Evaluation of antitrypanosomal properties and apoptotic effects of ochrolifuanine from Dyera costulata (Miq.) Hook.f against Trypanosoma brucei brucei.

Trypanosoma brucei parasites are flagellated kinetoplastid protozoan which is responsible for Human African Trypanosomiasis (HAT). Current chemotherapy drugs have a number of side effects and drug resistance has emerged as a major issue in current treatment. Active bisindole alkaloid compound ochrolifuanine was previously isolated from the leaves of Dyera costulata. In vitro antitrypanosomal activity of ochrolifuanine against Trypanosoma brucei brucei strain BS221 showed strong activity with an IC50 value of 0.05 ± 0.01 µg/ml. We compared the effect of ochrolifuanine and reference compound staurosporine in T. b. brucei apoptosis. The apoptosis-inducing activity of ochrolifuanine was evaluated using TUNEL assay and cell cycle analysis. Trypanosoma brucei brucei was shown to undergo apoptotic cells death as demonstrated by the appearance of several conical hallmarks of apoptosis. Ochrolifuanine was found to induce apoptosis in parasites in a dose- and time-dependent manner. The cell cycle study revealed 0.025 and 0.05 µg/ml of ochrolifuanine arrested the growth of T. b. brucei at two different growth phases (G0/G1 and in S phases). While at concentration 0.10 µg/ml arrested at the G2/M phase. In conclusion, the results indicate that ochrolifuanine displayed an antitrypanosomal effect on T. b. brucei by inducing apoptosis cell death and causing the arrest of parasite cells at different growth phases. The results suggested that ochrolifuanine may be a promising lead compound for the development of new chemotherapies for African trypanosomiasis.

Evaluation of antitrypanosomal properties and apoptotic effects of ochrolifuanine from Dyera costulata (Miq.) Hook.f against Trypanosoma brucei brucei

@#Trypanosoma brucei parasites are flagellated kinetoplastid protozoan which is responsible for Human African Trypanosomiasis (HAT). Current chemotherapy drugs have a number of side effects and drug resistance has emerged as a major issue in current treatment. Active bisindole alkaloid compound ochrolifuanine was previously isolated from the leaves of Dyera costulata. In vitro antitrypanosomal activity of ochrolifuanine against Trypanosoma brucei brucei strain BS221 showed strong activity with an IC50 value of 0.05 ± 0.01 µg/ml. We compared the effect of ochrolifuanine and reference compound staurosporine in T. b. brucei apoptosis. The apoptosis-inducing activity of ochrolifuanine was evaluated using TUNEL assay and cell cycle analysis. Trypanosoma brucei brucei was shown to undergo apoptotic cells death as demonstrated by the appearance of several conical hallmarks of apoptosis. Ochrolifuanine was found to induce apoptosis in parasites in a dose- and time-dependent manner. The cell cycle study revealed 0.025 and 0.05 µg/ml of ochrolifuanine arrested the growth of T. b. brucei at two different growth phases (G0/G1 and in S phases). While at concentration 0.10 µg/ml arrested at the G2/M phase. In conclusion, the results indicate that ochrolifuanine displayed an antitrypanosomal effect on T. b. brucei by inducing apoptosis cell death and causing the arrest of parasite cells at different growth phases. The results suggested that ochrolifuanine may be a promising lead compound for the development of new chemotherapies for African trypanosomiasis.

Chemical composition and in vitro antitrypanosomal activity of fractions of essential oil from Cymbopogon nardus L.

Essential oil from Cymbopogon nardus was evaluated for activity against Trypanosoma brucei brucei BS221 (IC50 = 0.31 ± 0.03 µg/mL) and cytotoxic effect on normal kidney (Vero) cells (IC50 = >100 µg/mL). The crude essential oil was subjected to various chromatography techniques afforded active sub fractions with antitrypanosomal activity; F4 (IC50 = 0.61 ± 0.06 µg/mL), F6 (IC50= 0.73 ± 0.33 µg/mL), F7 (IC50 = 1.15 ± 0 µg/mL) and F8 (IC50 = 1.11 ± 0.01 µg/mL). These active fractions did not exhibit any toxic effects against Vero cell lines and the chemical profiles investigation indicated presence of α-and γ-eudesmol, elemol, α-cadinol and eugenol by GC/MS analysis.

Chemical composition and in vitro antitrypanosomal activity of fractions of essential oil from Cymbopogon nardus L

Essential oil from Cymbopogon nardus was evaluated for activity against Trypanosoma brucei brucei BS221 (IC50 = 0.31 ± 0.03 μg/mL) and cytotoxic effect on normal kidney (Vero) cells (IC50 = >100 μg/mL). The crude essential oil was subjected to various chromatography techniques afforded active sub fractions with antitrypanosomal activity; F4 (IC50 = 0.61 ± 0.06 μg/mL), F6 (IC50= 0.73 ± 0.33 μg/mL), F7 (IC50 = 1.15 ± 0 μg/mL) and F8 (IC50 = 1.11 ± 0.01 μg/mL). These active fractions did not exhibit any toxic effects against Vero cell lines and the chemical profiles investigation indicated presence of α-and γ-eudesmol, elemol, α-cadinol and eugenol by GC/MS analysis.

Evaluation of Streptomyces sp. strain g10 for suppression of Fusarium wilt and rhizosphere colonization in pot-grown banana plantlets.

Streptomyces sp. strain g10 exhibited strong antagonism towards Fusarium oxysporum f.sp. cubense (Foc) races 1, 2 and 4 in plate assays by producing extracellular antifungal metabolites. Treating the planting hole and roots of 4-week-old tissue-culture-derived 'Novaria' banana plantlets with strain g10 suspension (10(8) cfu/ml), significantly (P < 0.05) reduced wilt severity when the plantlets were inoculated with 10(4) spores/ml Foc race 4. The final disease severity index for leaf symptom (LSI) and rhizome discoloration (RDI) was reduced about 47 and 53%, respectively, in strain g10-treated plantlets compared to untreated plantlets. Reduction in disease incidence was not significant (P < 0.05) when plantlets were inoculated with a higher concentration (10(6) spores/ml) of Foc race 4. Rhizosphere population of strain g10 showed significant (P = 0.05) increase of more than 2-fold at the end of the 3rd week compared to the 2nd week after soil amendment with the antagonist. Although the level dropped, the rhizosphere population at the end of the 6th week was still nearly 2-fold higher than the level detected after 2 weeks. In contrast, the root-free population declined significantly (P = 0.05), nearly 4-fold after 6 weeks when compared to the level detected after 2 weeks. Neither growth-inhibiting nor growth-stimulating effects were observed in plantlets grown in strain g10-amended soil.

Antagonistic effects of Streptomyces violaceusniger strain G10 on Fusarium oxysporum f.sp. cubense race 4: indirect evidence for the role of antibiosis in the antagonistic process.

Fusarium oxysporum f.sp. cubense is the causal pathogen of wilt disease of banana. A cost-effective measure of control for this disease is still not available. Streptomyces violaceusniger strain G10 acts as an antifungal agent antagonistic towards many different phytopathogenic fungi, including different pathogenic races of the Fusarium wilt pathogen. In an attempt to understand the mode of action of this antagonist in nature, the interaction between S. violaceusniger strain G10 and F. oxysporum f.sp. cubense was first studied by paired incubation on agar plates. Evidence for the in vitro antibiosis of strain G10 was demonstrated by inhibition zones in the "cross-plug" assay plates. Microscopic observations showed lysis of hyphal ends in the inhibited fungal colonies. Culture of strain G10 in liquid media produces antifungal metabolites, which showed in vitro antagonistic effects against F. oxysporum f.sp. cubense such as swelling, distortion and excessive branching of hyphae, and inhibition of spore germination. An indirect method was used to show that antibiosis is one of the mechanisms of antagonism by which strain G10 acts against F. oxysporun f.sp. cubense in soil. This study suggests the potential of developing strain G10 for the biological control of Fusarium wilt disease of banana.