Trypanocidal activity of extracts and compounds from the stem bark of Anogeissus leiocarpus and Terminalia avicennoides

Antiparasitic Activities of Plants From the Traditional Senegalese Pharmacopoeia: Isolation of Antitrypanosomal and Antileishmanial Ellagic Acid Derivatives From Terminalia Avicennioides

Parasitic diseases such as trypanosomiasis and leishmaniasis pose significant health challenges in Africa. The Senegalese Pharmacopoeia, known for its many medicinal plants with anti-infectious properties, can be a source of antiparasitic natural products. This study aimed to evaluate the in vitro antiparasitic activities of 33 methanolic extracts from 24 ethnopharmacologically selected plants against Trypanosoma brucei brucei (Tbb) and Leishmania mexicana mexicana (Lmm), as well as their cytotoxic activities on WI-38 cells. The most promising plant species were Balanites aegyptiaca, Eucalyptus camaldulensis, Vachellia nilotica and four Combretaceae species. In a second step, antitrypanosomal and antileishmanial compounds were isolated by preparative high-performance liquid chromatography from one of the most active plant extracts, Terminalia avicennioides leaves. Four ellagic acid derivatives were identified by nuclear magnetic resonance (1D & 2D) and high-resolution electrospray ionization-tandem mass spectrometry (HR-ESI-MS/MS) as 3,4,3-tri-O-methylellagic acid (2), 3,4,5-O-trimethyl-3',4'-O,O-methylideneflavellagic acid (3), hexamethylcoruleoellagic acid (4) and pentamethylflavellagic acid (5). In addition, HR-ESI-MS/MS-based dereplication analysis was performed to putatively identify compounds in active cyclohexane and dichloromethane sub-extracts. Pentamethylflavellagic acid (5) showed the most promising activity against Tbb (half-maximal inhibitory concentration = 6.20 µM). This is the first time that these compounds have been isolated from T. avicennioides and evaluated for their antitrypanosomal and antileishmanial activities.

In Vivo Anthelmintic Efficacy of Adansonia digitata and Anogeissus leiocarpa against Haemonchus contortus Infestation Induced in Sheep

The aim of the present study was to assay the in vivo anthelminthic activity of Anogeissus leiocarpa (Al) family of the Asteraceae and Adansonia digitata (Ad) family of Malvaceae leaf powder against the nematode Haemonchus contortus (Hc) in sheep. Twenty-eight sheep were artificially infected with 3000 Infective larvae (L3) of Hc and divided into four groups. Groups 1 and 2 received 3.2 g/kg of Ad and Al leaf powder according to the body weight for three days by oral route. This treatment was repeated after 14 days. Group 3 received albendazol 5 mg/kg and group 4 received water. The treatment was repeated 14 days later. Examination of faecal samples, packed cell volume and biochemical analyses and necropsy were carried out to determine egg counts, worm burdens, and reduction in worm fecundity and changes in blood parameters. The results showed a reduction in egg excretion of 72.22% and 88.49%, respectively, with Al and Ad leaf powder. Egg laying of adult female worms was reduced by 55.22% and 64.96% with Ad and Al, respectively. FAMACHA score (≤2 in the treated animals) and packed cell volume were improved with Ad and Al. The results of this study revealed that Ad and Al powder may be used as an alternative anthelminthic to control haemonchosis in small ruminants.

Antibacterial and anti-coronavirus investigation of selected Senegalese plant species according to an ethnobotanical survey

ETHNOPHARMACOLOGICAL RELEVANCE

In Senegal, upper and lower respiratory tract infections constitute a real health problem. To manage these disorders, most people rely on the use of local medicinal plants. This is particularly the case for species belonging to the botanical families, Combretaceae, Fabaceae, Myrtaceae and Rubiaceae, which are widely used to treat various respiratory problems such as colds, flu, rhinitis, sinusitis, otitis, angina, bronchitis, bronchiolitis and also pneumonia.

AIM OF THE STUDY

The aim of this study was to identify medicinal plants traditionally used for the management of infectious diseases, in particular those of the respiratory tract. On the basis of these ethnopharmacological uses, this study made it possible to highlight the antibacterial, antiviral and cytotoxic activities of selected plant species.

MATERIALS AND METHODS

An ethnobotanical survey was conducted in Senegal among informants, including herbalists, traditional healers, and households, using medicinal plants in the management of infectious diseases, with a focus on respiratory tract infections. The most cited plant species were evaluated in vitro on a panel of 18 human pathogenic bacteria may be involved in respiratory infections and against the human coronavirus HCoV-229E in Huh-7 cells. The antiviral activity of the most active extracts against HCoV-229E was also evaluated on COVID-19 causing agent, SARS-CoV-2 in Vero-81 cells. In parallel, cytotoxic activities were evaluated on Huh-7 cells.

RESULTS

A total of 127 informants, including 100 men (78.74%) and 27 women (21.26%) participated in this study. The ethnobotanical survey led to the inventory of 41 plant species belonging to 19 botanical families used by herbalists and/or traditional healers and some households to treat infectious diseases, with a specific focus on upper respiratory tract disorders. Among the 41 plant species, the most frequently mentioned in the survey were Guiera senegalensis J.F. Gmel. (95.2%), Combretum glutinosum Perr. Ex DC. (93.9%) and Eucalyptus spp. (82.8%). Combretaceae (30.2%) represented the most cited botanical family with six species, followed by Fabaceae (29.3%, 12 species). A total of 33 crude methanolic extracts of the 24 plant species selected for their number of citations were evaluated in vitro for their antimicrobial and cytotoxic activities. Guiera senegalensis, Combretum glutinosum, Vachellia nilotica subsp. tomentosa (Benth.) Kyal. & Boatwr, Eucalyptus camaldulensis Dehnh., and Terminalia avicennioides Guill. & Perr., showed antibacterial activities. The most active plants against HCoV-229E were: Ficus sycomorus L., Mitragyna inermis (Willd.) Kuntze, Pterocarpus erinaceus Poir., and Spermacoce verticillata L. One of these plants, Mitragyna inermis, was also active against SARS-CoV-2.

CONCLUSION

This work confirmed the anti-infective properties of plant species traditionally used in Senegal. Overall, the most frequently cited plant species showed the best antibacterial activities. Moreover, some of the selected plant species could be considered as a potential source for the management of coronavirus infections. This new scientific data justified the use of these plants in the management of some infectious pathologies, especially those of the respiratory tract.

A Review of the Antimalarial, Antitrypanosomal, and Antileishmanial Activities of Natural Compounds Isolated From Nigerian Flora

The West African country Nigeria features highly diverse vegetation and climatic conditions that range from rain forest bordering the Atlantic Ocean in the South to the Desert (Sahara) at the Northern extreme. Based on data from the World Conservation Monitoring Center of the United Nations Environmental Protection, Nigeria, with ~5,000 documented vascular plants, ranks amongst the top 50 countries in terms of biodiversity. Such a rich biodiversity implies that the country is rich in diverse secondary metabolites-natural products/unique chemicals produced by the plant kingdom to confer selective advantages to them. Like many tropical countries, Nigeria is also endemic to numerous infectious diseases particularly those caused by parasitic pathogens. These phytochemicals have been exploited for the treatment of diseases and as a result, a new branch of chemistry, natural product chemistry, has evolved, to try to reproduce and improve the therapeutic qualities of particular phytochemicals. In this review, we have compiled a compendium of natural products, isolated from Nigerian flora, that have been reported to be effective against certain protozoan parasites with the aim that it will stimulate interests for further investigations, and give impetus to the development of the natural products into registered drugs. In total 93 structurally characterized natural compounds have been identified with various levels of anti-parasite activity mainly from Nigerian plants. The synthesis protocol and molecular target for some of these natural anti-parasite agents have been established. For instance, the anti-plasmodial compound fagaronine (7), a benzophenanthridine alkaloid from Fagara zanthoxyloides has been successfully synthesized in the laboratory, and the anti-trypanosomal compound azaanthraquinone (55) elicits its effect by inhibiting mitochondrial electron transfer in trypanosomes. This review also discusses the barriers to developing approved drugs from phytochemicals, and the steps that should be taken in order to accelerate the development of new antiparasitics from the highlighted compounds.

In vitro and in vivo antitrypanosomal efficacy of combination therapy of Anogeissus leiocarpus, Khaya senegalensis and potash

ETHNOPHARMACOLOGICAL RELEVANCE

Pastoralists in Nigeria mix barks of Anogeissus leiocarpus (AL) Khaya senegalensis (KS) and potash (Pt) to treat animal African trypanosomosis.

AIM

To evaluate antitrypanosomal potential of A. leiocarpus, K. senegalensis and potash for insights into the traditional claim of antitrypanosomal combination therapy (ATCT).

MATERIALS AND METHODS

Fifty microliter each of six different concentrations of AL, KS, Pt, AL + KS, AL + KS + Pt and diminazene aceturate (DA, positive control) was incubated with 50 μL of parasite-laden blood containing 10⁸Trypanosoma congolense cells in a 96-well microtitre plate. Negative control wells were devoid of the extracts and drug but supplemented with phosphate-buffered saline (PBS). Efficacy of treatment was observed at 1 h interval for complete immobilisation or reduced motility of the parasites. Each incubated mixture was inoculated into mouse at the point of complete immobilisation of parasite motility or at the end of 6-h observation period for concentrations that did not immobilise the parasites completely. For in vivo assessment, thirty-five parasitaemic rats were randomly allocated into seven groups of 5 rats each. Each rat in groups I-V was treated with 500 mg/kg of AL, KS, Pt, AL + KS and AL + KS + Pt, respectively, for 7 days. Rats in groups VI and VII were treated with diminazene aceturate 3.5 mg/kg once and PBS 2 mL/kg (7 days), which served as positive and negative controls, respectively. Daily monitoring of parasitaemia through the tail vein, packed cell volume and malondialdehyde were used to assess efficacy of the treatments.

RESULTS

The AL + KS + Pt group significantly (p < 0.05) and dose-dependently reduced parasite motility and completely immobilized the parasites at 10, 5 and 2.5 μg/μL with an IC₅₀ of 9.1×10^-4 µg/µL. All the mice with conditions that produced complete cessation of parasite motility did not develop parasitaemia within one month of observation. The AL + KS group significantly (p < 0.05) lowered the level of parasitaemia and MDA, and significantly (p < 0.05) maintained higher PCV than PBS group.

CONCLUSION

The combination of A. leiocarpus and K. senegalensis showed better antitrypanosomal effects than single drug treatment and offers prospects for ATCT. Our findings support ethnopharmacological use of combined barks of A. leiocarpus and K. senegalensis by pastoralist in the treatment of animal African trypanosomosis in Nigeria.

The Genus Terminalia (Combretaceae): An Ethnopharmacological, Phytochemical and Pharmacological Review

Terminalia Linn, a genus of mostly medium or large trees in the family Combretaceae with about 250 species in the world, is distributed mainly in southern Asia, Himalayas, Madagascar, Australia, and the tropical and subtropical regions of Africa. Many species are used widely in many traditional medicinal systems, e.g., traditional Chinese medicine, Tibetan medicine, and Indian Ayurvedic medicine practices. So far, about 39 species have been phytochemically studied, which led to the identification of 368 compounds, including terpenoids, tannins, flavonoids, phenylpropanoids, simple phenolics and so on. Some of the isolates showed various bioactivities, in vitro or in vivo, such as antitumor, anti HIV-1, antifungal, antimicrobial, antimalarial, antioxidant, diarrhea and analgesic. This review covers research articles from 1934 to 2018, retrieved from SciFinder, Wikipedia, Google Scholar, Chinese Knowledge Network and Baidu Scholar by using "Terminalia" as the search term ("all fields") with no specific time frame setting for the search. Thirty-nine important medicinal and edible Terminalia species were selected and summarized on their geographical distribution, traditional uses, phytochemistry and related pharmacological activities.

Inhibitory and Reversal Effects of Extracts and Fractions of Anogeissus leiocarpa (DC.) Guill. & Perr. on Sodium Metabisulphite– induced Polymerization of Sickle Cell Haemoglobin

Background:

The leaves and stem bark of Anogeissus leiocarpa (DC.) Guill. & Pirr. (Combretaceae) are commonly included in recipes used for the management of sickle cell disease in western part of Nigeria.

Objective:

The present study was carried out to evaluate the potential of methanol extract and various fractions of A. leiocarpa leaves and stem bark to inhibit as well as reverse sodium metabisulphite induced polymerization of sickle cell haemoglobin.

Method:

The modified Emmel test was used to evaluate the inhibitory activity and the reversal effects of the extracts and fractions of both the leaves and the stem bark of A. leiocarpa in vitro.

Results:

Both the leaves and the stem bark extracts of A. leiocarpa were effective at inhibiting as well as reversing sodium metabisulphite induced polymerization of sickle cell haemoglobin, though the activity was higher in the leaves (94.52 ± 0.80% and 95.67 ± 0.67% respectively) when compared with the stem bark (51.79 ± 2.46 % and 50.45 ± 3.18 % respectively). The ethyl acetate fraction of both leaves and stem bark also gave good activities in both test methods with percentage reversal of 82.74 ± 1.82% and 67.63 ± 2.18% respectively.

Conclusions:

: A. leiocarpa extracts and ethyl acetate fractions exhibit good inhibition and reversal of sodium metabisulphite–induced polymerization of sickle cell haemoglobin thus justifying its inclusion in remedies used for the traditional management of sickle cell.

Qualitative Chemical Characterization and Multidirectional Biological Investigation of Leaves and Bark Extracts of Anogeissus leiocarpus (DC.) Guill. & Perr. (Combretaceae)

Anogeissus leiocarpus (DC.) Guill. & Perr. (Combretaceae) has a long history of use by folk populations for the management of multiple human ailments. Based on the published literature, there has been no attempt to conduct a comparative assessment of the biological activity and the phytochemical profiles of the leaves and stem bark of A. leiocarpus extracted using methanol, ethyl acetate, and water. By high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSⁿ) analysis, quinic, shikimic, gallic, and protocatechuic acids were tentatively identified from all the extracts, while chlorogenic, caffeic, ferulic, and dodecanedioic acids were only characterised from the leaves extracts. Additionally, a pharmacological study was carried out to evaluate potential protective effects that are induced by the extracts in rat colon and colon cancer HCT116 cell line. In general, the methanol and water extracts of A. leiocarpus leaves and stem bark showed potent radical scavenging and reducing properties. It was noted that the stem bark extracts were more potent antioxidants as compared to the leaves extracts. The methanol extract of A. leiocarpus leaves showed the highest acetyl (4.68 mg galantamine equivalent/g) and butyryl (4.0 mg galantamine equivalent/g) cholinesterase inhibition. Among ethyl acetate extracts, the pharmacological investigation suggested stem bark ethyl acetate extracts to be the most promising. This extract revealed ability to protect rat colon from lipopolysaccharide-induced oxidative stress, without exerting promoting effects on HCT116 cell line viability and migration. As a conclusion, A. leiocarpus represents a potential source of bioactive compounds in the development of novel therapeutic agents.

An aqueous extract of the Anogeissus leiocarpus bark (AEAL) induces the endothelium-dependent relaxation of porcine coronary artery rings involving predominantly nitric oxide

BACKGROUND

Anogeissus leiocarpus is a Sahel tree traditionally used by the residents of Burkina Faso for its antihypertensive properties. In this study, experiments were conducted to evaluate whether an aqueous extract of the Anogeissus leiocarpus (AEAL) trunk bark induces a vasorelaxant effect on porcine coronary artery rings and to investigate the underlying mechanism.

METHODS

AEAL-induced relaxations were assessed using porcine coronary artery rings suspended in organ chambers. The phosphorylation levels of Src, Akt and endothelial nitric oxide synthase (eNOS) were assessed in a primary endothelial cell culture by Western blot. The reactive oxygen species (ROS) formation was assessed using dihydroethidine.

RESULTS

In porcine coronary artery rings, AEAL at 0.1-300 μg/mL induced endothelium-dependent relaxations, which were inhibited in the presence of inhibitors of nitric oxide (NO) and the endothelium-derived hyperpolarization pathways. Moreover, the AEAL-induced NO-mediated relaxations were significantly reduced by the inhibitors of Src and PI3-kinase as well as by the membrane-permeant ROS scavengers. In cultured porcine coronary artery endothelial cells, treatment with AEAL is associated with an intracellular generation of ROS. Moreover, the AEAL induced the phosphorylations of Akt (Ser473), eNOS (Ser1177) and a transient phosphorylation of Src (Ser17) in a time-dependent manner.

CONCLUSIONS

These findings indicate that AEAL is a potent inducer of endothelium-dependent NO-mediated relaxations in porcine coronary arteries through the redox-sensitive Src/PI3-kinase/Akt pathway-dependent activation of eNOS.

Review on medicinal plants and natural compounds as anti-Onchocerca agents

Onchocerciasis is a filarial vector borne disease which affects several million people mostly in Africa. The therapeutic approach of its control was based on a succession of drugs which always showed limits. The last one: ivermectin is not the least. It was shown to be only microfilaricidal and induced resistance to the human parasite Onchocerca volvulus. The approach using medicinal plants used in traditional medicine is a possible alternative method to cure onchocerciasis. Onchocerca ochengi and Onchocerca gutturosa are the parasite models used to assess anthelmintic activity of potentially anthelmintic plants. Numerous studies assessed the in vitro and/or in vivo anthelmintic activity of medicinal plants. Online electronic databases were consulted to gather publications on in vitro and in vivo studies of anti-Onchocerca activity of plants from 1990 to 2017. Globally, 13 plant families were investigated for anti-Onchocerca activity in 13 studies. The most active species were Anacardium occidentale, Euphorbia hirta and Acacia nilotica each with an LC₅₀ value of 2.76, 6.25 and 1.2 μg/mL, respectively. Polycarpol, voacamine, voacangine, ellagic acid, gallic acid, gentisic acid, 3-O-acetyl aleuritolic acid and (-)-epigallocatechin 3-O-gallate were the isolated plant compounds with anti-Onchocerca activity. Most of the assessed extract/compounds showed a good safety after in vivo acute toxicity assays and/or in vitro cytotoxicity test. The exception was the ethanol extract of Trichilia emetica, which killed completely and drastically mice at a dose of 3000 mg/kg. Several plant groups of compounds were shown active against Onchocerca sp. such as tannins, alkaloids, triterpenoids and essential oils. Nevertheless, none of the active compounds was subjected to clinical trial, to assessment of its diffusibility through nodular wall or its capability to induce genetic resistance of Onchocerca sp.

In vitro antiprotozoan activity and mechanisms of action of selected Ghanaian medicinal plants against Trypanosoma, Leishmania, and Plasmodium parasites

Trypanosomiasis, leishmaniasis, and malaria are protozoan infections of public health importance with thousands of new cases recorded annually. Control of these infection(s) with existing chemotherapy is limited by drug toxicity, lengthy parenteral treatment, affordability, and/or the emergence of resistant strains. Medicinal plants on the other hand are used in the treatment of various infectious diseases although their chemical properties are not fully evaluated. In this study, we screened 112 crude extracts from 72 selected Ghanaian medicinal plants for anti-Trypanosoma, anti-Leishmania, and anti-Plasmodium activities in vitro and investigated their mechanisms of action. Twenty-three extracts from 20 plants showed significant antiprotozoan activity against at least 1 of 3 protozoan parasites screened with IC₅₀ values less than 20 μg/ml. Eleven extracts showed high anti-Trypanosoma activity with Bidens pilosa whole plant and Morinda lucida leaf extracts recording the highest activities. Their IC₅₀ (selectivity index [SI]) values were 5.51 μg/ml (35.00) and 5.96 μg/ml (13.09), respectively. Nine extracts had high anti-Leishmania activity with Annona senegalensis and Cassia alata leaf extracts as the most active. Their IC₅₀ (SI) values were 10.8 μg/ml (1.50) and 10.1 μg/ml (0.37), respectively. Six extracts had high anti-Plasmodium activity with the leaf and stem-bark extracts of Terminalia ivorensis recording the highest activity. Their IC₅₀ (SI) values were 7.26 μg/ml (129.36) and 17.45 μg/ml (17.17), respectively. Only M. lucida at 25 μg/ml induced significant apoptosis-like cell death in Trypanosoma parasites. Anti-Leishmania active extracts induced varying morphological changes in Leishmania parasites such as multiple nuclei and/or kinetoplast, incomplete flagella division, or nuclear fragmentation. Active extracts may be potential sources for developing new chemotherapy against these infections.

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.

The genus Anogeissus: A review on ethnopharmacology, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Anogeissus (axlewood tree, ghatti tree, button tree and chewing stick tree) belongs to Combretaceae, includes eight species that are distributed in Asia and Africa. Plants are used as an ethnomedicine in Asia and Africa to treat various ailments like diabetes, fever, diarrhoea, dysentery, tuberculosis, wound healing, skin diseases (eczema, psoriasis), snake and scorpion venom. Based on the traditional knowledge, different phytochemical and pharmacological activities have been at the focus of research. The aim of this review is to provide updated, comprehensive and categorized information on the ethnobotany, phytochemistry, pharmacological research and toxicity of Anogeissus species in order to identify their therapeutic potential and directs future research opportunities.

MATERIALS AND METHODS

The relevant data was searched by using the keyword "Anogeissus" in "Scopus", "Google Scholar", "Web of Science", "PubMed", and "ScienceDirect" databases. Plant taxonomy was validated by the databases "The Plant List" and A.J. Scott, 1979.

RESULTS

This review discusses the current knowledge of the ethnobotany, phytochemistry and in vitro as well as in vivo pharmacological evaluations carried out on the extracts and isolated main active constituents of Anogeissus genus. Among eight species, most of the phytochemical and pharmacological studies were performed on four species. About 55 secondary metabolites are isolated from the genus. Stem bark, leaf, seed, fruit, root of the plants are used for the treatment of several health disorders such as diabetes, fever, diarrhoea, dysentery, tuberculosis, wound healing, skin diseases (eczema, psoriasis), snake and scorpion venom. Gum ghatti obtained from Anogeissus latifolia is used after delivery as tonic and in spermatorrhoea. Many phytochemical investigations on this genus confirmed that it is rich in phenolic compounds. Modern pharmacology research has confirmed that the crude extracts or the isolated active compounds of the genus Anogeissus possess antioxidant, antimicrobial, wound healing, antiulcer, anti-inflammation, anti-diabetics, hepatoprotective, hypolipidemic, antiparasitic and neuroprotective effects.

CONCLUSIONS

This review confirms that some Anogeissus species have emerged as a good source of the traditional medicine for wound healing, inflammation, skin diseases, microbial infection and diabetes. Many traditional uses of Anogeissus species have now been validated by modern pharmacology research. Intensive investigations of all the species of Anogeissus regarding phytochemical and pharmacological properties, especially their mechanism of action, safety and efficacy could be the future research interests before starting clinical trials.

Antitrypanosomal activity of Verbascum sinaiticum Benth. (Scrophulariaceae) against Trypanosoma congolense isolates

BACKGROUND

African Trypanosomiasis is a neglected tropical disease with a large impact on the livelihood of the rural poor in Sub-Saharan Africa. The available drugs for managing this disease are old, expensive and are facing the problem of drug resistance. Thus, the aim of this study was to evaluate in vivo antitrypanosomal efficacy of aqueous and absolute methanol leaf extracts of Verbascum sinaiticum Benth. against Trypanosoma congolense field isolate.

METHODS

Verbascum sinaiticum (Local name 'qetetina') is a biennial plant, and 60-150 cm tall. It is traditionally used to treat wound, stomachache, viral infection, cancer, sunstroke, fever, abdominal colic, diarrhea, hemorrhage, anthrax, and hepatitis. The efficacy of aqueous and absolute methanol leaf extracts of V. sinaiticum was evaluated in a randomized experiment with Swiss albino mice infected with T. congolense field isolate. The extracts were administered at doses of 100, 200 and 400 mg/kg by intraperitoneal injection for seven days at 12 Days Post-Infection (DPI) when the peak parasitaemia level was approximately 10(8) trypanosomes/ml. Parasitaemia, Packed Cell Volume (PCV), mean survival time and change in body weight were used as indices for monitoring the efficacy of the extracts. Diminazene (28 mg/kg) was used as a positive control while 2 % Tween was used as the negative control. Phytochemicals screening were conducted following standard methods.

RESULTS

The extracts showed no toxicity effect in Swiss albino mice and had LD50 above 2000 mg/kg. The phytochemicals screened in V. sinaiticum were alkaloids, flavonoids, glycoside, saponins, steroids, phenolic compounds, and tannins. The mice treated with absolute methanol leaf extract of V. sinaiticum at 400 mg/kg dose had significantly lower mean parasitaemia (7.20 ± 0.16) (p < 0.001) as compared to the negative control group (8.82 ± 0.12) on day 14 of treatment. Animals treated with the same dose had significant (p < 0.001) higher PCV value and body weight and as well as the highest mean survival time of 40.20 ± 0.31 days as compared to the negative control at the end of the observation period.

CONCLUSION

This study established that Verbascum sinaiticum had trypanocidal activity. The crude extracts have partially eliminated trypanosomes in a dose-dependent manner. The study can be a basis for future in-depth analysis of the biologically active chemicals.

Achillea fragrantissima, rich in flavonoids and tannins, potentiates the activity of diminazine aceturate against Trypanosoma evansi in rats

OBJECTIVE

To evaluate activity of methanol extract of Achillea fragrantissima (meth) (A. fragrantissima) alone or in combination with diminazine aceturate (DA) against Trypanosoma evansi (T. evansi) in experimentally infected rats.

METHODS

Sixty adult male Wister albino rats were divided equally into 6 groups (A-F). Rats in groups A-E were experimentally infected with T. evansi and those in group F were uninfected. The groups were treated respectively as follows: group A-with 3.5 mg/kg DA; group B- with 1000 mg/kg meth A. fragrantissima; group C-3.5 mg/kg DA plus 500 mg/kg meth A. fragrantissima; group D-3.5 mg/kg DA plus 1000 mg/kg meth A. fragrantissima. Group E was left untreated. Parasitemia, survivability, packed cell volume, hemoglobin concentration, total leucocytes count, lymphocyte count, and serum malondialdehyde and reduced glutathione (GSH) levels were estimated. Phytochemical screening of meth A. fragrantissima was also performed.

RESULTS

The phytochemical analysis of the meth A. fragrantissima indicated a higher content from polyphenolic tannins and non tannins and flavonoids. The efficacy percentage against trypanosomiasis in groups A - E was respectively as follows 80, 40, 90, 100, 0. The administration of meth-A. fragrantissima (1000 mg/kg b.wt.) produced a moderate efficacy against trypanosomiasis. Untreated rats in group E died between 25 and 30 d post infection. The rats given DA and meth A. fragrantissima combinations (C and D) showed faster and higher recovery rates than the uninfected control and groups A and B. The initial reduction in packed cell volume, hemoglobin, total leucocytes count, increases in serum malondialdehyde and decreases in GSH levels were reversed by the treatments.

CONCLUSION

The administration of the methanol extracts of A. fragrantissima and DA combination therapy was more effective than each product alone in the treatment of rats infected with T. evansi and further studies are required to isolate more active ingredients.

Ethnoecological knowledge of ticks and treatment of tick-borne diseases among Maasai people in Northern Tanzania

AIM

The aim of this study was to understand traditional knowledge of tick ecology and remedies for tick-borne diseases (TBDs) among the Maasai people in northern Tanzania.

MATERIALS AND METHODS

Semi-structured interviews were conducted among specific groups likely to be knowledgeable about tick ecology and TBDs in livestock among the Maasai people.

RESULTS

A total of 25 plant species belonging to 18 families were used to treat 8 different TBDs of livestock. Most of the plant species used were of Fabaceae and Burseraceae families. Aloe volkensii, Cissus grandifolia, and Terminalia brownii were the most commonly used plant species. The major plant growth form used was trees, while stems and bark were the main plant parts used. Most treatments were taken orally.

CONCLUSION

Maasai people have substantial knowledge on tick ecology exemplified by their ability to differentiate between different tick species and the range of remedies for each of the TBDs. Because traditional ethnoveterinary remedies are frequently utilized, their effectiveness should be further investigated.

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

ETHNOPHARMACOLOGICAL RELEVANCE

African trypanosomiasis is one of the neglected tropical diseases caused by different species of trypanosomes that affect both human and livestock with devastating consequences in the continent. Most of the affected populations commonly use traditional medicinal plants for the treatment of the disease. Consequently, this prompted ethnopharmacological research activities on the anti-trypanosomal activity of a number of these African medicinal plants in order to validate their ethnomedicinal use. Furthermore, such studies could lead to the identification of chemical leads for the development of newer anti-trypanosomal agents from those plants. This review aims to provide updated information on the ethnopharmacological evidence of African medicinal plants with anti-trypanosomal activity.

METHODS

Literature was collected via electronic search (PubMed, Sciencedirect, Medline and Google Scholar) from published articles that report on the in vitro or in vivo anti-trypanosomal activity of plants that were collected from different parts of Africa.

RESULTS

African medicinal plants investigated for in vitro and in vivo anti-trypanosomal activity from January 1993 to October 2013 are systematically compiled and all the in vivo studies are critically discussed. A total of 264 plant species belonging to 79 families were investigated for anti-trypanosomal activity. However, only 48 bioactive anti-trypanosomal compounds were successfully isolated in pure forms. Furthermore, some of the plants were investigated for possible ameliorative effects on the trypanosome-induced pathological changes out of which 18 plants were reported to be effective while a few others were not. In spite of interesting preclinical ethnopharmacological evidence for anti-trypanosomal activity, not a single African medicinal plant was investigated in a clinical study.

CONCLUSION

Several African medicinal plants have demonstrated promising anti-trypanosomal effects but the studies on the anti-trypanosomal potentials of these plants are not taken beyond proof of concept stage. It is hoped that the article would stimulate future clinical studies because of the paucity of knowledge in this area.

Effect of Aqueous Allium cepa and Ixora brachiata Root Extract on Leishmania major Promastigotes

BACKGROUND

Leishmaniasis is a major worldwide public health problem with about two to three million humans threatened by this disease annually. Allium cepa (onion) is an important dietary vegetable and was used as a herbal medicine for centuries. The root of Ixora brachiata is medicinally important.

OBJECTIVES

The aim of this study was to investigate the anti-Leishmania effect of the ethanolic and methanolic extracts of Ixora brachiata root and aqueous onion extracts on Leishmania major promastigotes.

PATIENTS AND METHODS

The parasites isolated from cutaneous leishmaniasis were exposed with different concentrations of selected plant extracts and their inhibitory effects on the promastigotes were evaluated after 24 and 48 hours.

RESULTS

Among tested plant extracts, Ixora brachiata root extracts revealed the best activity against Leishmania major promastigotes with IC100 value of 2.5 mg/mL and IC50 value of 0.078 mg/mL.

CONCLUSIONS

This study showed that aqueous Allium cepa and Ixora brachiata root extracts as natural products could be used as alternative drugs in treatment of leishmaniasis.

Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR

Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside.

Saponins-rich fraction of Calotropis procera leaves elicit no antitrypanosomal activity in a rat model

OBJECTIVE

To examine the in vitro and in vivo anti-Trypanosoma evansi (T. evansi ) activity of saponins-rich fraction of Calotropis procera (cpsf) leaves as well as the effect of the fraction on the parasite-induced anemia.

METHODS

A 60-minutes time course experiment was conducted with various concentrations of the fraction using a 96-well microtiter plate technique, and subsequently used to treat experimentally T. evansi infected rats at 100 and 200 mg/kg body weight. Index of anemia was analyzed in all animals during the experiment.

RESULTS

The cpsf did not demonstrate an in vitro antitrypanosomal activity. Further, the cpsf treatments did not significantly (P>0.05) keep the parasites lower than the infected untreated groups. At the end of the experiment, all T. evansi infected rats developed anemia whose severity was not significantly (P>0.05) ameliorated by the cpsf treatment.

CONCLUSIONS

It was concluded that saponins derived from Calotropis procera leaves could not elicit in vitro and in vivo activities against T. evansi.

Phenolics-rich fraction of Khaya senegalensis stem bark: antitrypanosomal activity and amelioration of some parasite-induced pathological changes

CONTEXT

The stem bark of Khaya senegalensis A. Juss (Meliaceae) is currently used for the treatment of trypanosomiasis by traditional practitioners in Nigeria.

OBJECTIVES

The present study investigated the anti-Trypanosoma brucei brucei activity of phenolics-rich fraction of K. senegalensis (pfks) and its ameliorative effects on trypanosome-induced pathological changes.

MATERIALS AND METHODS

The fraction was initially analyzed by gas chromatography-mass spectrometry (GC-MS). A 60 min time course experiment was conducted with various concentrations of the fraction using a 96-well microtiter plate technique and was further used to treat T. brucei infected rats at 100, 200 and 300 mg/kg body weight (BW). Indices of anemia as well as hepatic and renal functions were analyzed in all experimental animals at the end of the experiment.

RESULTS

The GC-MS analysis of the pfks revealed that the most abundant phytochemicals are phloroglucinol (40.56%) and 3,4-(dihydroxyphenyl) acetic acid (41.76%). The fraction showed a concentration dependent in vitro antitrypanosomal activity. Interestingly, the fraction completely eliminated the parasites from the bloodstream of infected rats without relapse during the experimental period at the dose of 300 mg/kg BW and also kept the parasites consistently lower at 100 and 200 mg/kg BW than that was recorded in the untreated infected rats. Furthermore, the severity of T. brucei-induced anemia and hepatic damage was significantly (p < 0.05) ameliorated in the 300 mg/kg BW treatment group whereas the parasite-induced renal damage was significantly (p < 0.05) ameliorated in all treatment groups.

CONCLUSION

Data from this study may suggest that phenolics play an important role in the antitrypanosomal activity of K. senegalensis.

Stepwise elution of a three-phase solvent system in centrifugal partition extraction: a new strategy for the fractionation and phytochemical screening of a crude bark extract

INTRODUCTION

Tree bark represents an interesting source of bioactive molecules for the discovery of new pharmaceutical agents. However, the detailed screening of secondary metabolites in crude bark extracts is often hampered by the presence of tannins, which are difficult to separate from other plant constituents.

OBJECTIVE

In the present study, a new centrifugal partition extraction (CPE) method was developed in order to fractionate a crude bark extract of Anogeissus leiocarpus Guill. & Perr. (Combretaceae).

METHODS

A three-phase solvent system composed of n-heptane, methyl tert-butyl ether, acetonitrile and water was optimised for the stepwise elution at 20 mL/min of different phytochemical classes according to their hydrophobicity. Onedimensional and two-dimensional NMR analyses of the simplified fractions were then performed in order to characterise potentially interesting metabolites.

RESULTS

In one step, 5 g of the initial crude extract were efficiently fractionated to yield highly simplified fractions that contained triterpenes, ellagic acid derivatives, flavonoids and phenolic compounds. All undesired compounds, that is, the highly abundant water-soluble tannins (78.8%), were totally removed and each run was rapidly achieved in 90 min on a the multi-gram scale and with low solvent volumes.

CONCLUSION

Centrifugal partition extraction in the elution mode using a three-phase solvent system can thus be proposed as an efficient and cost-effective alternative for a rapid fractionation of crude bark extracts and for an effective screening of potentially active secondary metabolites.

Anthelmintic activity of phenolic acids from the axlewood tree Anogeissus leiocarpus on the filarial nematode Onchocerca ochengi and drug-resistant strains of the free-living nematode Caenorhabditis elegans

The effect of three phenols (ellagic, gentisic and gallic acids) from the axlewood tree Anogeissus leiocarpus on Onchocerca ochengi and drug-resistant strains of Caenorhabditis elegans, a model organism for research on nematode parasites, is investigated. Worms were incubated in different concentrations of phenols and their survival was monitored after 48 h. Among the three acids, ellagic acid strongly affected the survival of O. ochengi microfilariae, O. ochengi adults, a wild-type C. elegans and anthelmintic-resistant strains of C. elegans, namely albendazole (CB3474), levamisole (CB211, ZZ16) and ivermectin (VC722, DA1316), with LC50 values ranging from 0.03 mm to 0.96 mm. These results indicate that the binding of ellagic acid in the worm differs from that of resistant strains of C. elegans. The efficacy of both gallic and gentisic acids was not significantly changed in resistant strains of C. elegans treated with levamisole (ZZ16, LC50= 9.98 mm, with gallic acid), albendazole (CB3474, LC50= 7.81 mm, with gentisic acid) and ivermectin (DA1316, LC50= 10.62 mm, with gentisic acid). The efficacy of these three pure compounds is in accordance with the use of A. leiocarpus from its locality of origin. The in vivo toxicity data reveal that the thresholds are up to 200 times higher than the determined LC50 values. Thus, ellagic acid could be a potential option for the treatment of nematode infections, even in cases of drug resistance towards established anthelmintic drugs.

Antitrypanosomal potentials of the extract and fractions of Abrus precatorius seeds

OBJECTIVE

To evaluate the in vivo trypanocidal activity of the methanol extract and fractions of Abrus precatorius seeds in mice.

METHODS

Parasiteamia was induced unto mice by intraperitoneal injection of 1.25×10(5)Trypanosoma in normal saline. Five days when a high level of parasiteamia was established treatment commenced until ten days. The mice were treated with 10, 20 and 40 mg/kg bt. of the extract and 5 and 10 mg/kg bt. of the fraction (F(2)), respectively for 5 days. Diminazene aceturate at the dose of 3.5 mg/kg bt. for two days was used as the reference drug. The level of parasitaemia and packed cell volume (PCV) of the animals estimated.

RESULTS

At doses of 10, 20 and 40 mg/kg the crude extract showed a sharp reduction in the level of parasitaemia in mice compared with the untreated group. The mice treated with F(2) at doses of 5 and 10 mg/kg showed a sharp reduction in the level of parasitamia to zero in day 9, and a gradual recovery from the 12th day of treatment. This effect is comparable to that of the mice treated with 7 mg/kg of standard drug diminazene aceturate. The PCV of the treated showed a gradual decrease with time, but not as much as the untreated group. Phytochemical screening revealed the presence of glycosides, alkaloids, carbohydrates, tannins and proteins in the Abrus precatorius powder while F(2) was rich in alkaloids.

CONCLUSIONS

This study shows that both the extract and the fractions of Abrus precatorius seeds exhibited a promising trypanocidal property. Alkaloids may be responsible for the observed activity.

Differential effectiveness of berry polyphenols as anti-giardial agents

Following previous work on the anti-giardial effect of blueberry polyphenols, a range of polyphenol-rich extracts from berries and other fruits was screened for their ability to kill Giardia duodenalis, an intestinal parasite of humans. Polyphenol-rich extracts were prepared from berries using solid-phase extraction and applied to trophozoites of Giardia duodenalis grown in vitro. All berry extracts caused inhibition at 166 μg gallic acid equivalents (GAE)/ml phenol content but extracts from strawberry, arctic bramble, blackberry and cloudberry were as effective as the currently used drug, metronidazole, causing complete trophozoite mortality in vitro. Cloudberry extracts were found to be the most effective causing effectively complete trophozoite mortality at 66 μg GAE/ml. The polyphenol composition of the more effective berry extracts suggested that the presence of ellagitannins could be an important factor. However, the potency of cloudberry could be related to high ellagitannin content but also to the presence of substantial amounts of unconjugated p-coumaric acid and benzoic acid. These in vitro effects occur at concentrations easily achievable in the gut after berry ingestion and we discuss the likelihood that berry extracts could be effective anti-giardial agents in vivo.

In vitro antileishmanial and antitrypanosomal activities of five medicinal plants from Burkina Faso

After ethnobotanical surveys in central and western regions of Burkina Faso, five plants namely Lantana ukambensis (Verbenaceae), Xeoderris sthulmannii (Fabaceae), Parinari curatellifollia (Chrysobalanaceae), Ozoroa insignis (Anacardiaceae), and Ficus platyphylla (Moraceae) were selected for their traditional use in the treatment of parasitic diseases and cancer. Our previous studies have focused on the phytochemical, genotoxicity, antioxidant, and antiproliferative activities of these plants. In this study, the methanol extract of each plant was tested to reveal probable antileishmanial and antitrypanosomal activities. Colorimetric and spectrophotometric methods were used for the detection of antileishmanial and antitrypanosomal activities. Leishmania donovani (LV9 WT) and Trypanosoma brucei brucei GVR 35 were used to test the antileishmanial and antitrypanosomal activities, respectively. All extracts of tested plants showed a significant antitrypanosomal activity with minimum lethal concentrations between 1.5 and 25 μg/ml, the L. ukambensis extract being the most active. In the antileishmanial test, only the extract from L. ukambensis showed significant activity with an inhibitory concentration (IC(50)) of 6.9 μg/ml. The results of this study contribute to the promotion of traditional medicine products and are preliminary for the isolation of new natural molecules for the treatment of leishmaniasis and trypanosomiasis.

In vivo antitrypanosomal effects of some ethnomedicinal plants from Nupeland of north central Nigeria

Four medicinal plants Acacia nilotica, Bombax buonopozense, Terminalia avicennioides and Zanthoxylum zanthoxyloides traditionally used for treatment of sleeping sickness in Nupeland were investigated for in vivo antitrypanosomal activity. Methanol extracts of different parts of each plant (stem barks and fruits) were obtained and evaluated for their in vivo antitrypanosomal activities against Trypanosoma brucei brucei. Phytochemical screening of the methanol extracts of each plant were performed by standard procedures. Methanol extracts of A. nilotica (stem bark), B. buonopozense (stem bark), T. avicennioides (round fruit) and Z. zanthoxyloides (stem bark) were effective on trypanosomes. The extracts of A. nilotica and B. buonopozense exhibited antitrypanosomal effects at 200 and 300 mg/kg body weight respectively. Doses were able to clear the parasites from circulation within 6 and 7 days of treatment respectively with prolonging survival period of up to 30 days. While the extracts of T. avicennioides and Z. zanthoxyloides showed trypanostatic effects and could not clear the parasites completely. The methanol extracts of these plants contain metabolites that are associated with antitrypanosomal effects; therefore, these medicinal plants may be sources of new compounds that may be active against T. b. brucei. This study has also justified the claim that some medicinal plants of Nupeland possess antitrypanosomal activity and could be useful in the management of trypanosomiasis.