Pharmacogenomics of Cameroonian traditional herbal medicine for cancer therapy

In vitro cultivation of Vismia japurensis: Isolation of the new anthrone 1,8,10-trihydroxy-3,10-dimethyl-9(10H)-anthracenone

Vismia japurensis Reichardt is a plant of ecological and chemical importance from which a variety of bioactive substances have been isolated. The current study aimed to establish in vitro cultures of this species as a source of secondary metabolites. Appropriate decontamination treatments and germination tests were performed and, after in vitro culture establishment, the propagated plants were multiplied in a sterile environment to increase the biomass of available experimental material. Seeds showed low contamination and a high germination percentage on Woody Plant Medium (WPM) supplemented with gibberellic acid (both at concentrations of 5 and 10 mg/L). V. japurensis nodal segments rapidly regenerated when first grown in WPM and then transplanted to Murashige and Skoog medium (MS). After 60 days in MS medium, the propagated plants were removed, lyophilized, and extracted with hexane and methanol. The hexane extract was fractionated via open column chromatography, and the substance isolated was purified by high performance liquid chromatography. Structural determination of the isolated substance was carried out using one and two-dimensional nuclear magnetic resonance and mass spectrometry. The isolated substance was identified as 1,8,10-trihydroxy-3,10-dimethyl-9(10H)-anthracenone, which, based on the conducted literature search, is reported for the first time.

Hypericum roeperianum bark extract suppresses breast cancer proliferation via induction of apoptosis, downregulation of PI3K/Akt/mTOR signaling cascade and reversal of EMT

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum roeperianum is a medicinal spice traditionally used in West Africa to treat female sterility, fungal infections, and cancer. It has previously been reported that H. roeperianum exhibits cytotoxic potential by reducing the viability of cancer cells involving multidrug-resistant phenotypes, but its underlying molecular mechanism remains unknown.

AIM OF THE STUDY

The mechanistic involvement of H. roeperianum methanolic crude extract (HRC) in attenuating breast cancer progression by exploring the effects on mitochondrial apoptosis and epithelial-mesenchymal transition (EMT) was investigated.

MATERIALS AND METHODS

In the present study, we examined the anticancer properties of HRC through MTT assay, colony formation, wound healing assay, spheroid formation, DNA fragmentation and flow cytometry for cell cycle arrest, apoptosis (Annexin V/PI staining) and mitochondrial membrane potential (MMP) (JC-1) detection. In addition, western blot analysis of various proteins and quantitative real time PCR of various genes involved in apoptosis, EMT and the PI3K/Akt/mToR signal transduction pathway were performed.

RESULTS

This study revealed that HRC treatment significantly decreased breast cancer cell viability, colony forming efficiency and reduced the ability of cell migration and spheroid formation. HRC also induced apoptosis in MDA-MB-231 and MCF-7 via promoting G0/G1 cell cycle arrest, disruption of mitochondrial membrane potential and induction of DNA damage. The crude extract induced apoptosis by activating the intrinsic pathway with a stronger effect that relies on the combined potency of associated molecular markers including Bax, Bad, Bcl-2, cytochrome C, caspase-9, and cleaved-PARP. It was also found that HRC regulates the PI3K/Akt/mToR pathway. In addition, HRC inhibited EMT by expressional alteration of Vimentin and E-cadherin, as well as the regulatory transcription factors such as Snail and Slug. The in vitro findings reflected similar mechanistic approach in 4T1 cell induced syngeneic mice model, indicating the reduction of tumor volume along with the significant expressional alteration of EMT and apoptotic markers.

CONCLUSION

Taken together the findings concluded that H. roeperianum is a potential source of cytotoxic phytochemicals that exhibit abortifacient effect on breast cancer, both in vitro and in vivo, thus could further be utilized in breast cancer therapy.

Cytotoxicity, acute and sub-chronic toxicities of the leaves of Bauhinia thonningii (Schumach.) Milne-Redh. (Caesalpiniaceae)

BACKGROUND

Bauhinia thonningii is a plant traditionally used against many human diseases such as gastric ulcers, fever, inflammations, coughs, dysentery, diarrhea, and malaria. In the present investigation, the cytotoxicity of methanol extract of Bauhinia thonningii leaves (BTL), fractions and the isolated phytoconstituents was determined in a panel of 9 human cancer cell lines including drug sensitive and multidrug-resistant (MDR) phenotypes. The acute and sub-chronic oral toxicity of BTL was investigated as well.

METHODS

Compounds were isolated using chromatographic techniques while their chemical structures were determined using spectroscopic methods. The resazurin reduction assay (RRA) was used to evaluate the cytotoxicity of samples, propidium iodide (PI) for apoptosis, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining for mitochondrial membrane potential (MMP) analysis, 2´,7´-dichlorodihydrofluoresceine diacetate (H2DCFH-DA) staining for the quantification of reactive oxygen species (ROS), whereas Caspase Glo assays were combined by means of flow cytometry. Furthermore, the toxicological investigations were performed as recommended by the Organization for Economic Cooperation and Development (OECD).

RESULTS

The botanicals as well as 6-C-methylquercetin-3,7-dimethyl ether (2), quercetin-3-O-L-rhamnopyranoside (5), quercetin-3-O-β-glucopyranoside (6), 6,8-C-dimethylkaempferol 3,7-dimethyl ether (7), and 6,8-C-dimethylkaempferol-3-methyl ether (8) had promising cytotoxic effects in the 9 tested cancer cell lines. The IC50 values below 20 µg/mL (botanicals) or 10 µM (compounds) on at least 1/9 tested cancer cell lines were considered. The best cytotoxic effects with IC50 values below 5 µM were achieved with compounds 7 against CEM/ADR5000 leukemia cells (2.86 µM) and MDA-MB-231-pcDNA breast adenocarcinoma cells (1.93 µM) as well as 8 against CCRF-CEM leukemia cells (3.03 µM), CEM/ADR5000 cells (2.42 µM), MDA-MB-231-pcDNA (2.34 µM), and HCT116 p53-/- cells (3.41 µM). BTL and compound 8 induced apoptotic cell death in CCRF-CEM cells through caspase activation, alteration of MMP, and increased ROS production. BTL did not cause any adverse effects in rats after a single administration at 5000 mg/kg or a repeated dose of 250 mg/kg body weight (b. w.).

CONCLUSION

Bauhinia thonningii and its constituents are sources of cytotoxic drugs that deserve more in-depth studies to develop novel antiproliferative phytomedicine to fight cancer including resistant phenotypes.

Chemoprotective Effect of Scutellarin against Gastric Cancer in Rats: An in vitro and in vivo Study

This study evaluated the chemoprotective effect of scutellarin (SC) in vitro and in vivo against gastric carcinogenesis in rats and celllines and examined the underlying mechanism. Gastric cancer celllines (AGS) was used for the in vitro study and lactate dehydrogenase (LDH) profile, histone deacetylase (HDAC) assay, cell cycle & apoptosis ratio and antioxidant parameters were measured. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was used to induce gastric carcinogenesis in rats and the rats received the different doses of SC (10, 20 and 30 mg/kg). The body weight and tumor incidence were measured at regular time intervals. The antioxidant and pro-inflammatory cytokines were estimated. The finding of data showed that the drug was effective against AGS cell line. Supplementation of scutellarin revealed an upregulation in body weight compared with the MNNG group rats. Moreover, it also reduced the incidence of tumor. It also altered the significant DNA density, LDH content, mucus content and acidity. Scutellarin treated rats showed improved activity in enzymatic and non-enzymatic antioxidant profile and reversed the content of cytokines compared with MNNG induced gastric cancer group rats. This research reveals the chemoprotective property of the scutellarin and highlights the promising role of drug by alteration of inflammatory pathway by minimizing its adverse effect.

Ethnopharmacological Study of Medicinal Plants Used for the Treatment of Cardiovascular Diseases and Their Associated Risk Factors in sub-Saharan Africa

Cardiovascular diseases (CVDs) are the leading cause of global mortality, including deaths arising from non-communicable diseases in sub-Saharan Africa (SSA). Consequently, this study aimed to provide details of medicinal plants (MPs) employed in SSA for the treatment of CVDs and their related risk factors to open new avenues for the discovery of novel drugs. The extensive ethnopharmacological literature survey of these MPs in 41 SSA countries was based on studies from 1982 to 2021. It revealed 1,085 MPs belonging to 218 botanical families, with Fabaceae (9.61%), Asteraceae (6.77%), Apocynaceae (3.93%), Lamiaceae (3.75%), and Rubiaceae (3.66%) being the most represented. Meanwhile, Allium sativum L., Persea americana Mill., Moringa oleifera Lam., Mangifera indica L., and Allium cepa L. are the five most utilised plant species. The preferred plant parts include the leaves (36%), roots (21%), barks (14%), fruits (7%), and seeds (5%), which are mostly prepared by decoction. Benin, Mauritius, Nigeria, South Africa, and Togo had the highest reported use while most of the investigations were on diabetes and hypertension. Despite the nutraceutical advantages of some of these MPs, their general toxicity potential calls for caution in their human long-term use. Overall, the study established the need for governments of SSA countries to validate the efficacy/safety of these MPs as well as provide affordable, accessible, and improved modern healthcare services.

Telescoped Continuous Flow Synthesis of 2-Substituted 1,4-Benzoquinones via Oxidative Dearomatisation of para-Substituted Phenols Using Singlet Oxygen in Supercritical CO2

This paper describes a continuous multi-step synthesis in supercritical CO2. A continuous flow synthesis of 2-substituted 1,4-benzoquinones is reported, and details of the high-pressure reactors are given. This proceeds via the telescoped dearomatisation of p-substituted phenols using singlet oxygen in supercritical CO2 and an acid-mediated C–C migration. The process has a short residence time of 30 minutes, with overall yields and projected productivities of up to 83% and 9 g/day, respectively. This methodology enables a safe and efficient synthesis of 2-substituted 1,4-benzoquinones from photo-generated singlet oxygen, and cheap and readily available p-substituted phenols. The procedure has high atom efficiency, low photocatalyst loading, and substitutes potentially hazardous and corrosive reagents and solvents for molecular oxygen, CO2, and the less hazardous solid-supported acid Amberlyst-15.

Effects of Hibiscus sabdariffa Calyxes Aqueous Extract on Antioxidant Status and Histopathology in Mammary Tumor-Induced in Rats

Breast cancer is a major threat worldwide. Hibiscus sabdariffa is widely consumed as beverage in sub-Saharan Africa for its anticancer potential. The present study therefore aimed at scientifically verifying its anticancer effect in rats. For this, 48 Wistar rats (∼55 days) were treated either with tamoxifen at 3.3 mg/kg BW (standard) or with a decoction of H. sabdariffa (125, 250, and 500 mg/kg BW) or distilled water (vehicle). Breast cancer was induced by a single dose of 50 mg/kg of 7,12-dimethylbenz(a)anthracene (DMBA). At the end of the 21 weeks of treatment, the tumor incidence, tumor morphology, histopathology, as well as some biochemical parameters in the tumors were assessed. As a result, 86% of DMBA's rats developed mammary tumors. The H. sabdariffa extract (125 and 250 mg/kg) reduced tumor incidence by 63% and 75%, respectively; inhibited tumor burden by 84.86% and 38.78%, respectively, and decreased tumor volume by more than 72% compared to the DMBA group. It also protected rats against DMBA-induced diffuse breast neoplasia, and the optimal effect was recorded at 125 mg/kg. Furthermore, it significantly increases the SOD activity and decreases the MDA level. In summary, H. sabdariffa has antibreast tumor and antioxidant properties in rats, which could justify its common use to treat cancer.

Plumeria rubra L.- A review on its ethnopharmacological, morphological, phytochemical, pharmacological and toxicological studies

ETHNOPHARMACOLOGICAL RELEVANCE

Plumeria rubra L. (Apocynaceae) is a deciduous, commonly ornamental, tropical plant grown in home premises, parks, gardens, graveyards, because of its beautiful and attractive flowers of various colours and size. The different parts of the plant are used traditionally to treat various diseases and conditions like leprosy, inflammation, diabetic mellitus, ulcers, wounds, itching, acne, toothache, earache, tongue cleaning, pain, asthma, constipation and antifertility.

AIM OF THE REVIEW

The main aim of this review is to provide an overview and critically analyze the reported ethnomedical uses, phytochemistry, pharmacological activities and toxicological studies of P. rubra and to identify the remaining gaps and thus supply a basis for further investigations. The review also focuses towards drawing attention of people and researchers about the wide spread pharmaceutical properties of the plant for its better utilization in the coming future.

MATERIAL AND METHODS

All the relevant data and information on P. rubra was gathered using various databases such as PubMed, Springer, Taylor and Francis imprints, NCBI (National Center for Biotechnology Information), Science direct, Google scholar, Chemspider, SciFinder, research and review articles from peer-reviewed journals and unpublished data such as Phd thesis, etc. Some other 'grey literature' sources such as webpages, ethnobotanical books, chapters, wikipedia were also studied.

RESULTS

More than 110 chemical constituents have been isolated from P. rubra including iridoids, terpenoids, flavonoids and flavonoid glycosides, alkaloids, glycosides, fatty acid esters, carbohydrates, animo acids, lignan, coumarin, volatile oils, etc. The important chemical constituents responsible for pharmacological activities of the plant are fulvoplumierin, plumieride, rubrinol, lupeol, oleanolic acid, stigmasterol, taraxasteryl acetate, plumieride-p-E-coumarate, rubranonoside, rubrajalellol, plumericin, isoplumericin, etc. The plant possess a wide range of pharmacological activities present namely antibacterial, antiviral, anti-inflammatory, antipyretic, antidiabetic, hepatoprotective, anticancer, anthelmintic, antifertility and many other activities.

CONCLUSION

P. rubra is a valuable medicinal source and further study in this topic can validate the traditional and ethnobotanical use of the plant. However, many aspects of the plant have not been studied yet. The pharmacological activity of active chemical constituent isolated from the plant is proven only for a couple of activities hence, lack of bio-guided isolation strategies is observed. Further studies on bioavailability, pharmacokinetics, mechanism of action and structural activity relationship studies of isolated pure compounds will contribute more in understanding their pharmacological effects. Higher doses of plant extracts are administered to experimental animals, therefore their toxicity and side effects in humans are needed to be thoroughly studied, although no side effect or toxicity is seen or observed in experimental animals. Studies are also essential to investigate the long term in vivo toxicity and clinical efficacy of the plant.

Three phragmalin-type limonoids orthoesters and the structure of odoratone isolated from the bark of Entandrophragma candollei (Meliaceae)

The phytochemical exploration of the Entandrophragma candollei stem bark extract led to the isolation and identification of twenty compounds including three undescribed phragmalin-class limonoids named encandollens C-E (1-3), the undescribed protolimonoid 5 together with sixteen known compounds. The structures of all the isolated compounds were determined by interpretation of their spectroscopic and spectrometric data including HRMS, 1D and 2D NMR analyses. The assignment of the absolute and relative stereochemistry of the undescribed compounds was achieved using SC-XRD analyses as well as NOESY experiments. The previously reported structure of odoratone (5a) was corrected as 23 R,24 S-dihydroxy-22 S,25-epoxytirucall-7-en-3-one (5) based on its NMR and SC-XRD data. Prieurianin (4) exhibited high cytotoxic activity on KB3-1 cell lines with an IC₅₀ of 1.47 μM compared to the reference griseofulvin (IC₅₀ = 17-21 μM). The results of the in silico docking of compound 4 supported and delivered further insights on its cytotoxicity.

Natural tyrosine kinase inhibitors acting on the epidermal growth factor receptor: Their relevance for cancer therapy

Epidermal growth factor receptor (EGFR), also known as ErbB-1/HER-1, plays a key role in the regulation of the cell proliferation, migration, differentiation, and survival. Since the constitutive activation or overexpression of EGFR is nearly found in various cancers, the applications focused on EGFR are the most widely used in the clinical level, including the therapeutic drugs of targeting EGFR, monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs).Over the past decades, the compounds from natural sources have been a productive source of novel drugs, especially in both discovery and development of anti-tumor drugs by targeting the EGFR pathways as the TKIs. This work presents a review of the compounds from natural sources as potential EGFR-TKIs involved in the regulation of cancer. Moreover, high-throughput drug screening of EGFR-TKIs from the natural compounds has also been summarized.

Elucidation of the effect of plumbagin on the metastatic potential of B16F10 murine melanoma cells via MAPK signalling pathway

Melanoma is the most dangerous form of skin cancer with a very poor prognosis. Melanoma develops when unrepaired DNA damage causes to skin cells to multiply and form malignant tumors. The current therapy is limited by the highly ability of this disease to metastasize rapidly. Plumbagin is a naphthoquinone (5-hydroxy-2-methyl-1, 4-naphthoquinone), isolated from the roots of medicinal plant Plumbago zeylanica, and it is widely present in Lawsonia inermis L. It has been shown that plumbagin has an anti-proliferative and anti-invasive activities in various cancer cell lines; however, the anti-cancer and anti-metastatic effects of plumbagin are largely unknown against melanoma cells. In this study, we evaluated the effect of plumbagin on B16F10 murine melanoma cells . Plumbagin decreased B16F10 cell viability as well as the cell migration, adhesion, and invasion. The molecular mechanism was studied, and plumbagin downregulated genes relevant in MAPK pathway, matrix metalloproteinases (MMP's), and cell adhesion. Furthermore, plumbagin elevated the expression of apoptosis and tumors suppressor genes, and genes significant in reactive oxygen species (ROS) response. Taken together, our findings suggest that plumbagin has an anti-invasion and anti-metastasis effect on melanoma cancer cells by acting on MAPK pathway and its related genes.

Anil Kumar N, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, Abdulmajid Ayatollahi S, Valere Tsouh Fokou P, Kobarfard F, Amiruddin Zakaria Z, Iriti M, Taheri Y, Martorell M, Sureda A, N. Setzer W, Durazzo A, Lucarini M, Santini A, Capasso R, Adrian Ostrander E, -ur-Rahman A, Iqbal Choudhary M, C. Cho W, Sharifi-Rad J. Antidiabetic Potential of Medicinal Plants and Their Active Components

Diabetes mellitus is one of the major health problems in the world, the incidence and associated mortality are increasing. Inadequate regulation of the blood sugar imposes serious consequences for health. Conventional antidiabetic drugs are effective, however, also with unavoidable side effects. On the other hand, medicinal plants may act as an alternative source of antidiabetic agents. Examples of medicinal plants with antidiabetic potential are described, with focuses on preclinical and clinical studies. The beneficial potential of each plant matrix is given by the combined and concerted action of their profile of biologically active compounds.

Food applications of Irvingia gabonensis (Aubry-Lecomte ex. O'Rorke) Baill., the 'bush mango': A review

Irvingia gabonensis, also known as 'bush mango', is a multipurpose fruit tree, native to tropical Africa. It is a priority indigenous fruit tree in western and central Africa since its wood is used for making utensils and fruits are mostly used as food and medicine. The objective of this work is to provide an updated review of the available knowledge about physicochemical characteristics of I. gabonensis fruit in order to evaluate its potential use in the food industry. The fruit mesocarp contains various phytochemicals and ascorbic acid concentration higher than some vitamin C rich fruits, then it is consumed fresh or dried, used to produce juice and wine, or as a flavourant. I. gabonensis fruit kernel is rich in oil (63%-69% crude fat), mainly composed of myristic and lauric acids. Its triacylglycerol composition and, resultantly, melting curve and polymorphism indicate an aptitude for diverse applications, as it is solid at room temperature. Forty-one phenolic compounds were identified in the seeds and derived extracts and supplements, being ellagic acid and its derivates the most present. This review enhances our knowledge about nutritional content and health benefits of I. gabonensis whole fruit, especially its pulp and seed, evidencing the need for safer and more efficient production of value-added products.

Emerging role of plumbagin: Cytotoxic potential and pharmaceutical relevance towards cancer therapy

Plumbagin is a naphthoquinone derived yellow crystalline phytochemical. Plumbagin has a wide range of biological effects including cytotoxicity against cancer cells both in vitro and in vivo. Due to the pleiotropic nature of plumbagin, it shows the anticancer effect by targeting several molecular mechanisms including apoptosis and autophagic pathways, cell cycle arrest, anti-angiogenic pathways, anti-invasion and anti-metastasis pathways. Among many signaling pathways the key regulatory genes regulated by plumbagin are NF-kβ, STAT3, and AKT, etc. Plumbagin is also a potent inducer of ROS, suppressor of cellular glutathione, and causes DNA strand break by oxidative DNA base damages. In vivo studies suggested that plumbagin significantly reduces the tumor weight and volume in dose-dependent manner without any side effects in tested model organisms. Another exciting aspect of plumbagin is the ability to re-sensitize the chemo and radioresistant cancer cells when used in combination or alone. Nano encapsulation of plumbagin overcomes the poor water solubility and bioavailability obstacles, enhancing the pharmaceutical relevance with better therapeutic efficacy. Moreover, plumbagin can be introduced as a future phytotherapeutic anticancer drug after fully satisfied preclinical and clinical trials.

Cytotoxicity of naturally occurring phenolics and terpenoids from Kenyan flora towards human carcinoma cells

Background

Cancer constitutes a major hurdle worldwide and its treatment mainly relies on chemotherapy.

Objectives

The present study was designed to evaluate the cytotoxicity of eleven naturally occurring compounds including six phenolics amongst them were 4 chalcones and 2 flavanones as well as 5 terpenoids (3 clerodane and 2 trachylobane diterpenoids) against 6 human carcinoma cell lines and normal CRL2120 fibroblasts.

Materials and methods

The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of the compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle and mitochondrial membrane potential (MMP) were all analyzed via flow cytometry meanwhile levels of reactive oxygen species (ROS) was measured by spectrophotometry.

Results

Chalcones: 2′,4′-dihydroxy-6′-methoxychalcone (1); 4′,6′-dihydroxy-2′,5′-dimethoxychalcone (2); 2′,4′,6′-trihydroxy-5′-methoxychalcone (3); 2′,6′-diacetate-4′-methoxychalcone (4), trachylobane diterpenoids: 2,6,19-trachylobanetriol; (ent-2α,6α)-form (10) and 2,18,19-trachylobanetriol; (ent-2α)-form (11) as well as doxorubicin displayed IC₅₀ values below 110 μM in the six tested cancer cell lines. The IC₅₀ values of the most active compounds were between 6.30 μM and 46.23 μM for compound 1 respectively towards breast adenocarcinoma MCF-7 cells and small lung cancer A549 cells and between 0.07 μM and 1.01 μM for doxorubicin respectively against SPC212 cells and A549 cells. Compounds 1 induced apoptosis in MCF-7 cells mediated by increasing ROS production and MMP loss.

Conclusion

Chalcones 1–3 are potential cytotoxic phytochemicals that deserve more investigations to develop novel anticancer drugs against human carcinoma.

Bioactive Pentacyclic Triterpenes from the Root Bark Extract of Myrianthus arboreus, a Species Used Traditionally to Treat Type-2 Diabetes

Four new Δ¹² ursene-type pentacyclic triterpenes containing the trans-feruloyl moiety (1-4), along with ursolic acid (5), were isolated from a Myrianthus arboreus root bark ethanol extract, after bioassay-guided subfractionation of its hexane fraction. The structures of 1-4 were established on the basis of the results of standard spectroscopic analytical methods (IR, HRESIMS, GC-MS, 1D and 2D NMR). The compounds 3β- O- trans-feruloyl-2α,19α-dihydroxyurs-12-en-28-oic acid (1), 2α-acetoxy-3β- O- trans-feruloyl-19α-hydroxyurs-12-en-28-oic acid (3), and 5 were determined to decrease the activity of hepatocellular glucose-6-phosphatase (G6Pase) and to activate glycogen synthase (GS). Their action on G6Pase activity implicated both Akt and AMPK activation. In addition, these compounds were determined to stimulate GS via the phosphorylation of glycogen synthase kinase-3. Compound 3 showed the most potent effect in modulating glucose homeostasis in liver cells. This is the first comprehensive report on novel phytochemical components of the root bark extract of M. arboreus based on the isolation of the principles responsible for its antidiabetic effects.

Phytochemistry and pharmacology of the genus Entandrophragma over the 50 years from 1967 to 2018: a ‘golden’ overview

Objectives

For centuries, the genus Entandrophragma (Meliaceae), endemic to Africa, has been used in traditional medicine for the treatment of several illnesses. This review deals with large range of phytochemicals from the genus Entandrophragma and their pharmacological potentials covering the period from 1967 to 2018.

Key findings

Phytochemical investigations of the genus Entandrophragma led to the report of about 166 secondary metabolites which have been thoroughly summarized herein including some of their semisynthetic derivatives obtained from chemical transformations as well as their biological activities in the medicinal and agricultural domains. The limonoids or meliacins and their precursor called protolimonoids (protomeliacins) reported so far represent almost 69.28% of the total secondary metabolites obtained from the genus, and they display the most potent biological activities. Collectively, both classes of metabolites constitute the markers of Entandrophragma. However, squalene-type triterpenoids and sesquiterpenoids were reported only from the species E. cylindricum and therefore could be its chemotaxonomic markers.

Summary

The pharmacological investigations of the extracts of some species exhibited interesting results which support the traditional uses of these Entandrophragma plants in folk medicine. Some compounds revealed promising antiplasmodial and anti-inflammatory activities and deserve therefore further attention for new drug discovery.

Compounds from African Medicinal Plants with Activities Against Selected Parasitic Diseases: Schistosomiasis, Trypanosomiasis and Leishmaniasis

Parasitic diseases continue to represent a threat on a global scale, particularly among the poorest countries in the world. This is particularly because of the absence of vaccines, and in some cases, resistance against available drugs, currently being used for their treatment. In this review emphasis is laid on natural products and scaffolds from African medicinal plants (AMPs) for lead drug discovery and possible further development of drugs for the treatment of parasitic diseases. In the discussion, emphasis has been laid on alkaloids, terpenoids, quinones, flavonoids and narrower compound classes of compounds with micromolar range activities against Schistosoma, Trypanosoma and Leishmania species. In each subparagraph, emphasis is laid on the compound subclasses with most promising in vitro and/or in vivo activities of plant extracts and isolated compounds. Suggestions for future drug development from African medicinal plants have also been provided. This review covering 167 references, including 82 compounds, provides information published within two decades (1997-2017).

Integration of phytochemicals and phytotherapy into cancer precision medicine

Concepts of individualized therapy in the 1970s and 1980s attempted to develop predictive in vitro tests for individual drug responsiveness without reaching clinical routine. Precision medicine attempts to device novel individual cancer therapy strategies. Using bioinformatics, relevant knowledge is extracted from huge data amounts. However, tumor heterogeneity challenges chemotherapy due to genetically and phenotypically different cell subpopulations, which may lead to refractory tumors. Natural products always served as vital resources for cancer therapy (e.g., Vinca alkaloids, camptothecin, paclitaxel, etc.) and are also sources for novel drugs. Targeted drugs developed to specifically address tumor-related proteins represent the basis of precision medicine. Natural products from plants represent excellent resource for targeted therapies. Phytochemicals and herbal mixtures act multi-specifically, i.e. they attack multiple targets at the same time. Network pharmacology facilitates the identification of the complexity of pharmacogenomic networks and new signaling networks that are distorted in tumors. In the present review, we give a conceptual overview, how the problem of drug resistance may be approached by integrating phytochemicals and phytotherapy into academic western medicine. Modern technology platforms (e.g. “-omics” technologies, DNA/RNA sequencing, and network pharmacology) can be applied for diverse treatment modalities such as cytotoxic and targeted chemotherapy as well as phytochemicals and phytotherapy. Thereby, these technologies represent an integrative momentum to merge the best of two worlds: clinical oncology and traditional medicine. In conclusion, the integration of phytochemicals and phytotherapy into cancer precision medicine represents a valuable asset to chemically synthesized chemicals and therapeutic antibodies.

Neoboutonia melleri var velutina Prain: in vitro and in vivo hepatoprotective effects of the aqueous stem bark extract on acute hepatitis models

BACKGROUND

Hepatitis is a liver inflammation caused by different agents and remains a public health problem worldwide. Medicinal plants are an important source of new molecules being considered for treatment of this disease. Our work aims at evaluating the hepatoprotective properties of Neoboutonia velutina, a Cameroonian medicinal plant.

METHODS

The aqueous extract has been prepared using phytochemical methods. HepG2 cells were used to assess anti-inflammatory properties of the extract at different concentrations. Acute hepatitis models (Carbon tetrachloride and Concanavalin A) were performed in mice receiving or not receiving, different extract doses by gavage. Liver injury was assessed using histology, transaminases and pro-inflammatory markers. Extract antioxidant and radical scavenging capacities were evaluated.

RESULTS

The extract led to a significant decrease in pro-inflammatory cytokine expression in vitro and to a remarkable protection of mice from carbon tetrachloride-induced liver injury, as shown by a significant decrease in dose-dependent transaminases level. Upon extract treatment, inflammatory markers were significantly decreased and liver injuries were limited as well. In the Concanavalin A model, the extract displayed weak effects.

CONCLUSIONS

Taking into account underlying mechanisms in both hepatitis models, we demonstrate the extract's radical scavenging capacity. Neoboutonia velutina displays a potent hepatoprotective effect mediated through radical scavenging properties.

Anti-cancer agents in Saudi Arabian herbals revealed by automated high-content imaging

Natural products have been used for medical applications since ancient times. Commonly, natural products are structurally complex chemical compounds that efficiently interact with their biological targets, making them useful drug candidates in cancer therapy. Here, we used cell-based phenotypic profiling and image-based high-content screening to study the mode of action and potential cellular targets of plants historically used in Saudi Arabia’s traditional medicine. We compared the cytological profiles of fractions taken from Juniperus phoenicea (Arar), Anastatica hierochuntica (Kaff Maryam), and Citrullus colocynthis (Hanzal) with a set of reference compounds with established modes of action. Cluster analyses of the cytological profiles of the tested compounds suggested that these plants contain possible topoisomerase inhibitors that could be effective in cancer treatment. Using histone H2AX phosphorylation as a marker for DNA damage, we discovered that some of the compounds induced double-strand DNA breaks. Furthermore, chemical analysis of the active fraction isolated from Juniperus phoenicea revealed possible anti-cancer compounds. Our results demonstrate the usefulness of cell-based phenotypic screening of natural products to reveal their biological activities.

Potential of Central, Eastern and Western Africa Medicinal Plants for Cancer Therapy: Spotlight on Resistant Cells and Molecular Targets

Cancer remains a major health hurdle worldwide and has moved from the third leading cause of death in the year 1990 to second place after cardiovascular disease since 2013. Chemotherapy is one of the most widely used treatment modes; however, its efficiency is limited due to the resistance of cancer cells to cytotoxic agents. The present overview deals with the potential of the flora of Central, Eastern and Western African (CEWA) regions as resource for anticancer drug discovery. It also reviews the molecular targets of phytochemicals of these plants such as ABC transporters, namely P-glycoprotein (P-gp), multi drug-resistance-related proteins (MRPs), breast cancer resistance protein (BCRP, ABCG2) as well as the epidermal growth factor receptor (EGFR/ErbB-1/HER1), human tumor suppressor protein p53, caspases, mitochondria, angiogenesis, and components of MAP kinase signaling pathways. Plants with the ability to preferentially kills resistant cancer cells were also reported. Data compiled in the present document were retrieved from scientific websites such as PubMed, Scopus, Sciencedirect, Web-of-Science, and Scholar Google. In summary, plant extracts from CEWA and isolated compounds thereof exert cytotoxic effects by several modes of action including caspases activation, alteration of mitochondrial membrane potential (MMP), induction of reactive oxygen species (ROS) in cancer cells and inhibition of angiogenesis. Ten strongest cytotoxic plants from CEWA recorded following in vitro screening assays are: Beilschmiedia acuta Kosterm, Echinops giganteus var. lelyi (C. D. Adams) A. Rich., Erythrina sigmoidea Hua (Fabaceae), Imperata cylindrical Beauv. var. koenigii Durand et Schinz, Nauclea pobeguinii (Pobég. ex Pellegr.) Merr. ex E.M.A., Piper capense L.f., Polyscias fulva (Hiern) Harms., Uapaca togoensis Pax., Vepris soyauxii Engl. and Xylopia aethiopica (Dunal) A. Rich. Prominent antiproliferative compounds include: isoquinoline alkaloid isotetrandrine (51), two benzophenones: guttiferone E (26) and isoxanthochymol (30), the isoflavonoid 6α-hydroxyphaseollidin (9), the naphthyl butenone guieranone A (25), two naphthoquinones: 2-acetylfuro-1,4-naphthoquinone (4) and plumbagin (37) and xanthone V1 (46). However, only few research activities in the African continent focus on cytotoxic drug discovery from botanicals. The present review is expected to stimulate further scientific efforts to better valorize the African flora.

Cytotoxicity of the methanol extracts of Elephantopus mollis, Kalanchoe crenata and 4 other Cameroonian medicinal plants towards human carcinoma cells

BACKGROUND

Cancer still constitutes one of the major health concerns globally, causing serious threats on patients, their families, and the healthcare system.

METHODS

In this study, the cytotoxicity of the methanol extract of Elephantopus mollis whole plant (EMW), Enantia chlorantha bark (ECB), Kalanchoe crenata leaves (KCL), Lophira alata bark (LAB), Millettia macrophylla leaves (MML) and Phragmanthera capitata leaves (PCL) towards five human solid cancer cell lines and normal CRL2120 fibroblasts, was evaluated. Extracts were subjected to qualitative chemical screening of their secondary metabolite contents using standard methods. The cytotoxicity of samples was evaluated using neutral red uptake (NR) assay meanwhile caspase activation was detected by caspase-Glo assay. Flow cytometry was used to analyze the cell cycle distribution and the mitochondrial membrane potential (MMP) whilst spectrophotometry was used to measure the levels of reactive oxygen species (ROS).

RESULTS

Phytochemical analysis revealed the presence of polyphenols, triterpenes and sterols in all extracts. The IC₅₀ values of the best samples ranged from 3.29 μg/mL (towards DLD-1 colorectal adenocarcinoma cells) to 24.38 μg/mL (against small lung cancer A549 cells) for EMW, from 2.33 μg/mL (mesothelioma SPC212 cells) to 28.96 μg/mL (HepG2 hepatocarcinoma) for KCL, and from 0.04 μg/mL (towards SPC212 cells) to 0.55 μg/mL (towards A549 cells) for doxorubicin. EMW induced apoptosis in MCF-7 cells mediated by MMP loss and increased ROS production whilst KCL induced apoptosis via ROS production.

CONCLUSION

This study provides evidences of the cytotoxicity of the tested plant extract and highlights the good activity of Elephantopus mollis and Kalanchoe crenata. They deserve more exploration to develop novel cytotoxic drugs.

Ficus umbellata Vahl. (Moraceae) Stem Bark Extracts Exert Antitumor Activities In Vitro and In Vivo

A Ficus umbellata is used to treat cancer. The present work was therefore designed to assess antitumor potentials of F. umbellata extracts in nine different cell lines. Cell cycle, apoptosis, cell migration/invasion, levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), caspases activities as well as Bcl-2 and Bcl-xL protein content were assessed in MDA-MB-231 cells. The 7,12-dimethylbenz(a)anthracene (DMBA)-induced carcinogenesis in rats were also used to investigate antitumor potential of F. umbellata extracts. The F. umbellata methanol extract exhibited a CC50 of 180 μg/mL in MDA-MB-231 cells after 24 h. It induced apoptosis in MCF-7 and MDA-MB-231 cells, while it did not alter their cell cycle phases. Further, it induced a decrease in MMP, an increase in ROS levels and caspases activities as well as a downregulation in Bcl-2 and Bcl-xL protein contents in MDA-MB-231 cells. In vivo, F. umbellata aqueous (200 mg/kg) and methanol (50 mg/kg) extracts significantly (p < 0.001) reduced ovarian tumor incidence (10%), total tumor burden (58% and 46%, respectively), average tumor weight (57.8% and 45.6%, respectively) as compared to DMBA control group. These results suggest antitumor potential of F. umbellata constituents possibly due to apoptosis induction mediated through ROS-dependent mitochondrial pathway.

Cytotoxicity of Plumbagin, Rapanone and 12 other naturally occurring Quinones from Kenyan Flora towards human carcinoma cells

Background

Cancer is a major public health concern globally and chemotherapy remains the principal mode of the treatment of various malignant diseases.

Methods

This study was designed to investigate the cytotoxicity of 14 naturally occurring quinones including; 3 anthraquinones, 1 naphthoquinone and 10 benzoquinones against 6 human carcinoma cell lines and normal CRL2120 fibroblasts. The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of the compounds, whilst caspase-Glo assay was used to detect caspases activation. Cell cycle and mitochondrial membrane potential (MMP) were all analyzed via flow cytometry meanwhile levels of reactive oxygen species (ROS) were measured by spectrophotometry.

Results

Anthraquinone: emodin (2), naphthoquinone: plumbagin (4), and benzoquinones: rapanone (9), 2,5-dihydroxy-3-pentadecyl-2,5-cyclohexadiene-1,4-dione (10), 5-O-methylembelin (11), 1,2,4,5-tetraacetate-3-methyl-6-(14-nonadecenyl)-cyclohexadi-2,5-diene (13), as well as doxorubicin displayed interesting activities with IC₅₀ values below 100 μM in the six tested cancer cell lines. The IC₅₀ values ranged from 37.57 μM (towards breast adenocarcinoma MCF-7 cells) to 99.31 μM (towards small cell lung cancer A549 cells) for 2, from 0.06 μM (MCF-7 cells) to 1.14 μM (A549 cells) for 4, from 2.27 μM (mesothelioma SPC212 cells) to 46.62 μM (colorectal adenocarcinoma DLD-1 cells) for 9, from 8.39 μM (SPC212 cells) to 48.35 μM (hepatocarinoma HepG2 cells) for 10, from 22.57 μM (MCF-7 cells) to 61.28 μM (HepG2 cells) for 11, from 9.25 μM (MCF-7 cells) to 47.53 μM (A549 cells) for 13, and from 0.07 μM (SPC212 cells) to 1.01 μM (A549 cells) for doxorubicin. Compounds 4 and 9 induced apoptosis in MCF-7 cells mediated by increased ROS production and MMP loss, respectively.

Conclusion

The tested natural products and mostly 2, 4, 9, 10, 11 and 13 are potential cytotoxic compounds that deserve more investigations towards developing novel antiproliferative drugs against human carcinoma.

Cytotoxicity of methanol extracts of Annona muricata, Passiflora edulis and nine other Cameroonian medicinal plants towards multi-factorial drug-resistant cancer cell lines

BACKGROUND

Cancer cells rapidly acquire resistance leading to treatment failures. In the present study, we have evaluated the cytotoxicity of 17 methanol extracts from 11 Cameroonian medicinal plants against the sensitive leukemia CCRF-CEM cells and the best ones were further tested on a panel of 8 other human cancer cell lines, including various MDR phenotypes as well as against the normal AML12 hepatocytes.

METHODS

The cytotoxicity of the extracts was determined using a resazurin reduction assay meanwhile flow cytometry was used to measure cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species.

RESULTS

In an initial screening using leukemia CCRF-CEM cells, ten extracts from five plants namely Alchornea floribunda, Annona muricata, Euphorbia prostata, Pachypodanthium staudtii and Passiflora edulis displayed IC50 values below 20 µg/mL. They were further tested in 8 other cell lines as well as in normal AML12 hepatocytes. All selected extracts were active against leukemia CEM/ADR5000 cells with IC50 value below 40 µg/mL. IC50 values ranging from 10.13 µg/mL (towards CEM/ADR5000 cells) to 72.01 µg/mL [towards resistant colon carcinoma HCT116 (p53-/-) cells] for Pachypodanthium staudtii roots and from 0.11 µg/mL (towards CCRF-CEM cells) to 108 µg/mL (towards P-glycoprotein-over-expressing CEM/ADR5000 cells) for doxorubicin were obtained in the eight other cancer cell lines studied. Extracts from Annona muricata leaves (AML) and seeds (AMS), and Passiflora edulis fruit (PEF) had IC50 values below 1 µg/mL against CCRF-CEM cells and below 10 µg/mL against its MDR subline CEM/ADR5000 cells. AML, AMS and PEF induced MMP-loss-mediated apoptosis in CCRF-CEM cells.

CONCLUSIONS

Results of the present study suggest that some of the tested plants namely Alchornea floribunda, Annona muricata, Euphorbia prostata, Pachypodanthium staudtii and Passiflora edulis represent a source of anticancer drugs. Annona muricata and Passiflora edulis are good cytotoxic plants that could be exploited to develop phytomedicine to fight mostly hematological cancers including MDR phenotypes.

Cytotoxicity of methanol extracts of 10 Cameroonian medicinal plants towards multi-factorial drug-resistant cancer cell lines

Background

Cancer chemotherapy is still hampered by clinical failures due to multi-drug resistance (MDR) of tumor cells. In the present study, we have investigated the cytotoxicity of 20 methanol extracts from 10 medicinal plants against the sensitive leukemia CCRF-CEM cells. The most cytotoxic extracts were then further tested on a panel of 8 human cancer cell lines, including various MDR phenotypes.

Methods

The cytotoxicity of the 20 methanol extracts from 10 Cameroonian medicinal plants was determined using a resazurin reduction assay. Meanwhile, flow cytometry was used to measure cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS).

Results

In the preliminary assay using CCRF-CEM cells, 12 extracts from five plants displayed IC₅₀ values below 80 μg/mL, namely Albizia adianthifolia, Alchornea cordifolia, Alchornea laxiflora, Pennisetum purpureum, and Spathodea campanulata. the four best extracts were from two plants: Albizia adianthifolia roots (AAR) and bark (AAB) as well as Alchornea cordifolia leaves (ACL) and bark (ACB) had respective IC₅₀ values of 0.98 μg/mL, 1.45 μg/mL, 8.02 μg/mL and 12.57 μg/mL in CCRF-CEM cells. They were further tested in 8 other cell lines as well as in normal AML12 hepatocytes. IC₅₀ values ranging from 2.71 μg/mL (towards glioblastoma U87MG.ΔEGFR cells) to 10.30 μg/mL (towards breast adenocarcinoma MDA-MB-231-BCRP cells) for AAB, from 3.43 μg/mL (towards U87MG cells) to 10.77 μg/mL (towards colon carcinoma HCT116 (p53^−/−) cells) for AAR and from 0.11 μg/mL (towards CCRF-CEM cells) to 108 μg/mL (towards leukemia CEM/ADR5000 cells) for doxorubicin (as control drug) were obtained. ACL and ACB extracts displayed selective activities. AAR and ACL extracts induced apoptosis in CCRF-CEM cells, through caspases activation and loss of MMP, while apoptotic cell death was mediated by MMP diruption and increase ROS production for ACL.

Conclusion

Some of the tested plants namely Albizia adianthifolia, Alchornea cordifolia, Alchornea laxiflora, Pennisetum purpureum, Spathodea campanulata represent a potential source of novel anticancer drugs. Especially, Albizia adianthifolia and Alchornea cordifolia revealed considerable cytotoxic activities that could be exploited to develop phytomedicines to fight cancers including MDR phenotypes.

Cytotoxicity of 15 Cameroonian medicinal plants against drug sensitive and multi-drug resistant cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Cameroonian medicinal plants are traditionally used to treat many ailments, including cancer and related diseases. Cancer is characterized as a condition with complex signs and symptoms. It has been recommended that ethnopharmacological usages such as immune and skin disorders, inflammatory, infectious, parasitic and viral diseases should be taken into account when selecting plants for anticancer screenings, since these reflect disease states bearing relevance to cancer or cancer-like symptoms.

AIM OF THE STUDY

The present study aims at investigating 20 methanol extracts from 15 Cameroonian medicinal plants on a panel of human cancer cell lines, including various drug-resistant phenotypes. Possible modes of action of the of the most active plant were analyzed.

MATERIALS AND METHODS

Methanol extracts from different plant parts (leaves, bark, roots, fruits or whole plant) were evaluated for their cytotoxicity using resazurin reduction assay on a panel of nine sensitive and multi-drug resistant (MDR) cancer cell lines. Cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured by flow cytometry.

RESULTS

Prescreening of extracts at 80µg/mL showed that 6 extracts out of 20 inhibited more than 50% proliferation of leukemia CCRF-CEM cells; these include extracts from Anthocleista schweinfurthii fruits (ASF; 48.28%), Morus mesozygia bark (MMB; 42.76%), Nauclea latifolia bark (NLB; 38.75%), Tridesmostemon omphalocarpoides bark (TOB; 38.53%), Nauclea latifolia leaves (NLL; 35.17%) and Erythrina sigmoidea bark (ESB; 33.77%). Subsequent investigations revealed IC50 values below or around 20µg/mL for extracts from MMB, NLB, NLL and ESB towards sensitive CCRF-CEM cells and its resistant P-glycoprotein over-expressing subline CEM/ADR5000. The best extract, ESB also displayed IC50 values below 20µg/mL colon carcinoma HCT116 (p53(+/+)) cells with an IC50 value of 19.63µg/mL and it resistant p53 knockout subline HCT116 (p53(-)(/-)) with an IC50 value of 16.22µg/mL.

CONCLUSION

Erythrina sigmoidea, Anthocleista schweinfurthii, Morus mesozygia, Nauclea latifolia, Tridesmostemon omphalocarpoides used in African traditional medicine are good cytotoxic plants that can be exploited to develop phytomedicine to fight cancers including MDR phenotypes.

Is there a role of pharmacogenomics in Africa

Pharmacogenomics has the potential of transforming clinical research and improving healthcare in sub-Saharan Africa (SSA). The role of African genome diversity and the opportunities for pharmacogenomics research are highlighted and will enable discovery of novel genetic mechanisms and validation of established markers. African genomics and biobank consortia will play an important role in building capacity for pharmacogenomics in SSA.

In vitro antibacterial and antibiotic-potentiation activities of the methanol extracts from Beilschmiedia acuta, Clausena anisata, Newbouldia laevis and Polyscias fulva against multidrug-resistant Gram-negative bacteria

Background

The present study was designed to investigate the antibacterial activities of the methanol extracts from different parts of Beilschmedia acuta Kosterm (Lauraceae), Clausena anisata (Willd) Hook (Rutaceae), Newbouldia laevis Seem (Bignoniaceae) and Polyscias fulva (Hiern) Harms (Araliaceae) as well as their synergistic effects with antibiotics against a panel of Gram-negative bacteria, including multi-drug resistant (MDR) phenotypes expressing active efflux pumps.

Methods

Broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of the extracts, as well as those of antibiotics in association with the most active ones, B. acuta, N. laevis and P. fulva.

Results

MIC values obtained indicate that extracts from the bark of B. acuta were active on all the 26 tested Gram-negative bacteria, with MICs ranging from values below 8 to 256 μg/mL. Other samples displayed selective activities, their inhibitory effects being observed on 9 (34.62 %) of the 26 bacterial strains for N. laevis leaves extract, 6 (23.10 %) for both C. anisata leaves and roots extracts, 7 (26.9 %) and 4 (15.4 %) for leaves and roots extracts of P. fulva respectively. Extract from B. actua bark displayed the best antibacterial activity with MIC values below 100 μg/mL against 16 (61.5 %) of the 26 tested microorganisms. The lowest MIC values (below 8 μg/mL) were obtained with this extract against Escherichia coli W3110 and Klebsiella pneumoniae ATCC11296. The MIC values of this extract were lower than those of ciprofloxacin against E. coli W3110, Enterobacter aerogenes ATCC13048, CM64 and Providencia stuartii NAE16. At MIC/2, the best percentages of synergistic effects (100 %), were obtained with B. acuta bark extract and tetracycline (TET) as well as with P. fulva leaves extract and TET and kanamycin (KAN).

Conclusion

The overall results of the present study provide information for the possible use of the studied plants and mostly Beilschmedia acuta in the control of bacterial infections including MDR phenotypes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0944-5) contains supplementary material, which is available to authorized users.

Antibacterial and antibiotic resistance modifying activity of the extracts from Allanblackia gabonensis, Combretum molle and Gladiolus quartinianus against Gram-negative bacteria including multi-drug resistant phenotypes

BACKGROUND

Bacterial resistance to antibiotics is becoming a serious problem worldwide. The discovery of new and effective antimicrobials and/or resistance modulators is necessary to tackle the spread of resistance or to reverse the multi-drug resistance. We investigated the antibacterial and antibiotic-resistance modifying activities of the methanol extracts from Allanblackia gabonensis, Gladiolus quartinianus and Combretum molle against 29 Gram-negative bacteria including multi-drug resistant (MDR) phenotypes.

METHODS

The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of the samples meanwhile the standard phytochemical methods were used for the preliminary phytochemical screening of the plant extracts.

RESULTS

Phytochemical analysis showed the presence of alkaloids, flavonoids, phenols and tannins in all studied extracts. Other chemical classes of secondary metabolites were selectively presents. Extracts from A. gabonensis and C. molle displayed a broad spectrum of activity with MICs varying from 16 to 1024 μg/mL against about 72.41% of the tested bacteria. The extract from the fruits of A. gabonensis had the best activity, with MIC values below 100 μg/mL on 37.9% of tested bacteria. Percentages of antibiotic-modulating effects ranging from 67 to 100% were observed against tested MDR bacteria when combining the leaves extract from C. molle (at MIC/2 and MIC/4) with chloramphenicol, kanamycin, streptomycin and tetracycline.

CONCLUSION

The overall results of the present study provide information for the possible use of the studied plant, especially Allanblackia gabonensis and Combretum molle in the control of Gram-negative bacterial infections including MDR species as antibacterials as well as resistance modulators.

Cytotoxicity of medicinal plants of the West-Canadian Gwich׳in Native Americans towards sensitive and multidrug-resistant cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicine of the Native Americans has a long tradition of medicinal plants, which also influenced modern oncology. For instance, podophyllotoxin the active ingredient of Podophyllum peltatum L. (Berberidaceae) used by Native Americans to treat warts led to the development of etoposide and teniposide. In the present investigation, we studied 10 medicinal plants used by the Gwich׳in First Nation of West-Canada, which have been used against diverse diseases including cancer.

MATERIAL AND METHODS

Sensitive and multidrug-resistant (MDR) tumor cell lines expressing various ATP-binding cassette (ABC) transporters (P-glycoprotein/ABCB1/MDR1, MRP1/ABCC1, or BCRP/ABCG2) have been used. Cytotoxicity was determined by the resazurin assay.

RESULTS

Arctium minus Bernh. (Asteraceae). Lysichiton americanus Hultén & St. John (Araceae), and Maianthemum dilatatum (Alph.Wood) A.Nelson & J.F.Macbr.(Asparagaceae) were cytotoxic with IC50 values ranging from 2.40 to 86.35 µg/mL. The MDR cell lines did not exert cross-resistance to these extracts.

CONCLUSION

As these medicinal plants of the West-Canadian Gwich׳in First Nation were not involved in classical drug resistance mechanisms and might therefore be valuable to bypass anticancer drug resistance in refractory tumors.

African flora has the potential to fight multidrug resistance of cancer

Background. Continuous efforts from scientists of diverse fields are necessary not only to better understand the mechanism by which multidrug-resistant (MDR) cancer cells occur, but also to boost the discovery of new cytotoxic compounds to fight MDR phenotypes. Objectives. The present review reports on the contribution of African flora in the discovery of potential cytotoxic phytochemicals against MDR cancer cells. Methodology. Scientific databases such as PubMed, ScienceDirect, Scopus, Google Scholar, and Web of Knowledge were used to retrieve publications related to African plants, isolated compounds, and drug resistant cancer cells. The data were analyzed to highlight cytotoxicity and the modes of actions of extracts and compounds of the most prominent African plants. Also, thresholds and cutoff points for the cytotoxicity and modes of action of phytochemicals have been provided. Results. Most published data related to the antiproliferative potential of African medicinal plants were from Cameroon, Egypt, Nigeria, or Madagascar. The cytotoxicity of phenolic compounds isolated in African plants was generally much better documented than that of terpenoids and alkaloids. Conclusion. African flora represents an enormous resource for novel cytotoxic compounds. To unravel the full potential, efforts should be strengthened throughout the continent, to meet the challenge of a successful fight against MDR cancers.

Antibacterial and Antiproliferative Activities of Plumericin, an Iridoid Isolated from Momordica charantia Vine

Plumericin, an iridoid lactone, was isolated with relatively high yield from Momordica charantia vine using the supercritical fluid extraction (SFE) and the separation box (Sepbox) comprising dual combination of high-performance liquid chromatography and solid phase extraction. This compound showed antibacterial activity against Enterococcus faecalis and Bacillus subtilis with minimum inhibitory concentration (MIC) values better than cloxacillin. Plumericin potently inhibited proliferation of two leukemic cancer cell lines: they were acute and chronic leukemic cancer cell lines, NB4 and K562, with the effective doses (ED50) of 4.35 ± 0.21 and 5.58 ± 0.35 μg/mL, respectively. In addition, the mechanism of growth inhibition in both cell lines was induced by apoptosis, together with G2/M arrest in K562 cells.

Elucidation of Underlying Mechanisms by Which Millettia macrophylla Benth Induces Its Estrogenic Activity

Millettia macrophylla is used traditionally to treat menopause related symptoms. This plant was shown to exhibit estrogenic effects in vitro on human embryonic kidney cells and in vivo on ovariectomized rats. The present study aimed at elucidating underlying mechanisms by which M. macrophylla induced its estrogenic effects. To accomplish our goal, kidney Hek293T cells transiently transfected with estrogen alpha or beta receptor expression plasmids were cotreated with a pure antiestrogen ICI 182,780 and the dichloromethane or methanol soluble fractions of M. macrophylla. To follow up, we cotreated ovariectomized rats with both extracts and ICI 182,780 for 3 days in the classical uterotrophic assay. Animals were then sacrificed and the uterine wet weight, total protein levels in uteri, uterine, and vaginal epithelial heights, and mammary gland were assessed. In vitro, the results suggested that the induction of the estrogenic activity by M. macrophylla is due to the binding of its secondary metabolites to ERα and ERβ. In vivo, the cotreatment of extracts and ICI 182,780 significantly abrogated the biological responses induced by the extracts alone. Taken together, these results indicate that the active principles of M. macrophylla induce their beneficial effects on menopausal symptoms by activating the ERs.

Application of transcriptomics in Chinese herbal medicine studies

Transcriptomics using DNA microarray has become a practical and popular tool for herbal medicine study because of high throughput, sensitivity, accuracy, specificity, and reproducibility. Therefore, this article focuses on the overview of DNA microarray technology and the application of DNA microarray in Chinese herbal medicine study. To understand the number and the objectives of articles utilizing DNA microarray for herbal medicine study, we surveyed 297 frequently used Chinese medicinal herbs listed in Pharmacopoeia Commission of People's Republic of China. We classified these medicinal herbs into 109 families and then applied PudMed search using “microarray” and individual herbal family as keywords. Although thousands of papers applying DNA microarray in Chinese herbal studies have been published since 1998, most of the articles focus on the elucidation of mechanisms of certain biological effects of herbs. Construction of the bioactivity database containing large-scaled gene expression profiles of quality control herbs can be applied in the future to analyze the biological events induced by herbs, predict the therapeutic potential of herbs, evaluate the safety of herbs, and identify the drug candidate of herbs. Moreover, the linkage of systems biology tools, such as functional genomics, transcriptomics, proteomics, metabolomics, pharmacogenomics and toxicogenomics, will become a new translational platform between Western medicine and Chinese herbal medicine.

Cytotoxicity and modes of action of five Cameroonian medicinal plants against multi-factorial drug resistance of tumor cells

ETHNOPHARMACOLOGICAL RELEVANCE

Beilschmiedia acuta Kosterm, Clausena anisata (Willd) Hook, Fagara tessmannii Engl., Newbouldia laevis Seem., and Polyscias fulva (Hiern) Harms. are medicinal plants used in Cameroonian traditional medicine in the treatment of various types of cancers. The present study aims at investigating 11 methanolic extracts from the above Cameroonian medicinal plants on a panel of human cancer cell lines, including various drug-resistant phenotypes. Possible modes of action were analyzed for two extracts from Beilschmiedia acuta and Polyscia fulva and alpha-hederin, the representative constituent of Polyscia fulva.

MATERIALS AND METHODS

Cytotoxicity was determined using a resazurin assay. Cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured by flow cytometry. Cellular response to alpha-hederin was investigated by a mRNA microarray approach.

RESULTS

Prescreening of extracts (40µg/mL) showed that three of eleven plant extracts inhibited proliferation of CCRF-CEM cells by more than 50%, i.e. BAL (73.65%), the bark extract of Beilschmiedia acuta (78.67%) and PFR (68.72%). Subsequent investigations revealed IC50 values below or around 30µg/mL of BAL and PFR in 10 cell lines, including drug-resistant models, i.e. P-glycoprotein-overexpressing CEM/ADR5000, breast cancer resistance protein-transfected MDA-MB-231-BCRP, TP53 knockout cells (HCT116 p53(-/-)), and mutation-activated epidermal growth factor receptor-transfected U87MG.ΔEGFR cells. IC50 values below 5µg/mL of BAL were obtained for HCT116 (p53(-/-)) cells. IC50 values below 10µM of alpha-hederin were found for sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 cells. The BAL and PFR extracts induced cell cycle arrest between G0/G1 and S phases. PFR-induced apoptosis was associated with increased ROS generation and MMP breakdown. Microarray-based cluster analysis revealed a gene expression profile that predicted cellular response to alpha-hederin.

CONCLUSION

BAL, PFL and alpha-hederin, an exemplarily taken constituent of Beilschmiedia acuta and Polyscia fulva extracts revealed cytotoxicity towards cancer cell lines. Hence, Beilschmiedia acuta and Polyscia fulva may be valuable to develop drugs against otherwise drug-resistant cancer cells.

Cytotoxicity of Elaoephorbia drupifera and other Cameroonian medicinal plants against drug sensitive and multidrug resistant cancer cells

Background

Multidrug resistance (MDR) is a major hurdle for cancer treatment worldwide and accounts for chemotherapy failure in over 90% of patients with metastatic cancer. Evidence of the cytotoxicity of Cameroonian plants against cancer cell lines including MDR phenotypes is been intensively and progressively provided. The present work was therefore designed to evaluate the cytotoxicity of the methanol extracts of twenty-two Cameroonian medicinal plants against sensitive and MDR cancer cell lines.

Methods

The methanol maceration was used to obtain the crude plant extracts whilst the cytotoxicity of the studied extracts was determined using a resazurin reduction assay.

Results

A preliminary assay on leukemia CCRF-CEM cells at 40 μg/mL shows that six of the twenty plant extract were able to enhance less than 50% of the growth proliferation of CCRF-CEM cells. These include Crinum zeylanicum (32.22%), Entada abyssinica (34.67%), Elaoephorbia drupifera (35.05%), Dioscorea bulbifera (45.88%), Eremomastax speciosa (46.07%) and Polistigma thonningii (45.11%). Among these six plants, E. drupifera showed the best activity with IC₅₀ values below or around 30 μg/mL against the nine tested cancer cell lines. The lowest IC₅₀ value of 8.40 μg/mL was recorded with the extract of E. drupifera against MDA-MB231 breast cancer cell line. The IC₅₀ values below 10 μg/mL were recorded with the extracts of E. drupifera against MDA-MB231 breast cancer cells, C. zeylanicum against HCT116 p53⁺/⁺ and HCT116p53^-/^- colon cancer cells and E. abyssinica against HCT116 p53⁺/⁺ cells.

Conclusion

The results of the present study provide evidence of the cytotoxic potential of some Cameroonian medicinal plants and a baseline information for the potential use of Elaoephorbia drupifera in the treatment of sensitive and drug-resistant cancer cell lines.

Cytotoxicity and Modes of Action of the Methanol Extracts of Six Cameroonian Medicinal Plants against Multidrug-Resistant Tumor Cells

Introduction. The present study aims at evaluating the cytotoxicity of twelve parts from six Cameroonian medicinal plants on sensitive and drug-resistant cancer cell lines. We also studied the mode of action of the most active plants, Gladiolus quartinianus, Vepris soyauxii, and Anonidium mannii. Methods. The cytotoxicity of the extracts was determined using a resazurin assay. Flow cytometry was used for cell-cycle analysis and detection of apoptosis, analysis of mitochondrial membrane potential (MMP), and measurement of reactive oxygen species (ROS). Results. At 40 g/mL, three extracts showed a growth of CCRF-CEM leukemia cells by less than 50%. This includes the extracts from G. quartinianus (GQW; 25.69%), Vepris soyauxii leaves (VSL; 29.82%), and Anonidium mannii leaves (AML; 31.58%). The lowest IC₅₀ values below 30 μg/mL were obtained with GQW, AML and VSL against 7/9, 8/9, and 9/9 tested cancer cell lines, respectively. The lowest IC₅₀ values for each plant were 4.09 μg/mL, and 9.14 μg/mL (against U87MG.ΔEGFR cells), respectively, for VSL and AML and 10.57 μg/mL (against CCRF-CEM cells) for GQW. GQW induced cell cycle arrest between G0/G1 and S phases, whilst VSL and AML induced arrest in G0/G1. All three extracts induced apoptosis in CCRF-CEM cells by loss of MMP, whilst AML also enhanced production of ROS. Conclusion. The three active plants may be a source for the development of new anticancer drugs.

Antiangiogenic activity and pharmacogenomics of medicinal plants from traditional korean medicine

Aim. In the present study, we investigated the antiangiogenic properties of 59 plants used in traditional Korean medicine. Selected phytochemicals were investigated in more detail for their modes of action. Methods. A modified chicken-chorioallantoic-membrane (CAM) assay using quail eggs was applied to test for antiangiogenic effects of plant extracts. A molecular docking in silico approached the binding of plant constituents to the vascular endothelial growth factor receptors 1 and 2 (VEGFR1, VEGFR2). Microarray-based mRNA expression profiling was employed to correlate the 50% inhibition concentrations (IC₅₀) of a panel of 60 NCI cell lines to these phytochemicals. Results. Extracts from Acer mono leaves, Reynoutria sachalniensis fruits, Cinnamomum japonicum stems, Eurya japonica leaves, Adenophora racemosa whole plant, Caryopteris incana leaves-stems, and Schisandra chinensis stems inhibited angiogenesis more than 50% in quail eggs. Selected phytochemicals from Korean plants were analyzed in more detail using microarray-based mRNA expression profiles and molecular docking to VEGFR1 and VEGFR2. These results indicate multifactorial modes of action of these natural products. Conclusion. The antiangiogenic activity of plants used in traditional Korean medicine implicates their possible application for diseases where inhibition of blood vessel formation is desired, for example, cancer, macular degeneration, diabetic retinopathy and others.

Cytotoxicity and pharmacogenomics of medicinal plants from traditional korean medicine

Aim. The present study was designed to investigate the cytotoxicity of a panel of 280 Korean medicinal plants belonging to 73 families and 198 species against human CCRF-CEM leukemia cells. Selected phytochemicals were investigated in more detail for their mode of action. Methods. The resazurin assay was used to determine cytotoxicity of the plant extracts. Microarray-based mRNA expression profiling, COMPARE, and hierarchical cluster analyses were applied to identify which genes correlate with sensitivity or resistance to selected phytochemicals of the Korean plants. Results. The results of the resazurin assay showed that cytotoxicity extracts tested at 10  μ g/mL from 13 samples inhibited proliferation more than 50% (IC50 < 10  μ g/mL) and the most active plants are Sedum middendorffianum (15.33%) and Lycoris radiata (17.61%). Out of 13 selected phytochemicals from these plants, hopeaphenol and deoxynarciclasine were the most cytotoxic ones. Genes from various functional groups (transcriptional or translational regulation, signal transduction, cellular proliferation, intracellular trafficking, RNA metabolism, endoplasmic/sarcoplasmic reticulum function, etc.) were significantly correlated with response of tumor cell lines to these two compounds. Conclusion. The results provide evidence on the possible use of selected Korean medicinal plants and chemical constituents derived from them for the treatment of tumors.

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.