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The diterpenoid 7-keto-sempervirol, derived from Lycium chinense, displays anthelmintic activity against both Schistosoma mansoni and Fasciola hepatica.

Edwards J, Brown M, Peak E, Bartholomew B, Nash RJ, Hoffmann KF - PLoS Negl Trop Dis (2015)

Bottom Line: This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology.As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD50 = 17.7 μM).Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss. 7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom.

ABSTRACT

Background: Two platyhelminths of biomedical and commercial significance are Schistosoma mansoni (blood fluke) and Fasciola hepatica (liver fluke). These related trematodes are responsible for the chronic neglected tropical diseases schistosomiasis and fascioliasis, respectively. As no vaccine is currently available for anti-flukicidal immunoprophylaxis, current treatment is mediated by mono-chemical chemotherapy in the form of mass drug administration (MDA) (praziquantel for schistosomiasis) or drenching (triclabendazole for fascioliasis) programmes. This overreliance on single chemotherapeutic classes has dramatically limited the number of novel chemical entities entering anthelmintic drug discovery pipelines, raising significant concerns for the future of sustainable blood and liver fluke control.

Methodology/ principle findings: Here we demonstrate that 7-keto-sempervirol, a diterpenoid isolated from Lycium chinense, has dual anthelmintic activity against related S. mansoni and F. hepatica trematodes. Using a microtiter plate-based helminth fluorescent bioassay (HFB), this activity is specific (Therapeutic index = 4.2, when compared to HepG2 cell lines) and moderately potent (LD50 = 19.1 μM) against S. mansoni schistosomula cultured in vitro. This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology. As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD50 = 17.7 μM). Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss.

Conclusions/ significance: 7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases. This plant-derived, natural product is also active against both larval and adult developmental forms. As such, the data collectively indicate that 7-keto-sempervirol is an important starting point for anthelmintic drug development. Medicinal chemistry optimisation of more potent 7-keto-sempervirol analogues could lead to the identification of novel chemical entities useful for future combinatorial or replacement anthelmintic control.

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Related in: MedlinePlus

The diterpenoid 7-keto-sempervirol induces surface tegumental damage in adult Schistosoma mansoni males.Scanning Electron Microscopic (SEM) images of adult S. mansoni male worms cultured for 72 hr at 37°C and 5% CO2 in the presence (100 μM) or absence (1% v/v DMSO) of 7-keto-sempervirol. A) (left) 1.00K x magnification of a control (1% v/v DMSO) adult male surface (anterior end) and corresponding (right) 6.00K x magnification of normal tubercles. B) (left) 1.00K x magnification of a 7-keto-sempervirol treated (100 μM), adult male surface (anterior end) and enlarged (right) 9.00K x magnification of two indicated (black boxes) areas of tegumental damage. Holes in the surface tegument/tubercles are indicated by white arrows. These images are representative of 5 adult worms/condition.
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pntd.0003604.g004: The diterpenoid 7-keto-sempervirol induces surface tegumental damage in adult Schistosoma mansoni males.Scanning Electron Microscopic (SEM) images of adult S. mansoni male worms cultured for 72 hr at 37°C and 5% CO2 in the presence (100 μM) or absence (1% v/v DMSO) of 7-keto-sempervirol. A) (left) 1.00K x magnification of a control (1% v/v DMSO) adult male surface (anterior end) and corresponding (right) 6.00K x magnification of normal tubercles. B) (left) 1.00K x magnification of a 7-keto-sempervirol treated (100 μM), adult male surface (anterior end) and enlarged (right) 9.00K x magnification of two indicated (black boxes) areas of tegumental damage. Holes in the surface tegument/tubercles are indicated by white arrows. These images are representative of 5 adult worms/condition.

Mentions: Based on its anti-schistosomula activity, 7-keto-sempervirol’s ability to affect adult schistosome motility, surface-tegument morphology and egg development was subsequently measured using both WHO-adopted indices and microscopic measures. Here, 7-keto-semperivol displayed a significant effect on both male and female worm motility at the highest concentration used in this study (100 μM) at 24 hr and 48 hr post treatment compared to the DMSO (24 hr) control group (Fig. 3). For both genders, there was no significant difference between 48 hr and 72 hr treatments at this concentration (Fig. 3) nor in DMSO treated worms cultivated for 48 hr or 72 hr (S2 Fig.). Interestingly, female worms (unlike males) displayed a 7-keto-semperivol-induced hyperactivity at 24 hr post-treatment (Fig. 3). There were motility and phenotypic discrepancies observed for some individuals cultured in the presence of 10 μM 7-keto-sempervirol, but these differences were not significantly different compared to the DMSO control group (S3 Fig.). Scanning electron microscopy (SEM) of adult male worms co-cultured in the presence of 7-keto-sempervirol (100 μM for 72 hr) further revealed tubercle swelling, spine loss/shortening and surface holes across the tegument (Fig. 4).


The diterpenoid 7-keto-sempervirol, derived from Lycium chinense, displays anthelmintic activity against both Schistosoma mansoni and Fasciola hepatica.

Edwards J, Brown M, Peak E, Bartholomew B, Nash RJ, Hoffmann KF - PLoS Negl Trop Dis (2015)

The diterpenoid 7-keto-sempervirol induces surface tegumental damage in adult Schistosoma mansoni males.Scanning Electron Microscopic (SEM) images of adult S. mansoni male worms cultured for 72 hr at 37°C and 5% CO2 in the presence (100 μM) or absence (1% v/v DMSO) of 7-keto-sempervirol. A) (left) 1.00K x magnification of a control (1% v/v DMSO) adult male surface (anterior end) and corresponding (right) 6.00K x magnification of normal tubercles. B) (left) 1.00K x magnification of a 7-keto-sempervirol treated (100 μM), adult male surface (anterior end) and enlarged (right) 9.00K x magnification of two indicated (black boxes) areas of tegumental damage. Holes in the surface tegument/tubercles are indicated by white arrows. These images are representative of 5 adult worms/condition.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358835&req=5

pntd.0003604.g004: The diterpenoid 7-keto-sempervirol induces surface tegumental damage in adult Schistosoma mansoni males.Scanning Electron Microscopic (SEM) images of adult S. mansoni male worms cultured for 72 hr at 37°C and 5% CO2 in the presence (100 μM) or absence (1% v/v DMSO) of 7-keto-sempervirol. A) (left) 1.00K x magnification of a control (1% v/v DMSO) adult male surface (anterior end) and corresponding (right) 6.00K x magnification of normal tubercles. B) (left) 1.00K x magnification of a 7-keto-sempervirol treated (100 μM), adult male surface (anterior end) and enlarged (right) 9.00K x magnification of two indicated (black boxes) areas of tegumental damage. Holes in the surface tegument/tubercles are indicated by white arrows. These images are representative of 5 adult worms/condition.
Mentions: Based on its anti-schistosomula activity, 7-keto-sempervirol’s ability to affect adult schistosome motility, surface-tegument morphology and egg development was subsequently measured using both WHO-adopted indices and microscopic measures. Here, 7-keto-semperivol displayed a significant effect on both male and female worm motility at the highest concentration used in this study (100 μM) at 24 hr and 48 hr post treatment compared to the DMSO (24 hr) control group (Fig. 3). For both genders, there was no significant difference between 48 hr and 72 hr treatments at this concentration (Fig. 3) nor in DMSO treated worms cultivated for 48 hr or 72 hr (S2 Fig.). Interestingly, female worms (unlike males) displayed a 7-keto-semperivol-induced hyperactivity at 24 hr post-treatment (Fig. 3). There were motility and phenotypic discrepancies observed for some individuals cultured in the presence of 10 μM 7-keto-sempervirol, but these differences were not significantly different compared to the DMSO control group (S3 Fig.). Scanning electron microscopy (SEM) of adult male worms co-cultured in the presence of 7-keto-sempervirol (100 μM for 72 hr) further revealed tubercle swelling, spine loss/shortening and surface holes across the tegument (Fig. 4).

Bottom Line: This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology.As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD50 = 17.7 μM).Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss. 7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom.

ABSTRACT

Background: Two platyhelminths of biomedical and commercial significance are Schistosoma mansoni (blood fluke) and Fasciola hepatica (liver fluke). These related trematodes are responsible for the chronic neglected tropical diseases schistosomiasis and fascioliasis, respectively. As no vaccine is currently available for anti-flukicidal immunoprophylaxis, current treatment is mediated by mono-chemical chemotherapy in the form of mass drug administration (MDA) (praziquantel for schistosomiasis) or drenching (triclabendazole for fascioliasis) programmes. This overreliance on single chemotherapeutic classes has dramatically limited the number of novel chemical entities entering anthelmintic drug discovery pipelines, raising significant concerns for the future of sustainable blood and liver fluke control.

Methodology/ principle findings: Here we demonstrate that 7-keto-sempervirol, a diterpenoid isolated from Lycium chinense, has dual anthelmintic activity against related S. mansoni and F. hepatica trematodes. Using a microtiter plate-based helminth fluorescent bioassay (HFB), this activity is specific (Therapeutic index = 4.2, when compared to HepG2 cell lines) and moderately potent (LD50 = 19.1 μM) against S. mansoni schistosomula cultured in vitro. This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology. As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD50 = 17.7 μM). Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss.

Conclusions/ significance: 7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases. This plant-derived, natural product is also active against both larval and adult developmental forms. As such, the data collectively indicate that 7-keto-sempervirol is an important starting point for anthelmintic drug development. Medicinal chemistry optimisation of more potent 7-keto-sempervirol analogues could lead to the identification of novel chemical entities useful for future combinatorial or replacement anthelmintic control.

Show MeSH
Related in: MedlinePlus