Anti-trypanosomal activity of African medicinal plants: a review update

Antitrypanosomal secondary metabolites from medicinal plants: a review

Human African trypanosomiasis (HAT) or sleeping sickness is caused by two subspecies of extracellular protozoan parasites, namely, Trypanosoma brucei gambiense and T. brucei rhodesiense. On the other hand, Chagas disease is caused by Trypanosoma cruzi. There are currently six drugs available for the treatment of African sleeping sickness, namely, pentamidine, suramin, melarsoprol, nifurtimox, eflornithine, and fexinidazole. Besides, benznidazole and nifurtimox are drugs that are currently used for the treatment of Chagas disease. Most of the current chemotherapies for the treatment of HAT and Chagas disease are unsuitable for prescription for various reasons including high toxicity, poor efficacy, undesirable route of administration, and drug resistance. Medicinal plants are potential sources of therapeutics for many diseases. Thus, a search for compounds from plants that are active against trypanosomes could pave the way to the discovery of antitrypanosomal drugs. Therefore, the current review evaluates the potential of the secondary metabolites from medicinal plants for antitrypanosomal drug development. The literature review in the field of antitrypanosomal secondary metabolites from medicinal plants has been documented. Hence, the present study involves the discussion of antitrypanosomal natural products from medicinal plants that were not reported in these review articles present in literature. The literature search was carried out in various databases including ScienceDirect, Google Scholar, tandfonline.com, Journal of Natural Products, MDPI, WILEY Online Library, tandfonline.com, and The Lancet. In this article, the secondary metabolites organized in different classes including alkaloids, terpenoids, and flavonoids that have potency against trypanosomes are discussed.

Cytological profiling of trypanocidal principles from Aloe barbadensis and Taraxacum officinale

The use of herbal medicines to treat ailments is a common practice in several regions in Africa, relying on knowledge systems that have evolved over several generations. These herbal remedies are often based on anecdotal claims, many of which lack scientific validation. This study investigates the mode of action of two bioactive fractions, F1 (IC50: 8.5 µg/mL) and F5 (IC50: 7.4 µg/mL), derived from a dichloromethane extract of a herbal mixture, consisting of Aloe barbadensis and Taraxacum officinale, that is commonly used in Ghana to treat parasitic fevers. Both fractions exhibited trypanocidal effects with minimal cytotoxicity to mammalian cells. F5 induced necrotic cell death through mitochondrial oxidative stress, evidenced by a 3.5-fold increase in mitochondrial reactive oxygen species at 2 × IC50 (p< 0.0001) and significant mitochondrial membrane depolarization (p< 0.01). In contrast, F1 primarily disrupted kinetoplast segregation, increasing 2K1 N cells by 3.2-fold at 1 × IC50 (p< 0.0001) and instigating an accumulation of dyskinetoplastic cells (0KXN). Both fractions induced morphological distortions, nuclear fragmentation, and loss of flagellar integrity. This study provides the first mechanistic insights into the antitrypanosomal activity of bioactive fractions obtained from a mixture of A. barbadensis and T. officinale. The distinct targeting of mitochondrial ROS production (F5) and kinetoplast replication (F1) highlights their potential as leads for the development of new antitrypanosomal drugs with novel mechanisms of action. These findings reinforce the value of ethnomedicinal plants as sources of novel bioactive compounds.

Antitrypanosomal activity of Crossopteryx febrifuga and phytochemical profiling using LC-MS/MS analysis coupled to molecular network and SIRIUS

Crossopteryx febrifuga (Rubiaceae) is a plant widely used in traditional African medicine to treat tryapnosomiasis. The aim of our study was to evaluate the antitrypanosomal activity of C. febrifuga extracts and to identify the compounds responsible for this activity. We prepared 4 extracts by successive maceration of plant leaf powder in n-hexane, dichloromethane, methanol and water. The antitrypanosomal activity of the extracts was assessed on Trypanosoma brucei brucei and their selectivity on Leishmania mexicana mexicana and human non cancer WI38 fibroblast cells. The dichloromethane extract, the most antitrypanosomal (IC50 of 9.3 ± 0.8 μg/mL) was fractionated on an Open Column Chromatography to give 14 fractions. Fractions 6-9 were the most active with an IC50 ranging from 1.3 to 2.1 μg/mL. All fractions were analyzed by UPLC-ZenoTOFHRMS, followed by manual dereplication of metabolites detected in the most active fractions. Manual dereplication was aided by the Molecular Network (MN) and SIRIUS. Metabolic profiling of fractions 6-9 has enabled us to identify 33 compounds, most of which were reported for the first time in C. febrifuga. These include buddlenol C (6), naringenin (7), maslinic acid (22), corosolic acid or isomer (24), asperphenamate (25), hydroxyoctadecenoic acid (29), sumaresinolic acid or isomer I and II (30 and 31), glycyrrhetinic acid (32) and oleanolic acid (36). The bioactivity-based approach identified maslinic (22), corosolic (24), and oleanolic (36) acids as linked to the antitrypanosomal activity. The data obtained support the traditional use of C. febrifuga in the traditional treatment of trypanosomiasis. Further studies are required to verify the activity observed in vivo.

Maganin Gargajiya: Assessing the Benefits, Challenges, and Evidence of Traditional Medicine in Nigeria

In Nigeria, traditional medicine, commonly called "Maganin Gargajiya," holds a significant place in the healthcare system and is widely used due to its cultural relevance, accessibility, and perceived efficacy. This review seeks to evaluate whether traditional medicine is a net benefit or risk to public health. It will explore the pros, such as the care provided by traditional healers, and the cons, including delays in seeking conventional treatment and the potential health risks associated with unregulated herbal remedies. This article synthesizes existing studies on traditional medicine in Nigeria, evaluating both the benefits and risks associated with its use, based on secondary data analysis. The review aims to provide a balanced perspective on the role of traditional medicine in Nigeria, examining whether it should be integrated into, regulated alongside or divorced completely from modern healthcare to improve overall patient outcomes and safety.

The workshops on computational applications in secondary metabolite discovery (CAiSMD)

We report the outcomes of the second session of the free online open-access workshop "Computational Applications in Secondary Metabolite Discovery (CAiSMD) 2022" that took place from 09 to 11 March 2022. The first session was held from 08 to 10 March 2021 and drew the attention of many early career scientists from academia and industry. The 23 invited speakers of this year's workshop also came from academia and industry and 222 registered participants from five continents (Africa, Asia, Europe, South, and North America) took part in the workshop. The workshop highlighted the potential applications of computational methodologies in the search for secondary metabolites or natural products as drug candidates and drug leads. For three days, the participants of this online workshop discussed modern computer-based approaches for exploring NP discovery in the "omics" age. The invited experts gave keynote lectures, trained participants in hands-on sessions, and held round table discussions. These were followed by oral presentations during which much interaction between the speakers and the audience was observed. Selected applicants (early-career scientists) were offered the opportunity to give oral presentations (15 min) upon submission of an abstract. The final program available on the workshop website (https://indiayouth.info/index.php/caismd) comprised three keynote lectures, 14 oral presentations, two round table discussions, and four hands-on sessions. This meeting report also references internet resources for computational biology around secondary metabolites that are of use outside of the workshop areas and will constitute a long-term valuable source for the community.

Antiprotozoal Activity of Plants Used in the Management of Sleeping Sickness in Angola and Bioactivity-Guided Fractionation of Brasenia schreberi J.F.Gmel and Nymphaea lotus L. Active against T. b. rhodesiense

Folk medicine is widely used in Angola, even for human African trypanosomiasis (sleeping sickness) in spite of the fact that the reference treatment is available for free. Aiming to validate herbal remedies in use, we selected nine medicinal plants and assessed their antitrypanosomal activity. A total of 122 extracts were prepared using different plant parts and solvents. A total of 15 extracts from seven different plants exhibited in vitro activity (>70% at 20 µg/mL) against Trypanosoma brucei rhodesiense bloodstream forms. The dichloromethane extract of Nymphaea lotus (leaves and leaflets) and the ethanolic extract of Brasenia schreberi (leaves) had IC50 values ≤ 10 µg/mL. These two aquatic plants are of particular interest. They are being co-applied in the form of a decoction of leaves because they are considered by local healers as male and female of the same species, the ethnotaxon "longa dia simbi". Bioassay-guided fractionation led to the identification of eight active molecules: gallic acid (IC50 0.5 µg/mL), methyl gallate (IC50 1.1 µg/mL), 2,3,4,6-tetragalloyl-glucopyranoside, ethyl gallate (IC50 0.5 µg/mL), 1,2,3,4,6-pentagalloyl-β-glucopyranoside (IC50 20 µg/mL), gossypetin-7-O-β-glucopyranoside (IC50 5.5 µg/mL), and hypolaetin-7-O-glucoside (IC50 5.7 µg/mL) in B. schreberi, and 5-[(8Z,11Z,14Z)-heptadeca-8,11,14-trienyl] resorcinol (IC50 5.3 µg/mL) not described to date in N. lotus. Five of these active constituents were detected in the traditional preparation. This work provides the first evidence for the ethnomedicinal use of these plants in the management of sleeping sickness in Angola.

Therapeutic efficacy of β-sitosterol treatment on Trypanosoma congolense infection, anemia development, and trans-sialidase (TconTS1) gene expression

Background

African animal trypanosomiasis hinders sustainable livestock productivity in sub-Saharan Africa. About 17 million infected cattle are treated with trypanocides annually but most of the drugs are associated with drawbacks, necessitating the search for a promising chemotherapeutic agent.

Objectives

In this study, the effects of β-sitosterol on Trypanosoma congolense infection were investigated along with its effect on the trans-sialidase gene expressions.

Results

Oral treatment with β-sitosterol at 15 and 30 mg/kg body weight (BW) for 14 days significantly (p < 0.05) reduced parasitemia and ameliorated the parasite-induced anemia. Also, the parasite-induced increase in serum urea level and renal histopathological damage scores in addition to renal hypertrophy was significantly (p < 0.05) reverted following treatment with 30 mg/kg BW β-sitosterol. The compound also significantly (p < 0.05) down-regulated the expression of TconTS1 but not TconTS2, TconTS3, and TconTS4. Correlation analysis between free serum sialic acid with the TconTS1 and TconTS2 gene variants revealed negative correlations in the β-sitosterol-treated groups although they were non-significant (p > 0.05) in the group treated with 15 mg/kg BW β-sitosterol. Similarly, a non-significant negative (p > 0.05) correlation between the biomolecule and the TconTS3 and TconTS4 gene variants was observed in the β-sitosterol-treated groups while positive correlations were observed in the infected untreated control group.

Conclusion

The observed effect of β-sitosterol on T. congolense infection could make the compound a possible template for the design of novel trypanocides.

Ethnoveterinary survey of trypanocidal medicinal plants of the beninese pharmacopoeia in the management of bovine trypanosomosis in North Benin (West Africa)

Cattle breeding is of great socio-economic importance for Benin's cattle farmers in general and those of North Benin in particular. The objective of this study is to inventory the natural products of medicinal plants of the Beninese pharmacopoeia for the management of trypanosomes in cattle in North Benin. The methodology consisted of individual and semi-structured interviews with cattle farmers on the use of medicinal plants. A total of 360 cattle farmers were selected and interviewed in twelve villages in four municipalities (Tchaourou, N'dali, Bembèrèkè and Gogounou) in northern Benin. Different quantitative ethnobotanical indices were calculated to determine the level of use of plant species. The Relative Frequency of Citation (RFC), the Informant Consensus Factor (ICF = 0.918) and the Generic Coefficient (Rg = 1.04) were evaluated. The knowledge of medicinal plants was influenced by the level of education and the main activity of those who practiced animal husbandry. The results yielded 48 medicinal plants for veterinary use belonging to 46 genera and 28 families. The Leguminosae family (12.50%) was the most represented. The most cited plants with a RFC above 10% were K. senegalensis, P. africana, K. africana, M. inermis, S. latifolius, M. polyandra. The parts used were leaves (46.15%); barks (24.62%) and roots (15.38%). Decoction (53.23%), plundering (32.26%) and maceration (11.26%) were the main methods of preparation. The administration was mainly by oral route. The calculated indices show a high diversity of medicinal plants with trypanocidal properties in the control of cattle trypanosomosis in the Sudanese and Sudano-Guinean zones of northern Benin. Plant species with high citation and RFC values should be selected for comprehensive pharmacological and phytochemical research to validate this ethnomedical knowledge in the management of cattle trypanosomosis.

In Vitro Pharmacological Activity, and Comparison GC-ToF-MS Profiling of Extracts from Cissus cornifolia (Baker) Planch

Cissus cornifolia (Baker) Planch is traditionally used in South African traditional medicine (SATM) to treat a variety of human infections. The antimicrobial activity of extracts from C. cornifolia was investigated in vitro against a plethora of pathogenic microorganisms using the microdilution assay. The acetone extract exhibited a notable minimum inhibitory concentration (MIC) value of 0.10 mg/mL against Mycoplasma hominis and a further MIC of 0.20 mg/mL against Candida parapsilosis, Streptococcus agalactiae, Pseudomonas aeruginosa, and Enterococcus faecalis. In the antiproliferative assays, both the ethyl acetate and methanol extracts exhibited a potent inhibition of the MCF-7-21 cell line. In the anti-inflammatory assays, both the ethyl acetate and methanol extracts exhibited IC₅₀ values of 15.59 and 15.78 µg/mL against Cyclooxygenase-2 (COX-2), respectively. Methanol extract further exhibited potent dual inhibition of both COX-2 and 15-LOX enzymes, hence, recommended to curb both related cancers, particularly breast cancer and inflammation-borne diseases. In the comparative gas chromatography time-of-flight mass spectrometry (GC/TOF-MS), the acetone, ethyl acetate, and methanol extract contained significantly prevalent amounts of compound 2-(2',4',4',6',6',8',8'-Heptamethyltetrasiloxan-2'-yloxy)-2,4,4,6,6,8,8,10,10-nonamethylcyclopentasiloxane with % area ranging from 15.714 to 39.225. The findings in the current work validates the use of the plant species in SATM in the treatment of cancer-like infections, opportunistic infections associated with HIV-AIDS. Furthermore, the in vivo studies and the mechanisms of action still need to be explored.

Antitrypanosomal, Antitopoisomerase-I, and Cytotoxic Biological Evaluation of Some African Plants Belonging to Crassulaceae; Chemical Profiling of Extract Using UHPLC/QTOF-MS/MS

In our continuous study for some African plants as a source for antitrypanosomally and cytotoxic active drugs, nine different plants belonging to the Crassulaceae family have been selected for the present study. Sedum sieboldii leaves extract showed an antitrypanosomal activity against Trypanosoma brucei with an IC₅₀ value of 8.5 µg/mL. In addition, they have cytotoxic activities against (HCT-116), (HEPG-2) and (MCF-7), with IC₅₀ values of 28.18 ± 0.24, 22.05 ± 0.66, and 26.47 ± 0.85 µg/mL, respectively. Furthermore, the extract displayed inhibition against Topoisomerase-1 with an IC₅₀ value of 1.31 µg/mL. It showed the highest phenolics and flavonoids content among the other plants' extracts. In order to identify the secondary metabolites which may be responsible for such activities, profiling of the polar secondary metabolites of S. sieboldii extract via Ultra-Performance Liquid Chromatography coupled to High-Resolution QTOF-MS operated in negative and positive ionization modes, which revealed the presence of 46 metabolites, including flavonoids, phenolic acids, anthocyanidins, coumarin, and other metabolites.

Biological Activity and Chemical Composition of Detarium microcarpum Guill. and Perr-A Systematic Review

Historically, natural products have been the principal source of medications for the treatment of human diseases. Traditional medical practitioners employ Detarium microcarpum as a treatment for diabetes, malaria, wounds, inflammation, and even cancer. This study emphasizes the importance of harmonizing D. microcarpum research so that results from various sources may be directly compared to reach a scientific conclusion. We searched Google Scholar, Science Direct, Google.com, Wiley, PubMed, Hindawi, and Springer for research papers on Detarium microcarpum. This analysis excludes untrustworthy online data, thesis papers, and review publications on D. microcarpum. The leaves and stem bark were shown to have high antioxidant, anti-inflammatory, antibacterial, antidiabetic, and anticancer properties. The study also discovered that too much consumption is harmful. Polyphenols and flavonoids were the most commonly reported compounds. However, human safety and efficacy are yet to be fully evaluated, and further well-designed clinical trials are needed to confirm preclinical findings. The leaves and stem bark extracts and isolated compound mechanism of action should be investigated. It is necessary to set a standard dose and ensure its safety.

Chemotherapeutic potentials of β-ionone against Trypanosoma congolense infection: Inhibition of parasite proliferation, anemia development, trans-sialidase (TconTS3 and TconTS4) gene expressions, and phospholipase A2

Trypanosoma congolense is a pathogenic African animal trypanosome species causing devastating conditions leading to death of an infected host. The drawbacks of the existing trypanocidal drugs have led to the search for new drug candidates. In this study, β-ionone at 15 and 30 mg/kg body weight (BW) was orally administered to T. congolense infected rats for 14 days followed by an assessment of anemia, organ damages, and the expression of T. congolense trans-sialidase gene variants. A significant decrease in parasitemia (p < .05) was observed in the animals treated with 15 mg/kg BW β-ionone besides increased animal survival rate. A trypanosome-induced decrease in packed cell volume (PCV) and histopathological changes across tissues was significantly (p < .05) ameliorated following treatment with both doses of β-ionone. This is in addition to reversing the parasite-induced upsurge in free serum sialic acid (FSA) and expression of T. congolense trans-sialidase gene variants (TconTS1, TconTS3, and TconTS4). Correlation analysis revealed a positive correlation (p > .05) between FSA with the TconTS gene expressions. In addition, the compound inhibited partially purified T. congolense sialidase and phospholipase A₂ via mixed inhibition pattern with inhibition binding constants of 25.325 and 4.550 µM, respectively, while molecular docking predicted binding energies of -5.6 kcal/mol for both enzymes. In conclusion, treatment with β-ionone suppressed T. congolense proliferation and protected the animals against some of the parasite-induced pathologies whilst the effect on anemia development might be due to inhibition of sialidase and PLA₂ activities as well as the expression levels of TconTS3 and TconTS4.

Bioprospecting for Anti-COVID-19 Interventions From African Medicinal Plants: A Review

The emergence of the novel coronavirus (SARS-CoV-2) that emanated from Wuhan in China in 2019 has become a global concern. The current situation warrants ethnomedicinal drug discovery and development for delivery of phytomedicines with potential for the treatment of COVID-19. The aim of this review is to provide a detailed evaluation of available information on plant species used in African traditional medicines with antiviral, anti-inflammatory, immunomodulatory, and COVID-19 symptoms relieving effects. Literature from scientific databases such as Scopus, PubMed, Google scholar, African Journals OnLine (AJOL), Science Direct, and Web of Science were used for this review. A total of 35 of the 38 reviewed plants demonstrated a wide range of antiviral activities. Bryophyllum pinnatum, Aframomum melegueta, Garcinia kola, Sphenocentrum jollyanum, Adansonia digitata, Sutherlandia frutescens, Hibiscus sabdariffa, Moringa oleifera, and Nigella sativa possess a combination of antiviral, immunomodulatory, anti-inflammatory, and COVID-19 symptoms relieving activities. Nine, 13, and 10 of the plants representing 23.7%, 34.2%, and 26.3% of the plants studied had antiviral activity with 3 other activities, antiviral activity with 2 other activities, and antiviral with one pharmacological activity alone, respectively. The plants studied were reported to be relatively safe at the subchronic toxicity level, except for 2. The study provides baseline information on the pharmacological activities, toxicity, and chemical components of 9 African medicinal plants with antiviral, immunomodulatory, anti-inflammatory, and symptoms relieving activities, thereby making the plants candidates for further investigation for effectiveness against COVID-19.

Health benefits and biological activities of spiny monkey orange (Strychnos spinosa Lam.): An African indigenous fruit tree

ETHNOPHARMACOLOGICAL RELEVANCE

Spiny monkey orange (Strychnos spinosa Lam.) is an African endemic fruit tree that is widely consumed by humans and animals for its nutritional value. In folk medicine, different parts of S. spinosa are widely used for the management of the health and well-being of humans and livestock.

AIM

We provide a critical appraisal on the ethnobotanical uses, nutritional and pytochemical as well as the biological activities of S. spinosa.

METHODS

Articles were mined from online databases such as Google Scholar, PubMed, Science Direct, SciELO and SpringerLink. We captured research outputs that aligned with the scope of the review.

RESULTS

Strychnos spinosa remains a commonly consumed fruit due to its high nutritional (e.g. carbohydrates, crude protein and fats) content and energy. In folk medicine, different parts of S. spinosa are prescribed as remedy for diverse medical conditions especially for treating malaria, diabetes, snakebites, skin-related conditions and sexually transmitted infections in humans as well as sleeping sickness in livestock. Together with essential oils, more than 25 compounds have been profiled using Gas chromatography-mass spectrometry (GC-MS), and approximately 45 compounds have been isolated and structurally elucidated using diverse spectroscopic techniques such as UV-visible, Infrared (IR), Nuclear Magnetic Resonance (NMR) and mass spectroscopy (MS). Strychnos spinosa exerts varying degrees of biological activities against different microorganisms (bacteria and fungi) and parasites (plasmodia, trypanosomes and ticks) responsible for many diseases in humans and livestock. Furthermore, low to moderate enzyme-inhibitory effects of S. spinosa extracts suggest its ability to mitigate pains, inflammations and diabetics as well as snakebite venom. Increasing evidence from the in vivo studies support the use of the plant as a popular remedy for managing diabetics in folk medicine. The low cytotoxic effect of the plant extracts against different cell lines could be an indication of its relative safety.

CONCLUSION

Strychnos spinosa exhibits various health-promoting benefits due to its diverse nutritional and phytochemical constituents. Given that the majority of the existing evidence on these aforementioned therapeutic properties and safety are in vitro-based, the clinical significance of these results remain limited.

Benzophenone Glucosides and B-Type Proanthocyanidin Dimers from Zambian Cassia abbreviata and Their Trypanocidal Activities

Two benzophenone glucosides (1 and 2), five flavan-3-ol dimers (5-9), and 17 known compounds (3, 4, and 10-24) were identified from the bark extract of Cassia abbreviata. The chemical structures display two points of interest. First, as an unusual characteristic feature of the ¹H NMR spectra of 1 and 2, the signals for the protons on glucosidic carbons C-2 are shielded as compared to those generally observed for glucosyl moieties. The geometrically optimized 3D structures derived from conformational analysis and density functional theory (DFT) calculations revealed that this shielding effect originates from intramolecular hydrogen bonds in 1 and 2. Additionally, 3-15 were identified as dimeric B-type proanthocyanidins, which have 2R,3S-absolute-configured C-rings and C-4-C-8″ linkages, as evidenced by X-ray crystallography and by NMR and ECD spectroscopy. These results suggest the structure-determining procedures for some reported dimers need to be reconsidered. The trypanocidal activities of the isolated compounds against Trypanosoma brucei brucei, T. b. gambiense, T. b. rhodesiense, T. congolense, and T. evansi were evaluated, and the active compounds were identified.

Phloroglucinol as a Potential Candidate against Trypanosoma congolense Infection: Insights from In Vivo, In Vitro, Molecular Docking and Molecular Dynamic Simulation Analyses

Sub-Saharan Africa is profoundly challenged with African Animal Trypanosomiasis and the available trypanocides are faced with drawbacks, necessitating the search for novel agents. Herein, the chemotherapeutic potential of phloroglucinol on T. congolense infection and its inhibitory effects on the partially purified T. congolense sialidase and phospholipase A2 (PLA2) were investigated. Treatment with phloroglucinol for 14 days significantly (p < 0.05) suppressed T. congolense proliferation, increased animal survival and ameliorated anemia induced by the parasite. Using biochemical and histopathological analyses, phloroglucinol was found to prevent renal damages and splenomegaly, besides its protection against T. congolense-associated increase in free serum sialic acids in infected animals. Moreover, the compound inhibited bloodstream T. congolense sialidase via mixed inhibition pattern with inhibition binding constant (Ki) of 0.181 µM, but a very low uncompetitive inhibitory effects against PLA2 (Ki > 9000 µM) was recorded. Molecular docking studies revealed binding energies of -4.9 and -5.3 kcal/mol between phloroglucinol with modeled sialidase and PLA2 respectively, while a 50 ns molecular dynamics simulation using GROMACS revealed the sialidase-phloroglucinol complex to be more compact and stable with higher free binding energy (-67.84 ± 0.50 kJ/mol) than PLA2-phloroglucinol complex (-77.17 ± 0.52 kJ/mol), based on MM-PBSA analysis. The sialidase-phloroglucinol complex had a single hydrogen bond interaction with Ser453 while none was observed for the PLA2-phloroglucinol complex. In conclusion, phloroglucinol showed moderate trypanostatic activity with great potential in ameliorating some of the parasite-induced pathologies and its anti-anemic effects might be linked to inhibition of sialidase rather than PLA2.

Toxicity study and anti-trypanosomal activities of aqueous and methanol whole plant extracts of Brillantaisia owariensis on Trypanosoma brucei-induced infection in BALB/c mice

Background

The problem of drug resistance and toxicity in trypanosomiasis is ever-increasing, thereby creating a need to search for efficacious and safer alternatives that are of plant origin. We designed the present study to assess the oral acute toxicity, and anti-trypanosomal activity of Brillantaisia owariensis in mice.

Methods

Fifty-eight BALB/c mice were used for this study. For toxicity assessment, eighteen mice were divided into two groups of nine mice each, and acute single oral administration of the aqueous and methanol whole plant extracts of B. owariensis was assessed for each group as per Lorke’s method. Mice were observed for signs of toxicity of liver and kidney organs after two weeks of oral administration. For the anti-trypanosomal activity, forty mice were divided into eight groups of five mice. Mouse in each group was inoculated with 0.1 mL containing106T. brucei /mL. Following patency of 3 days, mice were treated at different dosages of methanol and aqueous extracts. Pre-infection, post-infection, and post-treatment data for rectal temperature, body weight, parasiteamia level, packed cell volume, and daily survival were monitored.

Results

The acute oral toxicity studies (LD50) for methanol and aqueous plant extracts in this study were calculated as 3535 mg/kg/body weight, and are non-toxic. No obvious histopathologic observation in the liver and kidney tissues. The mean daily rectal temperature and mean weights of all the treated mice were restored to normal values and significant (P, 0.05) in comparison to the positive control.

Parasitaemia clearance by both extracts was suppressive. The mean PCV values were significantly increased following treatment, and there was prolonged survival especially in mice treated with methanol extracts.

Conclusion

The study concludes that the extracts of B. owariensis are relatively non-toxic with a good safety margin when administered to mice orally. Crude methanol extract exhibited better suppressive and haematinic antitrypanosomal activities than the aqueous extract, and it has a promising effect by its ability to reduce anaemia in mice challenged with T. brucei brucei, and prolonged survival.

Effects of aqueous extract of fruit pulp of Adansonia digitata L. on the oxidative stress profile against Trypanosoma brucei brucei infection in albino rats

Background

Chemotherapy is the most widely used means of controlling trypanosomosis, however, effectiveness of the drugs available is limited by a number of factors. This study investigates the oxidative stress profile of aqueous extract of the fruit pulp of Adansonia digitata on some organs in rats infected with Trypanosoma brucei brucei.

Methods

Thirty-five male albino rats were divided into 7 groups of 5 rats each. Groups B, C, D, E, F and G were inoculated with 0.20 ml of suspension containing 106 T. b. brucei. Group A were neither infected nor treated. Group B were infected but not treated. At onset of parasitaemia, rats in group C were treated with diminazene aceturate at 3.5 mg/kg body weight once, while rats in group D were treated with vitamin C at 200 mg/kg body weight for 3 days consecutively. Rats in groups E, F and G were treated orally for 3 days with the aqueous extract of fruit pulp of A. digitata at a dosage of 40 mg/kg, 80 mg/kg and 160 mg/kg body weight respectively. Liver and kidney tissues of the rats were collected at necropsy (10 days PI) for oxidative stress analysis.

Results

There was a significant (p < 0.05) effect in the concentration levels of malondialdehyde, superoxide dismutase, glutathione peroxidase and catalase among the different groups treated with aqueous extract of fruit pulp of A. digitata.

Conclusion

The extract of A. digitata exert protective effects against tissue peroxidation in albino rats experimentally infected with T. b. brucei.

Use of herbal remedies in the management of sleeping sickness in four northern provinces of Angola

ETHNOPHARMACOLOGICAL RELEVANCE

This study reports for the first time on the use of folk medicine to treat sleeping sickness and its symptoms in four endemic provinces in northern Angola. By interviewing both traditional practitioners and confirmed patients, it highlights reasons to recourse to folk medicine, the plant species used for this affection as well as arises awareness about the use of particular plants showing potential risks.

AIM OF THE STUDY

The aims of this explorative study were three-fold. Firstly, it informed on access to, and use of plant-based medicine as first-choice treatment by infected persons. Secondly, it aimed at collecting comprehensive data from patients and traditional healers on herbal remedies in order to identify plant species used in the management of the disease. Thirdly, it served as contribution for primary indication of potential risk of use associated with the studied plants and their preparation.

MATERIALS AND METHODS

The study was conducted in 4 endemic provinces of Angola, namely Bengo, Zaire, Kwanza Norte and Uíge. We explored the use of herbal remedies by conducting structured and semi-structured interviews within two distinct study populations. The first group comprises 30 patients who had been diagnosed for trypanosomiasis and treated by the reference treatment. The second group included 9 traditional practitioners who had already treated sleeping sickness. The plants that were cited during the interviews were collected during field walks under supervision of a traditional healer, then authenticated and deposited at the National Herbarium in Luanda.

RESULTS

Of the 30 included patients, 12 (40%) had turned to folk medicine in the management of trypanosomiasis and related symptoms. 7 medicinal plants were reported by this group. Considering the key motivation to consult a traditional practitioner, two main factors accounted for half of the cases: "past experience with folk medicine" and "family habit". Out of 9 traditional practitioners' interviewees, 26 medicinal plants were cited. Roots and leaves were the most used plant parts, and decoction was the common mode of preparation. Evidence for antitrypanosomal activity in the scientific literature was found for 56% (17 of 30) of the identified plant species. The most cited plant was Crossopteryx febrifuga (UR = 6). Some of the cited plants, as for example Aristolochia gigantea, raised concern about potential toxicity.

CONCLUSIONS

With 40% of infected persons having turned first to folk medicine before consulting a medical doctor, this explorative study points out that plant-based medicines play an important role in local dynamics of health care. It highlights the need for primary assessment of potential risk of use related to the herbal recipes, and for reporting it to the concerned population. This first ethnobotanical study on trypanosomiasis in endemic provinces of Angola provides information on 30 plants, of which some had been identified as promising for further pharmacological research. Our results provide a first step towards the validation and valorization of Angolan herbal remedies for sleeping sickness.

The therapeutic potential of phytol towards Trypanosoma congolense infection and the inhibitory effects against trypanosomal sialidase

The search for novel therapeutic candidates against animal trypanosomiasis is an ongoing scientific endevour because of the negative impacts of the disease to the African livestock industry. In this study, the in vivo therapeutic potentials of phytol toward Trypanosoma congolense infection and the inhibitory effects on trypanosomal sialidase were investigated. Rats were infected with T. congolense and administered daily oral treatment of 50 and 100 mg/kg BW of phytol. Within the first 10 days of the treatment, no antitrypanosomal activity was recorded but a moderate trypanostatic activity was observed from day 17-day 21 pi. However, at 100 mg/kg BW, phytol demonstrated a significant (p < 0.05) ameliorative potentials toward T. congolense-induced host-associated pathological damages such as anaemia, hepatic and renal damages; and the data was comparable to diminazine aceturate. Moreover, the T. congolense caused a significant (p < 0.05) increase in free serum sialic acid level which was significantly (p < 0.05) prevented in the presence of phytol (100 mg/kg BW). In an in vitro analysis, phytol inhibited partially purified T. congolense sialidase using an uncompetitive inhibition pattern with inhibition binding constant of 261.24 μmol/mL. Subsequently, molecular docking revealed that the compound binds to homology modelled trypanosomal sialidase with a binding free energy of -6.7 kcal/mol which was mediated via a single hydrogen bond while Trp324 and Pro274 were the critical binding residues. We concluded that phytol has moderate trypanostatic activity but with a great potential in mitigating the host-associated cellular damages while the anaemia amelioration was mediated, in part, through the inhibition of sialidase.

Sustainable Elimination (Zero Cases) of Sleeping Sickness: How Far Are We from Achieving This Goal?

The recent massive reduction in the numbers of fresh Human African Trypanosomiasis (HAT) infection has presented an opportunity for the global elimination of this disease. To prevent a possible resurgence, as was the case after the reduced transmission of the 1960s, surveillance needs to be sustained and the necessary tools for detection and treatment of cases need to be made available at the points of care. In this review, we examine the available resources and make recommendations for improvement to ensure the sustenance of the already achieved gains to keep the trend moving towards elimination.

Biological, nutritional, and therapeutic significance of Moringa oleifera Lam

The genus Moringa Adans. comprises 13 species, of which Moringa oleifera Lam. native to India and cultivated across the world owing to its drought and frost resistance habit is widely used in traditional phytomedicine and as rich source of essential nutrients. Wide spectrum of phytochemical ingredients among leaf, flower, fruit, seed, seed oil, bark, and root depend on cultivar, season, and locality. The scientific studies provide insights on the use of M. oleifera with different aqueous, hydroalcoholic, alcoholic, and other organic solvent preparations of different parts for therapeutic activities, that is, antibiocidal, antitumor, antioxidant, anti-inflammatory, cardio-protective, hepato-protective, neuro-protective, tissue-protective, and other biological activities with a high degree of safety. A wide variety of alkaloid and sterol, polyphenols and phenolic acids, fatty acids, flavanoids and flavanol glycosides, glucosinolate and isothiocyanate, terpene, anthocyanins etc. are believed to be responsible for the pragmatic effects. Seeds are used with a view of low-cost biosorbent and coagulant agent for the removal of metals and microbial contamination from waste water. Thus, the present review explores the use of M. oleifera across disciplines for its prominent bioactive ingredients, nutraceutical, therapeutic uses and deals with agricultural, veterinarian, biosorbent, coagulation, biodiesel, and other industrial properties of this "Miracle Tree."

Interaction of Stigmasterol with Trypanosomal Uridylyl Transferase, Farnesyl Diphosphate Synthase and Sterol 14α-demethylase: An In Silico Prediction of Mechanism of Action

Background:

Trypanosomiasis is one of the neglected tropical diseases and continues to cause serious morbidity, mortality and economic loss. Current anti-trypanosomal drugs are antiquated and suffer from a number of serious setbacks, thereby necessitating the search for new drugs. Stigmasterol has previously demonstrated in vitro and in vivo anti-trypanosomal activity.

Methods:

Herein, stigmasterol was docked into three validated anti-trypanosomal drug targets; uridylyl transferase, farnesyl diphosphate synthase and sterol 14α-demethylase, in order to elucidate the possible biochemical targets for the observed anti-trypanosomal activity.

Results:

The binding free energy between stigmasterol and the enzymes was in the order; sterol 14α-demethylase (-8.9 kcal/mol) < uridylyl transferase (-7.9 kcal/mol) < farnesyl diphosphate synthase (-5.7 kcal/mol). At the lowest energy docked pose, stigmasterol interacts with the active site of the three trypanosomal enzymes via non-covalent interactions (apart from hydrogen bond) while highly hydrophobic stigmasterol carbon atoms (21 and 27) were crucial in the interaction with varying residues of the three anti-trypanosomal targets.

Conclusion:

Therefore, results from this study might suggest that stigmasterol mediated the antitrypanosomal activity through interaction with the three anti-trypanosomal targets but with more preference towards sterol 14α-demethylase.

Trypanostatic activity of geranylacetone: Mitigation of Trypanosoma congolense-associated pathological pertubations and insight into the mechanism of anaemia amelioration using in vitro and in silico models

Trypanosoma congolense is an important pathogen that wreaks havoc in the livestock industry of the African continent. This study evaluated the in vivo antitrypanosomal activity of geranylacetone and its ameliorative effect on the disease-induced anaemia and organ damages as well as its inhibitory effects against trypanosomal sialidase using in vitro and in silico techniques. Geranylacetone was used to treat T. congolense infected rats, at a dose of 50 and 100 mg/kg BW, for 14 days where it was found to reduce the parasite burden in the infected animals. Moreover, 100 mg/kg BW of geranylacetone significantly (p < 0.05) ameliorated the anaemia, hepatic and renal damages caused by the parasite. This is in addition to the alleviation of the parasite-induced hepatosplenomegaly and upsurge in free serum sialic acid levels in the infected animals which were associated with the observed anaemia amelioration by the compound. Consequently, bloodstream T. congolense sialidase was partially purified on DEAE cellulose column and inhibition kinetic studies revealed that the enzyme was inhibited by geranylacetone via an uncompetitive inhibition pattern. In silico analysis using molecular docking with Autodock Vina indicated that geranylacetone binds to trypanosomal sialidase with a minimum free binding energy of -5.8 kcal/mol which was mediated by 26 different kinds of non-covalent interactions excluding hydrogen bond whilst Asp163 and Phe421 had the highest number of the interactions. The data suggests that geranylacetone has trypanostatic activity and could protect animals against the T. congolense-induced anaemia through the inhibition of sialidase and/or the protection of the parasite-induced hepatosplenomegaly.

Antiprotozoal dimeric naphthylisoquinolines, mbandakamines B3 and B4, and related 5,8'-coupled monomeric alkaloids, ikelacongolines A-D, from a Congolese Ancistrocladus liana

From the leaves of a botanically and phytochemically as yet unexplored Ancistrocladus liana discovered in the rainforests of the Central region of the Democratic Republic of the Congo in the vicinity of the town of Ikela, six new naphthylisoquinoline alkaloids were isolated, viz., two constitutionally unsymmetric dimers, the mbandakamines B3 (3) and B4 (4), and four related 5,8'-linked monomeric alkaloids, named ikelacongolines A-D (5a, 5b, 6, and 7). The dimers 3 and 4 are structurally unusual quateraryls comprising two 5,8'-coupled monomers linked via a sterically strongly constrained 6',1''-connection between their naphthalene units. These compounds contain seven elements of chirality, four stereogenic centers and three consecutive chiral axes. They were identified along with two known related compounds, the mbandakamines A (1) and B2 (2), which had so far only been detected in two Ancistrocladus species indigenous to the Northwestern Congo Basin. In addition, five known monomeric alkaloids, previously found in related Central African Ancistrocladus species, were isolated from the here investigated Congolese liana, three of them belonging to the subclass of 5,8'-coupled naphthylisoquinoline alkaloids, whereas two compounds exhibited a less frequently occurring 7,8'-biaryl linkage. The stereostructures of the new alkaloids were established by spectroscopic (in particular HRESIMS, 1D and 2D NMR), chemical (oxidative degradation), and chiroptical (electronic circular dichroism) methods. The mbandakamines B3 (3) and B4 (4) displayed pronounced activities in vitro against the malaria parasite Plasmodium falciparum and the pathogen of African sleeping sickness, Trypanosoma brucei rhodesiense.

Antioxidant and nephroprotection activities of Combretum micranthum: A phytochemical, in-vitro and ex-vivo studies

Management of chronic renal failure is exceedingly expensive. Despite of encouraging experimental outcomes, there is a lack of potent nephroprotective drugable molecules in a clinics or market. To develop a nephroprotective phytomedicine, the present study was designed to do a literature survey on reported phytochemical and biological analysis of Combretum micranthum and to carry out chemoprofiling, in-vitro antioxidant and ex-vivo nephroprotective capacity of the title plant. The phytochemical and biological activity survey of C. micranthum has reveals the presence of many bioactive compounds such as flavonoids, terpenoids, steroids and alkaloids with many biological activities. Phytochemical investigation re-confirmed the presence of these compounds. Hydroalcoholic extract of C. micranthum (CM extract) showed a strong antioxidant activity by scavenging AAPH, DPPH, nitric oxide, hydrogen peroxide and chelating metal ions. CM extract exhibited significant (P < 0.001) dose dependent inhibition of ferric chloride-ascorbic acid induced lipid peroxidation. Diabetic nephropathy is a serious and common complication leading to end stage renal disease. Therefore, in the present study, glucose-induced toxicity was also studied in human embryonic kidney cells (HEK-293) as an in vitro model for diabetic nephropathy. The results showed that exposure of cells to high glucose (100 mM) for 72 h significantly reduced the cell viability resulting in morphological changes such as cell shrinkage, rounded cell shape and cytoplasmic vacuolation. Treatment with CM extract at 10 and 25 μg/mL resulted in significant improvement in cell viability from 10 to 23% compared to the high glucose control. This study demonstrated the potential antioxidant and nephroprotective properties of C. micranthum, justifying its traditional use in the treatment of various diseases.

Application of metabolomics and molecular networking in investigating the chemical profile and antitrypanosomal activity of British bluebells (Hyacinthoides non-scripta)

Bulb, leaf, scape and flower samples of British bluebells (Hyacinthoides non-scripta) were collected regularly for one growth period. Methanolic extracts of freeze-dried and ground samples showed antitrypanosomal activity, giving more than 50% inhibition, for 20 out of 41 samples. High-resolution mass spectrometry was used in the dereplication of the methanolic extracts of the different plant parts. The results revealed differences in the chemical profile with bulb samples being distinctly different from all aerial parts. High molecular weight metabolites were more abundant in the flowers, shoots and leaves compared to smaller molecular weight ones in the bulbs. The anti-trypanosomal activity of the extracts was linked to the accumulation of high molecular weight compounds, which were matched with saponin glycosides, while triterpenoids and steroids occurred in the inactive extracts. Dereplication studies were employed to identify the significant metabolites via chemotaxonomic filtration and considering their previously reported bioactivities. Molecular networking was implemented to look for similarities in fragmentation patterns between the isolated saponin glycoside at m/z 1445.64 [M + formic-H]- equivalent to C64H104O33 and the putatively found active metabolite at m/z 1283.58 [M + formic-H]- corresponding to scillanoside L-1. A combination of metabolomics and bioactivity-guided approaches resulted in the isolation of a norlanostane-type saponin glycoside with antitrypanosomal activity of 98.9% inhibition at 20 µM.

Active Essential Oils and Their Components in Use against Neglected Diseases and Arboviruses

The term neglected diseases refers to a group of infections caused by various classes of pathogens, including protozoa, viruses, bacteria, and helminths, most often affecting impoverished populations without adequate sanitation living in close contact with infectious vectors and domestic animals. The fact that these diseases were historically not considered priorities for pharmaceutical companies made the available treatments options obsolete, precarious, outdated, and in some cases nonexistent. The use of plants for medicinal, religious, and cosmetic purposes has a history dating back to the emergence of humanity. One of the principal fractions of chemical substances found in plants are essential oils (EOs). EOs consist of a mixture of volatile and hydrophobic secondary metabolites with marked odors, composed primarily of terpenes and phenylpropanoids. They have great commercial value and were widely used in traditional medicine, by phytotherapy practitioners, and in public health services for the treatment of several conditions, including neglected diseases. In addition to the recognized cytoprotective and antioxidative activities of many of these compounds, larvicidal, insecticidal, and antiparasitic activities have been associated with the induction of oxidative stress in parasites, increasing levels of nitric oxide in the infected host, reducing parasite resistance to reactive oxygen species, and increasing lipid peroxidation, ultimately leading to serious damage to cell membranes. The hydrophobicity of these compounds also allows them to cross the membranes of parasites as well as the blood-brain barrier, collaborating in combat at the second stage of several of these infections. Based on these considerations, the aim of this review was to present an update of the potential of EOs, their fractions, and their chemical constituents, against some neglected diseases, including American and African trypanosomiasis, leishmaniasis, and arboviruses, specially dengue.

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).

Moringa Genus: A Review of Phytochemistry and Pharmacology

Moringa is a genus of medicinal plants that has been used traditionally to cure wounds and various diseases such as colds and diabetes. In addition, the genus is also consumed as a source of nutrients and widely used for purifying water. The genus consists of 13 species that have been widely cultivated throughout Asia and Africa for their multiple uses. The purpose of this review is to provide updated and categorized information on the traditional uses, phytochemistry, biological activities, and toxicological research of Moringa species in order to explore their therapeutic potential and evaluate future research opportunities. The literature reviewed for this paper was obtained from PubMed, ScienceDirect, and Google Scholar journal papers published from 1983 to March 2017. Moringa species are well-known for their antioxidant, anti-inflammatory, anticancer, and antihyperglycemic activities. Most of their biological activity is caused by their high content of flavonoids, glucosides, and glucosinolates. By documenting the traditional uses and biological activities of Moringa species, we hope to support new research on these plants, especially on those species whose biological properties have not been studied to date.

Trypanosoma brucei Inhibition by Essential Oils from Medicinal and Aromatic Plants Traditionally Used in Cameroon (Azadirachta indica, Aframomum melegueta, Aframomum daniellii, Clausena anisata, Dichrostachys cinerea and Echinops giganteus)

Essential oils are complex mixtures of volatile components produced by the plant secondary metabolism and consist mainly of monoterpenes and sesquiterpenes and, to a minor extent, of aromatic and aliphatic compounds. They are exploited in several fields such as perfumery, food, pharmaceutics, and cosmetics. Essential oils have long-standing uses in the treatment of infectious diseases and parasitosis in humans and animals. In this regard, their therapeutic potential against human African trypanosomiasis (HAT) has not been fully explored. In the present work, we have selected six medicinal and aromatic plants (Azadirachta indica, Aframomum melegueta, Aframomum daniellii, Clausena anisata, Dichrostachys cinerea, and Echinops giganteus) traditionally used in Cameroon to treat several disorders, including infections and parasitic diseases, and evaluated the activity of their essential oils against Trypanosma brucei TC221. Their selectivity was also determined with Balb/3T3 (mouse embryonic fibroblast cell line) cells as a reference. The results showed that the essential oils from A. indica, A. daniellii, and E. giganteus were the most active ones, with half maximal inhibitory concentration (IC₅₀) values of 15.21, 7.65, and 10.50 µg/mL, respectively. These essential oils were characterized by different chemical compounds such as sesquiterpene hydrocarbons, monoterpene hydrocarbons, and oxygenated sesquiterpenes. Some of their main components were assayed as well on T. brucei TC221, and their effects were linked to those of essential oils.

Trypanosuppresive effects of ellagic acid and amelioration of the trypanosome-associated pathological features coupled with inhibitory effects on trypanosomal sialidase in vitro and in silico

BACKGROUND

The search for novel antitrypanosomal agents had previously led to the isolation of ellagic acid as a bioactive antitrypanosomal compound using in vitro studies. However, it is not known whether this compound will elicit antitrypanosomal activity in in vivo condition which is usually the next step in the drug discovery process.

PURPOSE

Herein, we investigated the in vivo activity of ellagic acid against bloodstream form of Trypanosoma congolense and its ameliorative effects on trypanosome-induced anemia and organ damage as well as inhibitory effects on trypanosomal sialidase.

METHODS

Rats were infected with T. congolense and were treated with 100 and 200mg/kg body weight (BW) of ellagic acid for fourteen days. The levels of parasitemia, packed cell volume and biochemical parameters were measured. Subsequently, T. congolense sialidase was partially purified on DEAE cellulose column and the mode of inhibition of ellagic acid on the T. congolense sialidase determined. Molecular docking study was also conducted to determine the mode of interaction of the ellagic acid to the catalytic domain of T. rangeli sialidase.

RESULTS

At a dose of 100 and 200mg/kg (BW), ellagic acid demonstrated significant (P < 0.05) trypanosuppressive effect for most of the 24 days experimental period. Further, the ellagic acid significantly (P < 0.05) ameliorated the trypanosome-induced anemia, hepatic and renal damages as well as hepatomegaly, splenomegaly and renal hypertrophy. The trypanosome-associated free serum sialic acid upsurge alongside the accompanied membrane bound sialic acid reduction were also significantly (P < 0.05) prevented by the ellagic acid treatment. The T. congolense sialidase was purified to a fold of 6.6 with a yield of 83.8%. The enzyme had a K_M and Vmax of 70.12mg/ml and 0.04µmol/min respectively, and was inhibited in a non-competitive pattern by ellagic acid with an inhibition binding constant of 1986.75μM. However, in molecular docking study, ellagic acid formed hydrogen bonding interaction with major residues R³⁹, R³¹⁸, and W¹²⁴ at the active site of T. rangeli sialidase with a predicted binding free energy of -25.584kcal/mol.

CONCLUSION

We concluded that ellagic acid possesses trypanosuppressive effects and could ameliorate the trypanosome-induced pathological alterations.

Herbal Drugs from Sudan: Traditional Uses and Phytoconstituents

Sudan folklore medicine is characterized by a unique combination of Islamic, Arabic, and African cultures. In poor communities, traditional medicine has remained as the most reasonable source of treatment of several diseases and microbial infections. Although the traditional medicine is accepted in Sudan, to date there is no updated review available, which focuses on most effective and frequently used Sudanese medicinal plants. Thus, this review aims to summarize the published information on the ethnobotanical uses of medicinal plants from Sudan, preparation methods, phytochemistry, and ethnopharmacology. The collected data demonstrate that Sudanese medicinal plants have been reported to possess a wide range of traditional medicinal uses including different microbial infections, gastrointestinal disorders, malaria, diabetes, rheumatic pain, respiratory system disorders, jaundice, urinary system inflammations, wounds, cancer, and different microbial infections. In most cases, the pharmacological studies were in agreement with traditional uses. Moreover, several bioactive compounds such as flavonoids, saponins, alkaloids, steroids, terpenes, tannins, fatty acids, and essential oils have been identified as active constituents. Although this review demonstrates the importance of ethnomedicine medicines in the treatment of several diseases in Sudan, further researches to validate the therapeutic uses and safety of these plants through phytochemical screening, different biological activity assays, and toxicological studies are still needed.

Trypanocidal activity of ethanolic extracts of Commiphora swynnertonii Burtt on Trypanosoma congolense

Background

African trypanosomosis is the disease caused by extracellular protozoan parasites of the genus Trypanosoma transmitted by tsetse flies. The current study has evaluated the trypanocidal activity of Commiphora swynnertonii extracts on Trypanosoma congolense.

Methods

The effect of ethanolic stem bark and resinous extracts on motility of T. congolense was evaluated by in vitro study at concentrations of 2 mg/ml and 4 mg/ml. Then, trypanocidal activity was evaluated by drug incubation infectivity test using mice at concentrations of 0.4 mg/ml and 2 mg/ml. In both studies negative (without drug) and positive (diminazene diaceturate) controls were used.

Results

The in vitro study showed that, ethanolic stem bark extract of C. swynnertonii at concentration of 4 mg/ml caused complete cessation of motility for T. congolense in 30 min. However, resinous ethanolic extract had delayed effect on cessation of motility of T. congolense observed at 90 and 100 min post-incubation at concentrations of 4 mg/ml and 2 mg/ml respectively. The drug incubation infectivity test study depicted that ethanolic stem bark extract at concentration of 2 mg/ml significantly (p = 0.000) reduced the infectivity of T. congolense in mice. However, it did not vary significantly (P =0.897) with group treated with diminazene diaceturate incubated mixture.

Conclusion

The current study has provided evidence that, ethanolic stem bark extract of C. swynnertonii possess trypanocidal activity against T. congolense. Based on these findings, further studies are recommended to determine its potential as a lead to trypanocidal drug discovery.

A systematic review of pentacyclic triterpenes and their derivatives as chemotherapeutic agents against tropical parasitic diseases

Parasitic infections are among the leading global public health problems with very high economic and mortality burdens. Unfortunately, the available treatment drugs are beset with side effects and continuous parasite drug resistance is being reported. However, new findings reveal more promising compounds especially of plant origin. Among the promising leads are the pentacyclic triterpenes (PTs) made up of the oleanane, ursane, taraxastane, lupane and hopane types. This paper reviews the literature published from 1985 to date on the in vitro and in vivo anti-parasitic potency of this class of phytochemicals. Of the 191 natural and synthetic PT reported, 85 have shown high anti-parasitic activity against various species belonging to the genera of Plasmodium, Leishmania, Trypanosoma, as well as various genera of Nematoda. Moreover, structural modification especially at carbon 3 (C3) and C27 of the parent backbone of PT has led to improved anti-parasitic activity in some cases and loss of activity in others. The potential of this group of compounds as future alternatives in the treatment of parasitic diseases is discussed. It is hoped that the information presented herein will contribute to the full exploration of this promising group of compounds as possible drugs for parasitic diseases.

The Chemistry and Biological Activities of Natural Products from Northern African Plant Families: From Taccaceae to Zygophyllaceae

Traditional medicinal practices have a profound influence on the daily lives of people living in developing countries, particularly in Africa, since the populations cannot generally afford the cost of Western medicines. We have undertaken to investigate the correlation between the uses of plants in Traditional African medicine and the biological activities of the derived natural products, with the aim to validate the use of traditional medicine in Northern African communities. The literature is covered for the period 1959-2015 and part III of this review series focuses on plant families with names beginning with letters T to Z. The authors have focused on curating data from journals in natural products and phytomedicine. Within each journal home page, a query search based on country name was conducted. All articles "hits" were then verified, one at a time, that the species was harvested within the Northern African geographical regions. The current data partly constitutes the bases for the development of the Northern African natural compounds database. The review discusses 284 plant-based natural compounds from 34 species and 11 families. It was observed that the ethnobotanical uses of less than 40 % of the plant species surveyed correlated with the bioactivities of compounds identified.

Chemical Characterization and Trypanocidal, Leishmanicidal and Cytotoxicity Potential of Lantana camara L. (Verbenaceae) Essential Oil

Drug resistance in the treatment of neglected parasitic diseases, such as leishmaniasis and trypanosomiasis, has led to the search and development of alternative drugs from plant origins. In this context, the essential oil extracted by hydro-distillation from Lantana camara leaves was tested against Leishmania braziliensis and Trypanosoma cruzi. The results demonstrated that L. camara essential oil inhibited T. cruzi and L. braziliensis with IC₅₀ of 201.94 μg/mL and 72.31 μg/mL, respectively. L. camara essential oil was found to be toxic to NCTC929 fibroblasts at 500 μg/mL (IC₅₀ = 301.42 μg/mL). The composition of L. camara essential oil analyzed by gas chromatography–mass spectrometry (GC/MS) revealed large amounts of (E)-caryophyllene (23.75%), biciclogermacrene (15.80%), germacrene D (11.73%), terpinolene (6.1%), and sabinene (5.92%), which might be, at least in part, responsible for its activity. Taken together, our results suggest that L. camara essential oil may be an important source of therapeutic agents for the development of alternative drugs against parasitic diseases.

Antileishmanial activity and trypanothione reductase effects of terpenes from the Amazonian species Croton cajucara Benth (Euphorbiaceae)

BACKGROUND

Leishmaniasis comprises several infectious diseases caused by protozoa parasites of Leishmania genus. In recent years, there has been a growing interest in the therapeutic use of natural products to treat parasitic diseases. Among them Croton cajucara Benth. (Euphorbiaceae) is a plant found in the Amazonian region with a history of safe use in folk medicine.

PURPOSE

The purpose of this study was to investigate the effects of clerodane diterpenes, trans-dehydrocrotonin (DCTN), trans-crotonin (CTN) and acetylaleuritolic acid (AAA) obtained from powdered bark of C. cajucara against promastigotes, axenic and intracellular amastigotes of Leishmania amazonensis. Furthermore, the effects of DCTN and CTN on the trypanotiona reductase enzyme were also investigated. The extraction of the terpenes was carried out as previously reported (Maciel et al., 1998; 2003).

METHODS

The effect of the isolated compounds (DCTN, CTN and AAA) from the bark of C. cajucara was assessed in vitro against promastigotes, axenic amastigotes and intracellular amastigotes of L. amazonensis by counting of remaining parasites in a Neubauer chamber in comparison to pentamidine used as standard drug. The action of natural products on trypanothione reductase was assessed using soluble protein fraction of promastigotes. The assays were performed by incubation with HEPES, EDTA, NADPH and trypanothione disulfide to quantify the NAPH consumption by TryR.

RESULTS

The results showed very high efficacy, especially of the diterpene DCTN, against promastigotes (IC50 = 6.30 ± 0.06 µg/ml) and axenic amastigotes (IC50 = 19.98 ± 0.05 µg/ml) of L. amazonenesis. The cytotoxic effect of the best active natural product was evaluated on mouse peritoneal infected macrophages (IC50 = 0.47 ± 0.03 µg/ml in 24 h of culture), and the treatment revealed that DCTN never reaches toxic concentrations while reducing the infection and, most importantly, with no toxicity (>100 µg/ml with 0% of macrophage kill) when compared to pentamidine (37.5 µg/ml with 100% of macrophage kill). Furthermore, all of the natural products assayed on the trypanothione reductase enzyme inhibited the enzyme activity compared to the control.

CONCLUSION

Clerodane diterpenes from C. cajucara showed promising in vitro antileishmanial effects against L. amazonensis, specially the DCTN with no macrophage toxicity up to the assayed concentration. In addition, the action on trypanothione reductase enzyme revealed a possible mechanism of action.

Medicinal plants: An invaluable, dwindling resource in sub-Saharan Africa

ETHNOPHARMACOLOGICAL RELEVANCE

The use of plant species for different therapeutic/medicinal purposes is well-entrenched in sub-Saharan Africa.

AIM OF THE REVIEW

To provide a critical and updated review of the enormous medicinal plant heritage in sub-Saharan Africa with regards to the abundance, importance, conservation status and potential means to help sustain their availability for future generations.

METHODS

A comprehensive literature search involving different online databases, books and theses were conducted in order to obtain, collate and synthesize available information on various fundamental aspects pertaining to African medicinal plants.

RESULTS

African biodiversity hotspots are endowed with a high level of endemic species with a significant portion possessing medicinal value. Apart from the extensive ethnobotanical uses of medicinal plants found in Africa, scientific validation of their biological potential such as antimicrobial, antioxidant, anti-inflammatory and anti-diabetic properties have been recognized. Together with the demand arising from their biological efficacies, other anthropogenic factors are exerting conservation strains of the wild population of these medicinal plants. Even though researchers have acknowledged the importance and value of conserving these medicinal plants, several challenges have hampered these efforts on the Continent as a whole.

CONCLUSIONS

The rich flora occurring in sub-Saharan Africa suggests enormous potential for discovery of new chemical entity with therapeutic value. However, concerted efforts focused on documenting the conservation status of African medicinal plants are pertinent. Application of different biotechnological techniques is needed to sustain these valuable botanical entities, especially to meet increasing pharmaceutical demand. Most importantly, increased public enlightenment and awareness may help eradicate the prejudice against cultivation of medicinal plants.