Antileishmanial activity mediated by apoptosis and structure-based target study of peganine hydrochloride dihydrate: an approach for rational drug design.
OBJECTIVE
The aim of this study was to resolve the putative pathway responsible for death induced by peganine hydrochloride dihydrate isolated from Peganum harmala seeds at cellular, structural and molecular level in Leishmania donovani, a causative agent of fatal visceral leishmaniasis.


METHODS
The mode of action was assessed using various biochemical approaches including phosphatidylserine exposure, estimation of mitochondrial transmembrane potential and in situ dUTP nick end labelling staining of nicked DNA in the parasite. Molecular modelling and molecular dynamics studies were conducted with DNA topoisomerase I to identify the target of peganine hydrochloride dihydrate mediating apoptosis. Further, DNA topoisomerase I inhibition by peganine hydrochloride dihydrate was also assessed using an L. donovani topoisomerase I relaxation assay.


RESULTS
Peganine hydrochloride dihydrate, besides being safe, was found to induce apoptosis in both the stages of L. donovani via loss of mitochondrial transmembrane potential. Molecular docking studies suggest that a binding interaction with DNA topoisomerase I of L. donovani (binding energy of -79 kcal/mol) forms a stable complex, indicating a possible role in apoptosis. The compound also inhibits L. donovani topoisomerase I.


CONCLUSIONS
The compound induces apoptosis in L. donovani and inhibits DNA topoisomerase I.
Misra
Pragya
P
Division of Parasitology, Central Drug Research Institute, Lucknow 226001, India.
Khaliq
Tanvir
T
Dixit
Anshuman
A
SenGupta
Souvik
S
Samant
Mukesh
M
Kumari
Shraddha
S
Kumar
Awanish
A
Kushawaha
Pramod K
PK
Majumder
H K
HK
Saxena
Anil K
AK
Narender
T
T
Dube
Anuradha
A
D000470:Alkaloids / Q000494:pharmacology* / Q000633:toxicity; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology* / Q000633:toxicity; D017209:Apoptosis; D015195:Drug Design; D007893:Leishmania donovani / Q000187:drug effects*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011799:Quinazolines / Q000494:pharmacology* / Q000633:toxicity; D013329:Structure-Activity Relationship; D059004:Topoisomerase I Inhibitors
D000470:Alkaloids; D000981:Antiprotozoal Agents; D011799:Quinazolines; D059004:Topoisomerase I Inhibitors; C019592:vasicine