Synthesis and cytotoxicity evaluation of oleanolic acid derivatives

Biological Activities of Novel Oleanolic Acid Derivatives from Bioconversion and Semi-Synthesis

Oleanolic acid (OA) is a vegetable chemical that is present naturally in a number of edible and medicinal botanicals. It has been extensively studied by medicinal chemists and scientific researchers due to its biological activity against a wide range of diseases. A significant number of researchers have synthesized a variety of analogues of OA by modifying its structure with the intention of creating more potent biological agents and improving its pharmaceutical properties. In recent years, chemical and enzymatic techniques have been employed extensively to investigate and modify the chemical structure of OA. This review presents recent advancements in medical chemistry for the structural modification of OA, with a special focus on the biotransformation, semi-synthesis and relationship between the modified structures and their biopharmaceutical properties.

Recent advances in the chemistry and biology of oleanolic acid and its derivatives

The pentacyclic triterpenes represent a significant class of plant bioactives with a variety of structures and a wide array of biological activities. These are biosynthetically produced via the mevalonate pathway although occasionally mixed pathways may also occur to introduce structural divergence. Oleanolic acid is one of the most explored bioactive from this class of compounds and possesses a broad spectrum of pharmacological and biological activities including liver protection, anti-cancer, atherosclerosis, anti-inflammation, antibacterial, anti-HIV, anti-oxidative, anti-diabetic etc. This review provides an overview of the latest research findings, highlighting the versatile medicinal and biological potential of oleanolic and its future prospects.

Recent advances in medicinal chemistry of oleanolic acid derivatives

Oleanolic acid (OA), a ubiquitous pentacyclic oleanane-type triterpene isolated from edible and medicinal plants, exhibits a wide spectrum of pharmacological activities and tremendous therapeutic potential. However, the undesirable pharmacokinetic properties limit its application and development. Numerous researches on structural modifications of OA have been carried out to overcome this limitation and improve its pharmacokinetic and therapeutic properties. This review aims to compile and summarize the recent progresses in the medicinal chemistry of OA derivatives, especially on structure-activity relationship in the last few years (2010-2021). It gives insights into the rational design of bioactive derivatives from OA scaffold as promising therapeutic agents.

Madecassic Acid—A New Scaffold for Highly Cytotoxic Agents

Due to their manifold biological activities, natural products such as triterpenoids have advanced to represent excellent leading structures for the development of new drugs. For this reason, we focused on the syntheses and cytotoxic evaluation of derivatives obtained from gypsogenin, hederagenin, and madecassic acid, cytotoxicity increased—by and large—from the parent compounds to their acetates. Another increase in cytotoxicity was observed for the acetylated amides (phenyl, benzyl, piperazinyl, and homopiperazinyl), but a superior cytotoxicity was observed for the corresponding rhodamine B conjugates derived from the (homo)-piperazinyl amides. In particular, a madecassic acid homopiperazinyl rhodamine B conjugate 24 held excellent cytotoxicity and selectivity for several human tumor cell lines. Thus, this compound was more than 10,000 times more cytotoxic than parent madecassic acid for A2780 ovarian cancer cells. We assume that the presence of an additional hydroxyl group at position C–6 in derivatives of madecassic, as well as the (2α, 3β) configuration of the acetates in ring A, had a beneficial effect onto the cytotoxicity of the conjugates, as well as onto tumor/non-tumor cell selectivity.

Corosolic acid and its structural analogs: A systematic review of their biological activities and underlying mechanism of action

BACKGROUND

The corosolic acid (CA), also known as plant insulin, is a pentacyclic triterpenoid extracted from plants such as Lagerstroemia speciosa. It has been shown to have anti-diabetic, anti-inflammatory and anti-tumor effects. Its structural analogs ursolic acid (UA), oleanolic acid (OA), maslinic acid (MA), asiatic acid (AA) and betulinic acid (BA) display similar individual pharmacological activities to those of CA. However, there is no systematic review documenting pharmacological activities of CA and its structural analogues. This study aims to fill this gap in literature.

PURPOSE

This systematic review aims to summarize the medical applications of CA and its analogues.

METHODS

A systematic review summarizes and compares the extraction techniques, pharmacokinetic parameters, and pharmacological effects of CA and its structural analogs. Hypoglycemic effect is one of the key inclusion criteria for searching Web of Science, PubMed, Embase and Cochrane databases up to October 2020 without language restrictions. 'corosolic acid', 'ursolic acid', 'oleanolic acid', 'maslinic acid', 'asiatic acid', 'betulinic acid', 'extraction', 'pharmacokinetic', 'pharmacological' were used to extract relevant literature. The PRISMA guidelines were followed.

RESULTS

At the end of the searching process, 140 articles were selected for the systematic review. Information of CA and five of its structural analogs including UA, OA, MA, AA and BA were included in this review. CA and its structural analogs are pentacyclic triterpenes extracted from plants and they have low solubilities in water due to their rigid scaffold and hydrophobic properties. The introduction of water-soluble groups such as sugar or amino groups could increase the solubility of CA and its structural analogs. Their biological activities and underlying mechanism of action are reviewed and compared.

CONCLUSION

CA and its structural analogs UA, OA, MA, AA and BA are demonstrated to show activities in lowering blood sugar, anti-inflammation and anti-tumor. Their oral absorption and bioavailability can be improved through structural modification and formulation design. CA and its structural analogs are promising natural product-based lead compounds for further development and mechanistic studies.

Anti-Cancer Potential of Synthetic Oleanolic Acid Derivatives and Their Conjugates with NSAIDs

Naturally occurring pentacyclic triterpenoid oleanolic acid (OA) serves as a good scaffold for additional modifications to achieve synthetic derivatives. Therefore, a large number of triterpenoids have been synthetically modified in order to increase their bioactivity and their protective or therapeutic effects. Moreover, attempts were performed to conjugate synthetic triterpenoids with non-steroidal anti-inflammatory drugs (NSAIDs) or other functional groups. Among hundreds of synthesized triterpenoids, still the most promising is 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO), which reached clinical trials level of investigations. The new group of synthetic triterpenoids are OA oximes. The most active among them is 3-hydroxyiminoolean-12-en-28-oic acid morpholide, which additionally improves the anti-cancer activity of standard NSAIDs. While targeting the Nrf2 and NF-κB signaling pathways is the main mechanism of synthetic OA derivatives′ anti-inflammatory and anti-cancer activity, most of these compounds exhibit multifunctional activity, and affect cross-talk within the cellular signaling network. This short review updates the earlier data and describes the new OA derivatives and their conjugates in the context of modification of signaling pathways involved in inflammation and cell survival and subsequently in cancer development.

Synthesis, antibacterial, and cytotoxicity evaluation of oleanolic acid-4-aminoquinoline based hybrid compounds

AIM

To prepare a class of oleanolic-based compounds.

BACKGROUND

Conventional drugs used to treat infectious diseases suffer from limitations such as drug toxicity and drug resistance. The resistance of microbes to antimicrobial agents is a significant challenge in treating microbial infections. Combining two or more drugs with different modes of action to treat microbial infections results in a delay in developing drug resistance by the microbes. However, it is challenging to select the appropriate choice of drugs for combination therapy due to the differences in stability and pharmacokinetic profile of the drugs.Therefore, developing hybrid compounds using the existing drugs is a promising approach to design effective antimicrobial agents.

OBJECTIVES

To prepare oleanolic-based hybrid compounds followed by characterization, in vitro antibacterial, and cytotoxicity evaluation.

METHODS

Oleanolic acid-4-aminoquinoline-based hybrid compounds weresynthesized via esterification and amidation. The compounds werecharacterized using FTIR, NMR, and UHPLC-HRMS. Oleanolic acid was isolated from the flower buds of Syszygium aromaticum (L.) Merr. & L.M.Perry, a specie from Kingdom Plantae, order Mytales in Myrtaceae family. Their antibacterial and cytotoxicity activity was determined against selected strains of bacteria assessed using the microdilution assay and sulforhodamine B assay against selected cancer cell lines.

RESULTS

The synthesized hybrid compounds exhibited significant antibacterial activity against the Gram-positive bacteria Enterococcus faecalis (ATCC13047), Bacillus subtilis (ATCC19659), Staphylococcus aureus as well as Gram-negative bacteria,Klebsiella oxytoca (ATCC8724), Escherischia coli (ATCC25922), and Proteus vulgaris (ATCC6380)with minimum inhibitory concentrations of 1.25 mg/mLcompared to oleanolic acid (2.5 mg/mL). Compounds 13 and 14 displayed significant cytotoxic effectsin vitro against the cancer cell lines (MCF-7 and DU 145) compared to the oleanolic acid (IC50 ˃ 200 µM).

CONCLUSION

The present study revealed that the modification of C28 of OA enhanced its biological properties.

Pseudocereal grains: Nutritional value, health benefits and current applications for the development of gluten-free foods

Nowadays, consumers are more conscious of the environmental and nutritional benefits of foods. Pseudocereals grains, edible seeds belonging to dicotyledonous plant species, are becoming a current trend in human diets as gluten-free (GF) grains with excellent nutritional and nutraceutical value. Pseudocereals are a good source of starch, fiber, proteins, minerals, vitamins, and phytochemicals such as saponins, polyphenols, phytosterols, phytosteroids, and betalains with potential health benefits. The present review aims to summarize the nutritional quality and phytochemical profile of the three main pseudocereal grains: quinoa, amaranth and buckwheat. In addition, current evidence about their health benefits in animal models and human studies is also provided in detail. Based on the accumulating research supporting the inclusion of pseudocereals grains in the diet of celiac persons, this review discusses the recent advances in their application for the development of new GF products. Future directions for a wider cultivation and commercial exploitation of these crops are also highlighted.

Effect of oleanolic acid for prevention of acute lung injury and apoptosis

Background

This study aims to evaluate the efficiency of oleanolic acid on acute lung injury and acute respiratory distress syndrome.

Methods

The study included 70 female Wistar albino rats (weighing 180 to 200 g). We created seven groups, each consisting of 10 rats. Then, we generated acute lung injuries by intra-tracheal peroxynitrite injection in every group except for the control group. We investigated the effect of oleanolic acid. For this purpose, we measured the levels of malondialdehyde, interleukin 1 beta, interleukin 4, interleukin 10 and tumor necrosis factor alpha in the collected blood samples from the rats. In addition, we examined the lung tissue samples histopathologically and assessed the rate of apoptosis.

Results

Peroxynitrite injected groups at 24 and 48 h showed a statistically significant increase in interleukin 1 beta, tumor necrosis factor alpha, interleukin 4, interleukin 10 and malondialdehyde levels, which are accepted as mediators of the inflammatory process, compared to the control group. When peroxynitrite injected groups at 24 and 48 h were compared to the treatment groups of the same hour, a statistically significant decrease was detected. According to histopathological examination, peroxynitrite injected groups at 24 and 48 h showed a significant increase of tissue injury scores compared to the control group. However, the groups that were treated with oleanolic acid showed a significant decrease compared to the peroxynitrite groups (p<0.001 for tumor necrosis factor alpha and apoptosis results at 48 h).

Conclusion

In this study, we confirmed that oleanolic acid can be an effective agent for the prevention of acute lung injury generated via peroxynitrite.

Self-assembled nanoparticles based on poly(ethylene glycol)–oleanolic acid conjugates for co-delivery of anticancer drugs

Oleanolic acid (OA) has shown promising antitumor activity.

Synthesis of acyl oleanolic acid-uracil conjugates and their anti-tumor activity

BACKGROUND

Oleanolic acid, which can be isolated from many foods and medicinal plants, has been reported to possess diverse biological activities. It has been found that the acylation of the hydroxyl groups of the A-ring in the triterpene skeleton of oleanolic acid could be favorable for biological activities. The pyrimidinyl group has been constructed in many new compounds in various anti-tumor studies.

RESULTS

Five acyl oleanolic acid-uracil conjugates were synthesized. Most of the IC₅₀ values of these conjugates were lower than 10.0 μM, and some of them were even under 0.1 μM. Cytotoxicity selectivity detection revealed that conjugate 4c exhibited low cytotoxicity towards the normal human liver cell line HL-7702. Further studies revealed that 4c clearly possessed apoptosis inducing effects, could arrest the Hep-G2 cell line in the G1 phase, induce late-stage apoptosis, and activate effector caspase-3/9 to trigger apoptosis.

CONCLUSIONS

Conjugates of five different acyl OA derivatives with uracil were synthesized and identified as possessing high selectivity toward tumor cell lines. These conjugates could induce apoptosis in Hep-G2 cells by triggering caspase-3/9 activity.Graphical abstractFive acyl oleanolic aicd-uracil conjugates were synthesized. These conjugates exhibited selective cytotoxicity toward tumor cells achieved via inducing apoptosis by activation of caspase-3/9.

Synthesis of α-santonin derivatives for diminutive effect on T and B-cell proliferation and their structure activity relationships

A new library of 20 compounds from α-santonin was synthesized and tested against Con-A induced T-cell proliferation and LPS-induced B-cell proliferation via MTT assay. The study resulted in the identification of potent immunosuppressant molecules, which were further screened along with α-santonin for Tumor Necrosis Factor Alpha (TNF-α) inhibitory activity. One of the molecules (7) at 10 μM showed equipotency to that of dexamethasone (1 μM conc.) used as a standard. Structure activity relationships of the synthesized compounds along with our earlier reported α-santonin derivatives have been studied. Inferences from the modifications carried out at all the three sites of α-santonin have been elaborated. Computational study of the active compounds shows TNF-α protein as its preferable target rather than Inosine Monophosphate Dehydrogenase (IMPDH).

Activity of compounds from Taxillus sutchuenensis as inhibitors of HCV NS3 serine protease

This study aimed to isolate active compounds from traditional Chinese medicinal Taxillus sutchuenensis to inhibit hepatitis C virus (HCV) NS3 protease activity. Under the guidance of bioassay, 10 compounds were isolated from the EtOAc extract fraction, which were identified as inhibitors of HCV NS3 protease. IC₅₀ values of these compounds were obtained, and a broad degree of anti-HCV activity was observed. The most active compounds were kaempferol-3,7-bisrhamnoside (19.4 μM) and (3S)-3-hydroxy-1,7-bis(4-hydroxy-phenyl)-6E-hepten-5-one (28.7 μM). In conclusion, flavonoids and diarylheptanoids were responsible for the anti-HCV constitution of Taxilli Herba. These inhibitors of HCV NS3 protease might serve as potential candidate of anti-HCV agents.

[Synthesis and Anticancer Activity of Betulonic Acid Imidazolides]

Synthesis of lupane C28-imidazolides, contained 3-oxo-, 3-oximino- and 2-cyano-2,3-seco-4(23)-en-frag ments in cycle A was carried out. The most antitumor activity at. in vitro testing showed 3-oximino-lup- 20(29)-en-28-yl-1H-imidazole-1-carboxylate; which inhibited the growth or induced apoptosis of non-small lung cancer, colon cancer, breast cancer, CNS cancer, ovarian cancer, prostate cancer, leucosis, melanoma cells. In experiments in mice its moderate antitumor activity against grafted breast adenocarcinoma Ca 755 and adenocarcinima of colon was observed.

Advancing the delivery of anticancer drugs: Conjugated polymer/triterpenoid composite

Exemplifying the synergy of anticancer properties of triterpenoids and ion retention qualities of conjugated polymers, we propose a conducting matrix to be a reservoir of anticancer compounds. In this study, poly(3,4-ethylenedioxythiophene), PEDOT, based matrix for electrically triggered and local delivery of the ionic form of anticancer drug, oleanolic acid (HOL), has been investigated. An initial, one-step fabrication procedure has been proposed, providing layers exhibiting good drug release properties and biological activity. Investigation of obtained systems and implementation of modifications revealed another route of fabrication. This procedure was found to yield layers possessing a significantly greater storage capacity of OL(-), as evidenced by the 52% increase in the drug concentrations attainable through electro-assisted release. Examination of the biological activity of immobilised and released OL(-) molecules proved that electrochemical treatment has negligible impact on the anticancer properties of OL(-), particularly when employing the three-step procedure, in which the range of applied potentials is limited. PEDOT/OL(-) composite has been demonstrated to be a robust and cost-effective material for controlled drug delivery.

Oleanolic Acid Loaded PEGylated PLA and PLGA Nanoparticles with Enhanced Cytotoxic Activity against Cancer Cells

Oleanolic acid (OA) is a natural triterpenoid with anticancer properties, but its hydrophobic nature and poor aqueous solubility pose challenges in pharmaceutical formulation development. The present study aimed at developing OA-loaded mPEG-PLGA or mPEG-PLA nanoparticles (NPs) to improve the delivery of OA. The NPs were prepared by nanoprecipitation, and their physicochemical properties were characterized. The OA encapsulation efficiency of the NPs was between 40 and 75%. The size of the OA-loaded NPs was around 200-250 nm, which fell within the range required for tumor targeting by means of the enhanced permeability and retention (EPR) effect, and the negatively charged NPs remained physically stable for over 20 weeks with no aggregation observed. The OA-loaded NPs produced significant cytotoxic effects through apoptosis in cancer cell lines. Overall, the OA-loaded mPEG-PLGA NPs and mPEG-PLA NPs shared similar physicochemical properties. The former, especially the OA-loaded mPEG-P(D,L)LGA NPs, were more cytotoxic to cancer cells and therefore were more efficient for OA delivery.

Triterpenes as potentially cytotoxic compounds

Triterpenes are compounds of natural origin, which have numerously biological activities: anti-cancer properties, anti-inflammatory, anti-oxidative, anti-viral, anti-bacterial and anti-fungal. These substances can be isolated from plants, animals or fungi. Nowadays, when neoplasms are main cause of death, triterpenes can become an alternative method for treating cancer because of their cytotoxic properties and chemopreventive activities.

A hydrophilic conjugate approach toward the design and synthesis of ursolic acid derivatives as potential antidiabetic agent

In this study, a series of novel ursolic acid (UA) derivatives were designed and synthesized successfully via conjugation of hydrophilic and polar groups at 3-OH and/or 17-COOH position.

Oleanane triterpenoids in the prevention and therapy of breast cancer: current evidence and future perspectives

Breast cancer is one of the most frequently diagnosed cancers and major cause of death in women in the world. Emerging evidence underscores the value of dietary and non-dietary phytochemicals, including triterpenoids, in the prevention and treatment of breast cancer. Oleanolic acid, an oleanane-type pentacyclic triterpenoid, is present in a large number of dietary and medicinal plants. Oleanolic acid and its derivatives exhibit several promising pharmacological activities, including antioxidant, anti-inflammatory, hepatoprotective, cardioprotective, antipruritic, spasmolytic, antiallergic, antimicrobial and antiviral effects. Numerous studies indicate that oleanolic acid and other oleanane triterpenoids modulate multiple intracellular signaling pathways and exert chemopreventive and antitumor activities in various in vitro and in vivo model systems. A series of novel synthetic oleanane triterpenoids have been prepared by chemical modifications of oleanolic acid and some of these compounds are considered to be the most potent anti-inflammatory and anticarcinogenic triterpenoids. Accumulating studies provide extensive evidence that synthetic oleanane derivatives inhibit proliferation and induce apoptosis of various cancer cells in vitro and demonstrate cancer preventive or antitumor efficacy in animal models of blood, breast, colon, connective tissue, liver, lung, pancreas, prostate and skin cancer. This review critically examines the potential role of oleanolic acid, oleanane triterpenoids and related synthetic compounds in the chemoprevention and treatment of mammary neoplasia. Both in vitro and in vivo studies on these agents and related molecular mechanisms are presented. Several challenges and future directions of research to translate already available impressive preclinical knowledge to clinical practice of breast cancer prevention and therapy are also presented.

Studies on cytotoxic constituents from the leaves of Elaeagnus oldhamii Maxim. in non-small cell lung cancer A549 cells

Elaeagnus oldhamii Maxim. is a commonly used traditional herbal medicine. In Taiwan the leaves of E. oldhamii Maxim. are mainly used for treating lung disorders. Twenty five compounds were isolated from the leaves of E. oldhamii Maxim. in the present study. These included oleanolic acid (1), 3-O-(Z)-coumaroyl oleanolic acid (2), 3-O-(E)-coumaroyl oleanolic acid (3), 3-O-caffeoyl oleanolic acid (4), ursolic acid (5), 3-O-(Z)-coumaroyl ursolic acid (6), 3-O-(E)-coumaroyl ursolic acid (7), 3-O-caffeoyl ursolic acid (8), 3β, 13β-dihydroxyolean-11-en-28-oic acid (9), 3β, 13β-dihydroxyurs-11-en-28-oic acid (10), uvaol (11), betulin (12), lupeol (13), kaempferol (14), aromadendrin (15), epigallocatechin (16), cis-tiliroside (17), trans-tiliroside (18), isoamericanol B (19), trans-p-coumaric acid (20), protocatechuic acid (21), salicylic acid (22), trans-ferulic acid (23), syringic acid (24) and 3-O-methylgallic acid (25). Of the 25 isolated compounds, 21 compounds were identified for the first time in E. oldhamii Maxim. These included compounds 1, 4, 5 and 8–25. These 25 compounds were evaluated for their inhibitory activity against the growth of non-small cell lung cancer A549 cells by the MTT assay, and the corresponding structure-activity relationships were discussed. Among these 25 compounds, compound 6 displayed the best activity against the A549 cell line in vitro (CC₅₀ = 8.56 ± 0.57 μg/mL, at 48 h of MTT asssay). Furthermore, compound 2, 4, 8 and 18 exhibited in vitro cytotoxicity against the A549 cell line with the CC₅₀ values of less than 20 μg/mL at 48 h of MTT asssay. These five compounds 2, 4, 6, 8 and 18 exhibited better cytotoxic activity compared with cisplatin (positive control, CC₅₀ value of 14.87 ± 1.94 μg/mL, at 48 h of MTT asssay). The result suggested that the five compounds might be responsible for its clinical anti-lung cancer effect.

Oleanolic acid and its synthetic derivatives for the prevention and therapy of cancer: preclinical and clinical evidence

Oleanolic acid (OA, 3β-hydroxyolean-12-en-28-oic acid) is a ubiquitous pentacyclic multifunctional triterpenoid, widely found in several dietary and medicinal plants. Natural and synthetic OA derivatives can modulate multiple signaling pathways including nuclear factor-κB, AKT, signal transducer and activator of transcription 3, mammalian target of rapamycin, caspases, intercellular adhesion molecule 1, vascular endothelial growth factor, and poly (ADP-ribose) polymerase in a variety of tumor cells. Importantly, synthetic derivative of OA, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), and its C-28 methyl ester (CDDO-Me) and C28 imidazole (CDDO-Im) have demonstrated potent antiangiogenic and antitumor activities in rodent cancer models. These agents are presently under evaluation in phase I studies in cancer patients. This review summarizes the diverse molecular targets of OA and its derivatives and also provides clear evidence on their promising potential in preclinical and clinical situations.

A new pentacyclic triterpene with potent antibacterial activity from Limnophila indica Linn. (Druce)

A new pentacyclic triterpenoid constituent, characterized as 3-oxo-olean-12(13),18(19)-dien-29α-carboxylic acid (1) on the basis of detailed spectral studies, was isolated from the aerial parts and roots of Limnophila indica (Scrophulariaceae). Compound 1 exhibited considerable antibacterial activity against three Gram-positive bacteria viz. Bacillus subtilis, Staphylococcus aureus and Listeria monocytogenes (MICs within a range of 25-30 μg/ml) and moderate activity against four Gram-negative bacteria Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, and Pantoea ananatis (MICs within a range of 30-100 μg/ml). The plant pathogenic bacterium P. ananatis and human pathogenic S. typhimurium responded at comparatively higher concentrations of the compound 1, which were 75 and 100 μg/ml respectively. The compound inhibited the growth of Gram-positive B. subtilis and Gram-negative P. aeruginosa completely with a clear bactericidal mode of action at their MIC values. The compound upon treatment on both B. subtilis and P. aeruginosa released substantial amount of nucleic acid in the external medium and also effected the change of morphology towards pleomorphicity, thereby indicating its probable action on cell membrane. Furthermore, the triterpenoid 1 was found not to inhibit a probiotic lactic acid bacterium Lactococcus lactis subsp. lactis LABW4 under in vitro condition and to possess no toxicity in Swiss albino mice.

1,2,3-triazole-substituted oleanolic Acid derivatives: synthesis and antiproliferative activity

Hybrid compounds are relevant products when searching for structure-activity relationships of natural products. Starting from the naturally occurring triterpene oleanolic acid, alkyl esters were prepared and treated with different aromatic azides using click chemistry to produce hybrid compounds. Some 18 new oleanolic acid derivatives were synthesized and the structures were confirmed by spectroscopic and spectrometric means. The antiproliferative activity of the new derivatives was evaluated towards normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), promyelocytic leukemia (HL-60), lung cancer (SK-MES-1) and bladder carcinoma (J82) cells. The alkyne esters 1 and 3 showed activity on all cell lines but without selectivity (19.6-23.1 μM and 14.1-56.2 μM, respectively), their respective methyl esters were inactive. Compounds with a benzene and p-anisole attached to the triazole ring, showed no antiproliferative effect. Introduction of a chlorine atom into the benzene ring (compound 9) elicited a selective effect against AGS cells (IC50 value: 8.9 μM). The activity was lost when the COOH function at C-28 was methylated. Better antiproliferative effect was found for compounds 11 and 15 bearing a p-toluenesulphonyl group, with values in the range of 10.8-47.1 μM and 11.5-22.2 μM, respectively. The effect, however, was not associated with selectivity.