Pregnenolone derivatives as potential anticancer agents

Pregnenolone (1) was used as a template to develop new anticancer compounds. Ring-D modification of 1 resulted in the synthesis of benzylidenes 2-17, pyrazolines 18-76, pyrazoles 85-91, hydrazones 77-84, and oximes 92-107 derivatives. The structure of compound 107 was also deduced through single crystal X-ray diffraction studies. The inclusion of furanyl and pyridyl rings to pregnenolone skeleton increases the cytotoxicity of all compounds significantly. Among benzylidene derivatives, only heterocyclic enone 8 (IC₅₀ = 0.74 μM/mL against HepG2), and 17 (IC₅₀ = 4.49 μM/mL against HepG2, IC₅₀ = 5.01 μM/mL against MDA-MB-230 cancer cell line) exhibited a significant activity. The cytotoxicity data of pyrazoline derivatives 18-76 revealed that only furanyl bearing pyrazolines 40, 42-44, 48, and 49 exhibited significant activities. While all (O-carboxymethyl) oximes, hydazones, and pyrazoles derivatives of pregnenolone did not show any significant activity against both the cell lines. Thus the furanyl bearing enone 8 (IC₅₀ = 0.74 μM/mL against HepG2), and its pyrazoline derivative 48 (IC₅₀ = 0.91 μM/mL against MDA-MB-230 cancer cell lines) were identified as the most active compounds in all derivatives of pregnenolone.     

Design and synthesis of 3-(azol-1-yl)phenylpropanes as microbicidal spermicides for prophylactic contraception

We designed a series of 25 3-(azol-1-yl)phenylpropanes which yielded 10 compounds (3, 4, 7, 8, 13, 14, 19, 21, 23, 26) that irreversibly immobilized 100% human sperm at 1% (w/v) concentration in 60 s; 12 compounds (8, 9, 15, 16, 19-21, 23-25, 27, 28) that showed potent microbicidal activity at 12.5-50 μg/mL against Trichomonas vaginalis; and 17 compounds (3-11, 13, 15, 19, 21, 23, 26, 28, 30) that exhibited potent anticandida activity with minimum inhibitory concentration (MIC) of 12.5-50 μg/mL. Almost all the compounds exhibited high level of safety towards normal vaginal flora (Lactobacillus) and human cervical (HeLa) cells in comparison to the marketed spermicide nonoxynol-9 (N-9). All the biological activities were evaluated in vitro. Two compounds (4, 8) with good safety profile exhibited multiple (spermicidal, antitrichomonas and anticandida) activities, warranting further lead optimization for furnishing a prophylactic vaginal contraceptive.     

Unexpectedly convenient and stereoselective synthesis of 4α-acyloxy-2-chloropodophyllotoxins in the presence of BF₃ ·Et₂O

Twenty-one 4α-acyloxy-2-chloropodophyllotoxin derivatives (5a-u), whose C-4 spatial configuration was mainly stereocontrolled by the configuration of C-2 chlorine atom, were unexpectedly prepared by the reaction of 2-chloropodophyllotoxin with carboxylic acids in the presence of BF₃·Et₂O. Compared with ordinary esterifications of carboxylic acids mediated by the condensation agent, for example, N,N’-diisopropylcarbodiimide (DIC), the present method made the procedure for the preparation of 4α-acyloxy-2-chloropodophyllotoxins more convenient, practical and easy. Meanwhile, the insecticidal activity of compounds 5a-u was preliminarily evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1 mg/mL.     

The novel 3,4-dihydropyrimidin-2(1H)-one urea derivatives of N-aryl urea: synthesis, anti-inflammatory, antibacterial and antifungal activity evaluation

A series of novel 3,4-dihydropyrimidin-2(1H)-one urea derivatives of biological interest were prepared by sequential Bigineli’s reaction, reduction followed by reaction of resulting amines with different arylisocynates. All the synthesized (1-23) compounds were screened against the pro-inflammatory cytokines (TNF-α and IL-6) and antimicrobial activity (antibacterial and antifungal). Biological activity evaluation study reveled that among all the compounds screened, compounds 12 and 17 found to have promising anti-inflammatory activity (68-62% TNF-α and 92-86% IL-6 inhibitory activity at 10 μM). Interestingly compounds 3, 4, 5, 6, 15, 22 and 23 revealed promising antimicrobial activity at MIC of 10-30 μg/mL against selected pathogenic bacteria and fungi.     

Synthesis and antitubercular activity of monocyclic nitroimidazoles: insights from econazole

We have designed and synthesized econazole-derived nitroimidazoles to investigate the antitubercular activity of the nitroimidazole compounds. The introduction of a nitro group at the 4-position of the imidazole on econazole abolished the antitubercular activity. However, alcoholic nitroimidazoles 4 and 6 compounds were active against Mycobacterium tuberculosis (Mtb). While the MIC value of econazole was 16 μg/mL, the MIC of 6a and 6f turned out to be 0.5 μg/mL. In particular, the activity of 6f against non-replicating Mtb was as good as PA-824, which is currently in clinical phase II studies as an antitubercular agent. Overall, alcohol compounds 4 and 6 tend to be more active than ether compounds 5 and 7.     

Limonoids from the seeds of a Godavari mangrove, Xylocarpus moluccensis

Ten limonoids, named godavarins A-J (1-7, 9-11), were isolated from seeds of an Indian mangrove (Xylocarpus moluccensis) collected in the mangrove wetlands of Godavari estuary, Andhra Pradesh. Eight known limonoids, viz. xyloccensins L (8), P (12), Q (13), mexicanolide (14), 6-deoxy-3-detigloyl-swietenine acetate (15), fissinolide (16), methyl 3β-acetoxy-1-oxomeliaca-8(30),14-dienoate (17), and methyl 3β-acetoxy-1-oxomeliaca-8(9),14-dienoate (18), were also obtained. The structures of these compounds were established on the basis of spectroscopic data or comparison with data in the literature (known compounds). The stereostructure of godavarin D was confirmed by means of single-crystal X-ray analysis. Godavarins A-C are the first mexicanolide derivatives with a C₇-C₂₈ ester-linked δ-lactone ring, while godavarins D-G are further additions to the small group of limonoids with a C₁-C₂₉ oxygen bridge. Godavarin H is a phragmalin with five acetoxy groups. Two limonoids, mexicanolide and fissinolide, were found to exhibit marked antifeedant activity against the third-instar larvae of Brontispa longissima (Gestro) at a concentration of 0.5 mg/mL. The most potent compound was mexicanolide. It also showed moderate insecticidal activity.     

Bioactive saponins from Microsechium helleri and Sicyos bulbosus

Eleven oleanane-type saponins (1-11) have been isolated from Microsechium helleri and Sicyos bulbosus roots and were evaluated for their antifeedant, nematicidal and phytotoxic activities. Saponins {3-O-β-d-glucopyranosyl (1 → 3)-β-d-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-[β-d-xylopyranosyl-(1 → 3)]-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranoside} (1), and {3-O-β-d-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-[β-d-xylopyranosyl-(1 → 3)]-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranoside} (2) were also isolated from M. helleri roots together with the two known compounds 3 and 4. Seven known structurally related saponins (5-11) were isolated from S. bulbosus roots. The structures of these compounds were established as bayogenin and polygalacic glycosides using one- and two-dimensional NMR spectroscopy and mass spectrometry. Compounds 7, 10, bayogenin (12) and polygalacic acid (13) showed significant (p < 0.05) postingestive effects on Spodoptera littoralis larvae, compounds 5-11 and 12 showed variable nematicidal effects on Meloydogyne javanica and all tested saponins had variable phytotoxic effects on several plant species (Lycopersicum esculentum, Lolium perenne and Lactuca sativa). These are promising results in the search for natural pesticides from the Cucurbitaceae family.     

Design, synthesis and in vitro antibacterial activity of 7-(4-alkoxyimino-3-aminomethylpiperidin-1-yl)fluoroquinolone derivatives

We report herein the design and synthesis of novel 7-(4-alkoxyimino-3-aminomethylpiperidin-1-yl) fluoroquinolone derivatives. The antibacterial activity of the newly synthesized compounds was evaluated and compared with gemifloxacin, levofloxacin and ciprofloxacin. Results reveal that compounds 10, 16, and 17 have good activity against all of the tested Gram-positive organisms including drug-resistance strains (MICs: 0.125-4 μg/mL). In addition, compounds 16 and 17 (MICs: 4 μg/mL) were 2- to 8-fold more potent than the reference drugs against Pseudomonas aeruginosa.     

Synthesis and evaluation of chromenyl barbiturates and thiobarbiturates as potential antitubercular agents

A novel series of barbiturate and thiobarbiturate analogs of 2-benzoyl-3-methyl-5-oxo-5H-furo[3,2-g]chromene-6-carbaldehydes (3a-g and 4a-d, respectively) and 6-methyl-4,8-dioxo-4,8-dihydropyrano[3,2-g]chromenes (7a-c), were synthesized and evaluated for their antitubercular activities against Mycobacterium tuberculosis H37RV, and cytotoxicity (CC₅₀) in the VERO cell MABA assay. The results indicate that the furanochromene series of compounds (3a-g and 4a-d) showed only weak to moderate antitubercular activity. However, the pyranochromene analog 7b showed good antitubercular activity (IC₉₀: 5.9 μg/mL) and cytotoxicity (CC₅₀: 14.27 μg/mL). The antitubercular activity of 7b was superior to the antituberculosis drug, pyrazinamide (PZA; IC₉₀: >20 μg/mL). Analog 7b was considered to be a lead compound for subsequent structural optimization.     

Phenolic compounds and their anti-oxidative properties and protein kinase inhibition from the Chinese mangrove plant Laguncularia racemosa

Phenolic compounds, named integracin D (1), (7′R, 8′S, 8S)-8-hydroxyisoguaiacin (3), (2R, 3R) pinobanksin-3-caffeoylate (5) and threo-8S-7-methoxysyringylglycerol (6), respectively, were isolated from the Chinese mangrove plant Laguncularia racemosa (L) Gaertn. f. (Combretaceae), together with 23 known phenolic metabolites. Their structures were elucidated on the basis of extensive spectroscopic analyses including that of IR, UV, MS, CD, 1D and 2D NMR spectra as well as by comparison with literature data. Compound 5 showed significant anti-oxidative activity in the DPPH and TEAC free-radical-scavenging assays, while several of the phenolic compounds were tested for protein kinase inhibitory activity in an assay involving 24 different human tumor related protein kinases. Compounds 5, 7, and 23 showed potential inhibition with IC₅₀ values between 2.2 and 3.6 μg/mL toward individual kinases. The ellagic acid derivatives were tested for insecticidal activity.     

Substituted imidazole derivatives as novel cardiovascular agents

A series of novel substituted imidazole derivatives were synthesized and have been screened in vivo for their hypotensive and acute toxicity activities. Out of seventeen compounds eight compounds (2b, 2c, 3b, 3c, 3f, 4a, 4b and 4c) have shown good hypotensive and bradycardiac responses. Compounds 3b, 3c, 3f and 4c have shown better activity than reference drug clonidine. All the compounds have shown ALD50 >1000 mg/kg with maximum in 2e and 4c (>1200 mg/kg).     

Preparation, spectroscopy, X-ray analysis, and water-solubility studies of the first bis-PTA (PTA = 1,3,5-triaza-7-phosphaadamantane) derivatives

The bis-phosphines, 1,1′-[1,2-phenylenebis(methylene)]bis-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.1]decane dibromide (1), 1,1′-[1,3-arenebis(methylene)]bis-[3,5-diaza-1-azonia-7-phosphatricyclo [3.3.1.1]decane dibromide (arene = phenyl (2), tolyl (3), anisolyl (4)), and 1,1′-[1,4-phenylenebis(methylene)]bis-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.1]decane dibromide (5) were prepared in over 90% yield by refluxing 1,2-bis(bromomethyl)benzene, 1,3-bis(bromomethyl)benzene, 1,3-bis(bromomethyl)-5-methyl-benzene, 1,3-bis(bromomethyl)-5-methoxy-benzene, and 1,4-bis(bromomethyl)benzene with 1,3,5-triaza-7-phosphaadamantane (PTA) in acetone or chloroform. Compounds 1-5 are the first phosphines reported that contain two PTA moieties. All five compounds were characterized by ESI-MS, elemental analysis, ¹H, ¹³C, and ³¹P NMR spectroscopy, while 3 and 4 were additionally analyzed via single crystal X-ray diffraction. The relative positions of the PTA units on the aromatic ring as well as the substituents of the ring had a pronounced effect on the water-solubilities of the systems. The ortho compound (1, 2000 mg/mL) was more than two orders of magnitude more soluble than the para compound (5, 12.5 mg/mL). The meta substituted phenyl (2) and tolyl (3) compounds had solubilities (810 mg/mL) that were more than triple that of PTA (235 mg/mL) while the anisolyl analog (4) was half as soluble (121 mg/mL).     

Synthesis and biological evaluation of glycal-derived novel tetrahydrofuran 1,2,3-triazoles by ‘click’ chemistry

Thirteen new 1,2,3-triazoles (5a-e, 15a-d, 17a-b, 19, and 21) were synthesized by ‘click’ reaction of sugar-derived azides with commercially available acetylenes. The synthesized triazoles were tested in vitro for their biological activity, and compound 5b displayed both antibacterial and antifungal activities at an MIC value of 12.5 μg/mL, while compounds 15b and 19 showed antibacterial activity at an MIC value of 25 μg/mL.     

Novel fungicidal benzylsulfanyl-phenylguanidines

A series of substituted benzylsulfanyl-phenylamines was synthesized, of which four substituted benzylsulfanyl-phenylguanidines (665, 666, 667 and 684) showed potent fungicidal activity (minimal fungicidal concentration, MFC ? 10 μM for Candida albicans and Candida glabrata). A benzylsulfanyl-phenyl scaffold with an unsubstituted guanidine resulted in less active compounds (MFC = 50-100 μM), whereas substitution with an unsubstituted amine group resulted in compounds without fungicidal activity. Compounds 665, 666, 667 and 684 also showed activity against single C. albicans biofilms and biofilms consisting of C. albicans and Staphylococcus epidermidis (minimal concentration resulting in 50% eradication of the biofilm, BEC50 ? 121 μM for both biofilm setups). Compounds 665 and 666 combined potent fungicidal (MFC = 5 μM) and bactericidal activity (minimal bactericidal concentration, MBC for S. epidermidis ? 4 μM). In an in vivo Caenorhabditis elegans model, compounds 665 and 667 exhibited less toxicity than 666 and 684. Moreover, addition of those compounds to Candida-infected C. elegans cultures resulted in increased survival of Candida-infected worms, demonstrating their in vivo efficacy in a mini-host model.     

Synthesis and biological activity of hydroxy substituted phenyl-benzo[d]thiazole analogues for antityrosinase activity in B16 cells

In this study, we synthesized hydroxy and/or alkoxy substituted phenyl-benzo[d]thiazole derivatives using substituted benzaldehydes and 2-aminothiophenol in MeOH. The structures of these compounds were established by ¹H and ¹³C NMR and mass spectral analyzes. All synthesized compounds were evaluated for their mushroom tyrosinase inhibition activity. Out the 12 generated compounds, 2a and 2d exhibited much higher tyrosinase inhibition activity (45.36-73.07% and 49.94-94.17% at 0.01-20 μM, respectively) than kojic acid (9.29-50.80% at 1.25-20 μM), a positive control.The cytotoxicity of 2a and 2d was evaluated using B16 cells and the compounds were found to be nontoxic. Compounds 2a and 2d were also demonstrated to be potent mushroom tyrosinase inhibitors, displaying IC₅₀ values of 1.14 ± 0.48 and 0.01 ± 0.0002 μM, respectively, compared with kojic acid, which has an IC₅₀ value of 18.45 ± 0.17 μM. We also predicted the tertiary structure of tyrosinase, simulated the docking with compounds 2a and 2d and confirmed that the compounds strongly interact with mushroom tyrosinase residues. Kinetic plots showed that 2a and 2d are competitive tyrosinase inhibitors. Substitutions with a hydroxy group at R³ or both R³ and R¹ of the phenyl ring indicated that these groups play a major role in the high binding affinity to tyrosinase. We further found that compounds 2a and 2d inhibit melanin production and tyrosinase activity in B16 cells. These results may assist in the development of new potent tyrosinase inhibitors against hyperpigmentation.     

Steroids from the leaves of Chinese Melia azedarach and their cytotoxic effects on human cancer cell lines

Three new (1-3) and several known (4-6) steroids were isolated from the leaves of Chinese Melia azedarach. The structures of the new compounds were elucidated by means of spectroscopic methods including 2D NMR techniques and mass spectrometry to be (20S)-5,24(28)-ergostadiene-3β,7α,16β,20-tetrol (1), (20S)-5-ergostene-3β,7α,16β,20-tetrol (2), and 2α,3β-dihydro-5-pregnen-16-one (3). The cytotoxicities of the isolated compounds against three human cancer cell lines (A549, H460, U251) were evaluated; only compounds 1, 2, and (20S)-5-stigmastene-3β,7α,20-triol (4) were found to show significant cyctotoxic effects with IC₅₀s from 12.0 to 30.1 μg/mL.     

Cytotoxic and antioxidant activities of diterpenes and sterols from the Vietnamese soft coral Lobophytum compactum

Two new diterpenes, lobocompactols A (1) and B (2), and five known compounds (3-7) were isolated from the methanol extract of the soft coral Lobophytum compactum using combined chromatographic methods and identified based on NMR and MS data. Each compound was evaluated for cytotoxic activity against A549 (lung) and HL-60 (acute promyelocytic leukemia) human cancer cell lines. Among them, compound 5 exhibited strong cytotoxic activity against the A549 cell line with an IC₅₀ of 4.97 ± 0.06 μM. Compounds 3, 4, and 7 showed moderate activity with IC₅₀ values of 23.03 ± 0.76, 31.13 ± 0.08, and 36.45 ± 0.01 μM, respectively. The cytotoxicity of 5 on the A549 cells was comparable to that of the positive control, mitoxantrone (MX). All compounds exhibited moderate cytotoxicity against the HL-60 cell line, with IC₅₀ values ranging from 17.80 ± 1.43 to 59.06 ± 2.31 μM. Their antioxidant activity was also measured using oxygen radical absorbance capacity method, compounds 1 and 2 exhibiting moderate peroxyl radical scavenging activity of 1.4 and 1.3 μM Trolox equivalents, respectively, at a concentration of 5 μM.     

Efficient synthesis of antifungal active 9-substituted-3-aryl-5H,13aH-quinolino[3,2-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines in ionic liquids

The title compounds, 9-substituted-3-aryl-5H,13aH-quinolino[3,2-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines 8, are synthesized from 5-aryl-3,4-diamino-1,2,4-triazoles 5 and 2-chloro-3-formylquinolines 7 in ionic liquid as solvent under microwave heating as well as using oil-bath heating at 80 °C. The products are obtained in the good to moderate yields and in high purity. These compounds have been screened for antifungal activity. The screening data indicate that the compounds 8a, 8b, 8c and 8d show excellent activity against Aspergillus niger 1000 μg concentration and Pencillium notatum species at 500 μg as well as 1000 μg concentrations whereas, these compounds show good to moderate activity against Aspergillus flavus and Rhizopus species at both the concentrations. Moreover, ionic liquid is found to be recyclable for at least three consecutive runs what makes the process cost-effective and economic that lead to the area of Green Chemistry as recyclability is one of the most important feature of Green Chemistry.     

Synthesis and antitubercular activity of novel Schiff bases derived from d-mannitol

Six Schiff base derivatives of d-mannitol, 1,6-dideoxy-1,6-bis-{[(E)-arylmethylidene]amino}-d-mannitol (6: aryl = XC₆H₄: X = o-, m- and p- Cl or NO₂), have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H₃₇Rv using the Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in μg/mL. All three nitro derivatives exhibit significant activities: activities of (6d: X = o-NO₂), (6e: X = m-NO₂) and (6f: X = p-NO₂) are 12.5, 25.0 and 25.0 μg/mL, respectively. When compared with first line drugs, such as ethambutol, they can be considered as a good starting point to develop new lead compounds for the treatment of multidrug-resistant tuberculosis. Characterization of the new compounds 6 is generally achieved spectroscopically. The structure of compound 3 has been confirmed by X-ray crystallography.     

Topical anti-inflammatory activity of boropinic acid and its natural and semi-synthetic derivatives

Boropinic acid is a natural isopentenyloxycinnamic acid extracted from the aerial parts of Boronia pinnata Sm. (Rutaceae) with soybean 5-lipoxygenase inhibitory activity. In this paper the topical anti-inflammatory activity of boropinic acid and some of its natural and semi-synthetic derivatives was evaluated using the Croton oil ear test in mice as a model of acute inflammation. Some of the tested compounds (15, 17, 19, 20) revealed an effect comparable (ID₅₀ = 0.18 ÷ 0.72 μmol/cm²) to that of the reference drug indomethacin (ID₅₀ = 0.23 μmol/cm²), a non-steroidal anti-inflammatory drug.