The anti-Trypanosoma activities of medicinal plants: A systematic review of the literature.

BACKGROUND: The existing drug treatments for trypanosomiases are limited and suffer from shortcomings due to their toxicity and the emergence of resistant parasites. Developing anti-trypanosomal compounds based on natural products is a promising way of fighting trypanosomiases. OBJECTIVES: This study aims to identify through scientific review a large variety of medicinal plants (anti-trypanosomal) used worldwide and scientifically shown to display anti-trypanosomal effects. METHODS: To collect data, the anti-trypanosomal activities of Africa, Asia, the Middle East, South America, North America, Europe and Oceania medicinal plants have been checked by considering the published paper. RESULTS: Based on collected data, 77 natural molecules were reported in the literature. Of which 59 were from the African region, 11 from Asia, 3 from Europe and 4 from Latin America. These active components belong to alkaloids, triterpenoids, lactone, quinoids, flavonoids, iridoids, lignans, steroids, lipids, oxygenated heterocycles, benzenoids, proteins, coumarins, phenylpropanoids and peptides. We also specified the prosperous plants with unique anti-trypanosomal activities. CONCLUSIONS: However, there is a need for further studies on the ability of the isolated compounds to ameliorate the trypanosome-induced pathological alterations and also the elucidation of their modes of actions and activities against other trypanosome species.

Anti-trypanosomal and anthelminthic properties of ethanol and aqueous extracts of Tetrapleura tetraptera Taub.

Trypanosomosis and helminthosis, considered as part of neglected tropical diseases, are parasitic infections of public health importance, especially in Africa. Medicinal plants have been used in most parts of Africa, to treat these parasitic infections. The study aims to determine the anti-trypanosomal and anthelminthic properties of Tetrapleura tetraptera (fruit and stembark). The aqueous extracts of T. tetraptera fruit (TTFaq) and stembark (TTSaq), as well as ethanol extracts of T. tetraptera fruit (TTFe) and stembark (TTSe), were screened for their in vitro anti-trypanosomal and anthelminthic activities against T. b. brucei and Pheretima posthuma worms, respectively. Preliminary phytochemical screening of all extracts and gas chromatography-mass spectrometry (GC-MS) analysis of most active extracts were conducted. TTFaq exhibited anti-trypanosomal activity with IC50 of 18.18 µg/mL. TTSe and TTFe had moderate anti-trypanosomal activity with IC50 of 34.76 and 34.84 µg/mL, respectively. TTSaq had relatively low activity against the parasite with IC50 of 55.03 µg/mL. The SI of T. tetraptera extracts was between the range of 0.14-2.09. TTFaq showed dose-dependent activity causing paralysis and death of the adult worms at all concentrations. At the least concentration of 0.625 mg/mL, TTFaq induced paralysis and death after 101.88 ± 0.8 and 242.64 ± 0.38 min of exposure, respectively compared with the negative control (p < 0.0001). TTFe, TTSe and TTSaq caused paralysis of worms after 318.32 ± 0.74, 422.5 ± 0.72, 422.20 ± 0.55 min of exposure at minimum concentrations of 2.5, 10 and 5 mg/mL, respectively (p < 0.0001). However, no death was observed in worms treated with TTFe, TTSe and TTSaq at all test concentrations. In the presence of sub-minimal inhibitory concentration of the extracts, TTFaq potentiated the anthelminthic activity of albendazole whiles TTFe, TTSaq and TTSe inhibited the activity of albendazole. Phytochemical screening revealed the presence of saponins, triterpenoids, reducing sugars, flavonoids (absent in TTFe), steroids (absent in TTFaq) and tannins (absent in TTSe and TTFe) in the extracts. GC-MS revealed the presence of 9-octadecenamide and betulic acid in TTFaq. Hence, there was evidence provided here that Tetrapleura tetraptera may be effective. This gives credence to their folkloric use. However, further study might be necessary to ascertain safety use in both humans and animals.

Eugenia uniflora and Syzygium samarangense extracts exhibit anti-trypanosomal activity: Evidence from in-silico molecular modelling, in vitro, and in vivo studies.

The parasite Trypanosoma brucei is the main cause of the sleeping sickness threatening millions of populations in many African countries. The parasitic infection is currently managed by some synthetic medications, most of them suffer limited activity spectrum and/or serious adverse effects. Some studies have pointed out the promising therapeutic potential of the plant extracts rich in polyphenols to curb down parasitic infections caused by T. brucei and other trypanosomes. In this work, the main components dominating Eugenia uniflora and Syzygium samarangense plant extracts were virtually screened, through docking, as inhibitors of seven T. brucei enzymes validated as potential drug targets. The in vitro and in vivo anti-T. brucei activities of the extracts in two treatment doses were evaluated. Moreover, the extract effects on the packed cell volume level, liver, and kidney functions were assessed. Five compounds showed strong docking and minimal binding energy to five target enzymes simultaneously and three other compounds were able to bind strongly to at least four of the target enzymes. These compounds represent lead hits to develop novel trypanocidal agents of natural origin. Both extracts showed moderate in vitro anti-trypanosomal activity. Infected animal groups treated over 5 days with the studied extracts showed an appreciable in vivo anti-trypanosomal activity and ameliorated in a dose dependent manner the anaemia, liver, and kidney damages induced by the infection. In conclusion, Eugenia uniflora and Syzygium samarangense could serve as appealing sources to treat trypanosomes infections.

Phytochemical, anti-inflammatory and anti-trypanosomal properties of Anthocleista vogelii Planch (Loganiaceae) stem bark.

ETHNOPHARMACOLOGICAL RELEVANCE: Anthocleista vogelii Planch (Loganiaceae) is used in African Traditional Medicine for the treatment of pain and inflammatory disorders as well as sleeping sickness. AIM OF THE STUDY: To determine the in vivo anti-inflammatory and in vitro anti-trypanosomal activities of the extracts of A. vogelii stem bark and identify the phytochemical classes of the fractions responsible for the activities. MATERIALS AND METHODS: The in vivo anti-inflammatory activity of the extracts was evaluated using the egg albumin-induced rat paw oedema model while the in vitro anti-trypanosomal activity was assessed on Trypanosoma brucei brucei. The in vitro cytotoxicity was assessed on HeLa (human cervix adenocarcinoma) cell line. RESULTS: The methanolic extract of A. vogelii stem bark, with 11.2% yield, gave LD50 > 5000 mg/kg. The n-hexane fraction of the extract contains steroids, terpenes and fatty acids and yielded non-cytotoxic terpenoidal column fraction with anti-trypanosomal IC50 of 3.0 µg/mL. The ethylacetate fraction at 100 mg/kg dose significantly (p < 0.05) provoked 37.8, 62.5 and 69.7% inhibition of oedema induced by egg-albumin at the second, fourth and sixth hours respectively. CONCLUSION: The study demonstrated that the anti-inflammatory and anti-trypanosomal activities of A. vogelii are probably due to non-cytotoxic terpenoids and validated the traditional use of A. vogelii in the treatment of inflammation and sleeping sickness.

Improving anti-trypanosomal activity of alkamides isolated from Achillea fragrantissima.

In previous studies the aerial parts of Achillea fragrantissima were found to have substantial antileishmanial and antitrypanosomal activity. A bioassay-guided fractionation of a dichloromethane extract yielded the isolation of the essential anti-trypanosomal compounds of the plant. Seven sesquiterpene lactones (including Achillolide-A), two flavonoids, chrysosplenol-D and chrysosplenetine, and four alkamides (including pellitorine) were identified. This is the first report for the isolation of the sesquiterpene lactones 3 and 4, chrysosplenetine and the group of alkamides from this plant. Bioevaluation against Trypanosoma brucei brucei TC221 (T.b brucei) using the Alamar-Blue assay revealed the novel alkamide 13 to have an IC50 value of 40.37µM. A compound library, derived from the alkamide pellitorine (10), was synthesized and bioevaluated in order to find even more active substances. The most active compounds 26 and 27 showed activities in submicromolar concentrations and selectivity indices of 20.1 and 45.6, respectively, towards macrophage cell line J774.1. Toxicity of 26 and 27 was assessed using the greater wax moth Galleria mellonella larvae as an in vivo model. No significant toxicity was observed for the concentration range of 1.25-20mM.

Steroid Alkaloids from Holarrhena africana with Strong Activity against Trypanosoma brucei rhodesiense.

In our continued search for natural compounds with activity against Trypanosoma brucei, causative agent of human African trypanosomiasis (HAT, "sleeping sickness"), we have investigated extracts from the leaves and bark of the West African Holarrhenaafricana (syn. Holarrhena floribunda; Apocynaceae). The extracts and their alkaloid-enriched fractions displayed promising in vitro activity against bloodstream forms of T. brucei rhodesiense (Tbr; East African HAT). Bioactivity-guided chromatographic fractionation of the alkaloid-rich fractions resulted in the isolation of 17 steroid alkaloids, one nitrogen-free steroid and one alkaloid-like non-steroid. Impressive activities (IC50 in µM) against Tbr were recorded for 3ß-holaphyllamine (0.40 ± 0.28), 3α-holaphyllamine (0.37 ± 0.16), 3ß-dihydroholaphyllamine (0.67 ± 0.03), N-methylholaphyllamine (0.08 ± 0.01), conessimine (0.17 ± 0.08), conessine (0.42 ± 0.09), isoconessimine (0.17 ± 0.11) and holarrhesine (0.12 ± 0.08) with selectivity indices ranging from 13 to 302. Based on comparison of the structures of this congeneric series of steroid alkaloids and their activities, structure-activity relationships (SARs) could be established. It was found that a basic amino group at position C-3 of the pregnane or pregn-5-ene steroid nucleus is required for a significant anti-trypanosomal activity. The mono-methylated amino group at C-3 represents an optimum for activity. ∆5,6 unsaturation slightly increased the activity while hydrolysis of C-12ß ester derivatives led to a loss of activity. An additional amino group at C-20 engaged in a pyrrolidine ring closed towards C-18 significantly increased the selectivity index of the compounds. Our findings provide useful empirical data for further development of steroid alkaloids as a novel class of anti-trypanosomal compounds which represent a promising starting point towards new drugs to combat human African trypanosomiasis.

New anti-trypanosomal active tetracyclic iridoid isolated from Morinda lucida Benth.

Human African trypanosomiasis (HAT), commonly known as sleeping sickness has remained a serious health problem in many African countries with thousands of new infected cases annually. Chemotherapy, which is the main form of control against HAT has been characterized lately by the viewpoints of toxicity and drug resistance issues. Recently, there have been a lot of emphases on the use of medicinal plants world-wide. Morinda lucida Benth. is one of the most popular medicinal plants widely distributed in Africa and several groups have reported on its anti-protozoa activities. In this study, we have isolated one novel tetracyclic iridoid, named as molucidin, from the CHCl3 fraction of the M. lucida leaves by bioassay-guided fractionation and purification. Molucidin was structurally elucidated by (1)H and (13)C NMR including HMQC, HMBC, H-H COSY and NOESY resulting in tetracyclic iridoid skeleton, and its absolute configuration was determined. We have further demonstrated that molucidin presented a strong anti-trypanosomal activity, indicating an IC50 value of 1.27 µM. The cytotoxicity study using human normal and cancer cell lines indicated that molucidin exhibited selectivity index (SI) against two normal fibroblasts greater than 4.73. Furthermore, structure-activity relationship (SAR) study was undertaken with molucidin and oregonin, which is identical to anti-trypanosomal active components of Alnus japonica. Overlapping analysis of the lowest energy conformation of molucidin with oregonin suggested a certain similarities of aromatic rings of both oregonin and molucidin. These results contribute to the future drug design studies for HAT.

Anti-trypanosomal cadinanes synthesized by transannular cyclization of the natural sesquiterpene lactone nobilin.

Acid-catalyzed transannular cyclization of the germacrene-type sesquiterpene lactone nobilin 1 was investigated with the aim of obtaining new anti-trypanosomal cadinane derivatives. The reaction was regiospecific in all tested reaction conditions. Compounds were fully characterized by spectroscopic and computational methods, and the anti-trypanosomal activity was evaluated and compared to nobilin (IC50 3.19±1.69µM). The tricyclic derivative 11 showed most potent in vitro activity against Trypanosoma brucei rhodesiense bloodstream forms (IC50 0.46±0.01µM). Acid-catalyzed transannular cyclization of natural cyclodecadienes is an efficient strategy to generate new natural product derivatives with anti-protozoal activity.

Studies of the antitrypanosomal and toxicological properties of Anogeissus leiocarpus (Dc.) Guill. & Perr. (Combretaceae) and Vitellaria paradoxa C. F. Gaertn (Sapotaceae) in mice / Estudios de las propiedades antitripanosómicas y toxicológicas de Anogeissus leiocarpus (Dc). Guill. & Perr. (Combretaceae) y Vitellaria paradoxa C. F. Gaertn (Sapotaceae) en ratones

African animal trypanosomosis (AAT) is a disease of concern with ravaging effects on the health of both animals and livestock in tropical Africa. This study investigates the anti-trypanosomal activities of Anogeissus leiocarpus (ALE) and Vitelleria paradoxa (VPE) stem bark extracts and also determines the toxicological profile of the active plant, with a view to establishing the anti-trypanosomal potential and safety of the plants. Laboratory mice (19 g – 26 g) and rats (140 g – 165 g) obtained from the Animal house, Faculty of Pharmacy, OAU, Ile-Ife were used for the study. The animals were treated according to the standard set criteria for animal use and care. VPE showed neither trypanocidal nor trypanostatic activities while ALE was found to be trypanostatic at 62.5 and 125 mg/kg body weight. However, the partitioned aqueous fraction of ALE was found to demonstrate comparable anti-trypanocidal effect as Diminal (standard agent). In conclusion, the ethanolic extract of A. leiocarpus possesses antitrypanosomal effect through the relative suppression or delay in parasite establishment in trypanosome-infected mice. The toxicological study of A. leiocarpus stem bark extract revealed that it is relatively safe for use in cattle and other grazing animals.

La tripanosomiasis africana de los animales es una enfermedad de preocupación que causa estragos sobre la salud de los animales y el ganado en África tropical. Este estudio investiga las actividades anti-tripanosomal de Anogeissus leiocarpus (ALE) y Vitelleria paradoxa (VPE) del tallo y extractos de corteza. También determina el perfil toxicológico de la planta activa, con el fin de establecer el potencial anti-tripanosomal y la seguridad de las plantas. Ratones de laboratorio (19 g - 26 g) y ratas (140 g - 165 g) obtenidos del Bioterio de la Facultad de Farmacia de la OUA, se utilizaron para el estudio. Los animales fueron tratados de acuerdo con los criterios estándar establecido para el uso y cuidado de animales. VPE mostró actividades no tripanocidas ni tripanostáticas mientras que en ALE se encontró que era tripanostático a 62,5 y 125 mg/kg de peso corporal. Sin embargo, se encontró que la fracción acuosa de ALE demostró un efecto anti-tripanocida comparable como Diminal (agente estándar). En conclusión, el extracto etanólico de A. leiocarpus posee efecto sobre tripanosomas a través de la supresión relativa o retraso en la creación de parásitos en ratones infectados con tripanosomosis. El estudio toxicológico del extracto de corteza del tallo A. leiocarpus reveló que es relativamente seguro para su uso en el ganado y otros animales de pastoreo.

Anti-trypanosomal activity of diarylheptanoids isolated from the bark of Alnus japonica.

The crude extract of Alnus japonica bark exhibited a strong effect on the growth of Trypanosoma brucei. Subsequent chromatographic separation resulted in the isolation of two novel diarylheptanoids, known as alnuside C (2) and alnuside D (3), and three known compounds, 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptan-3(R)-O-ß-D-glucopyranoside (1), oregonin (4) and hirsutanone (5). The structures of the isolates were elucidated based on the use of extensive spectroscopic and chemical methods. Among the isolated diarylheptanoids, oregonin (4) (a major component of plant bark) and hirsutanone (5) exhibited potent in vitro inhibitory activity against T. brucei growth in the bloodstream with IC50 values of 1.14 and 1.78 µM, respectively. We confirmed that oregonin (4) and hirsutanone (5) were not toxic to human normal skin fibroblast cells (NB1RGB) and colon cancer cells (HCT-15) at a concentration of 50 µM; however, lower levels of toxicity were observed for leukemia cells. To determine the structure activity relationships of the isolated components, we performed Conformation Search and found that the 3-oxo function of the heptane chain in the diarylheptanoid molecule is required for their trypanocidal activity.

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.

Anti-trypanosomal effect of Peristrophe bicalyculata extract on Trypanosoma brucei brucei-infected rats.

OBJECTIVE: To investigate the in vitro and in vivo effect of whole plant extracts of Peristrophe bicalyculata on Trypanosoma brucei brucei-infected rats. METHODS: THE EXPERIMENT WAS DIVIDED INTO TWO PHASES: In the first phase, the anti-trypanosomal activity of the hot water, cold water, methanol and butanol extracts of the whole plant were determined by incubating with Trypanosoma brucei brucei. The cold water extract was partially-purified and the anti-trypanosomal activity of the fractions determined. In the second phase, Trypanosoma brucei brucei-infected rats were treated with fraction 2c for nine days. Packed cell volume (PCV), high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triacylglycerol (TAG), aspartate aminotransferase, alanine aminotransferases (ALT), alkaline phosphatase (ALP), total and direct bilirubin levels were determined at the end of the experiment. RESULTS: Cold water extract immobilized 90% of the parasites after 60 min of incubation, and fraction 2c completely immobilized the parasites after 35 min. It significantly increased PCV in Trypanosoma brucei brucei-infected rats. Decreased TC, TAG, HDL and LDL levels of infected rats increased significantly when rats were treated with the fraction, while elevated levels of total bilirubin and ALT also decreased. The difference in urea, direct bilirubin and ALP was not significant when infected rats were compared to rats in other groups. CONCLUSIONS: The ability of the plant to ameliorate the infection-induced biochemical changes calls for detailed investigation of the potentials of the plant for antitrypanosomiasis drug delivery.

Anti-trypanosomal effect of Peristrophe bicalyculata extract on Trypanosoma brucei brucei-infected rats

Objective: To investigate the in vitro and in vivo effect of whole plant extracts of Peristrophe bicalyculata on Trypanosoma brucei brucei-infected rats. Methods: The experiment was divided into two phases: In the first phase, the anti-trypanosomal activity of the hot water, cold water, methanol and butanol extracts of the whole plant were determined by incubating with Trypanosoma brucei brucei. The cold water extract was partially-purified and the anti-trypanosomal activity of the fractions determined. In the second phase, Trypanosoma brucei brucei-infected rats were treated with fraction 2c for nine days. Packed cell volume (PCV), high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triacylglycerol (TAG), aspartate aminotransferase, alanine aminotransferases (ALT), alkaline phosphatase (ALP), total and direct bilirubin levels were determined at the end of the experiment. Results:Cold water extract immobilized 90%of the parasites after 60 min of incubation, and fraction 2c completely immobilized the parasites after 35 min. It significantly increased PCV in Trypanosoma brucei brucei-infected rats. Decreased TC, TAG, HDL and LDL levels of infected rats increased significantly when rats were treated with the fraction, while elevated levels of total bilirubin and ALT also decreased. The difference in urea, direct bilirubin and ALP was not significant when infected rats were compared to rats in other groups. Conclusions:The ability of the plant to ameliorate the infection-induced biochemical changes calls for detailed investigation of the potentials of the plant for antitrypanosomiasis drug delivery.

Bioactive diterpenes and sesquiterpenes from the rhizomes of wild ginger (Siphonochilus aethiopicus (Schweinf) B.L Burtt).

Wild ginger (Siphonochilus aethiopicus (Schweinf) B.L Burtt) is used in traditional medicines in the West and South of Africa. In the present study, the crude hexane extract of wild ginger was evaluated for in vitro bioactivity. The components isolated from the plant for the first time are: epi-curzerenone, furanodienone (sesquiterpenes), 8(17),12E-labdadiene-15,16-dial, 15-hydroxy-8(17),12E-labdadiene-16-al and 16-oxo-8(17),12E-labdadiene-15-oic acid (labdanes). Cytotoxicity determinations using five cell lines: SH-SY5Y (human, Caucasian, bone marrow, neuroblastoma), Jurkat (human, peripheral blood, leukaemia T cell), L929 (mouse, CH3/connective tissue, areolar and adipose tumour cells), Hep G2 (human, Caucasian, hepatocellular carcinoma) and Hs 27 (normal, human, foreskin cells) were carried out. Anti-trypanosomal activity against Trypanosoma brucei brucei (S427) blood stream forms and anti-bacterial activity against Mycobacterium aurum (CIP .104482) were also investigated. Activity against M. aurum was moderate and at 100µg/ml, the crude extract together with the labdanes showed specific cytotoxicity, indicating anti-cancer potency. Anti-trypanosomal activity was observed in the crude extract which increased with the pure components: 8(17),12E-labdadiene-15,16-dial (MIC = 5.3 µM) and the sesquiterpenoids (MIC = 6.9 µM) as compared to suramin activity (MIC = 10 µM). This anti-trypanosomal activity which is being reported for the first time indicates possible usage against sleeping sickness and nagana in cattle.

Anti-trypanosomal effects of aqueous extract of Ocimum gratissimum (Lamiaceae) leaf in rats infected with Trypanosoma brucei brucei.

The anti-trypanosomal effects of aqueous extract of the leaf of Ocimum gratissimum were evaluated in both in-vitro and in-vivo studies. The anti-trypanosomal activity of the extract against Trypanosoma brucei was investigated in-vitro. The survival and motility of the trypanosomes were completely inhibited within two hours of incubation in various concentrations of the extract. Parasite survival time was concentration dependent being longer in lower (25 and 12.5 mg/ml) than higher (100, 75 and 50 mg/ml) concentrations of the extract. The in-vivo anti-trypanosomal effect of the leaf extract of the leaf extract was investigated in rats infected with Trypanosoma brucei and treated with the extract. The infected rats treated with the extract had less dramatic clinical manifestations and mortality, survived longer and higher PCV values than their untreated counterparts, however, parasitaemia was not significantly reduced. The results suggest that the folkloric medicinal application of the aqueous extract of Ocimum gratissimum has no possible pharmacological basis.