Investigating the antiparasitic potential of the marine sesquiterpene avarone, its reduced form avarol, and the novel semisynthetic thiazinoquinone analogue thiazoavarone

The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The semisynthetic compound, as well as the natural metabolites avarone and avarol, were pharmacologically investigated in order to assess their antiparasitic properties against sexual and asexual stages of Plasmodium falciparum, larval and adult developmental stages of Schistosomamansoni (eggs included), and also against promastigotes and amastigotes of Leishmania infantum and Leishmania tropica. Furthermore, in depth computational studies including density functional theory (DFT) calculations were performed. A toxic semiquinone radical species which can be produced starting both from quinone- and hydroquinone-based compounds could mediate the anti-parasitic effects of the tested compounds

Synthesis and Evaluation of Cytostatic and Antiviral Activities of 3′ and 4′-Avarone Derivatives

A series of 3′ and 4′-substituted avarone derivatives were synthesized and tested in culture systems as antitumour and antiviral agents in comparison to avarol and avarone. 3′-alkylamino derivatives showed potent cytostatic activities against murine L1210 and human B (Raji) and T (C8166, H9) lymphoblast cells (ID50 range 1.7–3.7 μm). Avarol and avarone were six times less active. While none of the derivatives showed anti-human immunodeficiency virus (HIV) activity superior to that of the parent compounds, most of them, avarol and avarone included, were potent and selective inhibitors of poliovirus multiplication

Kovalentne modifikacije proteina biološki aktivnim hinonima

The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of beta-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10)-estradiene-1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of beta-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein Occurs. It Could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pl of the protein (5.4) upon modification toward lower values (from pl 5.0 to 5.3) indicated that lysine amino groups are the principal site of the reaction of beta-lactoglobulin with the quinones.Hinonsko/hidrohinonski par avaron/avarol pokazuje značajnu antitumorsku aktivnost. U ovom radu proučavane su kovalentne modifikacije β-laktoglobulina avaronom, sintetičkim steroidnim hinonom 2,5(10)-estradien-1,4,17-trionom i njihovim derivatima. Tehnike za praćenje hemijske modifikacije bile su: UV/Vis spektrofotometrija, SDS PAGE i izoelektrofokusiranje. Rezultati SDS PAGE ukazuju da se dešava polimerizacija proteina.Može se videti da protein od 18 kD daje trake od 20 kD, 36 kD, 40 kD, 45 kD, 64 kD i 128 kD u zavisnosti od agensa za modifikaciju. Pomeranje pI vrednosti proteina (5,4) nakon modifikacije ka nižim vrednostima (od pI 5,0 do 5,3) pokazuje da su amino-grupe lizina glavna mesta reakcije β-laktoglobulina sa hinonima

New perspective on type 2 diabetes and obesity treatment: study and development of new natural/synthetic inhibitors of tyrosine phosphatase 1B (PTP1B).

Type 2 diabetes mellitus (T2DM) is a complex disease characterized by impaired glucose homeostasis and serious long-term complications. First line therapeutic options for T2DM treatment are monodrug therapies, often replaced by multidrugs therapies to ensure that not responding patients maintain target levels of glycaemia. The use of multitarget drugs instead of mono- or multi-drugs therapies has been emerging as a main strategy to treat multifactorial diseases, including T2DM. Therefore, modern drug discovery in its early stages aims to identify potential modulators for multiple targets and exploration of the chemical space of natural products represents a powerful tool. For such purpose, we analyzed several natural/synthetic compounds which showed potent inhibition activity in vitro on PTP1B, the main negative regulator of insulin receptor and, for some of them, on aldose reductase (AR, target for treatment of T2D-related pathologies). These compounds are: the Epigallocatechin gallate (EGCG) obtained from tea extracts; Phosphoeleganin, a marine-derived phosphorylated polyketide; Gossypetin, which is the most potent inhibitor described so far within flavonoid class; Avarone, a sesquiterpene quinone obtained from the sponge Dysidea avara, and CA4-CA8, novel multi-target drugs specifically designed to target both PTP1B and AR. We analyzed their mechanisms of action, the kinetic behaviour coupled with in silico docking simulations and their effects on insulin-signalling pathway. We found that they acted as interesting antidiabetic agents by inhibiting PTP1B and enhancing glucose uptake in muscle cells even without the presence of insulin and, some of them also inhibited strongly the AR suggesting their usage as scaffold for multi-target drug development in order to deal with type 2 diabetes by acting on several targets involved at once

Further in vitro biological activity evaluation of amino-, thio- and ester-derivatives of avarol

The acetylcholinesterase inhibitory and/or antitumour activities of amino-, thio-and ester-derivatives of avarol selected were evaluated for the first time at in vitro conditions. Avarol-3',4'-dithioglycol (1) and avarol-4'-(3) mercaptopropionic acid (3) were shown to be the best inhibitors of the enzyme tested (0.50 mu g and IC50 0.05mM and 0.50 mg and IC50 0.12 mM, respectively), while 4'-tryptamine-avarone (9) and avarol-3'-(3) mercaptopropionic acid (2) exhibited the highest cytotoxicity against the human breast T-47D cancer cell line (IC50 0.66 mu g/mL and 1.25 mu g/mL, respectively). According to experimental data obtained, the sesquiterpenoid hydroquinone structure of bioactive avarol derivatives may inspire development of new pharmacologically useful substances to be used in the treatment of Alzheimer's disease and/or human breast tumour

Cytotoxic Terpene Quinones from Marine Sponges

The 1,4-benzoquinone moiety is a common structural feature in a large number of compounds that have received considerable attention owing to their broad spectrum of biological activities. The cytotoxic and antiproliferative properties of many natural sesquiterpene quinones and hydroquinones from sponges of the order Dictyoceratida, such as avarol, avarone, illimaquinone, nakijiquinone and bolinaquinone, offer promising opportunities for the development of new antitumor agents. The present review summarizes the structure and cytotoxicity of natural terpenequinones/hydroquinones and their bioactive analogues and derivatives

Alkylamino and aralkylamino derivatives of avarone and its mimetic as selective agents against non-small cell lung cancer cells, their antibacterial and antifungal potential

In this paper, the synthesis of fourteen alkylamino and arylamino derivatives of sesquiterpene quinone avarone and its model compound tert-butylquinone is described. Branched, cyclic, allylic and benzylic alkylamino/arylamino groups were introduced into the quinone moiety. For all the obtained derivatives, their biological activity and redox properties were studied. The cytotoxic activity of the synthesized derivatives towards multidrug resistant (MDR) human non-small cell lung carcinoma NCI-H460/R cells, their sensitive counterpart NCI-H460 and human normal keratinocytes (HaCaT) was investigated. The antimicrobial activity towards Gram-positive and Gram-negative bacteria, and fungal cultures was determined. Some of the synthesized derivatives showed selectivity for cancer cells, including MDR cells. Regarding their cell death induction potential, the most promising compounds were allylamino derivatives, preferentially triggering apoptosis, with high selectivity for cancer cells, including MDR cells. Several compounds showed promising antimicrobial activity, comparable to those of commercial antibiotic and antimycotic agents

The kinetics of the reduction of the lipophilic quinone avarone by n-alkyl-1,4-dihydronicotinamides of various lipophilicities

Several NADH model compounds, N-alkyl-1,4-dihydronicotinamides, some of them possessing amphiphilic properties, have been synthesized, and the kinetics of their reaction with a biologically active liphophilic quinone, avarone, has been studied in a protic solvent both in the presence and absence of cationic, anionic or non-ionic surfactants. In the absence of micellar agents, the medium- and long-chain N-dodecyl (3) and N-heptadecyl (4) derivatives show a significant increase in the reaction rates compared to other model compounds, due to the stabilization of the semiquinone intermediate. Anionic surfactants retard the reaction, non-ionic surfactants slightly accelerate the reaction with the short-chain derivatives, and retard the reaction with the medium- and long-chain derivatives, and the cationic surfactants increase the reaction rate with all derivatives except the long-chain 4. The results support the e-p-e mechanism of the reduction of lipophilic quinones by NADH models in protic medium

The Avarol-Avarone Redox Behaviour in Acetonitrile

The oxidation of avarol and the reduction of avarone were studied at a Pt electrode in acetonitrile-tetraethyl-ammonium perchlorate media. The oxidation of avarol in acetonitrile takes place by formation of a two electron oxidation product, presumably the »protonated avarone«. The reduction of avarone takes place in two steps by formation of the stable radical anion which is reduced to the dianion at amore negative potential

Hemijske modifikacije β-laktoglobulina hinonima

The avarone/avarol quinone/hydroquinone couple. as well as their derivatives show considerable antitumor activity. In this work, covalent modifications of beta-lactogglobulin. isolated from cow milk by avarone, its model compound 2-tert-butyl-1,4-benzoquinone. and several of their alkylthio derivatives were studied. The techniques applied for as-saying the modifications were: UV/VIS spectrophotometry, SDS PAGE and isoelectrofocusing. The results of the SDS PAGE suggest that polymerisation of the protein occurs. The shift of the pI of the protein upon modification toward lower values indicates that lysine amino groups are the principal site of die reaction of beta-lactoglobulin with the quinones.Hinonsko/hidrohinonski par avaron/avarol i njihovi derivati pokazuju značajnu antitumorsku aktivnost. U ovom radu proučavane su kovalentne modifikacije β-laktoglobulina, izolovanog iz kravljeg mleka, avaronom, njegovim model-jedinjenjem 2-tert-butil-1,4-benzohinonom i njihovim alkiltio-derivatima. Za ispitivanje modifikacija korišćene su UV/VIS spektrofotometrija, SDS PAGE i izoelektrofokusiranje. Rezultat SDS PAGE ukazuje da se protein polimerizuje. Pomeranje pI vrednosti proteina nakon modifikacije ka nižim vrednostima pokazuje da su amino grupe lizina glavna mesta reakcije β-laktoglobulina sa hinonima