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.

The new role of dipyrromethene chemosensor for absorbance-ratiometic and fluorescence "turn-on" sensing Zn2+ ions in water-organic solutions and real water samples

This study presents a dipyrromethene-based sensitive and selective probe for Zn2+ ions detection in aqueous and water-organic media. The probe demonstrates absorbance-ratiometric and "off-on" fluorescent sensing for Zn2+ in a DMSO/H2O (9:1, v/v) mixture. The 3,3',4,4',5,5'-hexamethyl-2,2'-dipyrromethene (HL), similar to its analogs, exhibits weak fluorescence (with a quantum yield of less than 0.001). However, upon the presence of Zn2+ ions in the sensor HL solution, there is a remarkable increase (up to 200-fold) in fluorescence intensity due to the formation of a stable intramolecular chelate complex [ZnL2]. This complex formation induces a significant hyperchromic effect and a red shift (57 nm) in the characteristic absorption bands. The sensing mechanism of the probe towards Zn2+ ions was thoroughly investigated through absorbance and fluorescent titrations, molar ratio plots, 1H NMR, and DFT/TDDFT studies. The fluorescence response exhibited a strong linear relationship with Zn2+ concentration within the range of 0 to 5.7 × 10-6 mol/L. The detection limit (LOD) and limit of quantitation (LoQ) for Zn2+ were determined as 2 × 10-8 mol/L and 6.6 × 10-8 mol/L, respectively. Moreover, the probe demonstrated high selectivity for Zn2+ ions over other metal ions (Na+, Mg2+, Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Pd2+, Cd2+, Hg2+, Pb2+). Test systems in the form of test-strips and cotton-pads were developed based on the dipyrromethene sensor for rapid "naked-eye" detection of zinc ions in water. The sensor was successfully applied for detecting Zn2+ ions in real water samples.

Unraveling the Mechanism of Platelet Aggregation Suppression by Thioterpenoids: Molecular Docking and In Vivo Antiaggregant Activity

Natural monoterpenes and their derivatives are widely considered the effective ingredients for the design and production of novel biologically active compounds. In this study, by using the molecular docking technique, we examined the effects of two series of "sulfide-sulfoxide-sulfone" thioterpenoids containing different (e.g., bornane and pinane) monoterpene skeletons on the platelet's aggregation. Our data revealed that all the synthesized compounds exhibit inhibitory activities on platelet aggregation. For example, compound 1 effectively inhibited platelet activation and demonstrated direct binding with CD61 integrin, a well-known platelet GPIIb-IIIa receptor on platelets. We further examined the antiaggregant activity of the most active compound, 1, in vivo and compared its activity with that of acetylsalicylic acid and an oral GPIIb-IIIa blocker, orbofiban. We found that compound 1 demonstrates antiaggregant activity in rats when administered per os and its activity was comparable with that of acetylsalicylic acid and orbofiban. Moreover, similarly, tirofiban, a well-known GPIIb-IIIa blocker, compound 1, effectively decreased the expression of P-selectin to the values similar to those of the intact platelets. Collectively, here, we show, for the first time, the potent antiaggregant activity of compound 1 both in vitro and in vivo due to its ability to bind with the GPIIb-IIIa receptor on platelets.

XPS and quantum chemical analysis of 4Me-BODIPY derivatives

The results of a X-ray photoelectron spectroscopy (XPS) and steady-state absorption spectroscopy study of the electronic structure, and cationic and excited states of a series of 1,3,5,7-tetramethyl-substituted BODIPYs (4Me,2R-BODIPYs) are presented. The experimental data were interpreted using high-level ab initio quantum chemical computations, including the algebraic diagrammatic construction method for the polarization propagator of the second order (ADC(2)), the outer-valence Green's function (OVGF) method, the density functional (DFT) approach, and the time-dependent DFT (TD-DFT) approach. Substitution effects on the XPS and absorption spectra were determined for 2,6-positions of 4Me,2R-BODIPY pyrrole nuclei (R = H, Br, Bu, benzyl). A very satisfactory performance of the DFT Koopmans theorem analogue was demonstrated with respect to the energy intervals between the electronic levels of 4Me,2R-BODIPY above 13 eV (BHHLYP functional) and the values of the HOMO-LUMO energy gap (ωB97X functional).

Thioterpenoids as Potential Antithrombotic Drugs: Molecular Docking, Antiaggregant, Anticoagulant and Antioxidant Activities

Natural monoterpenes and their derivatives are widely considered as effective ingredients for the design and production of new biologically active compounds with high antioxidant, antimicrobial and anti-protozoa properties. In this study, we synthesized two series of thiotherpenoids "sulfide-sulfoxide-sulfone", with different bicyclic monoterpene skeleton (bornane and pinane) structures. The effect of the obtained compounds on platelet aggregation was investigated by using the molecular docking technique. The obtained data revealed that all the synthesized compounds may act as potential inhibitors of platelet aggregation. Moreover, the studied sulfides have shown high antioxidant activity as revealed by lipid peroxidation (LPO) process inhibition in a non-cellular substrate containing animal lipids. The sulfides were able to inhibit erythrocyte oxidative hemolysis, to reduce the accumulation of secondary LPO products in cells and to prevent the oxidation of native oxyhemoglobin. Additionally, the corresponding sulfones and sulfoxides exhibited insignificant antioxidant activity. However, the sulfides were found to exhibit significant antiaggregant and anticoagulant effects. These findings suggest as well that the sulfides could serve as a leader compound for future research and possible practical applications.

Aggregation behavior and spectroscopic properties of red-emitting distyryl-BODIPY in aqueous solution, Langmuir-Schaefer films and Pluoronic® F127 micelles

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF₂-ms-phenyl-5,5'-bis(4-dimethylaminostyryl)-3,3'-dimethyl-2,2'-dipyrromethene (distyryl-BDP). The particular attention was paid to analysis of high sensitivity of the distyryl-BDP spectral characteristics to the solvent properties, and also the aggregation behavior features both in water-organic media and in mono- and multilayer Langmuir-Schaefer films. We selected the best conditions to obtain the hydrophilic micellar structures of distyryl-BDP with Pluronic® F127 having a high efficiency of dye solubilization. This method increasing the solubility improves the distyryl-BDP transport efficiency in physiological aqueous media. The aqueous solutions of distyryl-BDP-Pl micelles show the intense fluorescence in the phototherapy window region (λ_fl = 739 nm).

Dataset for the Synthesis of Boron-Dipyrrin Dyes, their fluorescent properties, their interaction with proteins, Triton-X-based surfactants, and micellar clusterization approaches to validation based on fluorescent dyes

The data presented here refer to the research article by Aleksei V. Solomonov, Yuriy S. Marfin, Alexander B. Tesler, Dmitry A. Merkushev, Elizaveta A. Bogatyreva, Elena V. Antina, Evgeniy V. Rumyantsev, and Ulyana Shimanovich "Spanning BODIPY fluorescence with self-assembled micellar clusters", Colloids and Surfaces B: Biointerfaces, 216, 2022, 112532. The present article provides details on optical characterization for a set of meso- and tetra-substituted boron-dipyrrin (BODIPY) complexes encapsulated inside of self-assembled Triton-X-based micellar coordination clusters (MCCs), based on Triton-X family surfactants. Changes in the optical properties of the BODIPY complexes upon interaction with bovine serum albumin, in a binary mixture of THF:H2O and titrated with Triton TX-114, were evaluated. The optical properties and the formation kinetics of the BODIPY-based MCCs and the BODIPY-supported micelle chelator aggregates (MCAs) are presented as well. The presented data provide additional insights into the structural and formation aspects of both the traditional and newly obtained micellar coordination clusters for their future optimization, control, and application. The synthetic procedures for the synthesis of a set of meso- and tetra-substituted BODIPY complexes and their optical properties in different media are also presented. The research is related to the paper (Solomonov et al., 2022).

Design, Spectral Characteristics, Photostability, and Possibilities for Practical Application of BODIPY FL-Labeled Thioterpenoid

This paper presents the design and a comparative analysis of the structural and solvation factors on the spectral and biological properties of the BODIPY biomarker with a thioterpene fragment. Covalent binding of the thioterpene moiety to the butanoic acid residue of meso-substituted BODIPY was carried out to find out the membranotropic effect of conjugate to erythrocytes, and to assess the possibilities of its practical application in bioimaging. The molecular structure of the conjugate was confirmed via X-ray, UV/vis-, NMR-, and MS-spectra. It was found that dye demonstrates high photostability and high fluorescence quantum yield (to ~100%) at 514–519 nm. In addition, the marker was shown to effectively penetrate the erythrocytes membrane in the absence of erythrotoxicity. The conjugation of BODIPY with thioterpenoid is an excellent way to increase affinity dyes to biostructures, including blood components.

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.

Effects of ms-aryl substitution on the structure and spectral properties of new CH(Ar)-bis(BODIPY) luminophores

In this article, we present synthesis, spectral characteristics, and results of DFT calculations of new CH(R)-bis(BODIPY) 1-3. They are characterized by the conformational mobility and sensitivity of fluorescence to polarity, proton-, electron donor ability and viscosity of the solvation environment. It is shown that fluorescence intensity of 1-3 increases in the homologous series of alcohols (ethanol, 1-propanol, 1-butanol, 1-octanol, 1-decanol) mainly due to decrease of medium acidic properties. The viscosity of the medium effects on the 1-3 fluorescence in a lesser degree. Compared to 1 and 2, the 3 is the most sensitive towards viscosity both in low-viscosity homologous alcohols and in high-viscosity ethanol-glycerol mixtures. In this regard, the sensitivity of fluorescence of CH(MeOPh)-bis(BODIPY) (compound 3) to the viscosity was studied in binary mixtures of polar DMF and low-polarity toluene with castor and vaseline oils, as well as to the macroviscosity of the solvate environment in mixtures of toluene with polystyrene. Prospects of the practical application of CH(R)-bis(BODIPY)s are proposed for the analysis of polarity, proton-donor properties and viscosity of the medium.

Design, Spectral Characteristics, and Possibilities for Practical Application of BODIPY FL-Labeled Monoterpenoid

This article describes the design and biological properties of a BODIPY FL-labeled monoterpenoid BF₂-meso-(4-((1″R)-6″,6″-dimethylbicyclo[3.1.1]hept-2″-ene-2″)yl-methoxycarbonylpropyl)-3,3',5,5'-tetramethyl-2,2'-dipyrromethene conjugate (BODIPYmyrt). The fluorophore was characterized using X-ray, NMR, MS, and UV/vis spectroscopy. The conjugate exhibits a high quantum yield (to ∼100%) in the region 515-518 nm. BODIPYmyrt effectively penetrates the membranes of the bacterial and fungal cells and therefore can be used to examine the features of a broad spectrum of Gram-positive and Gram-negative bacteria and pathogenic fungi as well. Moreover, BODIPYmyrt exhibits a moderate tropism to the subcellular structures in mammalian cells (e.g., mitochondria), thereby providing an attractive scaffold for fluorophores to examine these particular organelles.

A New «off-on» Fluorescence Zinc Ion Sensors Based on Iodo- and Bromosubstituted Dipyrromethenes

Monoiodo- and dibromsubstituted dipyrromethenes HL¹ - HL³ were described as a highly sensitive and selective «Off-On» fluorescent chemosensor for Zn²⁺ based on the chelation-enhanced fluorescence (CHEF) effect. Сoordination reactions of HL¹ - HL³ with Zn²⁺ cations are accompanied by a significant (124 to 215-fold) increase in fluorescence intensity against the background of other metal ions in the binary propanol-1/cyclohexane mixture (1:30). The fluorometric detection limit of Zn²⁺ ions using HL¹ - HL³ sensors is from 3.0∙10^-8 to 3.3·10^-9 mol/L. The presence of Na⁺, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Co²⁺, Pb²⁺ cations does not interfere with the detection of Zn²⁺. Complexation reactions are accompanied by a visual change in the color of the solution from yellow-orange to pink-raspberry so that the HL¹ - HL³ ligands can also be used as a «naked-eye» indicators of the presence of Zn²⁺ ions.

Luminescent properties of new 2,2-, 2,3- and 3,3-CH2-bis(BODIPY)s dyes: Structural and solvation effects

In this paper the synthesis and spectral properties of three new dimeric bis(BODIPY)s with two indacene domains connected by a methylene (-CH₂-) spacer at 2,2-, 2,3- or 3,3- positions were reported. It was found bis(BODIPY)s exhibit a high sensitivity of fluorescence to the medium properties. To interpret solvatochromic effects of bis(BODIPY)s, a multilinear correlation analysis of bis(BODIPY)s fluorescence quantum yields with respect to solvent different parameters was carried out. To understand the features of the spectral properties of bis(BODIPY)s, we carried out a thorough quantum-chemical analysis of the structural, conformational, and spectral characteristics of bis(BODIPY)s. The obtained bis(BODIPY)s have a high potential for application as sensors of medium polarity.

Novel Zinc(II) Bis(Dipyrromethenate)-Doped Ethyl Cellulose Sensors for Acetone Vapor Fluorescence Detection

In this paper, we report on the results of spectrofluorimetric study of new fluorescent sensor based on [Zn₂L₂] doped in ethyl cellulose. The sensor optical signal is based on the rapid fluorescence quenching in the presence of acetone vapor. The acetone vapor detection limit in a gas mixture by means of sensor based on [Zn₂L₂] doped in ethyl cellulose is 1.68 ppb. Being highly sensitive to the acetone acetone presence, instant in response and easy to use, the sensor can find an application for the noninvasive diagnostics of diabetes as well as for the monitoring of the content of acetone acetone in the air at industrial and laboratory facilities. Graphical Abstract.

Influence of structural and solvation factors on the spectral-fluorescent properties of alkyl-substituted BODIPYs in solutions

The spectral-fluorescent properties of alkyl-substituted BODIPYs 1-5 in organic solvents were investigated. The alkyl-substituted BODIPYs 1-5 exhibit intense chromophoric properties (lgε=4.60-5.00). Relative fluorescence quantum yield of studied compounds reaches 66-100% and weakly dependent on the structural and solvation effects. Introduction of methyl, propyl, amyl and heptyl substituents in the 2,6-positions of the pyrroles the results in a significant red shift (22-29nm) in the electronic absorption and fluorescence spectra.

«Оn-off» fluorescent sensors for aromatic analytes based on zinc(II) bis(dipyrromethenate)s

This paper presents the results of spectral-luminescence research of binuclear zinc(II) helicates with tetra-, octa-, and decamethylsubstituted 3,3'-bis(dipyrromethene)s ([Zn₂L₂]) in binary mixtures of cyclohexane with aromatic hydrocarbons (benzene, toluene, and m-xylene). Structure effects of zinc(II) helicates, and aromaticity criteria of analytes (HOMA, NICS, δ) on the fluorescence quenching efficiency of [Zn₂L₂] in the presence of aromatic compounds was considered. It was found that decamethylsubstituted 3,3'-bis(dipyrromethenate)s compared to tetra-, and octamethylsubstituted-analogs shows the highest fluorescence sensitivity to the presence of aromatic compounds. High specificity of spectral-luminescence characteristics changing in the presence of particular aromatic analytes provides the possibility of using [Zn₂L₂] helicates as new fluorescent sensors of aromatic compounds trace amount (120ppb to 56ppm) in organic media.

A New Sensitive and Selective Off-On Fluorescent Zn2+ Chemosensor Based on 3,3',5,5'-Tetraphenylsubstituted Dipyrromethene

3,3',5,5'-Tetraphenyl-2,2'-dipyrromethene was described as a highly sensitive and selective Off-on fluorescent colorimetric chemosensor for Zn²⁺ based on the chelation-enhanced fluorescence (CHEF) effect. The reaction of dipyrromethene ligand with Zn²⁺ induces the formation of the [ZnL₂] complex, which exhibits the increasing fluorescence in 120 fold compared with ligand in the propanol-1/cyclohexane (1:30) binary mixture. The Zn²⁺ detection limit was 1.4 × 10^-7 М. The UV-Vis and fluorescence spectroscopic studies demonstrated that the dipyrromethene sensor was highly selective toward Zn²⁺ cations over other metal ions (Na⁺, Mg²⁺, Co²⁺, Ni²⁺, Fe³⁺, Cu²⁺, Mn²⁺, Cd²⁺ and Pb²⁺), excluding Hg²⁺.

Influence of Solvation and Structural Contributions on Fluorescence of Dipyrrine Dyes

The results of quantum-chemical and spectral researches of zinc((II)) complexes with alkylated dipyrrine and 3,3'-, 2,3'- and 2,2'-bis(dipyrrine)s in non-polar and polar solvents and their binary mixtures are presented. It was investigated the efficiency of the fluorescence quenching of fluorophores depending on of the solvation and structural contributions. Found that 3,3'-bis(dipyrrinato)zinc((II)) demonstrates the highest sensitivity of the fluorescence to the presence of the electron-donor component compared with the studied complexes. The obtained results allow to offer dipyrrine and bis(dipyrrine) zinc((II)) complexes as new, highly sensitive and selective fluorescent sensors of the N- and O-containing toxicants. Graphical Abstract Influence of solvation and structural contributions on fluorescence of dipyrrine dyes.

The high sensitive and selective "off-on" fluorescent Zn2+ sensor based on the Bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)methane

A fluorescent chemosensor based on the 3,3'-bis(dipyrrin) bearing two chromophoric dipyrrin units was synthesized, which showed a strongly enhanced fluorescent intensity in the presence of Zn(2+) ions and a high selectivity toward Zn(2+) ions over a wide range of tested metal ions in organic solvents.