E-Z isomerization of 3-benzylidene-indolin-2-ones using a microfluidic photo-reactor

In vivo toxicological evaluation of 3-benzylideneindolin-2-one: antifungal activity against clinical isolates of dermatophytes

BACKGROUND

Dermatophytes, the primary causative agents of superficial cutaneous fungal infections in humans, present a significant therapeutic challenge owing to the increasing prevalence of recurrent infections and the emergence of antifungal resistance. To address this critical gap, this study was designed to investigate the antifungal potential of 3-benzylideneindolin-2-one against dermatophytes and assess its in vivo toxicological profile using brine shrimp and zebrafish embryo models.

METHODS

The antifungal activity of 3-benzylideneindolin-2-one was evaluated against 30 clinical isolates of dermatophyte species, including Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum gypseum, Microsporum canis, and Epidermophyton floccosum, by determining the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) using the broth microdilution method. The fungicidal activity was evaluated using time-kill assays. Toxicological effects were investigated using the brine shrimp lethality assay to determine Artemia salina nauplii mortality after 48 h of exposure, and the fish embryo acute toxicity test, which assessed lethality and developmental abnormalities in zebrafish (Danio rerio) embryos over a 96 h post-fertilization period.

RESULTS

3-Benzylideneindolin-2-one exhibited consistent fungicidal activity across all dermatophyte species, with MICs ranging from 0.25 to 8 mg/L and MFCs ranging from 1 to 32 mg/L. Time-kill assays revealed a concentration-dependent fungicidal effect on the microconidia. The compound exhibited moderate toxicity to A. salina nauplii, with LC50 values of 69.94 mg/L and 52.70 mg/L at 24 and 48 h, respectively, while showing no significant lethality within the MIC range. In zebrafish embryos, concentrations below 7.5 mg/L did not significantly affect lethality, hatchability, or induce morphological abnormalities. However, at a concentration of 10 mg/L, the compound induced mild toxicity in embryos, evidenced by a significant increase in mortality and the presence of morphological anomalies such as yolk-sac and pericardial edema compared to the control group.

CONCLUSIONS

The consistent antifungal activity of 3-benzylideneindolin-2-one against clinically significant dermatophyte species, combined with its low toxicity within the therapeutic window, underscores its potential as a promising lead compound for the development of effective therapeutics for dermatophytosis.

Synthesis of novel organophosphorus compounds via reaction of substituted 2-oxoindoline-3-ylidene with acetylenic diesters and triphenylphosphine or triphenyl phosphite

An efficient reaction between triphenylphosphine or triphenyl phosphite and 2-oxoindoline-3-ylidene derivatives in the presence of acetylenic esters leads to functionalized 2-oxoindoline-3-ylidene containing phosphorus ylieds or phosphonate esters. All compounds obtained in these reactions are stable and have good yields.

Skeletal rearrangement through photocatalytic denitrogenation: access to C-3 aminoquinolin-2(1H)-ones

The addition of an amine group to a heteroaromatic system is a challenging synthetic process, yet it is an essential one in the development of many bioactive molecules. Here, we report an alternative method for the synthesis of 3-amino quinolin-2(1H)-one that overcomes the limitations of traditional methods by editing the molecular skeleton via a cascade C-N bond formation and denitrogenation process. We used TMSN3 as an aminating agent and a wide variety of 3-ylideneoxindoles as synthetic precursors for the quinolin-2(1H)-one backbone, which demonstrates remarkable tolerance of sensitive functional groups. The control experiments showed that the triazoline intermediate plays a significant role in the formation of the product. The spectroscopic investigation further defined the potential reaction pathways.

Highly Efficient Oxindole-Based Molecular Photoswitches

3-Benzylidene-indoline-2-ones play a prominent role in the pharmaceutical industry due to the diverse biomedical applications of oxindole heterocycles. Despite the extensive reports on their biological properties, these compounds have hardly been studied for their photochemical activity. Here, we present 3-benzylidene-indoline-2-ones as a promising class of photoswitches with high yields, robust photochemical switching with quantum yields reaching up to 50 % and potential for biological applications.

Visible-Light-Mediated Intermolecular [2 + 2]-Cycloaddition Reaction of 3-Alkylideneindolin-2-one with Alkenes via Triplet Energy Transfer for the Synthesis of 3-Spirocyclobutyl Oxindoles

[2 + 2]-Cycloaddition is the most straightforward approach to the construction of cyclobutanes. In this paper, the intermolecular [2 + 2]-cycloaddition reaction of 3-alkylideneindolin-2-ones with alkenes was achieved. This reaction can be used in the synthesis of 3-spirocyclobutyl oxindoles, polycyclic oxindoles, and late stage modification of some drug molecules.

Is It Possible to Obtain a Product of the Desired Configuration from a Single Knoevenagel Condensation? Isomerization vs. Stereodefined Synthesis

The biological activity of compounds directly depends on the three-dimensional arrangement of affinity fragments since a high degree of pharmacophore compliance with the binding site is required. 3-Benzylidene oxindoles are privileged structures due to their wide spectrum of biological activity, synthetic availability, and ease of modification. In particular, both kinase inhibitors and kinase activators can be found among 3-benzylidene oxindoles. In this work, we studied model compounds obtained via oxindole condensation with aldehydes and alkylphenones. These condensation products can exist in the form of E- and Z-isomers and also undergo isomerization in solutions. The factors causing isomeric transformation of these compounds were established. Comparative kinetic studies to obtain quantitative characteristics of UV-driven isomerization were first performed. The results obtained indicate dramatic differences in two subclasses, which should be considered when developing biologically active molecules.

Blue LED-Mediated Synthesis of 3-Arylidene Oxindoles

Blue LED-promoted cross-coupling olefination of symmetrical and unsymmetrical 3-arylidene oxindoles has been described from diazoindolones and diphenylmethanethiones. Thermal olefin isomerization and stereoselective synthesis of 3-arylidene oxindoles were also demonstrated in good yield.

Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry

Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.

Inversion kinetics of some E/Z 3-(benzylidene)-2-oxo-indoline derivatives and their in silico CDK2 docking studies

The structure-based design of some CDK2 inhibitors with a 3-(benzylidene)indolin-2-one scaffold as potential anticancer agents was realized. Target compounds were obtained as E/Z mixtures and were resolved to corresponding E- and Z-diastereomers. In silico studies using MOE 2019.01 software revealed better docking on the targeted enzyme for the Z-diastereomer compared to the E-one. A time-dependent kinetic isomerization study was carried out for the inversion of E/Z diastereomers in DMSO-d6 at room temperature, and were found to obey the first order kinetic reactions. Furthermore, a determination of the kinetic inter-conversion rate order by graphical analysis method and calculation of the rate constant and half-life of this kinetic process were carried out. For the prediction of the stability of the diastereomer(s), a good multiple regression equation was generated between the reaction rates of isomerization and some QM parameters with significant p value.