Discovery of anticancer drugs from antimalarial natural products: a MEDLINE literature review

Assessment of cytoprotective and genoprotective effects of Moringa oleifera and Tinospora cordifolia extracts in vitro

Background

Moringa oleifera and Tinospora cordifolia is extensively used as an ingredient of food and in traditional medicine for the management of a variety of diseases.

Material and methods

The extracts of leaf of Moringa oleifera and stem of Tinospora cordifolia were assessed to examine their ability to inhibit the oxidative DNA damage (by DNA protection assay), cytoprotective and genoprotective potential (by Comet assay) in V79 cells individually and in combinations.

Result

It was found that these extracts could significantly inhibit the OH-dependent damage of pUC18 plasmid DNA. M. oleifera extract (160 and 320 μg/mL) and Tinospora cordifolia extract (640, 1,280 and 2,560 μg/mL) individually showed higher DNA protection activity. M. oleifera (1,280 μg/mL) combined with Tinospora cordifolia (640 μg/mL) showed best cytoprotective and genoprotective activities among different concentration combinations and various concentrations of individual plants in V79 cell line against hydrogen peroxide induced cytotoxicity and genotoxicity.

Conclusion

This study demonstrates the cytoprotective and genoprotective activity of M. oleifera and Tinospora cordifolia individually or in combination.

Natural Products/Bioactive Compounds as a Source of Anticancer Drugs

Cancer is one of the major deadly diseases globally. The alarming rise in the mortality rate due to this disease attracks attention towards discovering potent anticancer agents to overcome its mortality rate. The discovery of novel and effective anticancer agents from natural sources has been the main point of interest in pharmaceutical research because of attractive natural therapeutic agents with an immense chemical diversity in species of animals, plants, and microorganisms. More than 60% of contemporary anticancer drugs, in one form or another, have originated from natural sources. Plants and microbial species are chosen based on their composition, ecology, phytochemical, and ethnopharmacological properties. Plants and their derivatives have played a significant role in producing effective anticancer agents. Some plant derivatives include vincristine, vinblastine, irinotecan, topotecan, etoposide, podophyllotoxin, and paclitaxel. Based on their particular activity, a number of other plant-derived bioactive compounds are in the clinical development phase against cancer, such as gimatecan, elomotecan, etc. Additionally, the conjugation of natural compounds with anti-cancerous drugs, or some polymeric carriers particularly targeted to epitopes on the site of interest to tumors, can generate effective targeted treatment therapies. Cognizance from such pharmaceutical research studies would yield alternative drug development strategies through natural sources which could be economical, more reliable, and safe to use.

Identification of novel anti-cancer agents, applying in silico method for SENP1 protease inhibition

The SENP1 (Sentrin-Specific Protease1) is essential for desumoylation. SENP1 plays an essential role in many diseases such as cardiovascular disease, diabetes and cancer via targeting GATA2, NEMO, Pin1, SMAD4 and HIF-1α for deSUMOylation. Considering that, over expression of SENP1 was reported in cancer, thus an optional inhibitor of SENP1 can restitute the balance to the skewed system of SUMO and act as an effective therapeutic agent. The purpose of this study was to select and to sort inhibitors with a stronger binding affinity with SENP1. Molecular docking of SENP1 with natural compounds including Gallic acid, Caffeic acid, Thymoquinone, Thymol, Betaine, Alkannin, Ellagic acid, Betanin, Shikonin, Betanidin and Momordin IC was performed using AutoDock 4, then docking complexes for molecular dynamics (MD) simulation with GROMACS 4.6.5 were applied. Results with RMSD, RMSF, SASA, DSSP, gyrate, H-bond, ADMET and TOPKAT measurements, binding energy and structural features were surveyed. Among those, Gallic acid has shown the most significant results including RMSD and RMSF plots with high stability, high hydrogen bonds, high binding energy and the highest intermolecular bonds with SENP1. Gallic acid demonstrated strong connections and results of toxicity better than Momordin as control. Gallic acid is a phenolic compound which affects several pharmacological and biochemical pathways and has strong antioxidant, anti-inflammatory, antimutagenic and anticancer properties. Further research can improve the appropriate use of plant products drastically. Basic, pre-clinical and clinical research on Gallic acid may provide a roadmap for its ultimate application in the field of cancer prevention.Communicated by Ramaswamy H. Sarma.

Overview of Morin and Its Complementary Role as an Adjuvant for Anticancer Agents

The Global cancer incidence and mortality data released by the World Health Organization proposes that out of 18.1 million new cancer cases diagnosed, 9.8 million deaths occurred globally in 2018. Cancer is one of the major health burdens among non-communicable diseases globally responsible for impeding life expectancy in the present century. Disrupting hallmarks of cancer (such as prolonged inflammation, increased growth signal, tissue invasion and metastasis, unlimited proliferation and evasion of apoptosis) with dietary agents is of considerable focus for cancer prevention and therapy. In the last decade, a significant contribution has been provided in finding many plant-derived natural agents that can be identified as promising molecular cancer therapeutics. Our focus in this review is on one such natural dietary agent, Morin (3,5,7,2',4'-pentahydroxyflavone): a bioflavonoid. Morin exerts strong pharmacological properties against a multitude of cancer (liver cancer, cervical cancer, melanoma, breast cancer, prostate, and colon cancer). Recent progress has also been made in examining the potential of morin as a natural dietary agent for fostering the pharmacological effects of other well-known anticancer agents. This review provides an overview of morin and its derivatives in combination with anticancer agents for cancer prevention and therapy.

Antiproliferative evaluation of various aminoquinoline derivatives

Four classes of aminoquinoline derivatives were prepared: primaquine ureas 1a-f, primaquine bis-ureas 2a-f, chloroquine fumardiamides 3a-f and mefloquine fumardiamides 4a-f. Their antiproliferative activities against breast adeno-carcinoma (MCF-7), lung carcinoma (H460) and colon carcinoma (HCT 116 and SW620) cell lines were evaluated in vitro, using MTT cell proliferation assay. The results revealed a low activity of primaquine urea and bis-urea derivatives and high activity of all fumardiamides, with IC50 values in low micromolar range against all tested cancer cell lines.

Primaquine derivatives: Modifications of the terminal amino group

Numerous modifications of the well-known antimalarial drug primaquine, both at the quinoline ring and at the primary amino group, have been reported, mostly to obtain antimalarial agents with improved bioavailability, reduced toxicity and/or prolonged activity. Modifications of the terminal amino group were made with the main idea to prevent the metabolic pathway leading to inactive and toxic carboxyprimaquine (follow-on strategy), but also to get compounds with different activity (repurposing strategy). The modifications undertaken until 2009 were included in a review published in the same year. The present review covers various classes of primaquine N-derivatives with diverse biological profiles, prepared in the last decade by our research group as well as the others. We have summarized the synthetic procedures applied for their preparation and discussed the main biological results. Several hits for the development of novel antiplasmodial, anticancer, antimycobacterial and antibiofilm agents were identified.

Environmentally Friendly Antifouling Metabolites from Red Sea Organisms

Seventy-one marine organisms representing different classes of marine fauna and flora were collected from the Red Sea. They include sponges, hydrozoan, soft corals, sea cucumber, ascidian, cyanobacteria, and macroalgae. The methanolic extracts were evaluated for their toxicity and settlement inhibition effects by using cultured Balanus amphitrite. Thirty-three extracts displayed antifouling effects: four samples were highly potent at 1 μg/mL with a percentage of settlement inhibition above 31%, twenty-two were potent at 10 μg/mL with a percentage of settlement inhibition between 16 and 30%, and seven were active at 10 μg/mL with a percentage of settlement inhibition between 0 and 15%. Two promising extracts were purified by employing several chromatographic techniques, leading to the isolation of 12 known compounds. The isolated compounds were evaluated for their antifouling activities and demonstrated potent antifouling effects with EC50 values of less than 10 μg/mL.

Antiplasmodial activity and cytotoxicity, isolation of active alkaloids, and dereplication of Xylopia sericea leaves ethanol extract by UPLC-DAD-ESI-MS/MS

Objectives

To assess the antiplasmodial activity of the ethanol extract of Xylopia sericea leaves, Annonaceae, often associated with antimalarial use and to perform a bioguided isolation of active compounds.

Methods

Dereplication of ethanol extract by the UPLC-DAD-ESI-MS/MS technique allowed the identification of the major constituents, isolation and identification of alkaloids. The antiplasmodial and cytotoxic activity of the extract, fractions and isolated compounds was evaluated against the chloroquine-resistant W2 strain Plasmodium falciparum and HepG2 cells, respectively.

Key findings

Ethanol extract showed high reduction of parasitemia as well as moderate cytotoxicity (86.5 ± 3.0% growth inhibition at 50 μg/ml and CC50 72.1 ± 5.1 μg/ml, respectively). A total of eight flavonoids were identified, and two aporphine alkaloids, anonaine and O-methylmoschatoline, were isolated. Anonaine disclosed significant antiplasmodial effect and moderate cytotoxicity (IC50 23.2 ± 2.7 μg/ml, CC50 38.3 ± 2.3 μg/ml, SI 1.6) while O-methylmoschatoline was not active against P. falciparum and showed a low cytotoxicity (33.5 ± 1.9% growth inhibition at 50 μg/ml, CC50 274.4 ± 0.5 μg/ml).

Conclusions

Characterization of Xylopia sericea leaves ethanol extract by UPLC-DAD-ESI-MS/MS as well as its antiplasmodial activity and the occurrence of anonaine and O-methylmoschatoline in this Xylopia species are reported by the first time.

SAHAquines, Novel Hybrids Based on SAHA and Primaquine Motifs, as Potential Cytostatic and Antiplasmodial Agents

We report the synthesis of SAHAquines and related primaquine (PQ) derivatives. SAHAquines are novel hybrid compounds that combine moieties of suberoylanilide hydroxamic acid (SAHA), an anticancer agent with weak antiplasmodial activity, and PQ, an antimalarial drug with low antiproliferative activity. The preparation of SAHAquines is simple, cheap, and high yielding. It includes the following steps: coupling reaction between primaquine and a dicarboxylic acid monoester, hydrolysis, a new coupling reaction with O-protected hydroxylamine, and deprotection. SAHAquines 5 a-d showed significant reduction in cell viability. Among the three human cancer cell lines (U2OS, HepG2, and MCF-7), the most responsive were the MCF-7 cells. The antibodies against acetylated histone H3K9/H3K14 in MCF-7 cells revealed a significant enhancement following treatment with N-hydroxy-N'-{4-[(6-methoxyquinolin-8-yl)amino]pentyl}pentanediamide (5 b). Ethyl (2E)-3-({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)prop-2-enoate (2 b) and SAHAquines were the most active compounds against both the hepatic and erythrocytic stages of Plasmodium parasites, some of them at sub-micromolar concentrations. The results of our research suggest that SAHAquines are promising leads for new anticancer and antimalarial agents.

Apocynaceae species with antiproliferative and/or antiplasmodial properties: a review of ten genera

Apocynaceae is a large family of tropical trees, shrubs and vines with most species producing white latex. Major metabolites of species are triterpenoids, iridoids, alkaloids and cardenolides, which are known for a wide range of biological and pharmacological activities such as cardioprotective, hepatoprotective, neuroprotective, anti-inflammatory, anticancer and antimalarial properties. Prompted by their anticancer and antimalarial properties, the current knowledge on ten genera (Allamanda, Alstonia, Calotropis, Catharanthus, Cerbera, Dyera, Kopsia, Nerium, Plumeria and Vallaris) is updated. Major classes of metabolites are described using some species as examples. Species with antiproliferative (APF) and/or antiplasmodial (APM) properties have been identified. With the exception of the genus Dyera, nine genera of 22 species possess APF activity. Seven genera (Alstonia, Calotropis, Catharanthus, Dyera, Kopsia, Plumeria and Vallaris) of 13 species have APM properties. Among these species, Alstonia angustiloba, Alstonia macrophylla, Calotropis gigantea, Calotropis procera, Catharanthus roseus, Plumeria alba and Vallaris glabra displayed both APF and APM properties. The chemical constituents of these seven species are compiled for assessment and further research.

Biological activity, quantitative structure-activity relationship analysis, and molecular docking of xanthone derivatives as anticancer drugs

Background

Xanthone derivatives have a wide range of pharmacological activities, such as those involving antibacterial, antiviral, antimalarial, anthelmintic, anti-inflammatory, antiprotozoal, and anticancer properties. Among these, we investigated the anticancer properties of xanthone. This research aimed to analyze the biological activity of ten novel xanthone derivatives, to investigate the most contributing-descriptors for their cytotoxic activities, and to examine the possible mechanism of actions of xanthone compound through molecular docking.

Materials and methods

The cytotoxic tests were carried out on WiDR and Vero cell lines, by a 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay method. The structural features required for xanthone’s anticancer activity were conducted by using the semi-empirical Austin Model-1 method, and continued with quantitative structure-activity relationship (QSAR) analysis using BuildQSAR program. The study of the possible mechanism of actions of the selected xanthone compound was done through molecular docking with PLANTS.

Results

The three novel xanthone derivatives (compounds 5, 7, and 8) exhibited cytotoxic activity with compound 5 showed the highest degree of cytotoxicity at concentration 9.23 µg/mL (37.8 µM). The following best equation model was obtained from the BuildQSAR calculation: log 1/IC₅₀ = −8.124 qC1 −35.088 qC2 −6.008 qC3 + 1.831 u + 0.540 logP −9.115 (n = 10, r = 0.976, s = 0.144, F = 15.920, Q2 = 0.651, SPRESS = 0.390). This equation model generated 15 proposed new xanthone compounds with better-predicted anticancer activities. A molecular docking study of compound 5 showed that xanthone formed binding interactions with some receptors involved in cancer pathology, including telomerase, tumor-promoting inflammation (COX-2), and cyclin-dependent kinase-2 (CDK2) inhibitor.

Conclusion

The results suggested that compound 5 showed the best cytotoxic activity among the xanthone derivatives tested. QSAR analysis showed that the descriptors contributed to xanthone’s cytotoxic activity were the net atomic charge at qC1, qC2, and qC3 positions, also dipole moment and logP. Compound 5 was suspected to be cytotoxic by its inhibition of telomerase, COX-2, and CDK2 receptors.

Semisynthesis, cytotoxicity, antimalarial evaluation and structure-activity relationship of two series of triterpene derivatives

In this report, we describe the semisynthesis of two series of ursolic and betulinic acid derivatives through designed by modifications at the C-3 and C-28 positions and demonstrate their antimalarial activity against chloroquine-resistant P. falciparum (W2 strain). Structural modifications at C-3 were more advantageous to antimalarial activity than simultaneous modifications at C-3 and C-28 positions. The ester derivative, 3β-butanoyl betulinic acid (7b), was the most active compound (IC₅₀ = 3.4 µM) and it did not exhibit cytotoxicity against VERO nor HepG2 cells (CC₅₀ > 400 µM), showing selectivity towards parasites (selectivity index > 117.47). In combination with artemisinin, compound 7b showed an additive effect (CI = 1.14). While docking analysis showed a possible interaction of 7b with the Plasmodium protease PfSUB1, with an optimum binding affinity of -7.02 kcal/mol, the rather low inhibition displayed on a Bacillus licheniformis subtilisin A protease activity assay (IC₅₀ = 93 µM) and the observed accumulation of ring forms together with a delay of appearance of trophozoites in vitro suggests that the main target of 3β-butanoyl betulinic acid on Plasmodium may be related to other molecules and processes pertaining to the ring stage. Therefore, compound 7b is the most promising compound for further studies on antimalarial chemotherapy. The results obtained in this study provide suitable information about scaffolds to develop novel antimalarials from natural sources.

Chemical characterization and cytotoxic activity evaluation of Lebanese propolis

Chemical composition, anti-proliferative and proapoptotic activity as well as the effect of various fractions of Lebanese propolis on the cell cycle distribution were evaluated on Jurkat leukemic T-cells, glioblastoma U251 cells, and breast adenocarcinoma MDA-MB-231 cells using cytotoxic assays, flow cytometry as well as western blot analysis. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that ferulic acid, chrysin, pinocembrin, galangin are major constituents of the ethanolic crude extract of the Lebanese propolis, while the hexane fraction mostly contains chrysin, pinocembrin, galangin but at similar levels. Furthermore chemical analysis was performed using gas chromatography-mass spectrometry (GC-MS) to identify major compounds in the hexane fraction. Reduction of cell viability was observed in Jurkat cells exposed to the ethanolic crude extract and the hexane fraction, while viability of U251 and MDA-MB-231 cells was only affected upon exposure to the hexane fraction; the other fractions (aqueous phase, methylene chloride, and ethyl acetate) were without effect. Maximum toxic effect was obtained when Jurkat cells were cultivated with 90μg/ml of both the crude extract and hexane faction. Toxicity started early after 24h of incubation and remained till 72h. Interestingly, the decrease in cell viability was accompanied by a significant increase in p53 protein expression levels and PARP cleavage. Cell cycle distribution showed an increase in the SubG0 fraction in Jurkat, U251 and MDA-MB-231 cells after 24h incubation with the hexane fraction. This increase in SubG0 was further investigated in Jurkat cells by annexinV/PI and showed an increase in the percentage of cells in early and late apoptosis as well as necrosis. In conclusion, Lebanese propolis exhibited significant cytotoxicity and anti-proliferative activity promising enough that warrant further investigations on the molecular targets and mechanisms of action of Lebanese propolis.

Artesunate acts as fuel to fire in sensitizing HepG2 cells towards TRAIL mediated apoptosis via STAT3 inhibition and DR4 augmentation

In the present study, we investigated in vitro, the role of artesunate (ATS) with comparable potency to oxaliplatin (OXP) in sensitizing tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) resistant HepG2 cells towards apoptosis. ATS in consistency with OXP was found to reverse TRAIL resistant HepG2 cells towards TRAIL mediated apoptosis by enhancing caspase-3 and cleavage of PARP. Additionally, ATS also suppressed the nuclear translocation of activated signal transducers and activators of transcription 3 (STAT3) thereby sensitizing the HepG2 cells towards only death receptor 4 (DR4) mediated apoptosis. Furthermore, ATS exposure in TRAIL resistant cells resulted in significant increase of both DR4/DR5 expression and STAT3 inhibition thereby arbitrating TRAIL mediated apoptosis in HepG2 cells. The increase in expression was comparable to that of STAT3 silenced cells. From all the above observations, we conclude that ATS up-regulated DR4 expression by targeting STAT3, which in turn sensitized HepG2 cells to TRAIL mediated apoptosis.

Design, Synthesis and Biological Evaluation of Novel Primaquine-Cinnamic Acid Conjugates of the Amide and Acylsemicarbazide Type

In this paper design and synthesis of a scaffold comprising primaquine (PQ) motif and cinnamic acid derivatives (CADs) bound directly (compounds 3a-k) or via a spacer (compounds 7a-k) are reported. In the first series of compounds, PQ and various CADs were connected by amide bonds and in the second series by acylsemicarbazide functional groups built from the PQ amino group, CONHNH spacer and the carbonyl group originating from the CADs. PQ-CAD amides 3a-k were prepared by a simple one-step condensation reaction of PQ with a series of CAD chlorides (method A) or benzotriazolides 2 (method B). The synthesis of acylsemicarbazides 7a-k included activation of PQ with benzotriazole, preparation of PQ-semicarbazide 6 and its condensation with CAD chlorides 4. All synthesized PQ-CAD conjugates were evaluated for their anticancer, antiviral and antioxidative activities. Almost all compounds from series 3 were selective towards the MCF-7 cell line and active at micromolar concentrations. The o-fluoro derivative 3h showed high activity against HeLa, MCF-7 and in particular against the SW 620 cell line, while acylsemicarbazide 7f with a benzodioxole ring and 7c, 7g and especially 7j with methoxy-, chloro- or trifluoromethyl-substituents in the para position showed high selectivity and high inhibitory activity against MCF-7 cell line at micromolar (7c, 7f, 7g) and nanomolar (7j) levels. Acylsemicarbazide derivatives with trifluoromethyl group(s) 7i, 7j and 7k showed specific activity against human coronavirus (229E) at concentrations which did not alter the normal cell morphology. The same compounds exerted the most potent reducing activity in the DPPH test, together with 7d and 7g, while methoxy (compounds 7c-e), benzodioxole (7f), p-Cl (7g) and m-CF₃ (7i) acylsemicarbazides and amide 3f presented the highest LP inhibition (83%-89%). The dimethoxy derivative 7d was the most potent LOX inhibitor (IC50 = 10 μΜ). The performed biological tests gave evidence of acylsemicarbazide functional group as superior binding group in PQ-CAD conjugates.

Synthesis and antitumor evaluation of 5-(benzo[d][1,3]dioxol-5-ylmethyl)-4-(tert-butyl)-N-arylthiazol-2-amines

The strategy for designing target compounds as antitumor agents.

Canthin-6-one displays antiproliferative activity and causes accumulation of cancer cells in the G2/M phase

Canthinones are natural substances with a wide range of biological activities, including antipyretic, antiparasitic, and antimicrobial. Antiproliferative and/or cytotoxic effects of canthinones on cancer cells have also been described, although their mechanism of action remains ill defined. To gain better insight into this mechanism, the antiproliferative effect of a commercially available canthin-6-one (1) was examined dose-dependently on six cancer cell lines (human prostate, PC-3; human colon, HT-29; human lymphocyte, Jurkat; human cervix, HeLa; rat glioma, C6; and mouse embryonic fibroblasts, NIH-3T3). Cytotoxic effects of 1 were investigated on the same cancer cell lines by procaspase-3 cleavage and on normal human skin fibroblasts. Strong antiproliferative effects of the compound were observed in all cell lines, whereas cytotoxic effects were very dependent on cell type. A better definition of the mechanism of action of 1 was obtained on PC-3 cells, by showing that it decreases BrdU incorporation into DNA by 60% to 80% and mitotic spindle formation by 70% and that it causes a 2-fold accumulation of cells in the G2/M phase of the cell cycle. Together, the data suggest that the primary effect of canthin-6-one (1) is antiproliferative, possibly by interfering with the G2/M transition. Proapoptotic effects might result from this disturbance of the cell cycle.

A survey of marine natural compounds and their derivatives with anti-cancer activity reported in 2011

Cancer continues to be a major public health problem despite the efforts that have been made in the search for novel drugs and treatments. The current sources sought for the discovery of new molecules are plants, animals and minerals. During the past decade, the search for anticancer agents of marine origin to fight chemo-resistance has increased greatly. Each year, several novel anticancer molecules are isolated from marine organisms and represent a renewed hope for cancer therapy. The study of structure-function relationships has allowed synthesis of analogues with increased efficacy and less toxicity. In this report, we aim to review 42 compounds of marine origin and their derivatives that were published in 2011 as promising anticancer compounds.

Traditional West African pharmacopeia, plants and derived compounds for cancer therapy

Traditional pharmacopeia is strongly involved in the continuous search for the well being of African populations. The World Health Organization (WHO) estimates that 80% of the population of developing countries relies on traditional medicine for their primary care needs. Medicinal plants are the major resource of this folk medicine where several species are used for the treatment of diseases with an inflammatory and/or infectious component as it is the case of old wounds, skin diseases and malfunctions affecting internal organs such as liver, lung, prostate and kidney. Many of these pathologies described by practitioners of traditional medicine have similarities with certain cancers, but the lack of training of many of these healers does not allow them to establish a link with cancer. However, ethnobotanical and ethnopharmacological surveys conducted by several researchers allowed to identify plants of interest for cancer treatment. Most scientific investigations on these plants demonstrated an anti-inflammatory or antioxidant effect, and sometimes, antiproliferative and cytotoxic activities against cancer cells were reported as well. The emergence of resistance to cancer chemotherapy has forced researchers to turn to natural products of plant and marine origin. In the West African sub-region, research on natural anti-cancer molecules is still in its infancy stage because of very limited financial resources and the scarcity of adequate technical facilities. However, several plants were investigated for their anticancer properties through north-south or south-south partnerships. In this review, we will review the role of West African traditional pharmacopeia in cancer treatment as well as medicinal plants with anti-cancer properties.