Phytochemical Profile and Biological Activity of the Ethanolic Extract from the Aerial Part of Crocus alatavicus Regel & Semen Growing Wildly in Southern Kazakhstan

The composition of the ethanolic extract from the aerial parts of Crocus alatavicus Regel & Semen from southern Kazakhstan spontaneous flora was analyzed together with the determination of its antibacterial, antifungal, antiviral and anticancer activity. The phytochemical profile analysis by high-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC/ESI-QTOF-MS) revealed the presence of multiple kaempferol derivatives. High-performance reverse-phase liquid chromatography combined with a photodiode-array detection (RP-HPLC/PDA) found that kaempferol 3-O-dihexoside and kaempferol 3-O-acyltetrahexoside accounted for 70.5% of the kaempferol derivatives. The minimum inhibitory concentration (MIC) values of the extract for all the tested reference microorganisms were high, reaching 10 mg/mL for yeasts and 20 mg/mL for bacteria. In contrast, antiviral activity was observed at 2 mg/mL, resulting in the inhibition of the HSV-1-induced cytopathic effect and the reduction in virus infectious titer by 1.96 log, as well as the viral load by 0.85 log. Among the tested prostate cancer cell lines, significant cytotoxic activity of the extract was noted only on the LNCaP cell line, with an IC₅₀ value of 1.95 mg/mL. The LNCaP cell line treated with 2 mg/mL of the extract showed a noticeably reduced number of spindle-shaped cells with longer cellular projections, a significant increase in the peak corresponding to the population of apoptotic cells in the sub-G1 phase and a decreased intracellular glutathione (GSH) level, suggesting the prooxidative properties of the extract. The obtained data provide novel information about the flavonoids present in the aerial part of C. alatavicus and suggest its potential application as a source of the compounds active against HSV-1 and metastatic, androgen-sensitive prostate cancer.     

Traditional Medicinal Plants as a Source of Inspiration for Osteosarcoma Therapy

Osteosarcoma is one of the most common types of bone cancers among paediatric patients. Despite the advances made in surgery, chemo-, and radiotherapy, the mortality rate of metastatic osteosarcoma remains unchangeably high. The standard drug combination used to treat this bone cancer has remained the same for the last 20 years, and it produces many dangerous side effects. Through history, from ancient to modern times, nature has been a remarkable source of chemical diversity, used to alleviate human disease. The application of modern scientific technology to the study of natural products has identified many specific molecules with anti-cancer properties. This review describes the latest discovered anti-cancer compounds extracted from traditional medicinal plants, with a focus on osteosarcoma research, and on their cellular and molecular mechanisms of action. The presented compounds have proven to kill osteosarcoma cells by interfering with different pathways: apoptosis induction, stimulation of autophagy, generation of reactive oxygen species, etc. This wide variety of cellular targets confer natural products the potential to be used as chemotherapeutic drugs, and also the ability to act as sensitizers in drug combination treatments. The major hindrance for these molecules is low bioavailability. A problem that may be solved by chemical modification or nano-encapsulation.     

Kinetics of Ag300 nanoclusters formation: The catalytically effective nucleus via a steady-state approach

The kinetics of formation of silver nanoparticles consisting of nearly 300 metal atoms is investigated, which were prepared by reduction of silver nitrate with hydrazine in ethylene glycol at 25°C without any stabilizer other than the glycol solvent. The resulting sigmoidal kinetic curves are analyzed by using the 1997 Finke–Watzky two-step mechanism of slow continuous nucleation with subsequent fast autocatalytic surface growth. The kinetics of homogeneous nucleation of metal nanoparticles was analyzed using the assumption about the stepwise adjunction of precursor and the quasi steady-state approximation. The equations were proposed to calculate the concentration of the formed metal nanoparticles and their mean size from the experimentally determined values of the Finke–Watzky rate constants. It is shown that a stepwise nucleation process can be described in the terms of the catalytically effective nucleus concept and that the number of atoms in the catalytically effective nucleus can be estimated.     

Preparation of the diastereomerically pure 2S-hydroxy derivative of dihydrolevoglucosenone (cyrene)

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Radical Complexes of Nickel(II)/Copper(II) and Redox Non-innocent MB-DIPY Ligands: Unusual Stability and Strong Near-Infrared Absorption at λmax ∼1300 nm

The preparation of radicals with intense and redox-switchable absorption beyond 1000 nm is a long-standing challenge in the chemistry of functional dyes. Here we report the preparation of a series of unprecedented stable neutral nickel(II) and copper(II) complexes of “Manitoba dipyrromethenes” (MB-DIPYs) in which the organic chromophore is present in the radical-anion state. The new stable radicals have an intense absorption at λ_max∼1300 nm and can be either oxidized to regular [M^II(MB-DIPY)]⁺ (M=Cu or Ni) or reduced to [M^II(MB-DIPY)]⁻ compounds. The radical nature of the stable [M^II(MB-DIPY)] complexes was confirmed by EPR spectroscopy with additional insight into their electronic structure obtained by UV-Vis spectroscopy, electro- and spectroelectrochemistry, magnetic measurements, and X-ray crystallography. The electronic structures and spectroscopic properties of the radical-based chromophores were also probed by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. These nickel(II) and copper(II) complexes represent the first stable radical compounds with a MB-DIPY ligand.     

Synthesis and structure of new 2-aryl-substituted pyrrolidines containing phosphine oxide group

2-Aryl-substituted pyrrolidines containing phosphine oxide group have been obtained by the reaction of P-(4,4-diethoxybutylaminomethyl)- P,P-di-p-tolylphosphine oxide with polyatomic phenols.     

The Kinetic Rate Law for the Autocatalytic Growth of Citrate‐Stabilized Silver Nanoparticles

The formation of sodium citrate stabilized spherical silver nanoparticles synthesized by homogeneous nucleation in aqua solutions was monitored by the method of direct potentiometry. It was observed that the kinetic curve of Ag⁺ ions reduction can be described by the Finke–Watzky (FW) autocatalytic two–step mechanism in the case of a large excess of hydrazine and NaOH. To expand the FW minimalistic model, the impact of the starting concentrations of the reagents on the kinetics of Ag nanoparticles synthesis was studied. It was determined that the nucleation stage is limited by the homogeneous process of ions Ag⁺ reduction, and the reaction orders for the all reagents are calculated. A surface–dependent model of Ag nanoparticle growth is proposed, which takes into account the change in the hydrazine and alkali concentrations; the rate constants of the pseudoelementary reactions are also calculated.     

Multicomponent Synthesis of 2,3-Dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones: A Novel Heterocyclic Scaffold with Antibacterial Activity

A multicomponent reaction of 3-aminopyrazol-5-ones with substituted salicylic aldehydes and acetylacetic ester leading to the formation of novel 2,3-dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones was discovered. The elucidation of the reaction scope revealed that 5-aminopyrazoles, 3-amino-1,2,4-triazoles and 6-aminouracil could be used as the heterocyclic amine component. Selected heterocyclic products were found to possess notable antibacterial activities.