Assaying Chlamydia pneumoniae Persistence in Monocyte-Derived Macrophages Identifies Dibenzocyclooctadiene Lignans as Phenotypic Switchers

Antibiotic-tolerant persister bacteria involve frequent treatment failures, relapsing infections and the need for extended antibiotic treatment. The virulence of an intracellular human pathogen C. pneumoniae is tightly linked to its propensity for persistence and means for its chemosensitization are urgently needed. In the current work, persistence of C. pneumoniae clinical isolate CV6 was studied in THP-1 macrophages using quantitative PCR and quantitative culture. A dibenzocyclooctadiene lignan schisandrin reverted C. pneumoniae persistence and promoted productive infection. The concomitant administration of schisandrin and azithromycin resulted in significantly improved bacterial eradication compared to sole azithromycin treatment. In addition, the closely related lignan schisandrin C was superior to azithromycin in eradicating the C. pneumoniae infection from the macrophages. The observed chemosensitization of C. pneumoniae was associated with the suppression of cellular glutathione pools by the lignans, implying to a previously unknown aspect of chlamydia–host interactions. These data indicate that schisandrin lignans induce a phenotypic switch in C. pneumoniae, promoting the productive and antibiotic-susceptible phenotype instead of persistence. By this means, these medicinal plant -derived compounds show potential as adjuvant therapies for intracellular bacteria resuscitation

Synthesis and Cytotoxicity Evaluation of Spirocyclic Bromotyrosine Clavatadine C Analogs

Marine-originated spirocyclic bromotyrosines are considered as promising scaffolds for new anticancer drugs. In a continuation of our research to develop potent and more selective anticancer compounds, we synthesized a library of 32 spirocyclic clavatadine analogs by replacing the agmatine, i.e., 4-(aminobutyl)guanidine, side chain with different substituents. These compounds were tested for cytotoxicity against skin cancer using the human melanoma cell line (A-375) and normal human skin fibroblast cell line (Hs27). The highest cytotoxicity against the A-375 cell line was observed for dichloro compound 18 (CC50 0.4 ± 0.3 µM, selectivity index (SI) 2). The variation of selectivity ranged from SI 0.4 to reach 2.4 for the pyridin-2-yl derivative 29 and hydrazide analog of 2-picoline 37. The structure–activity relationships of the compounds in respect to cytotoxicity and selectivity toward cancer cell lines are discussed

Synthesis and Antiproliferative Activity of Marine Bromotyrosine Purpurealidin I and Its Derivatives

Peer reviewe

Structure-Function Studies of Sponge-Derived Compounds on the Cardiac CaV3.1 Channel

T-type calcium (CaV3) channels are involved in cardiac automaticity, development, and excitation–contraction coupling in normal cardiac myocytes. Their functional role becomes more pronounced in the process of pathological cardiac hypertrophy and heart failure. Currently, no CaV3 channel inhibitors are used in clinical settings. To identify novel T-type calcium channel ligands, purpurealidin analogs were electrophysiologically investigated. These compounds are alkaloids produced as secondary metabolites by marine sponges, and they exhibit a broad range of biological activities. In this study, we identified the inhibitory effect of purpurealidin I (1) on the rat CaV3.1 channel and conducted structure–activity relationship studies by characterizing the interaction of 119 purpurealidin analogs. Next, the mechanism of action of the four most potent analogs was investigated. Analogs 74, 76, 79, and 99 showed a potent inhibition on the CaV3.1 channel with IC50′s at approximately 3 µM. No shift of the activation curve could be observed, suggesting that these compounds act like a pore blocker obstructing the ion flow by binding in the pore region of the CaV3.1 channel. A selectivity screening showed that these analogs are also active on hERG channels. Collectively, a new class of CaV3 channel inhibitors has been discovered and the structure–function studies provide new insights into the synthetic design of drugs and the mechanism of interaction with T-type CaV channels

Synthesis, identification and structure-activity relationship analysis of GATA4 and NKX2-5 protein-protein interaction modulators

Transcription factors GATA4 and NKX2-5 directly interact and synergistically activate several cardiac genes and stretch-induced cardiomyocyte hypertrophy. Previously, we identified phenylisoxazole carboxamide 1 as a hit compound, which inhibited the GATA4-NKX2-5 transcriptional synergy. Here, the chemical space around the molecular structure of 1 was explored by synthesizing and characterizing 220 derivatives and structurally related compounds. In addition to the synergistic transcriptional activation, selected compounds were evaluated for their effects on transcriptional activities of GATA4 and NKX2-5 individually as well as potential cytotoxicity. The structure-activity relationship (SAR) analysis revealed that the aromatic isoxazole substituent in the southern part regulates the inhibition of GATA4-NKX2-5 transcriptional synergy. Moreover, inhibition of GATA4 transcriptional activity correlated with the reduced cell viability. In summary, comprehensive SAR analysis accompanied by data analysis successfully identified potent and selective inhibitors of GATA4-NKX2-5 transcriptional synergy and revealed structural features important for it.Peer reviewe

Synthesis and evaluation of marine-based spirocyclic clavatadine C -derivatives against melanoma cells

Merieliöiden tuottamat bioaktiiviset yhdisteet ovat erinomainen inspiraation lähde uusien lääkeaineiden suunnittelussa. Useat merisienten tuottamat bromia sisältävät alkaloidit, bromityrosiinit, ovat aktiivisia syöpää vastaan ja osa näistä luonnonaineista sisältävät spirosyklisiä rakenteita. Spiroyhdisteet ovat lääkesuunnittelussa mielenkiintoisia rakenteita niiden luontaisen kolmiulotteisuuden ja uutuusarvon vuoksi. Klavatadiini C on Suberea clavata -merisienestä eristetty bromia sisältävä spirosykloheksa-dienyyli-isoksatsoliinialkaloidi. Sen symmetrinen, spirosyklinen osa voidaan tulkita Pseudoceratina purpurea -merisienestä eristetyn purpurealidiini I:n avoketjuisten oksiimi-rakenteisten johdannaisten jäykistetyksi analogiksi. Aiemmin syntetisoidut purpurealidiini I:n johdannaiset ovat antaneet lupaavia tuloksia melanoomasoluja vastaan, jonka vuoksi syntetisoitiin kahdeksan spirosyklistä klavatadiini C -johdannaista aiemmin julkaistua synteesireittiä hyödyntäen. Seitsemän klavatadiini C:n johdannaisten aktiivisuudet määritettiin A375-melanoomasolulinjaa vastaan ja kaikki osoittautuivat aktiivisiksi CC50-arvojen ollessa 1,0 – 3,4 μM. Samalla määritettiin myös 10 muun aiemmin syntetisoitujen bromityrosiinijohdannaisten aktiivisuudet, joista neljän avoketjuisen oksiimin CC50-arvot olivat 13,5 – 27,8 μM. Aktiivisimmat johdannaiset olivat halogeeniton ja kloorisubstituoitu spirojohdannainen. Avoketjuisiin oksiimeihin verrattuna spirojohdannaisten aktiivisuudet olivat vähintään kaksin- ja jopa kahdeksankertaiset. Aktiivisten yhdisteiden selektiivisyys määritettiin testaamalla niiden sytotoksisuus Hs27 fibroblasteja kohtaan ja vertaamalla solulinjojen CC50-arvoja toisiinsa. Selektiivisin yhdiste oli bromattu johdannainen, jonka selektiivisyys oli kolminkertainen melanoomasoluja vastaan. Heikko selektiivisyys vastasi aiemmin avoketjuisilla oksiimianalogeilla saatuja tuloksia. Spiro-syklisten johdannaisten parempi aktiivisuus oksiimeihin verrattuna on lupaava tulos ja tukee meriperäisten spirosyklisten bromityrosiinijohdannaisten lisätutkimusta melanoomaa vastaan.Marine organisms can be regarded as a diverse source of bioactive compounds with the possibility to discover novel drug lead molecules. Sea sponges produce bromine containing alkaloids, bromotyrosines, from which several are active against cancer. Some bromotyrosines have spirocyclic structure and the innate three-dimensionality and structural novelty of spirocycles make them an interesting option in drug design. Clavatadine C, extracted from sponge Suberea clavata, is a bromine containing spirocyclohexa-dienylisoxazoline alkaloid. It’s symmetric spirocyclic core can be viewed as a restricted derivative of open chain oximes, such as purpurealidin I, a bromotyrosine extracted from Pseudoceratina purpurea. Earlier work with purpurealidin I derivatives against melanoma cell line has had some promising results. Inspired by these earlier results, eight spirocyclic clavatadine C derivatives were synthesized according the published synthesis route. The activities of seven synthesized clavatadine C derivatives were tested on A375 melanoma cell line. All spiro derivatives were active with CC50 values ranging between 1.0 μM and 3.4 μM. Also, the activities of 10 earlier synthesized bromotyrosine derivatives were tested, from which four open chain oximes had CC50 values between 13.5 μM and 27.8 μM. Interestingly, the most active compounds were chlorinated and unhalogenated spirocyclic derivatives. In general, the spirocyclic compounds were 2- to 8-fold more active than the corresponding open chain oximes. The selectivity of active compounds was determined as cytotoxicity against Hs27 fibroblasts and by comparing the CC50 values of these two cell lines. The most selective compound was brominated derivative which had three times better selectivity against melanoma cells. The weak selectivity was consistent with the trend with open chain oxime analogs. Despite the selectivity issue, the improved activity of spirocyclic derivatives are promising and support for further investigation of marine-based spirocyclic bromotyrosine derivatives against melanoma