Methoxy- and acetoxy-8-oxoberbines--synthesis, antitumor activity, and interaction with DNA

The Highly Potent AhR Agonist Picoberin Modulates Hh-Dependent Osteoblast Differentiation

Identification and analysis of small molecule bioactivity in target-agnostic cellular assays and monitoring changes in phenotype followed by identification of the biological target are a powerful approach for the identification of novel bioactive chemical matter in particular when the monitored phenotype is disease-related and physiologically relevant. Profiling methods that enable the unbiased analysis of compound-perturbed states can suggest mechanisms of action or even targets for bioactive small molecules and may yield novel insights into biology. Here we report the enantioselective synthesis of natural-product-inspired 8-oxotetrahydroprotoberberines and the identification of Picoberin, a low picomolar inhibitor of Hedgehog (Hh)-induced osteoblast differentiation. Global transcriptome and proteome profiling revealed the aryl hydrocarbon receptor (AhR) as the molecular target of this compound and identified a cross talk between Hh and AhR signaling during osteoblast differentiation.

Sulfonamides and Sulphonyl Ester of Quinolines as Non-Acidic, Non- Steroidal, Anti-inflammatory Agents

Background:

Quinolines are an important class of heterocyclic compounds possessing a wide range of biological activities. Previously, we had identified Schiff bases of quinoline as potential anti-inflammatory agents, thus the current work is the continuation of our previous study.

Objective:

In the current study, 3-, 5-, and 8-sulfonamide and 8-sulfonate derivatives of quinoline (1-50) were synthesized and their anti-inflammatory potential was evaluated. These synthetic analogs were evaluated for their anti-inflammatory activity via ROS (Reactive oxygen species) inhibitory effect produced from phagocytes from human whole blood.

Methods:

The sulfonamide and sulfonate derivatives of quinoline were synthesized via treating 5-, 3-, 8-amino, and 8-hydroxy quinolines with different substituted sulfonyl chlorides in pyridine. The synthetic molecules were characterized using various spectroscopic techniques and screened for their anti-inflammatory potential.

Results:

Among the synthetic derivatives 1-50, six compounds showed good to moderate antiinflammatory activity. Compounds 47 (IC50 = 2.9 ± 0.5 μg/mL), 36 (IC50 = 3.2 ± 0.2 μg/mL), and 24 (IC50 = 6.7 ± 0.3 μg/mL) exhibited enhanced activity as compared to the standard ibuprofen (IC50 = 11.2 ± 1.9 μg/mL). Compounds 20 (IC50 = 25.5 ± 0.7 μg/mL), 50 (IC50 = 42.9 ± 5.6 μg/mL), and 8 (IC50 = 53.9 ± 3.1 μg/mL) were moderately active, however, rest of the compounds were found to be inactive.

Conclusion:

The sulfonamide and sulfonate derivatives of quinoline were found to have promising anti-inflammatory activity. Further studies on the modification of these molecules may lead to the discovery of new and potential anti-inflammatory agents.

Syntheses and structure-activity relationships on antibacterial and anti-ulcerative colitis properties of quaternary 13-substituted palmatines and 8-oxo-13-substituted dihydropalmatines

In this study, quaternary palmatine is used as a lead compound to design and synthesize derivatives to evaluate bioactivities, with twenty-seven compounds of four series being obtained. Antibacterial activity was examined by determining the minimal inhibitory concentration (MIC) values on Staphylococcus aureus, Escherichia coli, and Candida albicans, three series of derivatives being found to exhibit activity in vitro with significant structure-activity relationship (SAR). Elongating the carbon chain led to the antibacterial activity increased, with quaternary 13-hexanoylpalmatine chloride, quaternary 13-(ω-ethoxycarbonyl)heptylpalmatine chloride, and 8-oxo-13-(N-n-nonyl)aminomethyldihydropalmatine, all of which possess the longest aliphatic carbon chain in the corresponding series of derivatives, showing the MIC values of 62.5, 7.81, and 15.63 µg/ml against S. aureus, respectively. The property of anti-ulcerative colitis (anti-UC) was assessed at the levels of both in vitro and in vivo, with X-box-binding protein 1 (XBP1) being targeted in vitro. Seven compounds were found not only to be hypocytotoxic toward intestinal epithelial cells, but also to exhibit activity of activating the transcription of XBP1 in vitro. Five compounds were found to possess significant dose-effect relationship with EC₅₀ values at a level of 10^-7 µM in vitro. 8-Oxo-13-formyldihydropalmatine as an intermediate was found to display significant curative effect on UC in vivo based on the biomarkers of body weight change, colon length change, and calculated values of disease activity index and colon macroscopic damage index of the experimental animals, as well as the examination into the pathological changes of the colon tissue of the modeled animals.

Quaternary protoberberine alkaloids

This contribution reviews some general aspects of the quaternary iminium protoberberine alkaloids. The alkaloids represent a very extensive group of secondary metabolites with diverse structures, distribution in nature, and biological effects. The quaternary protoberberine alkaloids (QPA), derived from the 5,6-dihydrodibenzo[a,g]quinolizinium system, belong to a large class of isoquinoline alkaloids. Following a general introduction, the plant sources of QPA, their biosynthesis, and procedures for their isolation are discussed. Analytical methods and spectral data are summarized with emphasis on NMR spectroscopy. The reactivity of QPA is characterized by the sensitivity of the iminium bond CN(+) to nucleophilic attack. The addition of various nucleophiles to the protoberberine skeleton is discussed. An extended discussion of the principal chemical reactivity is included since this governs interactions with biological targets. Quaternary protoberberine alkaloids and some related compounds exhibit considerable biological activities. Recently reported structural studies indicate that the QPA interact with nucleic acids predominantly as intercalators or minor groove binders. Currently, investigations in many laboratories worldwide are focused on the antibacterial and antimalarial activity, cytotoxicity, and potential genotoxicity of QPA.

Total Synthesis of (-)-Tetrahydropalmatine via Chiral Formamidine Carbanions: Unexpected Behavior with Certain Ortho-Substituted Electrophiles

A method has been developed by alkylation of chiral lithioformamidines to construct protoberberine alkaloids with a C(9) and C(10) D-ring substitution pattern. This ring pattern was established using an ortho-substituted hydroxymethylbenzene electrophile protected as a silyl ether to ultimately provide (-)-tetrahydropalmatine in 88% ee. Additionally, we have discovered limitations with ortho-substituted electrophiles in the asymmetric formamidine alkylation. These electrophiles have the potential to disrupt the lithium formamidine chelate and cause the selectivity in the alkylation to be uncharacteristically low. The total synthesis of (+/-)-canadine and (-)-tetrahydropalmatine along with the limitations to the formamidine alkylation technology are delineated herein.