Synthesis and biological evaluation of 1,2,4-oxadiazole core derivatives as potential neuroprotectants against acute ischemic stroke

Synthesis of 1,3,5-triphenyl-1,2,4-triazole derivatives and their neuroprotection by anti-oxidative stress and anti-inflammation and protecting BBB

Acute ischemic stroke (AIS) is a serious cardiovascular and cerebrovascular disease; Oxidative stress and neuroinflammation are important factors which destroy blood-brain barrier (BBB) in AIS. In the study, a series of 1,3,5-triphenyl-1,2,4-triazole derivatives were designed and synthesized; the optimal compound 9 was obtained by screening their anti-oxidant and anti-inflammatory effects; the neuroprotection effect of compound 9 was evaluated with a rat middle cerebral artery occlusion (MCAO) model. Subsequently, the mechanism of neuroprotection were explored via Western blot. The results prompt compound 9 maybe exert anti-AIS neuroprotection by inhibiting oxidative stress and neuroinflammation inhibition by inhibiting Keap1, COX-2 and iNOS. At the same time, it can protect BBB by reducing glycocalyx degradation and matrix metallopeptidase-9 levels. Its LD50 > 1000 mg/kg on mice and hERG channel inhibition IC50 > 30 μM, which lower acute toxicity and hERG channel inhibition would make compound 9 a promising stroke treatment candidate.

Diversity of sesquiterpenoids from Stellera chamaejasme with neuroprotective effects

Chromatographic fractionation of the 95% EtOH extract of the roots of Stellera chamaejasme yielded 20 sesquiterpenoids of four different types, guaiane-, carotane-, sesquicarane-, and alpiniane-types. Among them, sesquistrachanoids A-F were previously undescribed ones, whose structures including absolute configurations were elucidated by spectroscopic methods, the Mo₂(OAc)₄-induced ECD experiment, and analysis of experimental and calculated 1D NMR and ECD data. Sesquistrachanoid A is a 2,3-seco-guaiane-type sesquiterpenoid with a α-pyrone core and sesquistrachanoid B is the first example of 8,9-seco-guaiane-type sesquiterpenoid featured with an 1,8-δ-lactone core. Sesquistrachanoid C is a guaiane sesquiterpenoid characterized by a peroxide bridge between C-8 and C-10. All sesquiterpenoids were evaluated for their neuroprotective effects on cell damage induced by sodium nitroprusside in PC-12 cells. The bioassay results showed that six compounds at 10 μM could restore the cell viability, being comparable to that of the positive control edaravone. The mechanistic study on the most pronounced activity compound, stelleraguaianone B, demonstrated that it played a neuroprotective role by promoting the mRNA expression of antioxidant enzymes to reduce oxidative stress.

Research progress on the synthesis and pharmacology of 1,3,4-oxadiazole and 1,2,4-oxadiazole derivatives: a mini review

Oxadiazole is a five-membered heterocyclic compound containing two nitrogen atoms and one oxygen atom. The 1,3,4-oxadiazole and 1,2,4-oxadiazole have favourable physical, chemical, and pharmacokinetic properties, which significantly increase their pharmacological activity via hydrogen bond interactions with biomacromolecules. In recent years, oxadiazole has been demonstrated to be the biologically active unit in a number of compounds. Oxadiazole derivatives exhibit antibacterial, anti-inflammatory, anti-tuberculous, anti-fungal, anti-diabetic and anticancer activities. In this paper, we report a series of compounds containing oxadiazole rings that have been published in the last three years only (2020-2022) as there was no report or their activities described in any article in 2019, which will be useful to scientists in research fields of organic synthesis, medicinal chemistry, and pharmacology.

Tigliane and rhamnofolane glycosides from Euphorbia wallichii prevent oxidative stress-induced neuronal death in PC-12 cells

Tigliane and rhamnofolane diterpenoids bearing glycosyl substituents are rarely found in nature. In the current study, seven new tigliane glycosides, euphorwallsides A - G (1-7), and five new rhamnofolane glycosides, euphorwallsides H - L (8-12), were isolated from the whole plants of Euphorbia wallichii. Their structures were elucidated by a combination of spectroscopic, computational, and chemical means. The aglycones of 1-5 represent a rare class of 13-deoxygenated tiglianes, while those of 8-12 represent the first examples of 4-deoxygenated rhamnofolanes. 2, 3, 5, 7, 8, and 12 showed significant neuroprotective effects on sodium nitroprusside (SNP)-induced neuronal death in pheochromocytoma cell line PC-12 at 10 μM, being more active than the clinical drug, edaravone. Mechanistic study revealed that the most active compound, 3, could inhibit reactive oxygen species (ROS) accumulation and restore the mitochondrial membrane potential via modulating the Nrf2 signaling pathway in PC-12 cells.

Using RSM for Optimum of Optimum Production of Peptides from Edible Bird’s Nest By-Product and Characterization of Its Antioxidant’s Properties

In this research, the neutrase hydrolysis conditions of edible bird’s nest (EBN) by-products were optimized by response surface methodology (RSM). Antioxidant peptides were then isolated from the EBN by-products by ultrafiltration and chromatography taking the DPPH radical scavenging ability as an indicator. The antioxidant activity of the purified peptides was estimated by radical scavenging ability and sodium nitroprusside (SNP)-induced damage model in PC12 cells. When the enzyme concentration was10 kU/g-hydrolysis temperature was 45 °C, and hydrolysis time was 10.30 h, the degree of hydrolysis (DH) of EBN by-product hydrolysate (EBNH) was the highest. The purified peptide exerted strong scavenging ability with EC₅₀ values of 0.51, 1.31, and 0.65 mg/mL for DDPH, ABTS, and O₂⁻ radicals, respectively. In addition, the purified peptides could significantly reduce the SNP-induced oxidative damage of PC12 cells, and twelve peptides that were rich in leucine (Leu), valine (Val), and lysine (Lys) were identified by LC-MS/MS. These results suggested that EBN by-products have potential as new materials for natural antioxidant peptides.