an unprecedented carbon skeleton. The structures were elucidated by analysis of the spectroscopic data including single-crystal X-ray spectroscopy and computational methods. Hopeahainol A was an acetylcholinesterase inhibitor with an IC50 value of 4.33 microM, which is comparable to that of huperzine A, a presently prescribed drug for the treatment of Alzheimer, while other similar structures were inactive. This observation was complemented by a 3D interaction model of the inhibitor with active sites.

A novel heterocyclic compound: catena-poly[[[diaquasodium(I)]-di-mu-aqua] hemi(1,5-dihydroxy-4,8,9-trioxa-2,6-diazabicyclo[3.3.1]nona-2,6-diene-3,7-diolate)].

In the title compound, {[Na(H2O)4]2(C(4)H(2)N(2)O(7))}n, the 1,5-dihydroxy-4,8,9-trioxa-2,6-diazabicyclo[3.3.1]nona-2,6-diene-3,7-diolate anion lies across a twofold axis in the space group C2/c; there are two independent Na sites, one on a twofold axis and the other on a centre of inversion. Hydrogen bonds link the {[Na(H2O)4]+}n chains and diolate anions into a three-dimensional framework.

Polyphenols based on isoflavones as inhibitors of Helicobacter pylori urease.

Twenty polyphenols were synthesized and evaluated for their effect on Helicobacter pylori urease. Among these compounds, 4-(p-hydroxyphenethyl)pyrogallol (15) (IC(50)=0.03 mM) and 7,8,4'-trihydroxyisoflavone (19) (IC(50)=0.14 mM) showed potent inhibitory activities, and inhibited Helicobacter pylori urease in a time-dependent manner. The structure-activity relationship of these polyphenols revealed: the two ortho hydroxyl groups were essential for inhibitory activity of polyphenol. When the C-ring of isoflavone was broken, the inhibitory activity markedly decreased. As for deoxybenzoin, the carboxyl group was clearly detrimental.

Bioactive oligostilbenoids from the stem bark of Hopea exalata.

Hopeanolin (1), an unusual resveratral trimer with an ortho-quinone nucleus, was isolated and characterized from the stem bark of Hopea exalata. Also obtained were six known stibenoids, shoreaphenol (2), vaticanol G (3), alpha-viniferin (4), pauciflorol A (5), vaticanol A (6), and trans-3,5,4'-trihydroxystilbene 2-C-glucoside (7). The structure of 1 was determined by spectroscopic data interpretation. Compounds 1-7 were tested for antifungal activity and inhibitory effects against jack bean urease. Hopeanolin (1) demonstrated antifungal activity in the MIC value range 0.1-22.5 microg/mL.