Special Issue "Anticancer Compounds in Medicinal Plants"

A special issue of Pharmaceuticals (ISSN 1424-8247). This special issue belongs to the section "Natural Products".

Deadline for manuscript submissions: 30 June 2021.

Special Issue Editors

Prof. Paulo Santos
E-Mail Website
Guest Editor
Centro de Química - Vila Real, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
Interests: organic synthesis; functional dyes; structural analysis; natural products chemistry; bioactive compounds

Special Issue Information

Dear Colleagues,

Cancer, in its multiple forms, is presently one of the leading causes of death in both developing and developed countries, and it has become a major health problem and burden for most public health care systems worldwide. Although several decades of drug discovery and development have provided a number of useful chemotherapeutic agents, there is a continuous interest in the search for new chemical entities with improved anticancer effectiveness and safety.

Since ancient times, humankind has relied on herbal medicines for the treatment and prevention of a plethora of different ailments, and their beneficial properties have been recognized both by traditional medicines and more contemporary herbalism practices. Medicinal plants, which have made an important contribution to the collection of compounds that are now at our disposal for cancer therapy, constitute a reservoir of natural products able to provide new molecules with anticancer activity and new molecular frameworks capable of inspiring the design of derivatives with improved therapeutic ability. As plant-derived compounds are often not cytotoxic to normal human cells, the attention of scientific research has been increasingly driven towards natural compounds, as they may represent a source of anticancer molecules with less-toxic side effects compared to current chemotherapeutic drugs.

This Special Issue “Anticancer Compounds in Medicinal Plants” invites researchers to contribute original research or review articles related to natural compounds with anticancer properties isolated from medicinal plants. The contributions include the discovery of new compounds, the in vitro and in vivo assessment of the anticancer properties of compounds derived from medicinal plants, as well as the elucidation of their mechanisms of action and the design of derivatives with improved efficacy.

Prof. Paulo Santos
Dr. Lillian Barros
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pharmaceuticals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Natural products
  • Phytochemicals
  • Cancer
  • Secondary metabolites
  • Medicinal plants

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Published Papers (10 papers)

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Research

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Article
Structure-Based Virtual Screening and De Novo Design of PIM1 Inhibitors with Anticancer Activity from Natural Products
Pharmaceuticals 2021, 14(3), 275; https://doi.org/10.3390/ph14030275 - 18 Mar 2021
Viewed by 514
Abstract
Background: the proviral insertion site of Moloney murine leukemia (PIM) 1 kinase has served as a therapeutic target for various human cancers due to the enhancement of cell proliferation and the inhibition of apoptosis. Methods: to identify effective PIM1 kinase inhibitors, structure-based virtual [...] Read more.
Background: the proviral insertion site of Moloney murine leukemia (PIM) 1 kinase has served as a therapeutic target for various human cancers due to the enhancement of cell proliferation and the inhibition of apoptosis. Methods: to identify effective PIM1 kinase inhibitors, structure-based virtual screening of natural products of plant origin and de novo design were carried out using the protein–ligand binding free energy function improved by introducing an adequate dehydration energy term. Results: as a consequence of subsequent enzyme inhibition assays, four classes of PIM1 kinase inhibitors were discovered, with the biochemical potency ranging from low-micromolar to sub-micromolar levels. The results of extensive docking simulations showed that the inhibitory activity stemmed from the formation of multiple hydrogen bonds in combination with hydrophobic interactions in the ATP-binding site. Optimization of the biochemical potency by chemical modifications of the 2-benzylidenebenzofuran-3(2H)-one scaffold led to the discovery of several nanomolar inhibitors with antiproliferative activities against human breast cancer cell lines. Conclusions: these new PIM1 kinase inhibitors are anticipated to serve as a new starting point for the development of anticancer medicine. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Ursolic Acid Inhibits Collective Cell Migration and Promotes JNK-Dependent Lysosomal Associated Cell Death in Glioblastoma Multiforme Cells
Pharmaceuticals 2021, 14(2), 91; https://doi.org/10.3390/ph14020091 - 26 Jan 2021
Cited by 1 | Viewed by 795
Abstract
Ursolic acid (UA) is a bioactive compound which has demonstrated therapeutic efficacy in a variety of cancer cell lines. UA activates various signalling pathways in Glioblastoma multiforme (GBM) and offers a promising starting point in drug discovery; however, understanding the relationship between cell [...] Read more.
Ursolic acid (UA) is a bioactive compound which has demonstrated therapeutic efficacy in a variety of cancer cell lines. UA activates various signalling pathways in Glioblastoma multiforme (GBM) and offers a promising starting point in drug discovery; however, understanding the relationship between cell death and migration has yet to be elucidated. UA induces a dose dependent cytotoxic response demonstrated by flow cytometry and biochemical cytotoxicity assays. Inhibitor and fluorescent probe studies demonstrate that UA induces a caspase independent, JNK dependent, mechanism of cell death. Migration studies established that UA inhibits GBM collective cell migration in a time dependent manner that is independent of the JNK signalling pathway. Cytotoxicity induced by UA results in the formation of acidic vesicle organelles (AVOs), speculating the activation of autophagy. However, inhibitor and spectrophotometric analysis demonstrated that autophagy was not responsible for the formation of the AVOs. Confocal microscopy and isosurface visualisation determined co-localisation of lysosomes with the previously identified AVOs, thus providing evidence that lysosomes are likely to be playing a role in UA induced cell death. Collectively, our data identify that UA rapidly induces a lysosomal associated mechanism of cell death in addition to UA acting as an inhibitor of GBM collective cell migration. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Protopine/Gemcitabine Combination Induces Cytotoxic or Cytoprotective Effects in Cell Type-Specific and Dose-Dependent Manner on Human Cancer and Normal Cells
Pharmaceuticals 2021, 14(2), 90; https://doi.org/10.3390/ph14020090 - 26 Jan 2021
Viewed by 416
Abstract
The natural alkaloid protopine (PRO) exhibits pharmacological properties including anticancer activity. We investigated the effects of PRO, alone and in combination with the chemotherapeutic gemcitabine (GEM), on human tumor cell lines and non-tumor human dermal fibroblasts (HDFs). We found that treatments with different [...] Read more.
The natural alkaloid protopine (PRO) exhibits pharmacological properties including anticancer activity. We investigated the effects of PRO, alone and in combination with the chemotherapeutic gemcitabine (GEM), on human tumor cell lines and non-tumor human dermal fibroblasts (HDFs). We found that treatments with different PRO/GEM combinations were cytotoxic or cytoprotective, depending on concentration and cell type. PRO/GEM decreased viability in pancreatic cancer MIA PaCa-2 and PANC-1 cells, while it rescued the GEM-induced viability decline in HDFs and in tumor MCF-7 cells. Moreover, PRO/GEM decreased G1, S and G2/M phases, concomitantly with an increase of subG1 phase in MIA PaCa-2 and PANC-1 cells. Differently, PRO/GEM restored the normal progression of the cell cycle, altered by GEM, and decreased cell death in HDFs. PRO alone increased mitochondrial reactive oxygen species (ROS) in MIA PaCa-2, PANC-1 cells and HDFs, while PRO/GEM increased both intracellular and mitochondrial ROS in the three cell lines. These results indicate that specific combinations of PRO/GEM may be used to induce cytotoxic effects in pancreatic tumor MIA PaCa-2 and PANC-1 cells, but have cytoprotective or no effects in HDFs. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Extract of Herba Anthrisci cerefolii: Chemical Profiling and Insights into Its Anti-Glioblastoma and Antimicrobial Mechanism of Actions
Pharmaceuticals 2021, 14(1), 55; https://doi.org/10.3390/ph14010055 - 12 Jan 2021
Cited by 1 | Viewed by 645
Abstract
Anthriscus cerefolium (L.) Hoffm. is a plant traditionally used around the globe since antiquity. Although widely used in many traditional medicines in different cultures, from the scientific point of view it is poorly investigated. Glioblastoma, a tumor type with poor prognosis, is the [...] Read more.
Anthriscus cerefolium (L.) Hoffm. is a plant traditionally used around the globe since antiquity. Although widely used in many traditional medicines in different cultures, from the scientific point of view it is poorly investigated. Glioblastoma, a tumor type with poor prognosis, is the most common and lethal brain tumor in adults. Current therapeutic strategies for glioblastoma include surgery, radiation and chemotherapy. On the other hand, it has been revealed that patients with cancers are highly susceptible to microbial infections due to the invasive nature of cancer treatment approaches. This study was designed to investigate the chemical profile of herba Anthriscii cerefoli methanolic extract by applying UHPLC-LTQ OrbiTrap MS4 analysis and to analyze its anti-glioblastoma and antimicrobial activities. This study revealed that methanolic extract of herba Anthrisc cerefolii contained phenolic acids and flavonoids, with 32 compounds being identified. Anti-glioblastoma activity was investigated in vitro using A172 glioblastoma cell line. The cytotoxic effects of the extract on A172 cells were compared to the same effect on primary human gingival fibroblast (HGF-1) cells. Decreased rate of proliferation and changes in cell morphology were detected upon treatment of A172 cells with the extract. The antimicrobial activity of extract was tested against Staphylococcus aureus and Candida species. The extract was active against the tested bacterium and yeasts, inhibiting free floating cells and microbial biofilms. This study is the first one to provide a detailed description of the chemical profile of A. cerefolium extract dealing with scientific insights into its anti-glioblastoma and antimicrobial activities. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Anticancer Effect of Citrus hystrix DC. Leaf Extract and Its Bioactive Constituents Citronellol and, Citronellal on the Triple Negative Breast Cancer MDA-MB-231 Cell Line
Pharmaceuticals 2020, 13(12), 476; https://doi.org/10.3390/ph13120476 - 18 Dec 2020
Viewed by 1088
Abstract
Triple negative breast cancer is one of the most aggressive breast cancer type with abilities of early metastasis and chemoresistance. The tropical plant Citrus hystrix DC. has been reported to promote many biological activities including anticancer. However, the effect of C. hystrix against [...] Read more.
Triple negative breast cancer is one of the most aggressive breast cancer type with abilities of early metastasis and chemoresistance. The tropical plant Citrus hystrix DC. has been reported to promote many biological activities including anticancer. However, the effect of C. hystrix against triple negative breast cancer has not yet been identified. This study aimed to evaluate the anticancer properties of C. hystrix leaf extract and its bioactive constituents citronellol and citronellal against the triple negative breast cancer MDA-MB-231 cell line. C. hystrix leaves were powdered and sequentially macerated. The in vitro anticancer effects of C. hystrix leaf extracts, and its bioactive constituents (citronellol and citronellal) were evaluated against MDA-MB-231 cell line using cytotoxic MTT assay, cell proliferation, wound scratch migration, colony formation, cell cycle, apoptosis assay, Hoechst staining, RT-qPCR, and Western blot analysis. Results showed that crude hexane extract, citronellol, and citronellal significantly reduced cell proliferation, colony formation, and cell migration by inducing cell cycle arrest, while also inducing apoptosis in MDA-MB-231 cells through inhibition of anti-apoptotic Bcl-2 expression, leading to activation of the caspase-3-dependent pathway. This study is the first report to demonstrate the effect of C. hystrix, citronellol, and citronellal against triple negative breast cancer MDA-MB-231 cells. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
In Vitro Bioassay-Guided Identification of Anticancer Properties from Moringa oleifera Lam. Leaf against the MDA-MB-231 Cell Line
Pharmaceuticals 2020, 13(12), 464; https://doi.org/10.3390/ph13120464 - 15 Dec 2020
Viewed by 665
Abstract
Moringa oleifera Lam. (MO) is a medicinal plant distributed across the Middle East, Asia, and Africa. MO has been used in the traditional treatment of various diseases including cancer. This study aimed to perform bioassay-guided fractionation and identification of bioactive compounds from MO [...] Read more.
Moringa oleifera Lam. (MO) is a medicinal plant distributed across the Middle East, Asia, and Africa. MO has been used in the traditional treatment of various diseases including cancer. This study aimed to perform bioassay-guided fractionation and identification of bioactive compounds from MO leaf against MDA-MB-231 breast cancer cells. MO leaf was sequentially extracted with hexane, ethyl acetate (EtOAc), and ethanol. The most effective extract was subjected to fractionation. MO extract and its derived fractions were continuously screened for anti-cancer activities. The strongest fraction was selected for re-fractionation and identification of bioactive compounds using LC-ESI-QTOF-MS/MS analysis. The best anticancer activities were related to the fraction no. 7-derived crude EtOAc extract. This fraction significantly reduced cell viability and clonogenic growth and increased cells apoptosis. Moreover, sub-fraction no. 7.7-derived fraction no. 7 was selected for the identification of bioactive compounds. There were 10 candidate compounds tentatively identified by LC-ESI-QTOF-MS. Three of identified compounds (7-octenoic acid, oleamide, and 1-phenyl-2-pentanol) showed anticancer activities by inducing cell cycle arrest and triggering apoptosis through suppressed Bcl-2 expression which subsequently promotes activation of caspase 3, indicators for the apoptosis pathway. This study identified 10 candidate compounds that may have potential in the field of anticancer substances. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Reversal of Ovarian Cancer Cell Lines Multidrug Resistance Phenotype by the Association of Apiole with Chemotherapies
Pharmaceuticals 2020, 13(10), 327; https://doi.org/10.3390/ph13100327 - 21 Oct 2020
Cited by 2 | Viewed by 873
Abstract
Multidrug resistance (MDR) is the main obstacle in anticancer therapy. The use of drug combinations to circumvent tumor resistance is a well-established principle in the clinic. Among the therapeutic targets, glycoprotein-P (P-gp), an energy-dependent transmembrane efflux pump responsible for modulating MDR, is highlighted. [...] Read more.
Multidrug resistance (MDR) is the main obstacle in anticancer therapy. The use of drug combinations to circumvent tumor resistance is a well-established principle in the clinic. Among the therapeutic targets, glycoprotein-P (P-gp), an energy-dependent transmembrane efflux pump responsible for modulating MDR, is highlighted. Many pharmacological studies report the ability of calcium channel blockers to reverse tumor resistance to chemotherapy drugs. Isolated for the first time from parsley, the phenylpropanoid apiole is described as a potent calcium channel inhibitor. Taking this into account, herein, the ability of apiole to potentiate the action of well-established chemotherapeutics in the clinic, as well as the compound’s relationship with the reversal of the resistance phenomenon by blocking P-gp, is reported. The association of apiole with both chemotherapeutic drugs doxorubicin and vincristine resulted in synergistic effect, in a concentration-dependent manner, as evaluated by the concentration reduction index. Molecular docking analysis demonstrated the affinity between apiole and the active site of P-gp, corroborating the inhibitory effect. Moreover, apiole demonstrated druglikeness, according to ADME analysis. In conclusion, apiole possibly blocks the active P-gp site, with strong binding energy, which, in turn, inhibits doxorubicin and vincristine efflux, increasing the antiproliferative response of these chemotherapeutic agents. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Terminalia bentzoë, a Mascarene Endemic Plant, Inhibits Human Hepatocellular Carcinoma Cells Growth In Vitro via G0/G1 Phase Cell Cycle Arrest
Pharmaceuticals 2020, 13(10), 303; https://doi.org/10.3390/ph13100303 - 12 Oct 2020
Cited by 4 | Viewed by 1121
Abstract
Tropical forests constitute a prolific sanctuary of unique floral diversity and potential medicinal sources, however, many of them remain unexplored. The scarcity of rigorous scientific data on the surviving Mascarene endemic taxa renders bioprospecting of this untapped resource of utmost importance. Thus, in [...] Read more.
Tropical forests constitute a prolific sanctuary of unique floral diversity and potential medicinal sources, however, many of them remain unexplored. The scarcity of rigorous scientific data on the surviving Mascarene endemic taxa renders bioprospecting of this untapped resource of utmost importance. Thus, in view of valorizing the native resource, this study has as its objective to investigate the bioactivities of endemic leaf extracts. Herein, seven Mascarene endemic plants leaves were extracted and evaluated for their in vitro antioxidant properties and antiproliferative effects on a panel of cancer cell lines, using methyl thiazolyl diphenyl-tetrazolium bromide (MTT) and clonogenic cell survival assays. Flow cytometry and comet assay were used to investigate the cell cycle and DNA damaging effects, respectively. Bioassay guided-fractionation coupled with liquid chromatography mass spectrometry (MS), gas chromatography-MS, and nuclear magnetic resonance spectroscopic analysis were used to identify the bioactive compounds. Among the seven plants tested, Terminaliabentzoë was comparatively the most potent antioxidant extract, with significantly (p < 0.05) higher cytotoxic activities. T. bentzoë extract further selectively suppressed the growth of human hepatocellular carcinoma cells and significantly halted the cell cycle progression in the G0/G1 phase, decreased the cells’ replicative potential and induced significant DNA damage. In total, 10 phenolic compounds, including punicalagin and ellagic acid, were identified and likely contributed to the extract’s potent antioxidant and cytotoxic activities. These results established a promising basis for further in-depth investigations into the potential use of T. bentzoë as a supportive therapy in cancer management. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Article
Echinacea purpurea (L.) Moench: Chemical Characterization and Bioactivity of Its Extracts and Fractions
Pharmaceuticals 2020, 13(6), 125; https://doi.org/10.3390/ph13060125 - 20 Jun 2020
Cited by 5 | Viewed by 1234
Abstract
Echinacea purpurea (L.) Moench is widely known for its medicinal properties, being one of the most used medicinal plants for its immunostimulant properties. Nevertheless, there is still scarce information on its cytotoxic activity. Thus, this study aims at evaluating the cytotoxicity and antimicrobial [...] Read more.
Echinacea purpurea (L.) Moench is widely known for its medicinal properties, being one of the most used medicinal plants for its immunostimulant properties. Nevertheless, there is still scarce information on its cytotoxic activity. Thus, this study aims at evaluating the cytotoxicity and antimicrobial activity of several aqueous and organic extracts of the aerial parts of this plant and chemically characterizing the obtained extracts. The analysis was performed by HPLC–DAD–ESI/MS. Fifteen compounds were identified; of these, seven were phenolic acids and eight were flavonoids. Non-polar compounds were evaluated by GC/MS, with a total of sixty-four compounds identified, and the most abundant groups were the sterols, fatty acids and long-chain hydrocarbons. The highest antimicrobial activity was exhibited by the dichloromethane, ethyl acetate, and acetone extracts. Dichloromethane and n-hexane extracts showed the highest cytotoxic activity. Therefore, they were fractionated, and the obtained fractions were also assessed for their cytotoxicity. Notwithstanding, the cytotoxicity of the extracts was superior to that of the obtained fractions, evidencing a possible synergistic effect of different compounds in the whole extracts. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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Review

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Review
Status and Challenges of Plant-Anticancer Compounds in Cancer Treatment
Pharmaceuticals 2021, 14(2), 157; https://doi.org/10.3390/ph14020157 - 14 Feb 2021
Cited by 2 | Viewed by 1236
Abstract
Nowadays, cancer is one of the deadliest diseases in the world, which has been estimated to cause 9.9 million deaths in 2020. Conventional treatments for cancer commonly involve mono-chemotherapy or a combination of radiotherapy and mono-chemotherapy. However, the negative side effects of these [...] Read more.
Nowadays, cancer is one of the deadliest diseases in the world, which has been estimated to cause 9.9 million deaths in 2020. Conventional treatments for cancer commonly involve mono-chemotherapy or a combination of radiotherapy and mono-chemotherapy. However, the negative side effects of these approaches have been extensively reported and have prompted the search of new therapeutic drugs. In this context, scientific community started to look for innovative sources of anticancer compounds in natural sources, including traditional plants. Currently, numerous studies have evaluated the anticancer properties of natural compounds derived from plants, both in vitro and in vivo. In pre-clinical stages, some promising compounds could be mentioned, such as the sulforaphane or different phenolic compounds. On the other hand, some phytochemicals obtained positive results in clinical stages and were further approved for cancer treatment, such as vinca alkaloids or the paclitaxel. Nevertheless, these compounds are not exempt of limitations, such as low solubility, restricted effect on their own, negative side-effects, etc. This review aims to compile the information about the current phytochemicals used for cancer treatment and also promising candidates, main action mechanisms and also reported limitations. In this sense, some strategies to face the limitations have been considered, such as nano-based formulations to improve solubility or chemical modification to reduce toxicity. In conclusion, although more research is still necessary to develop more efficient and safe phytochemical drugs, more of these compounds might be used in future cancer therapies. Full article
(This article belongs to the Special Issue Anticancer Compounds in Medicinal Plants)
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