Investigation on the fungicide resistance mechanism against Botrytis cinerea β-tubulin inhibitor zoxamide by computational study

Discerning computational, in vitro and in vivo investigations of self-assembling empagliflozin polymeric micelles in type-2 diabetes

BACKGROUND

Empagliflozin (EMPA) is an SGLT2 inhibitor, a new class of anti-diabetic medication, indicated for treating type-2 diabetes. Its low permeability, poor solubility and bioavailability limits its use in management of diabetes. The study was aimed to formulate EMPA loaded polymeric micelles (PMs) to overcome these obstacles in oral absorption.

METHODOLOGY

In silico studies-molecular docking, molecular dynamic simulation (MDS), and quantum chemical calculation were employed to study the interaction of EMPA with different polymers. EMPA loaded TPGS polymeric micelles (EMPA-TPGS-PMs) were formulated by direct dissolution method and characterized in terms of surface morphology, entrapment, particle size, in vitro drug release, and in vitro cytotoxicity (HEK293 cells). In vivo pharmacokinetic and pharmacodynamic studies were also performed.

RESULTS

The results suggested a good interaction between TPGS and EMPA with lowest binding energy compared to other polymers. Further MDS results and DFT calculations validated the stable binding of the complex hence TPGS was selected for further wet lab experiments. The EMPA-TPGS complex displayed lower value of Total energy (T.E.) than its individual components, indicating the overall stability of the complex while, the energy band gap (∆E) value lied between the two individual molecules, signifying the better electron transfer between HOMO and LUMO of the complex. Based on the solubility, entrapment and cytotoxicity studies, 5% TPGS was selected for formulating drug loaded micelles. EMPA-TPGS5-PMs presented a size of 9.008 ± 1.25 nm, Polydispersity index (PDI) of 0.254 ± 0.100, a controlled release behaviour upto 24 h. SEM and AFM images of the nanoformulation suggested spherical particles whereas, DSC, and PXRD studies confirmed the loss of crystallinity of EMPA. A 3.12-folds higher AUC and a greater reduction in blood glucose levels was exhibited by EMPA-TPGS5-PMs in comparison to EMPA-SUSP in mice model.

CONCLUSION

EMPA-TPGS-PMs has exhibited better bio absorption and therapeutic effectiveness in diabetes treatment. This improved performance would open the possibility of dose reduction, reduced dosing frequency & dose-related side effects, improving pharmaco-economics and thereby improved overall compliance to the patient. However, this translation from bench to bedside would necessitate studies in higher animals and human volunteers.

Antifungal, Insecticidal, and Repellent Activities of Rosmarinus officinalis Essential Oil and Molecular Docking of Its Constituents against Acetylcholinesterase and β-Tubulin

The aim of this study was to determine the phytochemical composition and evaluate the antifungal and insecticidal properties of Rosmarinus officinalis essential oil (EO). GC-MS was employed to analyze the phytochemical profile of the EO. The antifungal activity of the EO was assessed by calculating growth inhibition rates for Alternaria alternata, Fusarium oxysporum, and Botrytis cinerea. Repellent capacity and toxicity were evaluated through inhalation and contact tests on Callosobruchus maculatus. Molecular docking techniques were utilized to test the insecticidal and antifungal activities of rosemary EO. The analysis revealed a total of sixteen components in R. officinalis EO, with 1,8-cineole (40.80%) being the major constituent, followed by α-pinene (26.18%) and camphor (19.53%). Antifungal evaluation demonstrated a significant inhibitory impact on the mycelial growth of the tested fungi, with complete inhibition observed against B. cinerea. In terms of insecticidal capacity, the EO induced complete mortality of C. maculatus adults at a concentration of 1 μL/L air, with an inhalation test LC50 value of 0.62 μL/L air. Concentration-dependent reductions were observed in the number of both laid eggs and emerged insects, reaching a 99.36% reduction. The EO also exhibited a moderate effectiveness in repelling insects, with an average repellency rate of 50.83%. In silico analysis identified borneol as the most active molecule against insect acetylcholinesterase (PDB: 6ARY) with a Glide score of -7.254 kcal/mol. α-Caryophyllene showed the highest activity against B. cinerea β-tubulin (PDB: 3N2G) with a Glide score of -7.025 kcal/mol. These findings suggest that the EO derived from Moroccan Rosmarinus officinalis has potential as an effective natural agent against pathogenic fungi and could serve as a sustainable and environmentally friendly alternative as a bioinsecticide.

Molecular Insights into the Covalent Binding of Zoxamide to the β-Tubulin of Botrytis cinerea

Botrytis cinerea is a fungal plant pathogen that causes significant economic losses in the agricultural industry worldwide. Fungicides that target microtubules, such as carbendazim (CBZ), diethofencarb (DEF), and zoxamide (ZOX), are widely used in crop protection against this pathogen. These groups of compounds exert their fungicidal activity by disrupting the microtubule assembly by binding to the β-tubulin subunit, provoking cell-cycle arrest and cell death. However, with the appearance of isolates resistant to these compounds, it is necessary to search for new alternatives to control this pathogenic fungus. In this work, we gained insight into the binding and stability of these fungicides in the benzimidazole binding site of B. cinerea β-tubulin through different computational approaches. Our molecular dynamics simulation replicas showed that R enantiomers of ZOX and its analog RH-4032 had better interaction profiles at the site compared to S enantiomers. The simulations also revealed that while the R-isomer fungicides formed H-bonds with the main chain carbonyl of V236 or the side chain residue of S314, only CBZ interacted with E198. Previous experimental data have identified key mutations in B. cinerea's β-tubulin gene that lead to the development of resistance or, on the contrary, increased sensitivity for treatment with these fungicide compounds. In agreement with experimental findings, alchemical free energy calculations showed that E198A and E198V mutations in B. cinerea β-tubulin have high sensitivity to (R)-ZOX, whereas the E198K mutation decreased its affinity. Similarly, the results obtained explain the resistance to CBZ of B. cinerea isolates with E198A/V/K mutations and the insensitivity of the wild-type organism to DEF. Our work provides a deeper insight into the molecular mechanism of action of these fungicides, highlighting the importance of understanding the interaction profiles to develop more effective antifungal agents.

Virulence Factors in the Phytopathogen-Host Interactions: An Overview

Phytopathogens are responsible for great losses in agriculture, once they are able to subvert or elude the host defense mechanisms through virulence factors secretion for their dissemination. Herein, it is reviewed phytotoxins that act as virulence factors and are produced by bacterial phytopathogens (Candidatus Liberibacter spp., Erwinia amylovora, Pseudomonas syringae pvs and Xanthomonas spp.) and fungi (Alternaria alternata, Botrytis cinerea, Cochliobolus spp., Fusarium spp., Magnaporthe spp., and Penicillium spp.), which were selected in accordance to their worldwide importance due to the biochemical and economical aspects. In the current review, it is sought to understand the role of virulence factors in the pathogen-host interactions that result in plant diseases.

In silico design of peptide inhibitors of tubulin: amyloid-β as a lead compound

Microtubule is one of the most studied targets in cancer research. Stabilizing and destabilizing of the microtubule by targeting its building block tubulin are common mechanisms of microtubule targeting agents. Cancer associates inversely with Alzheimer's disease (AD). So the rate of developing AD is significantly slower in patients with cancer and vice versa. Amyloid-β (Aβ) peptide inhibits tubulin polymerization and induces apoptotic death of cancer cells. We studied the interactions of Aβ with tubulin using protein-protein docking and MD simulation. Aβ bond to the vicinity of the vinblastine binding site and interacted with the H6-H7 loop. Interaction of Aβ with H6-H7 loop blocked nucleotide exchange and may be attributed as a possible reason for blocking of tubulin polymerization. We designed new Aβ-based peptidic inhibitors of tubulin using visual inspection and alanine scanning method. P1 (FRHYHHFFELV) and P9 (HYHHF) bound efficiently to tubulin and also interacted with the H6-H7 loop. Obtained results indicated that proposed peptides could potentially inhibit nucleotide exchange as Aβ.Communicated by Ramaswamy H. Sarma.