The leaves of Caesalpinia bonducella and Croton joufra are traditionally used anthelmintics by the Mishing tribe in Assam, India. In vitro studies have shown them to be effective as anthelmintics. This study evaluates their effects on the tegument of Hymenolepis diminuta (Cestoda) and the cuticle of Syphacia obvelata (Nematoda) using scanning electron microscopy. The effects were compared with negative control parasites and the one exposed to reference drugs (positive control). Parasites were collected from freshly necropsied animals and were exposed to 30 mg/ml of the methanolic leaf extract of the two plants. Paralysed worms were then processed for ultrastructural studies as per standard methods.

Adult and juvenile H. diminuta exposed to extracts of both the test plants showed damaged scolex, suckers and altered tegument. S. obvelata treated with C. bonducella showed damaged apical region, closed mouth, and a damaged cuticle. Worms exposed to C. joufra showed deformations in the apical region with closed mouth, loss of cephalic papillae, distorted lips and damaged cuticle.

In conclusion, the findings of this study demonstrate that the extract of these plants acts via a tegumental/cuticular mode. This study also validates the traditional knowledge system of the Mishing tribe in Assam, India.