Ultrastructural alterations in Schistosoma mansoni juvenile and adult male worms after in vitro incubation with primaquine.
BACKGROUND
Praziquantel has been cited as the only drug for treating schistosomiasis. However, concerns over drug resistance have encouraged the search for novel drug leads. The antimalarial drug primaquine possesses interesting anti-schistosmal properties.


OBJECTIVE
This study is the first to document the potential role of primaquine as a schistosomicide and the ultrastructural changes induced by primaquine on juvenile or adult male worms of Schistosoma mansoni.


METHODS
Ultrastructural alterations in the tegumental surface of 21-day-old juvenile and adult male worms of S. mansoni were demonstrated following primaquine treatment at different concentrations (2, 5, 10, 15, and 20 µg/mL) and incubation periods (1, 3, 6, 24, and 48 h) in vitro, using both scanning and transmission electron microscopy.


RESULTS
At low concentrations (2, 5, and 10 µg/mL) both juvenile and adult male worms were alive after 24 h of incubation, whereas contraction, paralysis, and death of all worms were observed after 24 h of drug exposure at 20 µg/mL. The tegument of juvenile and adult male worms treated with primaquine exhibited erosion, peeling, and sloughing. Furthermore, extensive damage of both tegumental and subtegumental layers included embedded spines, and shrinkage of muscles with vacuoles. The in vitro results confirmed that primaquine has dose-dependent effects with 20 µg/mL as the most effective concentration in a short incubation period.


CONCLUSIONS
The schistosomicidal activity of primaquine indicates that this drug possesses moderate in vitro activity against juvenile and adult male worms, since it caused high mortality and tegumental alterations. This study confirmed that the antimalarial drug primaquine possesses anti-schistosomal activity. Further investigation is needed to elucidate its mechanism of action.
Ain Shams University, Women College for Arts, Science and Education, Department of Zoology, Asmaa Fahmey St., Cairo, Egypt.
Reem Osama A
RO
Kamel
Ain Shams University, Women College for Arts, Science and Education, Department of Zoology, Asmaa Fahmey St., Cairo, Egypt.
Fatma El-Zahraa Anwar
FE
Bayaumy
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D011223:Praziquantel / Q000494:pharmacology*; D011319:Primaquine / Q000494:pharmacology*; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000648:ultrastructure*; D013997:Time Factors
D000871:Anthelmintics; D011223:Praziquantel; D011319:Primaquine