Synthesis of a new class of bisheterocycles via the Heck reaction of eudesmane type methylene lactones with 8-bromoxanthines

Synthesis and exploration of anticancer potential of spirocyclic 1,2,3-triazoline and aziridine derivatives of natural eudesmanolide isoalantolactone

Eudesmane-type sesquiterpene lactone isoalantolactone 1 is of great interest due to its availability, biological activity and synthetic application. Respective series of original spirocyclic (11S,5') (1,2,3-triazoline-eudesma-4,15-enolides) and (11S)-aziridine-eudesma-4,15-enolides were efficiently synthesized via a chemoselective 1,3-dipolar cycloaddition reaction of organic azides to the exocyclic double bond of the lactone ring of isoalantolactone or 13E-(aryl)isoalantolactones by heating in DMF or toluene. The thermal reactions of isoalantolactone with benzyl azide, 2-azidoethanol, or n-butyl azide in 2-methoxyethanol afforded 13-(alkyamino)isoalantolactones formed as a mixture of (Z) and (E)-isomers. The results of in vitro biological assays showed that novel spirocyclic isoalantolactone derivatives exhibited cytotoxicity against human breast cancer and glioblastoma cells at low micromolar concentrations. The most cytotoxic and selective (11S,5')-spiro-1,2,3-triazoline from 13E-(fluorophenyl)isoalantolactone 20 (IC50(MCF-7) = 8 ± 0.1 µM, SI(MCF-7) > 12.5) was found to induce ROS-dependent death of MCF-7 human breast cancer cells via mitochondrial apoptosis. The corresponding (11S)-spiroaziridine derivatives 21 at non-toxic concentrations (10 and 20 µM) effectively suppressed motility, clonogenicity and adhesion of glioblastoma cells and exhibited synergistic cytotoxicity in combination with temozolomide. In silico analysis revealed the potential ability of the 13-aryl (11S)-spiroaziridine derivative 21 to bypass the blood-brain barrier and exhibit anti-glioblastoma activity probably based on the direct interaction with Hsp90α.

Sesquiterpene Lactones as Promising Anti-Glioblastoma Drug Candidates Exerting Complex Effects on Glioblastoma Cell Viability and Proneural-Mesenchymal Transition

Glioblastoma is one of the most aggressive brain cancers, characterized by active infiltrative growth and high resistance to radiotherapy and chemotherapy. Sesquiterpene triterpenoids (STLs) and their semi-synthetic analogs are considered as a promising source of novel anti-tumor agents due to their low systemic toxicity and multi-target pharmacological effects on key processes associated with tumor progression. The current review aims to systematize the knowledge on the anti-glioblastoma potential of STLs accumulated over the last decade and to identify key processes in glioblastoma cells that are most susceptible to the action of STLs. An analysis of published data clearly demonstrated that STLs, which can successfully cross the blood-brain barrier, exert a complex inhibitory effect on glioblastoma cells through the induction of the "mitochondrial dysfunction-oxidative stress-apoptosis" axis, the inhibition of glucose metabolism and cell cycle phase transition, and the suppression of glioblastoma cell motility and invasion through the blockade of proneural-mesenchymal transition. Taken together, this review highlights the promising anti-glioblastoma potential of STLs, which are not only able to induce glioblastoma cell death, but also effectively affect their diffusive spread, and suggests the possible directions for further investigation of STLs in the context of glioblastoma to better understand their mechanism of action.

Synthetic and Pharmacological Activities of Alantolactone and Its Derivatives

Alantolactone, a sesquiterpene lactone, is isolated from the traditional Chinese medicinal herb Inula helenium L. (Asteraceae). Alantolactone is known as its wide spectrum of biological effects, including antimicrobial, antifungal, antiviral, and anthelmintic activities; anti-inflammatory activities; and antiproliferative effects on several cancer cell lines. Thus, it has received extensive attention, causing in-depth research in medicinal chemistry, and numerous undescribed alantolactone derivatives have been synthesized through different strategies. Herein, recent advances in diverse bioactivities and mechanism of alantolactone, including its derivatives, were summarized.

Isoalantolactone: a review on its pharmacological effects

Isoalantolactone (ISA) is a sesquiterpene lactone that could be isolated from Inula helenium as well as many other herbal plants belonging to Asteraceae. Over the past 2 decades, lots of researches have been made on ISA, which owns multiple pharmacological effects, such as antimicrobial, anticancer, anti-inflammatory, neuroprotective, antidepressant-like activity, as well as others. The anticancer effects of ISA involve proliferation inhibition, ROS overproduction, apoptosis induction and cell cycle arrest. Through inhibiting NF-κB signaling, ISA exerts its anti-inflammatory effects which are involved in the neuroprotection of ISA. This review hackled the reported pharmacological effects of ISA and associated mechanisms, providing an update on understanding its potential in drug development.

Anti-Inflammatory Activities of 8-Benzylaminoxanthines Showing High Adenosine A2A and Dual A1/A2A Receptor Affinity

Chronic inflammation plays an important role in the development of neurodegenerative diseases, such as Parkinson's disease (PD). In the present study, we synthesized 25 novel xanthine derivatives with variable substituents at the N1-, N3- and C8-position as adenosine receptor antagonists with potential anti-inflammatory activity. The compounds were investigated in radioligand binding studies at all four human adenosine receptor subtypes, A1, A2A, A2B and A3. Compounds showing nanomolar A2A and dual A1/A2A affinities were obtained. Three compounds, 19, 22 and 24, were selected for further studies. Docking and molecular dynamics simulation studies indicated binding poses and interactions within the orthosteric site of adenosine A1 and A2A receptors. In vitro studies confirmed the high metabolic stability of the compounds, and the absence of toxicity at concentrations of up to 12.5 µM in various cell lines (SH-SY5Y, HepG2 and BV2). Compounds 19 and 22 showed anti-inflammatory activity in vitro. In vivo studies in mice investigating carrageenan- and formalin-induced inflammation identified compound 24 as the most potent anti-inflammatory derivative. Future studies are warranted to further optimize the compounds and to explore their therapeutic potential in neurodegenerative diseases.