In vitro effects and mechanisms of action of Bidens pilosa in Trypanosoma brucei.

Background and aim: African trypanosomiasis poses serious health and economic concerns to humans and livestock in several sub-Saharan African countries. The aim of the present study was to identify the antitrypanosomal compounds from B. pilosa (whole plant) through a bioactivity-guided isolation and investigate the in vitro effects and mechanisms of action against Trypanosoma brucei (T. brucei). Experimental procedure: Crude extracts and fractions were prepared from air-dried pulverized plant material of B. pilosa using the modified Kupchan method of solvent partitioning. The antitrypanosomal activities of the fractions were determined through cell viability analysis. Effects of fractions on cell death and cell cycle of T. brucei were determined using flow cytometry, while fluorescence microscopy was used to investigate alterations in cell morphology and distribution. Results and conclusion: The solvent partitioning dichloromethane (BPFD) and methanol (BPFM) fractions of B. pilosa exhibited significant activities against T. brucei with respective half-maximal inhibitory concentrations (IC50s) of 3.29 µg/ml and 5.86 µg/ml and resulted in the formation of clumpy subpopulation of T. brucei cells. Butyl (compound 1) and propyl (compound 2) esters of tryptophan were identified as the major antitrypanosomal compounds of B. pilosa. Compounds 1 and 2 exhibited significant antitrypanosomal effects with respective IC50 values of 0.66 and 1.46 µg/ml. At the IC50 values, both compounds significantly inhibited the cell cycle of T. brucei at the G0-G1 phase while causing an increase in G2-M phase. The results suggest that tryptophan esters may possess useful chemotherapeutic properties for the control of African trypanosomiasis.

Anti-inflammatory activity and mechanism of action of ethanolic leaf extract of Morinda lucida Benth.

BACKGROUND AND AIM: Most developing countries resort to medicinal plants for treating diseases, but few of these have scientific backing for their use. The aim of the study was to validate traditional use of Morinda lucida leaves in treating inflammation and determine the mechanism of action. EXPERIMENTAL PROCEDURE: Effect of hydroethanolic leaf extract of M. lucida (HEML) on localized inflammation was evaluated using rat paw edema presented by sub-planter injections of λ-carrageenan, histamine or serotonin in separate experiments. Systemic inflammation was evaluated by lipopolysaccharide (LPS)-induced hyperthermia. Antioxidant activity of HEML was also evaluated using the free-radical scavenging assay. RESULTS AND CONCLUSION: No mortalities were recorded in acute toxicity assay after administering 5000 mg/kg HEML to rats. It showed very good activity against localized and systemic inflammation in inverse dose-dependent manner and caused reduction in nitric oxide and prostaglandin E-2 levels by affecting expression of inducible nitric oxide synthase, but not cyclooxygenases-2 in LPS-activated RAW 264.7 murine macrophages. HEML reduced pro-inflammatory cytokines interleukin (IL)-1ß and tumor necrotic factor, but elevated levels of anti-inflammatory cytokine IL-10 in vitro. HEML contains saponins, reducing sugars, polyphenols and flavonoids and showed antioxidant activity with EC50 = 0.6415 ± 0.0027 mg/ml. In conclusion, this study provides evidence that HEML possesses anti-inflammatory activity, possibly through modulation of production of early/late phase inflammation mediators.

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.

Antitrypanosomal Effects of Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler Extracts on African Trypanosomes.

African trypanosomiasis is a disease caused by the parasitic protozoa of the Trypanosoma genus. Despite several efforts at chemotherapeutic interventions, the disease poses serious health and economic concerns to humans and livestock of many sub-Saharan African countries. Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler (Z. zanthoxyloides LZT) is a plant species of important phytochemical and pharmacological relevance in the subtropical zones of the African continent. However, the mechanisms of its antitrypanosomal effects in African trypanosomes remain to be elucidated. The aim of the study was to determine the in vitro effects and mechanisms of action of Z. zanthoxyloides LZT (root) fractions against Trypanosoma brucei. T. brucei (GUTat 3.1 strain), L. donovani (D10 strain), P. falciparum (3D 7 strain), Jurkat cells, and Chang liver cells were cultivated in vitro to the log phase in their respective media at 37°C. Crude extracts and fractions were prepared from air-dried pulverized plant material of Z. zanthoxyloides LZT (root) using the modified Kupchan method of solvent partitioning. Half-maximal inhibitory concentrations (IC50) were determined through the alamar blue cell viability assay. Effects of fractions on cell death and cell cycle of T. brucei were determined using flow cytometry. Fluorescence microscopy was used to investigate the effects of fractions on the morphology and distribution of T. brucei. Antitrypanosomal compounds of fractions were characterized using high-performance liquid chromatography (HPLC) and attenuated total reflectance infrared (ATR-IR) spectroscopy. Methanol, butanol, and dichloromethane fractions were selectively active against T. brucei with respective IC50 values of 3.89, 4.02, and 5.70 µg/ml. Moreover, methanol, butanol, and dichloromethane fractions significantly induced apoptosis-like cell death with remarkable alteration in the cell cycle of T. brucei. Furthermore, dichloromethane and methanol fractions altered the morphology, induced aggregation, and altered the ratio of nuclei to kinetoplasts in the parasite. The HPLC chromatograms and ATR-IR spectra of the active fractions suggested the presence of aromatic hydrocarbons with hydroxyl, carbonyl, amine, or amide functional groups. The results suggest that Z. zanthoxyloides LZT have potential chemotherapeutic effects on African trypanosomes with implications for novel therapeutic interventions in African trypanosomiasis.