Neo-clerodane diterpenoids and other constituents from Baccharis species

A new neo-clerodane dilactone, desoxyarticulin, and dihydrotucumanoic acid, together with other known compounds, were isolated from Baccharis pedicellata and Baccharis marginalis. The structures of the new compounds were elucidated by spectroscopic methods.     

One new flavonoid xyloside and one new natural triterpene rhamnoside from the leaves of Syzygium grande

One new flavonoid glycoside, myricetin 4′-methyl ether 3-O-β-d-xylopyranoside (1) and one new natural triterpene glycoside, grandoside (2) were isolated from a MeOH extract of the leaves of Syzygium grande, together with thirteen known compounds (3–15). The structures of the new compounds were determined through a combination of spectroscopic and chemical analyses. All of the isolated compounds were evaluated for their antifungal, antibacterial, anti-leishmania, DPPH radical-scavenging and cytotoxic activities by means of MTT assay.     

Galloylarbutin and other polyphenols from Bergenia purpurascens

Two new polyphenols, 4,6-di-O-galloylarbutin and 2,4,6-tri-O-galloyl-D-glucose, were isolated from the root of Bergenia purpurascens, which also contains 6-O-galloylarbutin, bergenin and its gallates, and five other phenolic compounds. The structures of the new compounds were determined by chemical and spectroscopic methods.     

6-Hydroxyflavones from Thymbra spicata

Four flavonoids, including two new compounds, were isolated from the leaf extract of Thymbra spicata. The new compounds were the 7,3′-dimethyl and 7,3′,4′-trimethyl ethers of 6-hydroxyluteolin. All the compounds were identified by spectral methods.     

Flavonoids from Gutierrezia grandis

Thirteen flavonoids, including three new compounds, were isolated from Gutierrezia grandis. The structures of the new compounds were 3,5,7,3′,4′-pentahydroxy-6,8-dimethoxyflavone, 5,7,3′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone and 5,7,3′,5′-tetrahydroxy-3,6,8,4′-tetramethoxyflavone 3′-O-glucoside.     

Statistical molecular design of a focused salicylidene acylhydrazide library and multivariate QSAR of inhibition of type III secretion in the Gram-negative bacterium Yersinia

A combined application of statistical molecular design (SMD), quantitative structure–activity relationship (QSAR) modeling and prediction of new active compounds was effectively used to develop salicylidene acylhydrazides as inhibitors of type III secretion (T3S) in the Gram-negative pathogen Yersinia pseudotuberculosis. SMD and subsequent synthesis furnished 50 salicylidene acylhydrazides in high purity. Based on data from biological evaluation in T3S linked assays 18 compounds were classified as active and 25 compounds showed a dose-dependent inhibition. The 25 compounds were used to compute two multivariate QSAR models and two multivariate discriminant analysis models were computed from both active and inactive compounds. Three of the models were used to predict 4416 virtual compounds in consensus and eight new compounds were selected as an external test set. Synthesis and biological evaluation of the test set in Y. pseudotuberculosis and the intracellular pathogen Chlamydia trachomatis validated the models. Y. pseudotuberculosis and C. trachomatis cell-based infection models showed that compounds identified in this study are selective and non-toxic inhibitors of T3S dependent virulence.     

New 1,4-di-N-oxide-quinoxaline-2-ylmethylene isonicotinic acid hydrazide derivatives as anti-Mycobacterium tuberculosis agents

The increase in the prevalence of drug-resistant tuberculosis cases demonstrates the need of discovering new and promising compounds with antimycobacterial activity. As a continuation of our research and with the aim of identifying new antitubercular drugs candidates, a new series of quinoxaline 1,4-di-N-oxide derivatives containing isoniazid was synthesized and evaluated for in vitro anti-tuberculosis activity against Mycobacterium tuberculosis H37Rv strain. Moreover, various drug-like properties of new compounds were predicted. Taking into account the biological results and the promising drug-likeness profile of these compounds, make them valid leads for further experimental research.     

Design,synthesis and antibacterial activity of novel andrographolide derivatives

A series of andrographolide derivatives were synthesized through a facile condensation reaction with different carboxylic acids. The new compounds were characterized and screened for their antibacterial activities. A number of the new compounds significantly reduced bacterial quorum sensing virulence factors production in Pseudomonas aeruginosa, essential for pathogenesis. Compound 11b showed the best activity among all the new compounds.     

Highly hydroxylated steroids of the starfish Archaster typicus from the Vietnamese waters

Five new steroidal compounds, including an unusual glucoside, along with several known steroids were isolated from the starfish Archaster typicus collected in shallow waters of Quang Ninh province (Vietnam). Three new compounds are 27-nor-cholestane derivatives and the other two are 24,26-dihydroxycholestane derivatives. A biogenesis pathway for the unusual side chain of 27-nor-cholestane derivatives is proposed. Isolated compounds presented moderate toxic effects in the sperm- and 8-blastomere tests on embryonal development of the sea urchin Strongylocentrotusintermedius.     

Flavonoids of Wyethia angustifolia and W. helenioides

Seventeen flavonoids, including seven new natural products, were isolated from a dichloromethane extract of Wyethia angustifolia. Known compounds are:8-C-prenyleriodictyol, 6-C-prenyleriodictyol, 8-C-prenylnaringenin, 6-C-prenylnaringenin, orobol 7-methyl ether, orobol 3′-methyl ether, naringenin 4′-methyl ether, orobol, eriodictyol and naringenin. The new compounds are 6-C-prenylorobol, 6-C-prenylorobol 3′-methyl ether, orobol 7,3′-dimethyl ether, 8-C-prenyldihydroisorhamnetin, 7,8-dihydrooxepinocriodictyol, 7,8-dihydrooxepinodihydroquercetin and 3′,4′-dihydrooxepino-6′-hydroxybutein. A dichloromethane extract of Wyethia heleniodes yielded eleven compounds only five of which were previously reported from the species. All these compounds appear to occur on the leaf surface.     

Two triterpenoids from Boehmeria excelsa

Two new triterpenoids, boehmerone and boehmerol, and the known compounds ursolic acid and betulinic acid were isolated from the bark of Boehmeria excelsa. The structures of the new compounds were established by spectroscopic methods and X-ray analysis.     

Cytotoxic meroterpenoids from the macroalga Cystoseira abies-marina

Two new meronorsesquiterpenes (cystoazorones A and B) and two new meroditerpenes (cystoazorols A and B), along with benzoic acid were isolated from the brown macroalga Cystoseira abies-marina. The structures of the new compounds were established by 1D and 2D NMR as well as HRMS spectral analysis. The in vitro cytotoxicity and antioxidant activity of the isolated compounds were also evaluated. Cystoazorones A and B, and cystoazorol A exhibited in vitro growth inhibitory activity against HeLa cells. The HeLa cell line in log phase was found to be more sensitive to cystoazorol A than when it was in lag phase. Cystoazorol A also showed a selectivity index higher than taxol, which was used as a positive control. Cystoazorols A and B were found to be the strongest antioxidants among the compounds tested.     

Synthesis and acrosin inhibitory activity of substituted 4-amino-N-(diaminomethylene) benzenesulfonamide derivatives

A series of new substituted 4-amino-N-(diaminomethylene) benzenesulfonamides were synthesized and their in vitro acrosin inhibitory activities were evaluated. Most of the compounds showed potent acrosin inhibitory activities with compounds 4o and 4p being significantly more potent than the control compound N-alpha-tosyl-l-lysyl-chloromethyl-ketone (TLCK). The compounds provide a new scaffold for the development of acrosin inhibitory agents.     

New diterpenoids from Caesalpinia species and their cytotoxic activity

Chemical investigation on Caesalpinia crista afforded two new diterpenoids, 6β-cinnamoyloxy-7β-acetoxyvouacapen-5α-ol and 6β,7β-dibenzoyloxyvouacapen-5α-ol and on Caesalpinia pulcherrima another new diterpenoid, 12-demethyl neocaesalpin F along with several known constituents. The structures of the new compounds were settled from their 1D and 2D NMR spectral data. The cytotoxicity of these compounds was measured on two different cancer cell lines.     

A New Set of Chemical Starting Points with Plasmodium falciparum Transmission-Blocking Potential for Antimalarial Drug Discovery

The discovery of new antimalarials with transmission blocking activity remains a key issue in efforts to control malaria and eventually eradicate the disease. Recently, high-throughput screening (HTS) assays have been successfully applied to Plasmodium falciparum asexual stages to screen millions of compounds, with the identification of thousands of new active molecules, some of which are already in clinical phases. The same approach has now been applied to identify compounds that are active against P. falciparum gametocytes, the parasite stage responsible for transmission. This study reports screening results for the Tres Cantos Antimalarial Set (TCAMS), of approximately 13,533 molecules, against P. falciparum stage V gametocytes. Secondary confirmation and cytotoxicity assays led to the identification of 98 selective molecules with dual activity against gametocytes and asexual stages. Hit compounds were chemically clustered and analyzed for appropriate physicochemical properties. The TCAMS chemical space around the prioritized hits was also studied. A selection of hit compounds was assessed ex vivo in the standard membrane feeding assay and demonstrated complete block in transmission. As a result of this effort, new chemical structures not connected to previously described antimalarials have been identified. This new set of compounds may serve as starting points for future drug discovery programs as well as tool compounds for identifying new modes of action involved in malaria transmission.     

Two new compounds from the aerial parts of Elsholtzia densa

Two new compounds, named edensa acid (1), and edensaoside A (2), as well as twenty-nine known compounds (3–31) were isolated from the aerial parts of Elsholtzia densa Benth. The chemical structures of the new compounds were determined by spectrometric data interpretation using NMR, HRESIMS, IR and UV spectroscopy. In addition, all compounds were evaluated for their anti-influenza virus activities against A/WSN/33(H1N1). Among these, compounds 18 and 19 exhibited moderate anti-influenza virus activities with IC₅₀ values of 18.79 μM and 59.87 μM respectively.     

Cytotoxic components of Zingiber zerumbet,Curcuma zedoaria and C. domestica

One new and five known compounds, which all showed cytotoxic activity, were isolated from the rhizomes of Zingiber zerumbet. The new compound was 3″,4″-O-diacetylafzelin. The known compounds were zerumbone, zerumbone epoxide, diferuloylmethane, feruloyl-p-coumaroylmethane and di-p-coumaroylmethane. Several substituted cinnamoylmethanes were synthesized and tested for cytotoxic properties. Among these were tricinnamoylmethane and triferuloylmethane. The structures were elucidated mainly by spectroscopic methods and ¹³C NMR data are given.     

Synthetic bioregulators of poly-cis carotenoid biosynthesis

Seventeen new bioregulators were synthesized and tested for their ability to induce the biosynthesis of poly-cis carotenes in the flavedo of Marsh white seedless grapefruit. The effects of these new bioregulators are the same as that of the previously reported dibenzylamines, but several of the new compounds are more effective and cause the accumulation of up to 162 μg/g dry wt of poly-cis carotenes in the flavedo as compared to the maximum of 74 μg/g dry wt observed previously. The compounds tested were substituted N-benzyl furfurylamines, N-benzyl, N-methyl furfurylamines and N-alkyl, N-methyl benzylamines. They demonstrate the ability of tertiary as well as secondary amines to stimulate the formation of poly-cis carotenes. The interaction of N-(4-bromobenzyl) furfurylamine, one of the more effective of the new compounds, with lycopene and β-carotene inducers is also reported.     

Design and synthesis of aminoester heterodimers containing flavone or chromone moieties as modulators of P-glycoprotein-based multidrug resistance (MDR)

In this study, a new series of heterodimers was synthesized. These derivatives are N,N-bis(alkanol)amine aryl esters or N,N-bis(ethoxyethanol)amine aryl esters carrying a methoxylated aryl residue combined with a flavone or chromone moiety. The new compounds were studied to evaluate their P-gp modulating activity on a multidrug-resistant leukemia cell line. Some of the new compounds show a good MDR reversing activity; interestingly this new series of compounds does not comply with the structure-activity relationships (SAR) outlined by previously synthesized analogs carrying different aromatic moieties. In the case of the compounds described in this paper, activity is linked to different features, in particular the characteristics of the spacer, which seem to be critical for the interaction with the pump. This fact indicates that the presence of a flavone or chromone residue influences the SAR of these series of products, and that flexible molecules can find different productive binding modes with the P-gp recognition site. These results support the synthesis of new compounds that might be useful leads for the development of drugs to control P-gp-dependent MDR.     

New cis-ent-clerodanes from Linaria japonica

Five new cis-ent-clerodanes, linarenones A–E (1–5) and two known compounds (6 and 7) were isolated from whole plant of Linaria japonica. The structures of these compounds were determined by various spectroscopic analyses (UV, IR, HR–ESI–MS, 1D and 2D NMR). The absolute configuration of five new diterpenoids was confirmed by circular dichroism (CD) analysis and chemical conversion. Cytotoxicity of the isolated compounds against A549 cell lines and Leishmania major were evaluated. The new cis-ent-clerodane 3 was found to be moderately active against A549 cell lines, and new cis-ent-clerodanes 1, 6 and desacetyl-linarienone (7) were active against L. major.