Comparing anti-HIV,antibacterial, antifungal,micellar, and cytotoxic properties of tricarboxylato dendritic amphiphiles

Three series of homologous dendritic amphiphiles—RCONHC(CH₂CH₂COOH)₃, 1(n); ROCONHC(CH₂CH₂COOH)₃, 2(n); RNHCONHC(CH₂CH₂COOH)₃, 3(n), where R = n-C_nH_2n+1 and n = 13–22 carbon atoms—were assayed for their potential to serve as antimicrobial components in a topical vaginal formulation. Comparing epithelial cytotoxicities to the ability of these homologues to inhibit HIV, Neisseria gonorrhoeae, and Candida albicans provided a measure of their prophylactic/therapeutic potential. Measurements of the ability to inhibit Lactobacillus plantarum, a beneficial bacterium in the vagina, and critical micelle concentrations (CMCs), an indicator of the potential detergency of these amphiphiles, provided additional assessments of safety. Several amphiphiles from each homologous series had modest anti-HIV activity (EC₅₀ = 110–130 μM). Amphiphile 2(18) had the best anti-Neisseria activity (MIC = 65 μM), while 1(19) and 1(21) had MICs against C. albicans of 16 and 7.7 μM, respectively. Two measures of safety showed promise as all compounds had relatively low cytotoxic activity (EC₅₀ = 210–940 μM) against epithelial cells and low activity against L. plantarum, 1(n), 2(n), and 3(n) had MICs ? 490, 1300, and 940 μM, respectively. CMCs measured in aqueous triethanolamine and in aqueous potassium hydroxide showed linear dependences on chain length. As expected, the longest chain in each series had the lowest CMC—in triethanolamine: 1(21), 1500 μM; 2(22), 320 μM; 3(22), 340 μM, and in potassium hydroxide: 1(21), 130 μM; 3(22), 40 μM. The CMC in triethanolamine adjusted to pH 7.4 was 400 μM for 1(21) and 3900 μM for 3(16). The promising antifungal activity, low activity against L. plantarum, relatively high CMCs, and modest epithelial cytotoxicity in addition to their anti-Neisseria properties warrant further design studies with dendritic amphiphiles to improve their safety indices to produce suitable candidates for antimicrobial vaginal products.     

New nemadectin congeners with acaricidal and nematocidal activity from Streptomyces microflavus neau3 Y-3

Two nemadectin congeners 1 and 2 were isolated from the fermentation broth of a mutant strain (Y-3) of Streptomyces microflavus neau3. Their structures were determined on the basis of extensive spectroscopic analysis and comparison with data from the literature. Compound 2 possessed a 5-membered ring lactone that is unprecedented among known milbemycins and avermectins. Both compounds 1 and 2 exhibited potent acaricidal activity and nematocidal activity. Especially, compound 2 demonstrated impressive acaricidal activity against adult mites with an IC₅₀ of 2.3 ± 0.9 μg/mL and mite eggs with an IC₅₀ of 17.5 ± 2.1 μg/mL and nematocidal activity against Caenorhabditis elegans with an IC₅₀ of 0.7 ± 0.2 μg/mL, which are higher than those of nemadectin and the known commercial acaricide and nematocide milbemycin A3/A4.     

Synthesis and QSAR study of novel α-methylene-γ-butyrolactone derivatives as antifungal agents

Thirty-six new α-benzylidene-γ-lactone compounds based α-methylene-γ-butyrolactone substructure were prepared and characterized by spectroscopic analysis. All compounds were evaluated for antifungal activities in vitro against six plant pathogenic fungi and the half maximal inhibitory concentration (IC₅₀) against Botrytis cinerea and Colletotrichum lagenarium were investigated. Compounds 5c-3 and 5c-5 with the halogen atom exhibited excellent fungicidal activity against B. cinerea (IC₅₀ = 22.91, 18.89 μM). The structure-activity relationships (SARs) analysis indicated that the derivatives with electron-withdrawing substituents at the meta- or para-positions improves the activity. Via the heuristic method, the generated quantitative structure-activity relationship (QSAR) model (R² = 0.961) revealed a strong correlation of antifungal activity against B. cinerea with molecular structures of these compounds. Meanwhile, the cytotoxicity of 20 representative derivatives was tested in the human tumor cells line (HepG2) and the hepatic L02 cells line, the result indicated that the synthesized compounds showed significant inhibitory activity and limited selectivity. Compound 5c-5 has the highest fungicidal activity with IC₅₀ = 18.89 μM (against B. cinerea.) but low cytotoxicity with IC₅₀ = 35.4 μM (against HepG2 cell line) and IC₅₀ = 68.8 μM (against Hepatic L02 cell line). These encouraging results can be providing an alternative, promising use of α-benzylidene-γ-lactone through the design and exploration of eco-friendly fungicides with low toxicity and high efficiency.     

Design,synthesis, in silico and in vitro evaluation of thiophene derivatives: A potent tyrosine phosphatase 1B inhibitor and anticancer activity

A series of novel methyl 4-(4-amidoaryl)-3-methoxythiophene-2-carboxylate derivatives were designed against the active site of protein tyrosine phosphatise 1B (PTP1B) enzyme using MOE.2008.10. These molecules are also subjected for in silico toxicity prediction studies and considering their corresponding drug scores, it implied that, the molecules are promising as anticancer agents. The designed compounds were synthesized by using suitable methods and characterized. They were subjected to inhibitory activity against PTP1B and in vitro anticancer activity by MTT assay. Most of the tested compounds showed potent inhibitory activity against PTP1B, among the compounds tested, compound 5b exhibited the highest activity (IC₅₀ = 5.25 µM) and remarkable cytotoxic activity at 0.09 µM of IC₅₀ against the MCF-7 cell line. In addition to this, compound 5c also showed potential anticancer activity at 2.22 µM of IC₅₀ against MCF-7 and 0.72 µM against HepG2 cell lines as well as PTP1B inhibitory activity at IC₅₀ of 6.37 µM.     

Identification of new potent inhibitor of aldose reductase from Ocimum basilicum

Recent efforts to develop cure for chronic diabetic complications have led to the discovery of potent inhibitors against aldose reductase (AKR1B1, EC 1.1.1.21) whose role in diabetes is well-evident. In the present work, two new natural products were isolated from the ariel part of Ocimum basilicum; 7-(3-hydroxypropyl)-3-methyl-8-β-O-d-glucoside-2H-chromen-2-one (1) and E-4-(6′-hydroxyhex-3′-en-1-yl)phenyl propionate (2) and confirmed their structures with different spectroscopic techniques including NMR spectroscopy etc. The isolated compounds (1, 2) were evaluated for in vitro inhibitory activity against aldose reductase (AKR1B1) and aldehyde reductase (AKR1A1). The natural product (1) showed better inhibitory activity for AKR1B1 with IC₅₀ value of 2.095 ± 0.77 µM compare to standard sorbinil (IC₅₀ = 3.14 ± 0.02 µM). Moreover, the compound (1) also showed multifolds higher activity (IC₅₀ = 0.783 ± 0.07 µM) against AKR1A1 as compared to standard valproic acid (IC₅₀ = 57.4 ± 0.89 µM). However, the natural product (2) showed slightly lower activity for AKR1B1 (IC₅₀ = 4.324 ± 1.25 µM). Moreover, the molecular docking studies of the potent inhibitors were also performed to identify the putative binding modes within the active site of aldose/aldehyde reductases.     

Aspernolides F and G,new butyrolactones from the endophytic fungus Aspergillus terreus

Two new butyrolactones: aspernolides F (6) and G (7), together with three stigmasterol derivatives: (22E,24R)-stigmasta-5,7,22-trien-3-β-ol (1), stigmast-4-ene-3-one (2), and stigmasta-4,6,8(14), 22-tetraen-3-one (3), two meroterpenoids: terretonin A (4) and terretonin (5), and a butyrolactone derivative: butyrolactone VI (8) have been isolated from the endophytic fungus Aspergillus terreus isolated from the roots of Carthamus lanatus (Asteraceae). Their structures were determined by spectroscopic means (1D, 2D NMR, and HRESIMS), as well as optical rotation measurement and comparison with literature data. The isolated compounds were evaluated for their anti-microbial, anti-malarial, anti-leishmanial, and cytotoxic activities. Compound 1 displayed a potent activity against MRSA and C. neoformans with IC₅₀ values of 0.96 μg/mL and 4.38 μg/mL, respectively compared to ciprofloxacin (IC₅₀ 0.07 μg/mL) and amphotericin B (IC₅₀ 0.34 μg/mL), respectively. While, 6 showed good activity against C. neoformans (IC₅₀ 5.19 μg/mL) and mild activity against MRSA (IC₅₀ 6.39 μg/mL). Moreover, 1 and 2 exhibited very good anti-leishmanial activity towards L. donovani with IC₅₀ values of 4.61 and 6.31 μg/mL, respectively and IC₉₀ values of 6.02 and 16.71 μg/mL, respectively.     

Design and synthesis of γ-butyrolactone derivatives as potential spermicidal agents

A series of γ-butyrolactone derivatives has been designed and synthesized from commercially available 2-acetyl butyrolactone (3-acetyldihydrofuran-2(3H)-one, 1) by aminoalkylating its active methylene followed by condensation with different aldehydes. Compounds having amino group were further converted to their respective tartrate salts and were evaluated for spermicidal activity against human sperm in vitro. Compounds showing appreciable spermicidal activity at ⩽0.5% [3c, 4d (0.5%); 2c, 3d (0.1%); 2d, 4c (0.05%)] were tested for safety studies against human cervical (HeLa) cell line. These compounds were found safer than, Nonoxynol-9. One of the two most active compounds was also found to be the safest (IC₅₀ = 961 μg/ml; 4c), while the second compound exhibited lower safety against HeLa (IC₅₀ = 269 μg/ml; 2d). The compound 4c significantly reduced the number of free thiols on human sperm. All the compounds were inactive against Trichomonas vaginalis.     

Rational design,synthesis and biological evaluation of 1,3,4-oxadiazole pyrimidine derivatives as novel pyruvate dehydrogenase complex E1 inhibitors

On the basis of previous study on 2-methylpyrimidine-4-ylamine derivatives I, further synthetic optimization was done to find potent PDHc-E1 inhibitors with antibacterial activity. Three series of novel pyrimidine derivatives 6, 11 and 14 were designed and synthesized as potential Escherichia coli PDHc-E1 inhibitors by introducing 1,3,4-oxadiazole-thioether, 2,4-disubstituted-1,3-thiazole or 1,2,4-triazol-4-amine-thioether moiety into lead structure I, respectively. Most of 6, 11 and 14 exhibited good inhibitory activity against E. coli PHDc-E1 (IC₅₀ 0.97–19.21 μM) and obvious inhibitory activity against cyanobacteria (EC₅₀ 0.83–9.86 μM). Their inhibitory activities were much higher than that of lead structure I. 11 showed more potent inhibitory activity against both E. coli PDHc-E1 (IC₅₀ < 6.62 μM) and cyanobacteria (EC₅₀ < 1.63 μM) than that of 6, 14 or lead compound I. The most effective compound 11d with good enzyme-selectivity exhibited most powerful inhibitory potency against E. coli PDHc-E1 (IC₅₀ = 0.97 μM) and cyanobacteria (EC₅₀ = 0.83 μM). The possible interactions of the important residues of PDHc-E1 with title compounds were studied by molecular docking, site-directed mutagenesis, and enzymatic assays. The results indicated that 11d had more potent inhibitory activity than that of 14d or I due to its 1,3,4-oxadiazole moiety with more binding position and stronger interaction with Lsy392 and His106 at active site of E. coli PDHc-E1.     

Design,synthesis, molecular docking and biological evaluation of thiophen-2-iminothiazolidine derivatives for use against Trypanosoma cruzi

In this study, we designed and synthesized a series of thiophen-2-iminothiazolidine derivatives from thiophen-2-thioureic with good anti-Trypanosoma cruzi activity. Several of the final compounds displayed remarkable trypanocidal activity. The ability of the new compounds to inhibit the activity of the enzyme cruzain, the major cysteine protease of T. cruzi, was also explored. The compounds 3b, 4b, 8b and 8c were the most active derivatives against amastigote form, with significant IC₅₀ values between 9.7 and 6.03 μM. The 8c derivative showed the highest potency against cruzain (IC₅₀ = 2.4 μM). Molecular docking study showed that this compound can interact with subsites S1 and S2 simultaneously, and the negative values for the theoretical energy binding (E_b = −7.39 kcal·mol⁻¹) indicates interaction (via dipole–dipole) between the hybridized sulfur sp³ atom at the thiazolidine ring and Gly66. Finally, the results suggest that the thiophen-2-iminothiazolidines synthesized are important lead compounds for the continuing battle against Chagas disease.     

Design,synthesis, antiviral and cytostatic activity of ω-(1H-1,2,3-triazol-1-yl)(polyhydroxy)alkylphosphonates as acyclic nucleotide analogues

The efficient synthesis of a new series of polyhydroxylated dibenzyl ω-(1H-1,2,3-triazol-1-yl)alkylphosphonates as acyclic nucleotide analogues is described starting from dibenzyl ω-azido(polyhydroxy)alkylphosphonates and selected alkynes under microwave irradiation. Selected O,O-dibenzylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and for cytostatic activity against murine leukemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Compound (1S,2S)-16b exhibited antiviral activity against Influenza A H3N2 subtype (EC₅₀ = 20 μM—visual CPE score; EC₅₀ = 18 μM—MTS method; MCC >100 μM, CC₅₀ >100 μM) in Madin Darby canine kidney cell cultures (MDCK), and (1S,2S)-16k was active against vesicular stomatitis virus and respiratory syncytial virus in HeLa cells (EC₅₀ = 9 and 12 μM, respectively). Moreover, compound (1R,2S)-16l showed activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC₅₀ = 2.9 and 4 μM, respectively) and feline herpes virus in CRFK cells (EC₅₀ = 4 μM) but at the same time it exhibited cytotoxicity toward uninfected cell (MCC ⩾ 4 μM). Several other compounds have been found to inhibit proliferation of L1210, CEM as well as HeLa cells with IC₅₀ in the 4–50 μM range. Among them compounds (1S,2S)- and (1R,2S)-16l were the most active (IC₅₀ in the 4–7 μM range).     

Schistosomicidal and trypanocidal structure-activity relationships for (±)-licarin A and its (-)- and (+)-enantiomers

(±)-Licarin A (1) was obtained by oxidative coupling, and its enantiomers, (?)-licarin A (2) and (+)-licarin A (3), were resolved by chiral HPLC. Schistosomicidal and trypanocidal activities of these compounds were evaluated in vitro against Schistosoma mansoni adult worms and trypomastigote forms of Trypanosoma cruzi. The racemic mixture (1) displayed significant schistosomicidal activity with an LC₅₀ value of 53.57 μM and moderate trypanocidal activity with an IC₅₀ value of 127.17 μM. On the other hand, the (?)-enantiomer (2), displaying a LC₅₀ value of 91.71 μM, was more active against S. mansoni than the (+)-enantiomer (3), which did not show activity. For the trypanocidal assay, enantiomer 2 showed more significant activity (IC₅₀ of 23.46 μM) than enantiomer 3, which showed an IC₅₀ value of 87.73 μM. Therefore, these results suggest that (±)-licarin A (1) and (?)-licarin A (2) are promising compounds that could be used for the development of schistosomicidal and trypanocidal agents.     

Design,synthesis, and docking studies of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (12a–e, 13a–f, 14a–f and 15a–i) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7) and c-Met kinase. Five selected compounds (13b, 15b, 15d, 15e and 15f) were further evaluated for the activity against HepG2 and Hela cell lines. Eighteen of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Seven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15f showed superior activity to Foretinib, with the IC₅₀ values of 1.04 ± 0.11 μM, 0.02 ± 0.01 μM and 9.11 ± 0.55 μM against A549, PC-3 and MCF-7 cell lines, which were 0.62 to 19.5 times more active than Foretinib (IC₅₀ values: 0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that replacement of quinoline nucleus of the previous active compounds with 1H-pyrrolo[2,3-b]pyridine moiety maintained even improved the potent cytotoxic activity. The results suggested that the introduction of fluoro atoms to the aminophenoxy part of target compounds or the phenyl group of pyrimidine substituted on C-4 position was benefit for the activity.     

In vitro growth inhibitory effects of 13,28-epoxyoleanane triterpene saponins in cancer cells

Two new 13,28-epoxyoleanane triterpene saponins, magnosides A (1) and B (2), were isolated from the 95% ethanolic extract of Cybianthus magnus (Mez) Pipoly roots. Their structures were deduced by a combination of spectral analyses and chemical evidences as compared to data reported in the literature. The hemolytic activity of both compounds was measured. Compound 1 was shown to exhibit the strongest hemolytic activity with a HD₅₀ of 3.8 μM followed by 2 with a HD₅₀ of 33.5 μM. The bioactivity of compounds 1 and 2 was also evaluated in vitro against different cellular models including Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, mouse peritoneal macrophages and eight cancer cell lines. While neither of the tested compounds displayed any activity against M. tuberculosis, both exhibited anti-leishmanial activity against axenic amastigotes as well as in vitro growth inhibitory activity against all tested cancer cell lines with IC₅₀ growth inhibitory concentrations ranging between 4 μM and 33 μM. The compounds displayed similar growth inhibitory activity in cancer cell lines sensitive to pro-apoptotic stimuli versus those displaying various levels of resistance to such stimuli. Quantitative videomicroscopy analyses revealed that compounds 1 and 2 are cytotoxic.     

Tirucallane triterpenoids from the stem bark of Araliopsis synopsis

Two new tirucallane triterpenoids, 21-methoxy-21,23-epoxy-tirucalla-7,24-dien-3α-ol (1) and 21-methoxy-21,23-epoxy-tirucalla-7,24-diene-1α,3α-diol (2), together with thirteen known compounds were isolated from the CH₂Cl₂ extract of the stem bark of Araliopsis synopsis. The structures of the compounds were determined by comprehensive analyses of their 1D and 2D NMR, mass spectral (EI and ESI) data and comparison with previously known analogs. Compounds 1–10 were tested against bacteria, fungi and plant pathogen oomycetes by the paper disk agar diffusion assay resulting in missing to low activities corresponding with MICs > 1 mg/mL. However, compounds 5–10 exhibited high cytotoxic activity against the human Caucasian prostate adenocarcinoma cell PC-3 line, with IC₅₀ 8.5–12.5 μM compared to the standard Doxorubicin with IC₅₀ = 0.9 μM, while compounds 1, 3 and 4 showed low activity.     

Synthesis,and docking studies of phenylpyrimidine-carboxamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpyrimidine-carboxamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (14a–e, 15a–g, 16a–e and 17a–g) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7). Four selected compounds (15e, 16a–b and 17a) were further evaluated for the activity against c-Met kinase, HepG2 and Hela cell lines. Most of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Eleven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15e showed superior activity to Foretinib against A549, PC-3 and MCF-7 cell lines, with the IC₅₀ values of 0.14 ± 0.08 μM, 0.24 ± 0.07 μM and 0.02 ± 0.01 μM, which were 4.6, 1.6 and 473.5 times more active than Foretinib (0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that the replacement of phenylpicolinamide scaffold with phenylpyrimidine fragment of the target compounds was benefit for the activity. What’s more, the introduction of fluoro atom to the aminophenoxy part played no significant impact on the activity and any substituent group on aryl group is unfavourable for the activity.     

Triterpenes from the roots of Lantana montevidensis with antiprotozoal activity

Bioassay guided fractionation of the roots of Lantana montevidensis (Verbenaceae) has resulted in the isolation and identification of three new triterpenoids; 13β-hydroxy-3-oxo-olean-11-en-28-oic acid (1), 12β,13β-dihydroxyolean-3-oxo-28-oic acid (2) and 12β,13β,22β-trihydroxyolean-3-oxo-28-oic acid (3) in addition to nine known compounds: oleanonic acid (4), oleanolic acid (5), 3β,25β-dihydroxy-olean-12-en-28-oic acid (6), lantadene A (7), 19α-hydroxy-3-oxo-olean-12-en-28-oic acid (8) pomolic acid (9), camaric acid (10) together with β-sitosterol (11) and β-sitosterol-3-O-β-d-glucoside (12). The structures of the isolated metabolites were elucidated based on comprehensive 1D and 2D NMR spectroscopic data as well as HR-ESI–MS. The extracts and the isolated metabolites were evaluated for their antiprotozoal and antimicrobial activities. Compound 2 showed antibacterial activity against Staphylococcus aureus and methicillin resistant S. aureus with IC₅₀ values against both organisms of 2.1 μM and compound 10 showed activity against same organisms with IC₅₀ values 8.74 and 8.09 μM, respectively, compared to the positive control ciprofloxacin (IC₅₀ = 0.3 μM against S. aureus and MRSA). Compounds 1, 4, 5, 6, and 10 showed moderate antileishmanial activity with IC₅₀ values ranging between (2.54–14.95 μM) and IC₉₀ values ranging between (11.90–19.47 μM), using pentamidine as a control (IC₅₀ values 2.09 ≥ 16.8 μM) and IC₉₀ values ranging between (4.72 ≥ 16.8 μM). These compounds also showed highly potent antitrypanosomal activity with IC₅₀ values ranging between (0.39–7.12 μM) and IC₉₀ values ranging between (1.91–10.51 μM), which are more efficient than the DFMO, the antitrypanosomal drug employed as positive control (IC₅₀ and IC₉₀values 11.82 and 30.82 μM).     

Isolation,structure, and bioactivities of abiesadines A–Y, 25 new diterpenes from Abies georgei Orr

Twenty-five new (abiesadines A–Y, 1–25) and 29 known (26–54) diterpenes were isolated from the aerial parts of Abies georgei. Abiesadine A (1) is a novel 8,14-seco-abietane, while abiesadine B (2) is a novel 9,10-seco-abietane. The structures of the new compounds were established on the basis of spectroscopic data analysis. Manool (52) showed the strongest effect against LPS-induced NO production in RAW264.7 macrophages with the IC₅₀ value of 11.0 μg/mL. In another anti-inflammatory assay against TNFα-triggered NF-κB activity, (12R,13R)-8,12-epoxy-14-labden-13-ol (54) exhibited the strongest effect (IC₅₀ = 8.7 μg/mL). For antitumor assays, pomiferin A (26) and 8,11,13-abietatriene-7α,18-diol (29) both showed the most significant activity against LOVO cells (IC₅₀ = 9.2 μg/mL). While 7-oxocallitrisic acid (46) exhibited significant cytotoxicity against QGY-7703 tumor cells (IC₅₀ = 10.2 μg/mL).     

3-Aryl-4-acyloxyethoxyfuran-2(5H)-ones as inhibitors of tyrosyl-tRNA synthetase: Synthesis,molecular docking and antibacterial evaluation

Thirty-eight 3-aryl-4-acyloxyethoxyfuran-2(5H)-ones were designed, prepared and tested for antibacterial activities. Some of them showed significant antibacterial activity against Gram-positive organism, Gram-negative organism and fungus. Out of these compounds, 4-(2-(3-chlorophenylformyloxy)ethoxy)-3-(4-chlorophenyl)furan-2(5H)-one (d40) showed the widest spectrum of activity with MIC₅₀ of 2.0 μg/mL against Staphylococcus aureus, 4.3 μg/mL against Escherichia coli, 1.5 μg/mL against Pseudomonas aeruginosa and 1.2 μg/mL against Candida albicans. Our data disclosed that MIC₅₀ values against whole cell bacteria are positive correlation with MIC₅₀ values against tyrosyl-tRNA synthetase. Meanwhile, molecular docking of d40 into S. aureus tyrosyl-tRNA synthetase active site was also performed, and the inhibitor tightly fitting the active site might be an important reason why it has high antimicrobial activity.     

Synthesis and biological evaluation of 5-carbamoyl-2-phenylpyrimidine derivatives as novel and potent PDE4 inhibitors

5-Carbamoyl-2-phenylpyrimidine derivative 2 has been identified as a phosphodiesterase 4 (PDE4) inhibitor with moderate PDE4B inhibitory activity (IC₅₀ = 200 nM). Modification of the carboxylic acid moiety of 2 gave N-neopentylacetamide derivative 10f, which had high in vitro PDE4B inhibitory activity (IC₅₀ = 8.3 nM) and in vivo efficacy against lipopolysaccharide (LPS)-induced pulmonary neutrophilia in mice (ID₅₀ = 16 mg/kg, ip). Furthermore, based on the X-ray crystallography of 10f bound to the human PDE4B catalytic domain, we designed 7,8-dihydro-6H-pyrido[4,3-d]pyrimidin-5-one derivative 39 which has a fused bicyclic lactam scaffold. Compound 39 exhibited excellent inhibitory activity against LPS-induced tumor necrosis factor alpha (TNF-α) production in mouse splenocytes (IC₅₀ = 0.21 nM) and in vivo anti-inflammatory activity against LPS-induced pulmonary neutrophilia in mice (41% inhibition at a dose of 1.0 mg/kg, i.t.).     

Constituents of Nelumbo nucifera leaves and their antimalarial and antifungal activity

From the leaves of Nelumbo nucifera (an aquatic plant), one new compound, 24(R)-ethylcholest-6-ene-5α-ol-3-O-β-d-glucopyranoside (1), along with 11 known metabolites (2–12), were isolated and identified by spectroscopic methods including 1D- and 2D NMR. Antifungal activity for (R)-roemerine (3) (IC₅₀/MIC = 4.5/10 μg/mL against Candida albicans) and antimalarial activity for (R)-roemerine (3) and N-methylasimilobine (5) (IC₅₀ = 0.2 and 4.8 μg/mL for the D6 clone, respectively, and 0.4 and 4.8 μg/mL for the W2 clone, respectively) was observed. None of the compounds were cytotoxic to Vero cells up to a concentration of 23.8 μg/mL. NMR data for 10-eicosanol (7) and 7,11,15-trimethyl-2-hexadecanone (10) are presented for the first time. An analysis of the structure–activity relationship shows that the substituents in position C-1 and C-2 of aporphine alkaloids are crucial for the antimalarial activity.