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Sesquiterpene lactones (SL) are widely distributed in nature (formed biosynthetically in plants from farnesyl pyrophosphate) and are a structurally diverse class of terpenoids with 15 carbon atoms in the skeleton and, in addition to the lactone cycle, can contain various functional groups. Some of them exhibit biological activity both in a rather wide range and in relation to a specific target. An increase in the number of undescribed natural plant compounds of this class, as well as detection in various plant species, opens up new possibilities for their use for the purposes of medical chemistry, phytochemistry, pharmacognosy, chemotaxonomy, and related fields. Using the example of SL of the eudesmane structural type found in plants of the genus Inula, this review attempts to show the relevance of studies of such compounds that investigate the mechanism of action on various biological models, including the goal of developing new effective antitumor agents.

Abstract— Derivatives of sesquiterpene lactones modified at the lactone ring with a thiophenol residue have been synthesized. The resulting conjugates with thiophenol have capacity for the oxidation–elimination reaction by the action of ROS of a tumor cell with the release of initial cytotoxic lactones. It has been proposed to use the resulting sulfur-containing conjugates as ROS-activated prodrugs of sesquiterpene lactones. The antiproliferative properties of the conjugates have been examined on tumor and pseudonormal cell lines. The cytotoxicity of the conjugates is lower than that of parent lactones; however, in some cases, as with the conjugates of alantolactone with artemisiten, it remains moderate in all tumor cell lines tested.

The reaction of DL-valine hydroxamic acid with triacetonamine proceeds as the N,N'-regioselective condensation to form (±)-1-hydroxy-3-isopropyl-7,7,9,9-tetramethyl-1,4,8-triazaspiro[4,5]decan-2-one. A study of the antimetastatic and antitumor activities of the resulting hydroxamic acid in vivo by the combined therapy with a cytostatic of the alkylation type on a model of experimental transplanted mouse melanoma B16 showed that the compound is capable of increasing the sensitivity of the tumor to the known antitumor drug cyclophosphamide applied at a subtherapeutic dose. The chemosensitizing activity of hydroxamic acid combined with cyclophosphamide led to an almost twofold increase in the antitumor effect of the cytostatic and a marked decrease in the number of metastases, which showed up as an increase in the metastasis inhibition index (MII) to 74%.

Oncological diseases have always been among the most significant pathologies. Therefore, development of effective antitumor drugs is considered one of the priorities of modern healthcare. Inhibitors of proteins, enzymes, and receptors that regulate the signaling pathways of tumor cells, as well as apoptosis inductors, are used for tumor chemotherapy. The most significant and studied signaling pathways are the Raf/MEK/ERK and phosphoinositide-3 kinase (PI3K). Changes in the cascades of these pathways lead to the modulation of many cellular functions, such as cell growth and survival, proliferation, differentiation, and adhesion. These signaling cascades are closely related to Ras proteins. Oncogenic forms of Ras proteins are detected in a large number of tumor diseases—more than 30% of all forms of neoplasms. The literature data of the last 30 years on the study of the key stages of signaling cascades initiated by oncogenic Ras proteins are considered in this review. The processing features of Ras proteins, which are currently considered as promising molecular targets for the development of antitumor drugs, are analyzed separately. Literature data on new strategies to search for effective antineoplastic agents, which are based on Ras proteins signaling pathways, and bipharmacophore compounds are presented and discussed.

Hydroxamic acids are a promising class of chemical compounds with proven antitumor potential, primarily due to their ability to inhibit the activity of histone deacetylase enzymes. The analysis of modern experimental data shows a wide range of biological activities of hydroxamic acids, which make them equally worthy candidates for the fight against neuropathologies. A characteristic feature of hydroxamic acids is their ability to act simultaneously on several promising molecular targets for the correction of both neuropathologies and oncological diseases, thereby exhibiting multifunctionality. This review discusses the effect of hydroxamic acids on key parts of cancer and neurodegenerative disorders' pathogenesis. Pathological changes in the processes associated with oxidative stress, the functioning of mitochondria, and the activity of metal enzymes of the class of histone deacetylases, as the main links in the epigenetic regulation of pathological conditions, are such molecular targets.

Reactions of natural epoxyalantolactone with primary and secondary amines, which lead to hydrated benzo[g]furo[4,3,2-cd]indolones and eudesmane-type amino derivatives, respectively, have been studied. Epoxyalantolactone conjugates have been synthesized with the involvement of pharmacophoric amines, and their cytotoxic activity toward some tumor cell lines has been tested. The involvement of the signaling pathway of protein p53 in the death of tumor cells, the contribution of oxidative stress, and the induction of apoptosis have been investigated in experiments in vitro.

The daunorubicin and doxorubicin anthracycline antibiotics were modified with the Inula helenium L. sesquiterpene lactones (alantolactone, isoalantolactone, and alloalantolactone) and with their epoxy derivatives. Antiproliferative properties of these conjugates were studied on tumor and normal cell lines. The daunorubicin conjugates with the sesquiterpene lactones (isoalantolactone, allantolactone, and alloalantolactone) and with their epoxy derivatives were found to exhibit the higher activity against human tumor cell lines than the corresponding doxorubicin conjugates. The daunorubicin conjugate with epoxyisoalantolactone proved to be the most effective compound, because it was more cytotoxic than daunorubicin towards a number of cell lines, including those daunorubicin-resistant, and did not affect normal human cells.

Natural sesquiterpene lactones which contain an exocyclic methylene group in the β-position of the lactone ring react readily with N-nucleophiles. When studying the reaction of the natural epoxyalantolactone with the primary amines we demonstrate the formation of a new heterocyclic system - the hydrogenated benzo[g]furo[4,3,2-cd]indol-3(1H)-one. Spectral data on the characteristics of the synthesized compounds are presented. The data on the reaction mechanisms and its applicability for the preparation are discussed.

Zinc is one of the most important essential trace elements. It is involved in more than 300 enzyme systems and is an indispensable participant in many biochemical processes. Zinc deficiency causes a number of disorders in the human body, the main ones being the delay of growth and puberty, immune disorders, and cognitive dysfunctions. There are over two billion people in the world suffering from zinc deficiency conditions. Acyzol, a zinc-containing medicine, developed as an antidote against carbon monoxide poisoning, demonstrates a wide range of pharmacological activities: Anti-inflammatory, reparative, detoxifying, immunomodulatory, bacteriostatic, hepatoprotective, adaptogenic, antioxidant, antihypoxic, and cardioprotective. The presence of zinc in the composition of Acyzol suggests the potential of the drug in the treatment and prevention of zinc deficiency conditions, such as Prasad’s disease, immune system pathology, alopecia, allergodermatoses, prostate dysfunction, psoriasis, stomatitis, periodontitis, and delayed mental and physical development in children. Currently, the efficiency of Acyzol in the cases of zinc deficiency is shown in a large number of experimental studies. So, Acyzol can be used as a highly effective drug for pharmacologic therapy of a wide range of diseases and conditions and it opens up new perspectives in the treatment and prevention of zinc deficiency conditions.

Novel 3,5-bis(arylidene)-4-piperidones modified with diethyl[(aryl)methyl]phosphonate moiety attached to the piperidone nitrogen atom have been synthesized by crotonic condensation of aromatic aldehydes with diethyl[(4-oxopiperidin-1-yl)(aryl)methyl]phosphonates in the presence of LiClO4/Et3N system or acetonitrile solution of boron trifluoride etherate. The synthesized phosphonate derivatives of 3,5-bis(arylidene)-4-piperidone series displayed inhibitory properties toward RD, PC3, HCT116, and MCF7 human cancer cell lines with IC50 values in the range of 2.5–8.5 μM, as assessed by an in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

The reactions with amines of the sesquiterpene lactones britanin and inuchinenolide C isolated from Inula britannica were studied. Migration of the acetyl group during the addition reaction was observed and depended on the nature of the amine and solvent. Compounds with antitumor activity were found among the new amine derivatives.

In this study, male rats were intragastrically exposed to fullerene C60 for 1-day and 30-day periods at daily doses of 2000 and 250 mg/kg of body weight, respectively. Fullerene was detected in organs and tissues by HPLC after the extraction from biosamples with toluene. No statistically significant differences in hematological and biochemical parameters of control and treated rats were found after single and multiple administrations. Throughout the observation periods no lethality was observed. At necropsy, no pathomorphological changes in internal organs were recorded. Fullerene was found in stomach, small intestine, liver, lungs, spleen, kidneys, and blood. The amounts of the detected fullerene in comparison to the administered doses are far smaller which is the evidence of its efficient excretion. Hence, it can be assumed that fullerene nanoparticles penetrate from the gastrointestinal tract of rats into the bloodstream and translocate into secondary organs with no pronounced toxic effect in experimen...

Hydrogenated 3-aminomethylnaphtho[2,3-b]furan-2-ones were synthesized by the reaction of natural alantolactones with pharmacophoric amines. Determination of the newly formed asymmetric center configuration by two-dimensional NMR data is presented. The structure of the obtained compounds was proved by X-ray structural analysis.

Previously unknown adducts of substituted tryptamines with sesquiterpene lactones, viz., isoalantolactone and its epoxy derivative, were synthesized by the Michael reaction. The compounds obtained were tested for various types of biological activity.

Previously unknown compounds combining fragments of a sesquiterpene lactone and a natural alkaloid were synthesized. Derivatives of alantolactone were modified using a Michael reaction with alkaloids of various structural types.

A series of 9-amino-14-oxa-7-azatetracyclo[6.6.1.01.11.02,7]pentadeca-11-en-13-ones were synthesized. The starting material was the natural alkaloid securinine, which underwent a Michael reaction with pharmacophoric tryptamines and substituted piperazines. The structure and stereochemistry of the previously unknown adduct with 5-methoxytryptamine were established using two-dimensional NMR experiments (COSY and NOESY). The biological activity of the synthesized securinine amino-derivatives was investigated. It was shown that several of the synthesized securinine conjugates exhibited antioxidant and iron-chelating activity and were interesting for further studies as potential pharmacologically active compounds.

Previously unknown amino-derivatives of the natural sesquiterpene lactone α-santonin were synthesized. The activity of the products against several human tumor-cell lines was studied.

A method for stereospecific synthesis of allomargaritarin and other amination products of the natural alkaloid securinine was developed. Stereoselective nucleophilic addition of an amine at the double bond of the azobicyclooctane moiety of securinin was achieved by using ytterbium triflate as the catalyst. The biological activity of securining caused by adding pharmacophores to the molecule was shown to change experimentally.

A series of derivatives of the natural sesquiterpene lactones alantolactone (1) and isoalantolactone (2) was prepared. The α-methylene-γ-lactone moiety was retained in the structures of these for further modifications using reactions that affected exclusively the nonconjugated double bonds of the decalin ring.

We performed screening of potential antioxidants among natural lactone and alkaloid derivatives and characterized their antioxidant effects. The substances exhibiting antioxidant and metal-chelating potential, in particular, tryptamine derivatives, are promising neuroprotector agents.

Natural sesquiterpene lactones which contain an exocyclic methylene group in the -position of the lactone ring react readily with N-nucleophiles to give compounds having novel forms of biological activity when compared with the starting compounds [1]. When the reaction was carried out with 5-epoxyalantolactone (1) (a secondary metabolite of the plant genus Inula L. [2]) and the tryptamine derivatives 2a,b we were able to show the formation of the novel heterocyclic system, namely the hydrogenated benzo[g]furo[4,3,2-cd]indolones 3a,b.

The new natural compound lavandoside with the structure ferulic acid 4-O-β-D-glucopyranoside was isolated by column chromatography over silica gel and polyamide from the extract of Lavandula spica flowers. The chemical structure of lavandoside was established using UV, NMR, and mass spectra and chemical transformations.