Evaluation of the In Vitro Efficacy of Artemisia annua, Rumex abyssinicus, and Catha edulis Forsk Extracts in Cancer and Trypanosoma brucei Cells

Computational biology and in vitro studies for anticipating cancer-related molecular targets of sweet wormwood (Artemisia annua)

BACKGROUND

Cancer is one of the leading causes of death worldwide. Recently, it was shown that many natural extracts have positive effects against cancer, compared with chemotherapy or recent hormonal treatments. A. annua is an annual medicinal herb used in the traditional Chinese medicine. It has also been shown to inhibit the proliferation of various cancer cell lines.

METHODS

Multi-level modes of action of A. annua constituents in cancer therapy were investigated using an integrated approach of network pharmacology, molecular docking, dynamic simulations and in-vitro cytotoxicity testing on both healthy and cancer cells.

RESULTS

Network pharmacology-based analysis showed that the hit Artemisia annua constituents related to cancer targets were 3-(2-methylpropanoyl)-4-cadinene-3,11-diol, artemisinin G, O-(2-propenal) coniferaldehyde, (2-glyceryl)-O-coniferaldehyde and arteamisinin III, whereas the main cancer allied targets were NFKB1, MAP2K1 and AR. Sixty-eight significant signaling KEGG pathways with p < 0.01 were recognized, the most enriched of which were prostate cancer, breast cancer, melanoma and pancreatic cancer. Thirty-five biological processes were mainly regulated by cancer, involving cellular response to mechanical stimulus, positive regulation of gene expression and transcription. Molecular docking analysis of the top hit compounds against the most enriched target proteins showed that 3-(2-methylpropanoyl)-4-cadinene-3,11-diol and O-(2-propenal) coniferaldehyde exhibited the most stabilized interactions. Molecular dynamics simulations were performed to explain the stability of these two compounds in their protein-ligand complexes. Finally, confirmation of the potential anticancer activity was attained by in-vitro cytotoxicity testing of the extract on human prostate (PC-3), breast (MDA-MB-231), pancreatic (PANC-1) and melanoma (A375) cancerous cell lines.

CONCLUSION

This study presents deeper insights into A. annua molecular mechanisms of action in cancer for the first time using an integrated approaches verifying the herb's value.

Antileishmanial anthraquinones from the rhyzomes of Rumex abyssinicus Jacq (Polygonaceae)

Phytochemical investigation of the rhyzomes of Rumex abyssinicus (Polygonaceae) afforded six anthraquinones viz chrysophanol (1), physcion (2), emodin (3), mixture of physcion-8-O-β,D-glucopyranoside (4) and chrypsophanol-8-O-β,D-glucopyranoside (5), and emodin-8-O-β,D-glucopyranoside (6). All the compounds were characterised and identified by comparison of their MS and NMR data with available literature data. The isolated compounds were evaluated for their antileishmanial activity. Emodin (3) was the most active compounds with IC50 13.82 and 0.26 µg/mL against Leishmania donovani amastigotes and promastigotes, respectively. Emodin-8-O-β,D-glucopyranoside (6) also showed a moderate activity with IC50 27.53 and 37.08 µg/mL. This is the first report of antileishmanial compounds from R. abyssinicus and the antileishmanial activities of compounds 2, 4, 5 and 6 are here reported for the first time.

Medicinal uses, chemical constituents and biological activities of Rumex abyssinicus: A Comprehensive review

Rumex abyssinicus is a valuable medicinal plant species that is native to tropical Africa. Traditionally, R. abyssinicus is used to treat different disease such as, liver diseases, hepatitis, malaria, scabies, blood pressure, jaundice, wound and pneumonia. The purpose of the current study was to review the literature on the ethnomedicinal uses, chemical constitutes and biological activities of R. abyssinicus in an attempt to create information for future studies aimed towards exploring the therapeutic ability of the species. A scientific search engines, namely Google Scholar, PubMed, Scopus, Science Direct and Web of knowledge for the search terms: Rumex abyssinicus, ethnomedicinal studies, phytochemical investigations, and pharmacological activities were undertaken. The search strategy included all articles with descriptors that were available until December 30, 2021. Only published works in English have been used on this study. The data was collected using textual descriptions of the studies, tabulation, grouping, and figures. The principal phytochemicals of R. abyssinicus are anthraquinones, flavonoids, terepenoids and phenolic compounds. The in vitro and in vivo studies on the crude extracts and compounds of R. abyssinicus showed antibacterial, antioxidant, anticancer, anti-inflammatory, antifungal, wound healing, antialzeimer’s and hepatoprotective activities of it. R. abyssinicus afforded drug leads such as helminthosporin (4) with anti-alzheimer and physicon (3) with antifungal and antioxidant activity. R. abyssinicus have traditionally been used to cure a variety of diseases. Pharmacological actions of phytochemicals were shown to be promising. Despite this, further studies on crude extracts and promising compounds are needed to find new drug candidates.

Ethiopian Medicinal Plants Traditionally Used for the Treatment of Cancer, Part 2: A Review on Cytotoxic, Antiproliferative, and Antitumor Phytochemicals, and Future Perspective

This review provides an overview on the active phytochemical constituents of medicinal plants that are traditionally used to manage cancer in Ethiopia. A total of 119 articles published between 1968 and 2020 have been reviewed, using scientific search engines such as ScienceDirect, PubMed, and Google Scholar. Twenty-seven medicinal plant species that belong to eighteen families are documented along with their botanical sources, potential active constituents, and in vitro and in vivo activities against various cancer cells. The review is compiled and discusses the potential anticancer, antiproliferative, and cytotoxic agents based on the types of secondary metabolites, such as terpenoids, phenolic compounds, alkaloids, steroids, and lignans. Among the anticancer secondary metabolites reported in this review, only few have been isolated from plants that are originated and collected in Ethiopia, and the majority of compounds are reported from plants belonging to different areas of the world. Thus, based on the available bioactivity reports, extensive and more elaborate ethnopharmacology-based bioassay-guided studies have to be conducted on selected traditionally claimed Ethiopian anticancer plants, which inherited from a unique and diverse landscape, with the aim of opening a way forward to conduct anticancer drug discovery program.

Phytochemical Screening and Cytotoxic Properties of Ethanolic Extract of Young and Mature Khat Leaves

The khat plant has been culturally used in many parts of Africa and the Arabian Peninsula for many years to induce psycho-stimulating effect. Because of the global wide-spreading nature, khat chewing is being considered as a universally growing problem. Catha abbottii, Catha edulis, and Catha transvaalensis are the three species of khat commonly chewed in Saudi Arabia and nearby regions. Khat users usually prefer to chew young leaves over mature ones due to the diverse effects produced by both. Though many of the constituents of khat leaves have been identified, the complete phytochemical profile of young and mature leaves was not performed or compared; also, no evidence is available to affirm the cytotoxicity of young or mature leaves. Therefore, this study aimed to investigate the phytochemical basis of the differential response of the young and mature leaves and to assess the cytotoxicity of young and mature khat leaves. Ethanolic extracts of young and mature leaves of three khat cultivars were subjected to GC-MS. Hierarchical cluster analysis revealed the existence of two major clusters. The extracts of young leaves were found to contain the maximum content of cathinone; however, methoxyamphetamine was found in only one extract of young leaves. Cytotoxicity investigations were also conducted on both types of leaves using three cancer cell lines, human breast adenocarcinoma, human ovary adenocarcinoma, and human colon adenocarcinoma and also normal human fetal lung fibroblast cell line was used. All extracts showed comparable cytotoxicity, IC50 ranging from 22–59 μg/mL on the cancer cells; however, we observed more cytotoxicity against normal cells (IC50: 6–41 μg/mL). The predominant cytotoxicity on normal cells may pose many health hazards to khat consumers.

Discovery of Helminthosporin, an Anthraquinone Isolated from Rumex abyssinicus Jacq as a Dual Cholinesterase Inhibitor

Natural products have extensively contributed toward the discovery of new leads for Alzheimer's disease. During our search for new inhibitors of cholinesterase enzymes from natural sources, the ethyl acetate (EtOAc) extract of Rumex abyssinicus Jacq was identified as a dual cholinesterase inhibitor with IC₅₀ values of 2.7 and 11.4 μg/mL against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively. The phytochemical investigation of the EtOAc extract has resulted in isolation of four anthraquinones, namely, helminthosporin, emodin, chrysophanol, and physcion, amongst which the helminthosporin has been isolated for the first time from Rumex sp. All isolated secondary metabolites have displayed significant inhibition of EeAChE with IC₅₀ values of 2.63, 15.21, 33.7, and 12.16 μM, respectively. In addition, the helminthosporin was also found to inhibit BChE with an IC₅₀ value of 2.99 μM. The enzyme kinetic study has indicated that helminthosporin inhibits AChE and BChE in a noncompetitive manner with k _i values of 10.3 and 12.3 μM, respectively. The results of molecular modeling and propidium iodide displacement assay have revealed that helminthosporin occupies the peripheral anionic site of the active site gorge of AChE. In the PAMPA-BBB permeability assay, helminthosporin was found to possess high BBB permeability (P _e = 6.16 × 10^-6 cm/s). In a nutshell, helminthosporin has been identified as a brain permeable dual cholinesterase inhibitor, and thus its further synthetic exploration is warranted for optimization of its potency.

Evaluation of the Bioactivities of Rumex crispus L. Leaves and Root Extracts Using Toxicity, Antimicrobial, and Antiparasitic Assays

Traditional folks in different parts of the world use Rumex crispus L. for the treatment of microbial infections, malaria, and sleeping sickness in the form of decoction or tincture. In the search for a natural alternative remedy, this study aimed to evaluate the antimicrobial, antitrypanosomal, and antiplasmodial efficacy and the toxicity of R. crispus extracts. Antimicrobial potency of the extracts was evaluated using the agar dilution method to determine the minimum inhibitory concentration (MIC). The antitrypanosomal activity of the extracts was evaluated with the Trypanosoma brucei brucei model while the antimalaria potency was tested using Plasmodium falciparum 3D7 strain. Toxicity was then tested with brine shrimp assay and cytotoxicity (HeLa cells). The acetone extract of the root (RT-ACE) reveals the highest antimicrobial potency with the lowest MIC value of <1.562 mg/mL for all bacteria strains and also showed high potent against fungi. RT-ACE (IC₅₀: 13 μg/mL) and methanol extract of the leaf (LF-MEE; IC₅₀: 15 μg/mL) show a strong inhibition of P. falciparum. The ethanol extract of the root (RT-ETE: IC₅₀: 9.7 μg/mL) reveals the highest inhibition of T.b. brucei parasite. RT-ETE and RT-ACE were found to have the highest toxicity in brine shrimp lethality assay (BSLA) and cytotoxicity which correlates in the two assays. This research revealed Rumex crispus has potency against microorganisms, Trypanosoma, and Plasmodium and could be a potential source for the treatment of these diseases.

Methanolic Extract from Aerial Parts of Artemisia Annua L. Induces Cytotoxicity and Enhances Vincristine-Induced Anticancer Effect in Pre-B Acute Lymphoblastic Leukemia Cells

Background: Nowadays, remarkable attention has been drawn towards the effective therapeutic characteristic of natural products targeting cancerous cells. This study aimed to investigate the anti-cancer effect of Artemisia annua extract (AAE), a Chinese herbal medicine alone and in combination with a microtubule binding agent used in ALL treatment, vincristine (VCR), in B-Acute lymphoblastic leukemia (ALL) Nalm-6 and Reh cells. Materials and Methods: Cytotoxic activity of AAE and VCR was determined using MTT assay in Nalm-6, and Reh cell lines and synergism was evaluated using the CompuSyn software. Caspase 3 activity and Annexin/PI staining were performed for apoptosis assessment. The expression level of apoptosis-related genes, caspase 3, Bax and Bcl-2 were determined using real time-PCR. One-way ANOVA and post hoc Tukey multiple comparisons were used for statistical analysis. Results: Our findings revealed that a single administration of AAE exerted an anti-leukemic effect in both ALL-derived cells in a time- and dose-dependent manner. Interestingly, the growth inhibitory activity of the extract was more potentiated when combined with 0.1 and 1 nM VCR through caspase 3-dependent apoptosis. Moreover, real-time PCR analysis showed that VCR-induced cytotoxicity was augmented by AAE through alteration of Bax, and Bcl-2 mRNA expression. Conclusion: Overall, owing to the nontoxic nature of AAE and its explicit role in enhancing VCR effectiveness, our study provided new insight into the development of a novel combinatorial approach in ALL using natural herbs. The practical implication of the research requires further investigation through clinical trials, opening avenues for forthcoming treatment improvements.

Untargeted LC-MS metabolomic studies of Asteraceae species to discover inhibitors of Leishmania major dihydroorotate dehydrogenase

INTRODUCTION

Interesting data about the family Asteraceae as a new source of Leishmania major dihydroorotate dehydrogenase (LmDHODH) inhibitors are presented. This key macromolecular target for parasites causing neglected diseases catalyzes the fourth reaction of the de novo pyrimidine biosynthetic pathway, which takes part in major cell functions, including DNA and RNA biosynthesis.

OBJECTIVES

We aimed to (1) determine LmDHODH inhibitor candidates, revealing the type of chemistry underlying such bioactivity, and (2) predict the inhibitory potential of extracts from new untested plant species, classifying them as active or inactive based on their LC-MS based metabolic fingerprints.

METHODS

Extracts from 150 species were screened for the inhibition of LmDHODH, and untargeted UHPLC-(ESI)-HRMS metabolomic studies were carried out in combination with in silico approaches.

RESULTS

The IC₅₀ values determined for a subset of 59 species ranged from 148 µg mL^-1 to 9.4 mg mL^-1. Dereplication of the metabolic fingerprints allowed the identification of 48 metabolites. A reliable OPLS-DA model (R² > 0.9, Q² > 0.7, RMSE_CV < 0.3) indicated the inhibitor candidates; nine of these metabolites were identified using data from isolated chemical standards, one of which-4,5-di-O-E-caffeoylquinic acid (IC₅₀ 73 µM)-was capable of inhibiting LmDHODH. The predictive OPLS model was also effective, with 60% correct predictions for the test set.

CONCLUSION

Our approach was validated for (1) the discovery of LmDHODH inhibitors or interesting starting points for the optimization of new leishmanicides from Asteraceae species and (2) the prediction of extracts from untested species, classifying them as active or inactive.

The activity of Artemisia spp. and their constituents against Trypanosomiasis

BACKGROUND

Trypanosomiasis belongs to the neglected tropical diseases. Although standard therapies are available, the safety and efficacy of current synthetic drugs are limited due to the development of drug resistance and adverse side effects.

PURPOSE

Artemisia annua and artemisinin are not only active against Plasmodia, but also other protozoa. Therefore, we reviewed the literature on species of the genus Artemisia and their phytochemicals regarding their activity against trypanosomes.

STUDY DESIGN

A PubMed search for "Artemisia/Artemisinin and Trypanosoma" has been conducted for literature until December 2017.

RESULTS

Interestingly, not only A. annua L. and its active principle, artemisinin revealed inhibitory activity towards trypanosomes. Other Artemisia species (A. absinthium, A. abyssinica, A. afra, A. douglasia, A. elegantissima, A. maciverae, A. mexicana, and A. roxburghiana) also inhibited T. brucei, T. cruzi, or T. congolense. The plants contained numerous chemical constituents including 3',4'-dihydroxybonanzin, apigenin, betulinic acid, bonanzin, dehydroleucodine, dihydroluteolin, dracunculin and bis-dracunculin, helenalin, nepetin, scoparol, scopoletin, stigmasterol, (Z)-p‑hydroxy cinnamic acid, β-sitosterol and others. In addition to artemisinin from A. annua, artemether and artesunate, further novel artemisinin derivatives and nanotechnological preparations may also be useful to combat Trypanosoma infections.

CONCLUSION

There are numerous results reporting on the anti-trypanosomal activity the genus Artemisia, artemisinin and its derivatives and other phytochemicals from Artemisia species. This field of research is, however, still in its infancy and more intensive research is required to explore the full potential of diverse Artemisia species and their chemical ingredients for eradication of trypanosomal infections.

Effect of Rumex Abyssinicus on preneoplastic lesions in dimethylhydrazine induced colon carcinogenesis in rats

BACKGROUND

Cancer as a multistage process can be reversed or blocked by using chemopreventive agents. Colon cancer chemoprevention has been widely investigated using cyclooxygenase inhibitors and many other chemicals of synthetic or natural origin. This particular study was carried out to assess the colon cancer chemopreventive effect of hydro-methanol extract of Rumex abyssinicus rhizome on rats.

METHOD

Colon cancer chemopreventive potential of hydro-methanol extract of Rumex abyssinicus rhizome was determined based on the number and multiplicity of aberrant crypt foci (ACF). Fifteen DMH (1, 2-dimethylhydrazine) treated and five untreated Wistar female rats were used. DMH was administered subcutaneously 30 mg/kg, after its pH was adjusted to 6.5-7. Treatment groups started receiving extract after six weeks of weekly DMH injections. The rats were divided in to four groups: Group 1 received only oral normal saline, Group 2 received DMH and normal saline, Group 3 and 4 received DMH plus 250 mg/kg and 500 mg/kg extract, respectively. Specific phytoconstituents of the plant, which were reviewed from original articles, were virtually evaluated for cyclooxygenase-2 (COX-2) inhibition. The binding energies and interactions of the phytochemicals from Rumex abyssinicus against COX-2 were determined by Autodock4.2.

RESULTS

There was a statistically significant reduction (p-value < 0.05) in the number of aberrant crypt (AC) and aberrant crypt foci (ACF) at both administered doses. However, significant association (p-value > 0.05) was not observed in reducing crypt multiplicity. The docking process resulted in estimated binding energies [-6.83 kcal/mol to -7.9 kcal/mol] which are closer to the positive controls or Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) [-4.55 kcal/mol to -10.84 kcal/mol]. The phytochemical-COX-2 interaction indicated the involvement of key amino acid residues in inhibition of cyclooxygenase like ARG120, TYR355, TYR385, SER530 and GLY526.

CONCLUSIONS

Rumex abyssinicus had demonstrated a chemopreventive potential at post-initiation stage. As the virtual screening data suggested, COX-2 inhibition by the anthraquinones in the extract could be one mechanism for the observed chemopreventive effect.

Ethyl Pyruvate Emerges as a Safe and Fast Acting Agent against Trypanosoma brucei by Targeting Pyruvate Kinase Activity

Background

Human African Trypanosomiasis (HAT) also called sleeping sickness is an infectious disease in humans caused by an extracellular protozoan parasite. The disease, if left untreated, results in 100% mortality. Currently available drugs are full of severe drawbacks and fail to escape the fast development of trypanosoma resistance. Due to similarities in cell metabolism between cancerous tumors and trypanosoma cells, some of the current registered drugs against HAT have also been tested in cancer chemotherapy. Here we demonstrate for the first time that the simple ester, ethyl pyruvate, comprises such properties.

Results

The current study covers the efficacy and corresponding target evaluation of ethyl pyruvate on T. brucei cell lines using a combination of biochemical techniques including cell proliferation assays, enzyme kinetics, phasecontrast microscopic video imaging and ex vivo toxicity tests. We have shown that ethyl pyruvate effectively kills trypanosomes most probably by net ATP depletion through inhibition of pyruvate kinase (Ki = 3.0±0.29 mM). The potential of ethyl pyruvate as a trypanocidal compound is also strengthened by its fast acting property, killing cells within three hours post exposure. This has been demonstrated using video imaging of live cells as well as concentration and time dependency experiments. Most importantly, ethyl pyruvate produces minimal side effects in human red cells and is known to easily cross the blood-brain-barrier. This makes it a promising candidate for effective treatment of the two clinical stages of sleeping sickness. Trypanosome drug-resistance tests indicate irreversible cell death and a low incidence of resistance development under experimental conditions.

Conclusion

Our results present ethyl pyruvate as a safe and fast acting trypanocidal compound and show that it inhibits the enzyme pyruvate kinase. Competitive inhibition of this enzyme was found to cause ATP depletion and cell death. Due to its ability to easily cross the blood-brain-barrier, ethyl pyruvate could be considered as new candidate agent to treat the hemolymphatic as well as neurological stages of sleeping sickness.