Pharmacophore, QSAR, and ADME based semisynthesis and in vitro evaluation of ursolic acid analogs for anticancer activity

Linking Variability in Phytochemical Composition with Safety Profile of Thymus carnosus Boiss. Extracts: Effect of Major Compounds and Evaluation of Markers of Oxidative Stress and Cell Death

Natural products are generally considered safe for human consumption, but this classification is often based on ethnobotanical surveys or their use in traditional medicine over a long period of time. However, edaphoclimatic factors are known to produce different chemotypes, which may affect the safety profile and bioactivities, and are not commonly considered for plants exploited as crops worldwide. Thymus carnosus Boiss., a thyme species with various health-promoting effects, has potential pharmaceutical applications, but edaphoclimatic factors were found to significantly impact its phytochemical composition. Thus, we aimed to assess the safety profile of T. carnosus extracts obtained from plants harvested in two locations over three consecutive years and to establish an association with specific components, an essential study in the search for new sources of nutraceuticals. Thus, the antiproliferative effect of an aqueous decoction (AD), hydroethanolic (HE) extracts, and major extracts' components of T. carnosus was evaluated on intestinal (Caco-2) and hepatic (HepG2) cell models, revealing effects dependent on extract type, cell line, and tested compounds. Flavonoids induced different cytotoxic patterns, which could be attributed to molecular structural differences. Flow cytometry analysis showed apoptosis and necrosis induction, mediated by the modulation of intracellular reactive oxygen species and mitochondrial membrane potential, effects that were dependent on the cell line and phytochemical composition and on the synergism between extracts components, rather than on the activity of an isolated compound. While ursolic acid was the component with the strongest impact on the difference between extraction methods, flavonoids assumed a pivotal role in the response of different cell lines to the extracts. We report for the first time, for Thymus spp. extracts, that variations in the phytochemical composition clearly influence the cellular response, thus highlighting the need for extract standardization for medicinal applications.

Evidence of the Beneficial Effects of Ursolic Acid against Lung Cancer

Lung cancer is the leading cause of cancer-related deaths globally. Despite current treatment approaches that include surgery, chemotherapy, radiation and immunotherapies, lung cancer accounted for 1.79 million deaths worldwide in 2020, emphasizing the urgent need to find novel agents and approaches for more effective treatment. Traditionally, chemicals derived from plants, such as paclitaxel and docetaxel, have been used in cancer treatment, and in recent years, research has focused on finding other plant-derived chemicals that can be used in the fight against lung cancer. Ursolic acid is a polyphenol found in high concentrations in cranberries and other fruits and has been demonstrated to have anti-inflammatory, antioxidant and anticancer properties. In this review, we summarize recent research examining the effects of ursolic acid and its derivatives on lung cancer. Data from in vitro cell culture and in vivo animal studies show potent anticancer effects of ursolic acid and indicate the need for clinical studies.

Therapeutic Potential of Ursolic Acid in Cancer and Diabetic Neuropathy Diseases

Ursolic acid (UA) is a pentacyclic triterpenoid frequently found in medicinal herbs and plants, having numerous pharmacological effects. UA and its analogs treat multiple diseases, including cancer, diabetic neuropathy, and inflammatory diseases. UA inhibits cancer proliferation, metastasis, angiogenesis, and induced cell death, scavenging free radicals and triggering numerous anti- and pro-apoptotic proteins. The biochemistry of UA has been examined broadly based on the literature, with alterations frequently having been prepared on positions C-3 (hydroxyl), C12-C13 (double bonds), and C-28 (carboxylic acid), leading to several UA derivatives with increased potency, bioavailability and water solubility. UA could be used as a protective agent to counter neural dysfunction via anti-oxidant and anti-inflammatory effects. It is a potential therapeutic drug implicated in the treatment of cancer and diabetic complications diseases provide novel machinery to the anti-inflammatory properties of UA. The pharmacological efficiency of UA is exhibited by the therapeutic theory of one-drug → several targets → one/multiple diseases. Hence, UA shows promising therapeutic potential for cancer and diabetic neuropathy diseases. This review aims to discuss mechanistic insights into promising beneficial effects of UA. We further explained the pharmacological aspects, clinical trials, and potential limitations of UA for the management of cancer and diabetic neuropathy diseases.

Nanoformulations of Ursolic Acid: A Modern Natural Anticancer Molecule

Background: Ursolic acid (UA) is a natural pentacyclic triterpene derived from fruit, herb, and other plants. UA can act on molecular targets of various signaling pathways, inhibit the growth of cancer cells, promote cycle stagnation, and induce apoptosis, thereby exerting anticancer activity. However, its poor water-solubility, low intestinal mucosal absorption, and low bioavailability restrict its clinical application. In order to overcome these deficiencies, nanotechnology, has been applied to the pharmacological study of UA.

Objective: In this review, we focused on the absorption, distribution, and elimination pharmacokinetics of UA in vivo, as well as on the research progress in various UA nanoformulations, in the hope of providing reference information for the research on the anticancer activity of UA.

Methods: Relevant research articles on Pubmed and Web of Science in recent years were searched selectively by using the keywords and subheadings, and were summarized systematically.

Key finding: The improvement of the antitumor ability of the UA nanoformulations is mainly due to the improvement of the bioavailability and the enhancement of the targeting ability of the UA molecules. UA nanoformulations can even be combined with computational imaging technology for monitoring or diagnosis.

Conclusion: Currently, a variety of UA nanoformulations, such as micelles, liposomes, and nanoparticles, which can increase the solubility and bioactivity of UA, while promoting the accumulation of UA in tumor tissues, have been prepared. Although the research of UA in the nanofield has made great progress, there is still a long way to go before the clinical application of UA nanoformulations.

Coumarin-1,2,3-triazole Hybrid Molecules: An Emerging Scaffold for Combating Drug Resistance

Undoubtedly, antibiotics have saved billions of lives, but lack of novel antibiotics, development of resistance mechanisms in almost all clinical isolates of bacteria, and recurrent infections caused by persistent bacteria hamper the successful treatment of the infections. Due to the widespread emergence of resistance, even the new families of anti-microbial agents have a short life expectancy. Drugs acting on a single target often lead to drug resistance and are associated with various side effects. For overcoming this problem, either multidrug therapy, or a single drug acting on multiple targets may be used. The latter is called 'hybrid molecules,' which are formed by clubbing two biologically active pharmacophores together, with or without an appropriate linker. In this rapidly evolving era, the development of natural product-based hybrid molecules may be a super-alternative to multidrug therapy, for combating drug resistance caused by various bacterial and fungal strains. Coumarins (benzopyran-2-one) are one of the earliest reported plant secondary metabolites having a clinically proven diverse range of pharmacological properties. On the other hand, 1,2,3-triazole is a common pharmacophore in many drugs responsible for polar interactions, improving the solubility and binding affinity to biomolecular targets. In this review, we discuss recent advances in Coumarin-1,2,3-triazole hybrids as potential anti-bacterial agents, aiming to provide a useful platform for the exploration of new leads with a broader spectrum, more effectiveness and less toxicity with multiple modes of action for the development of cost-effective and safer drugs in the future.

Ursolic and Oleanolic Acids: Plant Metabolites with Neuroprotective Potential

Ursolic and oleanolic acids are secondary plant metabolites that are known to be involved in the plant defence system against water loss and pathogens. Nowadays these triterpenoids are also regarded as potential pharmaceutical compounds and there is mounting experimental data that either purified compounds or triterpenoid-enriched plant extracts exert various beneficial effects, including anti-oxidative, anti-inflammatory and anticancer, on model systems of both human or animal origin. Some of those effects have been linked to the ability of ursolic and oleanolic acids to modulate intracellular antioxidant systems and also inflammation and cell death-related pathways. Therefore, our aim was to review current studies on the distribution of ursolic and oleanolic acids in plants, bioavailability and pharmacokinetic properties of these triterpenoids and their derivatives, and to discuss their neuroprotective effects in vitro and in vivo.

Spermine amides of selected triterpenoid acids: dynamic supramolecular system formation influences the cytotoxicity of the drugs

Cancer is a global disease of great importance, and the need for novel cytotoxic drugs is still eminent. A series of spermine amides of several selected triterpene acids (betulonic, heterobetulonic, oleanolic, ursolic and platanic acid) have been synthesized to search for new cytotoxic and antimicrobial agents. The compounds have also been subjected to the investigation of their physico-chemical characteristics (ability to self-assemble), and to an in silico comparative calculation of their physico-chemical and ADME parameters. In the in vitro screening tests with several target compounds (8a-8c and 11c), their cytotoxicity changed with prolonged time, which appeared to be a result of formation of dynamic supramolecular networks. This phenomenon is important in investigation of the effect of self-assembly on biological activity. The most important compounds in this series were spermine derivatives of heterobetulonic acid (3b) and ursolic acid (8b), showing cytotoxicity <5 μM and <10 μM, respectively, on all tested cancer cell lines. Comparable cytotoxicity was also displayed by 13b, formerly a model compound prepared for testing of the synthetic procedures, the 1,2-diaminoethane derivative. The target compounds 3b and 8b displayed antimicrobial activity on Staphylococcus aureus, Streptococcus mutans and Listeria monocytogenes at a concentration 6.25 μM. Supramolecular characteristics of several compounds were documented by the TEM and SEM micrographs showing fibrous, partially helical, networks, and UV measurements showing changes in the intensity of UV signals, also indicating formation of supramolecular systems.

Design, synthesis and antiproliferative activity evaluation of fluorine-containing chalcone derivatives

A series of new chalcones containing fluoro atom at B ring have been designed, synthesized, and evaluated to be antiproliferative activity against a panel of human tumor cell lines. Some of the analogs (8, 9, 12, 45, 46 and 48) displayed powerful antiproliferative effects to certain human tumor cells, but all of them were devoid of any cytotoxicity towards the normal HEK 293. Acridine orange staining data supported that the cytotoxic and antiproliferative effects of the synthesized analogs on tumor cells are mediated through apoptosis. The compounds 12 and 46 manifested concentration-dependent antiproliferative activity in human hepatocellular carcinoma cell lines using an xCELLigence assay. The structures and antiproliferative activity relationship were further supported by in silico molecular docking study of the compounds against tubulin protein which suggests our compounds interference to cell division. Communicated by Ramaswamy H. Sarma.

Hyphenated 3D-QSAR statistical model-drug repurposing analysis for the identification of potent neuraminidase inhibitor

The Influenza A virus is one of the principle causes of respiratory illness in human. The surface glycoprotein of the influenza virus, neuraminidase (NA), has a vital role in the release of new viral particle and spreads infection in the respiratory tract. It has been long recognized as a valid drug target for influenza A virus infection. Oseltamivir is used as a standard drug of choice for the treatment of influenza. However, the emergence of mutants with novel mutations has increased the resistance to potent NA inhibitor. In the present investigation, we have employed computer-assisted combinatorial techniques in the screening of 8621 molecules from Drug Bank to find potent NA inhibitors. A three-dimensional pharmacophore model was generated from the previously reported 28 carbocylic influenza NA inhibitors along with oseltamivir using PHASE module of Schrödinger Suite. The model generated consists of one hydrogen bond acceptor (A), one hydrogen bond donors (D), one hydrophobic group (H), and one positively charged group (P), ADHP. The hypothesis was further validated for its integrity and significance using enrichment analysis. Subsequently, an atom-based 3D-QSAR model was built using the common pharmacophore hypothesis (CPH). The developed 3D-QSAR model was found to be statistically significant with R² value of 0.9866 and Q² value of 0.7629. Further screening was accomplished using three-stage docking process using the Glide algorithm. The resultant lead molecules were examined for its drug-like properties using the Qikprop algorithm. Finally, the calculated pIC₅₀ values of the lead compounds were validated by the AutoQSAR algorithm. Overall, the results from our analysis highlights that lisinopril (DB00722) is predicted to bind better with NA than currently approved drug. In addition, it has the best match in binding geometry conformations with the existing NA inhibitor. Note that the antiviral activity of lisinopril is reported in the literature. However, our paper is the first report on lisinopril activity against influenza A virus infection. These results are envisioned to help design the novel NA inhibitors with an increased antiviral efficacy.

Picolyl amides of betulinic acid as antitumor agents causing tumor cell apoptosis

A series of picolyl amides of betulinic acid (3a-3c and 6a-6c) was prepared and subjected to the cytotoxicity screening tests. Structure-activity relationships studies resulted in finding differences in biological activity in dependence on o-, m- and p-substitution of the pyridine ring in the target amides, when cytotoxicity data of 3a-3c and 6a-6c were obtained and compared. The amides 3b and 3a displayed cytotoxicity (given in the IC₅₀ values) in G-361 (0.5 ± 0.1 μM and 2.4 ± 0.0 μM, respectively), MCF7 (1.4 ± 0.1 μM and 2.2 ± 0.2 μM, respectively), HeLa (2.4 ± 0.4 μM and 2.3 ± 0.5 μM, respectively) and CEM (6.5 ± 1.5 μM and 6.9 ± 0.4 μM, respectively) tumor cell lines, and showed weak effect in the normal human fibroblasts (BJ). Selectivity against all tested cancer cells was determined and compared to normal cells with therapeutic index (TI) between 7 and 100 for compounds 3a and 3b. The therapeutic index (TI = 100) was calculated for human malignant melanoma cell line (G-361) versus normal human fibroblasts (BJ). The cytotoxicity of other target amides (3c and 6a-6c) revealed lower effects than 3a and 3b in the tested cancer cell lines.

The potential role of in silico approaches to identify novel bioactive molecules from natural resources

In recent years, integration of in silico approaches to natural product (NP) research reawakened the declined interest in NP-based drug discovery efforts. In particular, advancements in cheminformatics enabled comparison of NP databases with contemporary small-molecule libraries in terms of molecular properties and chemical space localizations. Virtual screening and target fishing approaches were successful in recognizing the untold macromolecular targets for NPs to exploit the unmet therapeutic needs. Developments in molecular docking and scoring methods along with molecular dynamics enabled to predict the target-ligand interactions more accurately taking into consideration the remarkable structural complexity of NPs. Hence, innovative in silico strategies have contributed valuably to the NP research in drug discovery processes as reviewed herein. [Formula: see text].

Bioactivity-guided mixed synthesis and evaluation of α-alkenyl-γ and δ-lactone derivatives as potential fungicidal agents

In view of the great antifungal activities of sesquiterpene lactones and natural product Tulipalin A, 52 derivatives derived from α-methylene-γ-butyrolactone substructures were synthesized to study antifungal activities.

Hyaluronidase Inhibitory Activity of Pentacylic Triterpenoids from Prismatomeris tetrandra (Roxb.) K. Schum: Isolation, Synthesis and QSAR Study

The mammalian hyaluronidase degrades hyaluronic acid by the cleavage of the β-1,4-glycosidic bond furnishing a tetrasaccharide molecule as the main product which is a highly angiogenic and potent inducer of inflammatory cytokines. Ursolic acid 1, isolated from Prismatomeris tetrandra, was identified as having the potential to develop inhibitors of hyaluronidase. A series of ursolic acid analogues were either synthesized via structure modification of ursolic acid 1 or commercially obtained. The evaluation of the inhibitory activity of these compounds on the hyaluronidase enzyme was conducted. Several structural, topological and quantum chemical descriptors for these compounds were calculated using semi empirical quantum chemical methods. A quantitative structure activity relationship study (QSAR) was performed to correlate these descriptors with the hyaluronidase inhibitory activity. The statistical characteristics provided by the best multi linear model (BML) (R² = 0.9717, R²cv = 0.9506) indicated satisfactory stability and predictive ability of the developed model. The in silico molecular docking study which was used to determine the binding interactions revealed that the ursolic acid analog 22 had a strong affinity towards human hyaluronidase.

New α-Methylene-γ-Butyrolactone Derivatives as Potential Fungicidal Agents: Design, Synthesis and Antifungal Activities

In consideration of the fact that the α-methylene-γ-butyrolactone moiety is a major bio-functional group in the structure of carabrone and possesses some agricultural biological activity, forty-six new ester and six new ether derivatives containing α-methylene-γ-butyrolactone moieties were synthesized, and their fungicidal activities against Colletotrichum lagenarium and Botrytis cinerea were investigated. Most of the synthesized compounds showed moderate to significant fungicidal activity. Among them, halogen atom-containing derivatives showed better activity than others, especially compounds 6a,d which exhibited excellent fungicidal activity against C. lagenarium, with IC₅₀ values of 7.68 and 8.17 μM. The structure-activity relationship (SAR) analysis indicated that ester derivatives with electron-withdrawing groups on the benzene ring showed better fungicidal activity than those with electron-donating groups. A quantitative structure-activity relationship (QSAR) model (R² = 0.9824, F = 203.01, S² = 0.0083) was obtained through the heuristic method. The built model revealed a strong correlation of fungicidal activity against C. lagenarium with the molecular structures of these compounds. These results are expected to prove helpful in the design and exploration of low toxicity and high efficiency α-methylene-γ-butyrolactone-based fungicides.

Polyamine derivatives of betulinic acid and β-sitosterol: A comparative investigation

β-Sitosterol and betulinic acid were used in designing their conjugates with selected polyamines bearing either an amide bond, or an ester and an amide bond simultaneously in the target molecule. The synthesized compounds were subjected to basic cytotoxic and antimicrobial tests. The synthetic protocol is described separately for each of the three series of the target amides, because each series of compounds required a different synthetic approach. The cytotoxicity was tested on cells derived from human T-lymphoblastic leukemia, breast adenocarcinoma and cervical cancer, and compared with the tests on normal human fibroblasts. Most of the target compounds (5a-5c, 11a-11c and 16a-16c) showed medium to high cytotoxicity (0.7-7.8 μM), however, in some cases the compounds showed high cytotoxicity even toward normal human fibroblasts (11a-11c). Two compounds of this series (11c and 16c) also displayed antimicrobial activity with high and selective microbe specificity. The compound 11c was potent against Escherichia coli (minimal inhibition concentration (MIC) 6.25 μg mL(-1), i.e. 9.75 nM mL(-1)) and Staphylococcus aureus (MIC 12.5 μg mL(-1), i.e. 19.5 nM mL(-1)), and showed medium activity against Pseudomonas aeruginosa. The compound 16c was highly active against Enterococcus faecalis and S. aureus (both, MIC 3.125 μg mL(-1), i.e. 4.22 nM mL(-1)), both Gram-positive bacteria, however showed only weak activity against E. coli and no activity against P. aeruginosa, both Gram-negative bacteria, which indicates possible microbe specificity of 16c. Comparing β-sitosterol-based series (5a-5c) and betulinic acid series (11a-11c and 16a-16c) of the target compounds, the latter one gave more promising structures. The compounds 11c and 16c showed effects which may be described as multifarious activity (pleiotropic effects).

QSAR-guided semi-synthesis and in vitro validation of antiplasmodial activity in ursolic acid derivatives

As a part of antimalarial drug discovery programme, a QSAR model was developed for the prediction of antiplasmodial activity in ursolic acid derivatives, followed by semi-synthesis of virtually active derivatives and their biological evaluation.

In vitro, in silico and in vivo studies of ursolic acid as an anti-filarial agent

As part of our drug discovery program for anti-filarial agents from Indian medicinal plants, leaves of Eucalyptus tereticornis were chemically investigated, which resulted in the isolation and characterization of an anti-filarial agent, ursolic acid (UA) as a major constituent. Antifilarial activity of UA against the human lymphatic filarial parasite Brugia malayi using in vitro and in vivo assays, and in silico docking search on glutathione-s-transferase (GST) parasitic enzyme were carried out. The UA was lethal to microfilariae (mf; LC100: 50; IC50: 8.84 µM) and female adult worms (LC100: 100; IC50: 35.36 µM) as observed by motility assay; it exerted 86% inhibition in MTT reduction potential of the adult parasites. The selectivity index (SI) of UA for the parasites was found safe. This was supported by the molecular docking studies, which showed adequate docking (LibDock) scores for UA (-8.6) with respect to the standard antifilarial drugs, ivermectin (IVM -8.4) and diethylcarbamazine (DEC-C -4.6) on glutathione-s-transferase enzyme. Further, in silico pharmacokinetic and drug-likeness studies showed that UA possesses drug-like properties. Furthermore, UA was evaluated in vivo in B. malayi-M. coucha model (natural infection), which showed 54% macrofilaricidal activity, 56% female worm sterility and almost unchanged microfilaraemia maintained throughout observation period with no adverse effect on the host. Thus, in conclusion in vitro, in silico and in vivo results indicate that UA is a promising, inexpensive, widely available natural lead, which can be designed and developed into a macrofilaricidal drug. To the best of our knowledge this is the first ever report on the anti-filarial potential of UA from E. tereticornis, which is in full agreement with the Thomson Reuter's 'Metadrug' tool screening predictions.

Synthesis of 2-alkoxy and 2-benzyloxy analogues of estradiol as anti-breast cancer agents through microtubule stabilization

2-Methoxyestradiol (2ME2) is an investigational anticancer drug. In the present study, 2-alkoxyesters/acid and 2-benzyloxy analogues of estradiol have been synthesized as analogues of 2ME2. Three of the derivatives exhibited significant anticancer activity against human breast cancer cell lines. The best analogue of the series i.e. 24 showed stabilization of tubulin polymerisation process. It was substantiated by confocal microscopy and molecular docking studies where 24 occupied 'paclitaxel binding pocket' to stabilize the polymerisation process. Compound 24 significantly inhibited MDA-MB-231 cells (IC50: 7 μM) and induced arrest of cell cycle and apoptosis in MDA-MB-231 cells. In acute oral toxicity, 24 was found to be non-toxic and well tolerated in Swiss albino mice up to 1000 mg/kg dose.

Synthesis and quantitative structure–activity relationship (QSAR) studies of novel rosin-based diamide insecticides

The quantitative structure–activity relationship (QSAR) of two series of rosin-based diamides with insecticidal activity against P. xylostella was studied.

Chemo- and bioinformatics resources for in silico drug discovery from medicinal plants beyond their traditional use: a critical review

An overview of databases andin silicotools for discovery of the hidden therapeutic potential of medicinal plants.

Amides derived from heteroaromatic amines and selected steryl hemiesters

The current interest of the team has been focused on investigation of novel amides with potential cytotoxicity. The presented series of compounds was synthesized from selected steryl hemiesters and heteroaromatic amines. The synthetic protocol was designed in a simple and economic way, and divided into several general methodologies applicable to the compounds synthesized. The cytotoxicity was tested on cells derived from human T-lymphoblastic leukemia, breast adenocarcinoma and cervical cancer, and compared with tests on normal human fibroblasts. Most of the lanosterol-based compounds (3-5 and 7-10) showed medium to good cytotoxicity, while only two derivatives of cholesterol (18 and 19) showed medium cytotoxicity on human T-lymphoblastic leukemia cell line. The compounds 8 and 9 displayed the reasonable cytotoxicity among this series of amides, tested on the cell lines of T-lymphoblastic leukemia [14.5±0.4 μM (8) and 18.5±3.9 μM (9)], breast adenocarcinoma [19.5±2.1 μM (8) and 23.1±4.0 μM (9)] and cervical cancer [24.8±5.3 μM (8) and 29.1±4.7 μM (9)]. Only the compound 8 was adequately less active on normal human fibroblasts (40.4±11.1 μM).

Synthesis of combretastatin A4 analogues on steroidal framework and their anti-breast cancer activity

Combretastatin A4 analogues were synthesized on steroidal framework from gallic acid with a possibility of anti-breast cancer agents. Twenty two analogues were synthesized and evaluated for cytotoxicity against human breast cancer cell lines (MCF-7 & MDA-MB 231). The best analogue 22 showed potent antitubulin effect. Docking experiments also supported strong binding affinity of 22 to microtubule polymerase. In cell cycle analysis, 22 induced apoptosis in MCF-7 cells significantly. It was found to be non-toxic up to 300 mg/kg dose in Swiss albino mice in acute oral toxicity. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Ursolic acid in cancer prevention and treatment: molecular targets, pharmacokinetics and clinical studies

Discovery of bioactive molecules and elucidation of their molecular mechanisms open up an enormous opportunity for the development of improved therapy for different inflammatory diseases, including cancer. Triterpenoids isolated several decades ago from various medicinal plants now seem to have a prominent role in the prevention and therapy of a variety of ailments and some have already entered Phase I clinical trials. One such important and highly investigated pentacyclic triterpenoid, ursolic acid has attracted great attention of late for its potential as a chemopreventive and chemotherapeutic agent in various types of cancer. Ursolic acid has been shown to target multiple proinflammatory transcription factors, cell cycle proteins, growth factors, kinases, cytokines, chemokines, adhesion molecules, and inflammatory enzymes. These targets can potentially mediate the chemopreventive and therapeutic effects of ursolic acid by inhibiting the initiation, promotion and metastasis of cancer. This review not only summarizes the diverse molecular targets of ursolic acid, but also provides an insight into the various preclinical and clinical studies that have been performed in the last decade with this promising triterpenoid.

Pkb/Akt1 mediates Wnt/GSK3β/β-catenin signaling-induced apoptosis in human cord blood stem cells exposed to organophosphate pesticide monocrotophos

Inhibition mechanisms of protein kinase B (Pkb)/Akt and its consequences on related cell signaling were investigated in human umbilical cord blood stem cells (hUCBSCs) exposed to monocrotophos (MCP, an organophosphate pesticide). In silico data reveal that MCP interacts with kinase and c-terminal regulatory domains of Akt1, resulting into a total docking score of 5.2748 and also forms H-bond between its N-H and Thr-291 residue of Akt1, in addition to possessing several hydrophobic interactions. The main cause of Akt inhibition is considered to be the strong hydrogen bond between N-H and Thr-291, and hydrophobic interactions at Glu-234, and Asp-292 in the vicinity, which is usually occupied by the ribose of ATP, and interaction with residue Phe-161, thus leading to a significant conformational change in that particular portion of the protein. In silico data on Akt inhibition were confirmed by examining the downregulation of phosphorylated (Thr308/Ser493) Akt1 in MCP-exposed hUCBSCs. MCP-mediated altered levels of pAkt downstream targets viz., downregulated pGSK3β (Ser9), unchanged GSK3αβ, and upregulated levels of Bad, P(53), and caspase-9 further confirm the inhibition of pAkt. The cellular fate of such pAkt inhibition was confirmed by increased terminal deoxynucleotide transferase dUTP nick-end labeling positive cells, reduced mitochondrial membrane potential, and the activation of various MAPKs, proapoptotic markers-Bax, and caspases-9/3. Our data demonstrate that Akt1 plays a key role in MCP-induced apoptosis in hUCBSCs. We also identified that such cellular responses of human cord blood stem cells against MCP were due to strong binding and inhibition of kinase and AGC-Kinase-C terminal regulatory domains of Akt1.