Biological Activity of S-Containing Monoterpenoids

Effect of meso-substituents and medium properties on the photo- and pH-stability, penetration efficiency into bacterial and microscopic fungi cells of terpene-BODIPY conjugates

In order to expand the arsenal of tools and areas for practical use of BODIPY dyes as bifunctional fluorescent theranostics, we studied the effect of the meso-substituents nature and medium properties on photo- and pH-stability, efficiency of singlet oxygen generation, and affinity to biostructures of terpene-BODIPY conjugates. The BODIPYs fused with myrtenol or thiotherpenoid via carboxylic acid residues exhibit high stability over a wide pH range and the presence of a bulky substituent at the meso-position of BODIPY conjugates increases their photostability two-fold compared to structurally related meso-unsubstituted analogues. Furthermore, the photodegradation rate of the conjugates directly depends on their ability to generate singlet oxygen and the course probability of the corresponding red-ox reactions involving reactive oxygen species. The conjugate of BODIPY with a thiotherpenoid demonstrated high ability to penetrate the membranes of filamentous and yeast-like fungi and bind to membrane of organelles in the fungal cell. At the same time, this compound also had a high ability to penetrate into biofilms of Staphylococcus aureus and Klebsiella pneumoniae and into bacterial cells within the matrix, which makes this compound promising for staining intracellular structures of eukaryotic cells and bacteria embedded into biofilms.

Monoterpene Thiols: Synthesis and Modifications for Obtaining Biologically Active Substances

Monoterpene thiols are one of the classes of natural flavors that impart the smell of citrus fruits, grape must and wine, black currants, and guava and are used as flavoring agents in the food and perfume industries. Synthetic monoterpene thiols have found an application in asymmetric synthesis as chiral auxiliaries, derivatizing agents, and ligands for metal complex catalysis and organocatalysts. Since monoterpenes and monoterpenoids are a renewable source, there are emerging trends to use monoterpene thiols as monomers for producing new types of green polymers. Monoterpene thioderivatives are also known to possess antioxidant, anticoagulant, antifungal, and antibacterial activity. The current review covers methods for the synthesis of acyclic, mono-, and bicyclic monoterpene thiols, as well as some investigations related to their usage for the preparation of the compounds with antimicrobial properties.

Synthesis and Antimicrobial Activity of Sulfenimines Based on Pinane Hydroxythiols

The widespread presence of multidrug-resistant pathogenic microorganisms challenges the development of novel chemotype antimicrobials, insensitive to microbial tools of resistance. To date, various monoterpenoids have been shown as potential antimicrobials. Among many classes of molecules with antimicrobial activity, terpenes and terpenoids are an attractive basis for the design of antimicrobials because of their low toxicity and availability for various modifications. In this work, we report on the synthesis of sulfenimines from chiral trifluoromethylated and non-fluorinated pinane-type thiols. Final compounds were obtained with yields of up to 81%. Among the 13 sulfenimines obtained, 3 compounds were able to repress the growth of both bacteria (S. aureus, both MSSA and MRSA; P. aeruginosa) and fungi (C. albicans) with an MIC of 8-32 µg/mL. Although compounds exhibited relatively high cytotoxicity (the therapeutic index of 3), their chemotype can be used as a starter point for the development of disinfectants and antiseptics for targeting multidrug-resistant pathogens.

Conjugate of meso-carboxysubstituted-BODIPY with thioterpenoid as an effective fluorescent probe: Synthesis, structure, spectral characteristics, and molecular docking

This paper is devoted to the design of a fluorescent probe based on meso-carboxysubstituted-BODIPY with a thioterpene fragment. The functional replacement of the methoxy group in the BODIPY molecule on a thioterpene fragment was carried out in order to find out the antiplatelet and anticoagulant action mechanisms of thioterpenoids and to assess the membrane and receptor factors contributions. The molecular structure of the conjugate was confirmed via UV/vis-, NMR- and MS-spectra. It is found that the probe is a high fluorescence quantum yield (to ∼ 100%) in the blue-green region at 509-516 nm. Molecular docking of all studied molecules showed that the BODIPY with terpenoid conjugation is an excellent way to increase their affinity to platelet receptor P2Y₁₂.

BODIPY Conjugates as Functional Compounds for Medical Diagnostics and Treatment

Fluorescent dyes absorbing and emitting in the visible and near-IR regions are promising for the development of fluorescent probes for labeling and bio-visualization of body cells. The ability to absorb and emit in the long-wavelength region increases the efficiency of recording the spectral signals of the probes due to the higher permeability of the skin layers. Compared to other fluorescent dyes, BODIPYs are attractive due to their excellent photophysical properties-narrow absorption and emission, intense fluorescence, simple signal modulation for the practical applications. As part of conjugates with biomolecules, BODIPY could act as a biomarker, but as therapeutic agent, which allows solving several problems at once-labeling or bioimaging and treatment based on the suppression of pathogenic microflora and cancer cells, which provides a huge potential for practical application of BODIPY conjugates in medicine. The review is devoted to the discussion of the recent, promising directions of BODIPY application in the field of conjugation with biomolecules. The first direction is associated with the development of BODIPY conjugates with drugs, including compounds of platinum, paclitaxel, chlorambucil, isoxazole, capsaicin, etc. The second direction is devoted to the labeling of vitamins, hormones, lipids, and other biomolecules to control the processes of their transport, localization in target cells, and metabolism. Within the framework of the third direction, the problem of obtaining functional optically active materials by conjugating BODIPY with other colored and fluorescent particles, in particular, phthalocyanines, is being solved.

Synthesis and Oxidative Transformations of New Chiral Pinane-Type γ-Ketothiols: Stereochemical Features of Reactions

Chiral γ-ketothiols, thioacetates, thiobenzoate, disulfides, sulfones, thiosulfonates, and sulfonic acids were obtained from β-pinene for the first time. New compounds open up prospects for the synthesis of other polyfunctional compounds combining a biologically active pinane fragment with various pharmacophore groups. It was shown that the syntheses of sulfanyl and sulfonyl derivatives based on 2-norpinanone are characterized by high stereoselectivity in comparison with similar reactions of pinocarvone. The conditions for the preparation of diastereomerically pure thioacetyl and thiobenzoyl derivatives based on pinocarvone, as well as for the chemoselective oxidation of γ-ketothiols with chlorine dioxide to the corresponding thiolsulfonates and sulfonic acids, were selected. The effect of the VO(acac)₂ catalyst on the increase in the yields of thiosulfonates was shown. A new direction of the transformation of thiosulfonates with the formation of sulfones was revealed. In the case of pinocarvone-based sulfones, the configuration is inversed at the C2 atom. An epimerization scheme is proposed.

Bioactive thionic compounds and aromatic glycosides from Ligusticum chuanxiong

Three new thionic compounds, (S)-2-(2-carboxyl-2-hydroxyethylthio)-ferulic acid (1), (E)-2-methoxy-4-(3-(methylsulfonyl)prop-1-en-1-yl)phenol (2), and thiosenkyunolide C (3), together with two new aromatic glycosides (4 and 5) were isolated from the rhizome of Ligusticum chuanxiong Hort. Two known compounds (6 and 7) were also obtained. Their structures were elucidated based on extensive spectroscopic data (UV, IR, 1D and 2D NMR, and HR-ESI-MS). Furthermore the absolute configurations were established by comparison of their calculated and experimental circular dichroism spectra and by a dimolybdenum tetraacetate [Mo₂(AcO)₄]-induced circular dichroism procedure. All compounds were evaluated against lipopolysaccharide (LPS)-induced NO production in BV2 cells, and compounds 4 and 5 showed strong inhibitory activities with IC₅₀ values of 2.03 and 3.09 µmol/L, respectively (positive control curcumin, IC₅₀ = 6.17 µmol/L). In addition, compound 1 showed weak proteintyrosine phosphatase-1B (PTP1B) inhibitory activity.

Sulfur-Containing Monoterpenoids as Potential Antithrombotic Drugs: Research in the Molecular Mechanism of Coagulation Activity Using Pinanyl Sulfoxide as an Example

In this article we present the synthesis of enantiomerically pure sulfoxide and study the influence of this compound on hemostasis. Detailed NMR studies and molecular dynamics simulations using sodium dodecyl sulfate (SDS) membrane models indicated that the bicyclic fragment of sulfoxide was embedded into the SDS micelle whereas the -SO(CH₂)₂OH fragment remained on the surface of the micelle and was in contact with the solvent. We also found that the pro-coagulative activity of sulfoxide was due to its ability to inhibit platelet activation and inhibited the catalytic activity of phospholipid surface which was involved in formation of coagulation clotting factor complexes.