Neuroprotective activity of Colocasia esculenta (L.) Schott leaves against monosodium glutamate-induced excitotoxicity in rats: phytochemical and molecular docking study

Colocasia esculenta (L.) Schott is a food crop with long history of use in treatment of various disorders including neurological diseases. The methanolic leaves extract (ME) and its n-butanol fraction (n-BF) demonstrated significant in vivo neuroprotective activity in monosodium glutamate induced excitotoxicity in rats. Sixteen and fifteen polyphenolic compounds were identified in n-BF and ME, respectively, using HPLC. Phytochemical investigation of n-BF followed by 1D (1H and 13C NMR) spectroscopic analyses led to isolation and identification of daucosterol (1), thermopsoside (2) and chrysoeriol 7-O-β-D-neohesperidoside (3) for the first time from genus Colocasia, in addition to orientin (4). LC/MS/MRM analysis of fraction V obtained from n-BF revealed identification of 13 polyphenolic compounds. Molecular docking of isolated compounds confirmed binding of all compounds at the target pocket with higher energy than crystallised ligand. The current study evaluated and confirmed the mechanistic aspects of neuroprotective activity of C. esculenta leaves for the first time.

Antimicrobial, antiproliferative activities and molecular docking of metabolites from Alternaria alternata

Endophytic fungi allied to plants have sparked substantial promise in discovering new bioactive compounds. In this study, propagation of the endophytic fungus Alternaria alternata HE11 obtained from Colocasia esculanta leaves led to the isolation of Ergosterol (1), β-Sitosterol (2), Ergosterol peroxide (3), in addition to three dimeric naphtho-γ-pyrones, namely Fonsecinone A (4), Asperpyrone C (5), and Asperpyrone B (6), which were isolated from genus Alternaria for the first time. Structures of the isolated compounds were established on the basis of extensive 1D and 2D NMR and, MS measurements. The ethyl acetate extract, as well as compounds 1, 3, 4 and 6 were evaluated for their antimicrobial activity using agar well-diffusion and broth microdilution assays. Molecular docking study was carried out to explore the pharmacophoric moieties that governed the binding orientation of antibacterial active compounds to multidrug efflux transporter AcrB and the ATP binding site to E. coli DNA gyrase using MOE software. Results revealed that the most active antibacterial compounds 4 and 6 bind with high affinity in the phenylalanine-rich cage and are surrounded with other hydrophobic residues. The antiproliferative activity of all isolated compounds was in vitro evaluated using the human prostatic adenocarcinoma cell lines DU-145, PC-3, PC-3 M, 22Rv1 and CWR-R1ca adopting MTT assay. Compound 4 was the most active against almost all tested cell lines, with IC₅₀ values 28.6, 21.6, 17.1 and 13.3 against PC-3, PC-3 M, 22Rv1 and CWR-R1ca cell lines, respectively.

Novel pyrrolopyrimidine derivatives: design, synthesis, molecular docking, molecular simulations and biological evaluations as antioxidant and anti-inflammatory agents

Current medical approaches to control the Covid-19 pandemic are either to directly target the SARS-CoV-2 via innovate a defined drug and a safe vaccine or indirectly target the medical complications of the virus. One of the indirect strategies for fighting this virus has been mainly dependent on using anti-inflammatory drugs to control cytokines storm responsible for severe health complications. We revealed the discovery of novel fused pyrrolopyrimidine derivatives as promising antioxidant and anti-inflammatory agents. The newly synthesised compounds were evaluated for their in vitro anti-inflammatory activity using RAW264.7 cells after stimulation with lipopolysaccharides (LPS). The results revealed that 3a, 4b, and 8e were the most potent analogues. Molecular docking and simulations of these compounds against COX-2, TLR-2 and TLR-4 respectively was performed. The former results were in line with the biological data and proved that 3a, 4b and 8e have potential antioxidant and anti-inflammatory effects.

Synthesis of novel calcium channel blockers with ACE2 inhibition and dual antihypertensive/anti-inflammatory effects: A possible therapeutic tool for COVID-19

Hypertension has been recognized as one of the most frequent comorbidities and risk factors for the seriousness and adverse consequences in COVID-19 patients. 3,4-dihydropyrimidin-2(1H) ones have attracted researchers to be synthesized via Beginilli reaction and evaluate their antihypertensive activities as bioisosteres of nifedipine a well-known calcium channel blocker. In this study, we report synthesis of some bioisosteres of pyrimidines as novel CCBs with potential ACE2 inhibitory effect as antihypertensive agents with protective effect against COVID-19 infection by suppression of ACE2 binding to SARS-CoV-2 Spike RBD. All compounds were evaluated for their antihypertensive and calcium channel blocking activities using nifedipine as a reference standard. Furthermore, they were screened for their ACE2 inhibition potential in addition to their anti‐inflammatory effects on LPS-stimulated THP‐1 cells. Most of the tested compounds exhibited significant antihypertensive activity, where compounds 7a, 8a and 9a exhibited the highest activity compared to nifedipine. Moreover, compounds 4a,b, 5a,b, 7a,b, 8a,c and 9a showed promising ACE2:SARS-CoV-2 Spike RBD inhibitory effect. Finally, compounds 5a, 7b and 9a exerted a promising anti-inflammatory effect by inhibition of CRP and IL-6 production. Ultimately, compound 9a may be a promising antihypertensive candidate with anti-inflammatory and potential efficacy against COVID-19 via ACE2 receptor inhibition.

Molecular modelling insights into a physiologically favourable approach to eicosanoid biosynthesis inhibition through novel thieno[2,3-b]pyridine derivatives

In this research, we exploited derivatives of thieno[2,3-b]pyridine as dual inhibitors of the key enzymes in eicosanoid biosynthesis, cyclooxygenase (COX, subtypes 1 and 2) and 5-lipoxygensase (5-LOX). Testing these compounds in a rat paw oedema model revealed potency higher than ibuprofen. The most active compounds 7a, 7b, 8b, and 8c were screened against COX-1/2 and 5-LOX enzymes. Compound 7a was the most powerful inhibitor of 5-LOX with IC₅₀ = 0.15 µM, while its p-chloro analogue 7b was more active against COX-2 (IC₅₀ = 7.5 µM). The less desirable target COX-1 was inhibited more potently by 8c with IC₅₀ = 7.7 µM. Surflex docking programme predicted that the more stable anti- conformer of compound (7a) formed a favourable complex with the active site of 5-LOX but not COX-1. This is in contrast to the binding mode of 8c, which resembles the syn-conformer of series 7 and binds favourably to COX-1.

Allosteric HIV-1 integrase inhibitors promote aberrant protein multimerization by directly mediating inter-subunit interactions: Structural and thermodynamic modeling studies

Allosteric HIV-1 integrase (IN) inhibitors (ALLINIs) bind at the dimer interface of the IN catalytic core domain (CCD), and potently inhibit HIV-1 by promoting aberrant, higher-order IN multimerization. Little is known about the structural organization of the inhibitor-induced IN multimers and important questions regarding how ALLINIs promote aberrant IN multimerization remain to be answered. On the basis of physical chemistry principles and from our analysis of experimental information, we propose that inhibitor-induced multimerization is mediated by ALLINIs directly promoting inter-subunit interactions between the CCD dimer and a C-terminal domain (CTD) of another IN dimer. Guided by this hypothesis, we have built atomic models of inter-subunit interfaces in IN multimers by incorporating information from hydrogen-deuterium exchange (HDX) measurements to drive protein-protein docking. We have also developed a novel free energy simulation method to estimate the effects of ALLINI binding on the association of the CCD and CTD. Using this structural and thermodynamic modeling approach, we show that multimer inter-subunit interface models can account for several experimental observations about ALLINI-induced multimerization, including large differences in the potencies of various ALLINIs, the mechanisms of resistance mutations, and the crucial role of solvent exposed R-groups in the high potency of certain ALLINIs. Our study predicts that CTD residues Tyr226, Trp235 and Lys266 are involved in the aberrant multimer interfaces. The key finding of the study is that it suggests the possibility of ALLINIs facilitating inter-subunit interactions between an external CTD and the CCD-CCD dimer interface.