Original Article Efficacy of netropsin dihydrochloride against the viability, cytopathogenicity and hemolytic activity of Trichomonas vaginalis clinical isolates * Maha Marzouk Abou Gamra 1 , Hanan Hussein Kamel 1 , Hayam Mohamed Ezz Eldin *, 1 , Fatima Mohamed Taha Zahran 1 Parasitology Department, Faculty of Medicine, Ain-Shams University, Abbasia, Cairo, Egypt article info Article history: Received 8 February 2019 Received in revised form 12 April 2019 Accepted 16 May 2019 Available online xxx Keywords: Netropsin T. vaginalis DNA minor groove binder Scanning electron microscopy MCDK cell line Metronidazole resistance abstract Trichomonas vaginalis (T. vaginalis) is a common sexually transmitted infection, affecting the urogenital tract. Trichomoniasis is customarily treated with metronidazole (MTZ). MTZ is known to cause unde- sirable side effects and there is several reports on MTZ resistant T. vaginalis. Thus, the present study aimed to in-vitro evaluate the activity of DNA minor groove binder drug ''Netropsin dihydrochloride'' against metronidazole-sensitive T. vaginalis isolates (G and U isolates) and resistant T. vaginalis isolate (ATCC50138) (R isolate). Netropsin was tested at concentrations ranging from 3.5 to 200 mg/ml. It showed effectiveness against all isolates with MLC of 12.5 mg/ml for G and U isolates and of 25 mg/ml for R isolate. Cytotoxicity assay of isolates exposed to the respective MLC of netropsin for 42 h showed a highly sig- nificant reduction in the death percentage of MCDK cell line as compared to the effect elicited by drug free controls. The hemolytic activity was evaluated by hemolytic assay and by monitoring the interaction of T. vaginalis isolates with human erythrocytes by inverted microscopy and scanning electron micro- scopy. The hemolytic assay showed (0%) hemolysis of RBCs incubated with T. vaginalis isolates treated with the corresponding MLC of netropsin for 24 h. Scanning electron microscopy revealed cytoskeletal deformities of netropsin treated isolates. Taken together, these observations suggest that netropsin is a promising therapy for T. vaginalis infection affecting its viability, virulence, cytopathogenic and hemolytic activity with a mechanism of action that might overcome T. vaginalis resistance to metronidazole. © 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved. 1. Introduction Trichomonas vaginalis (T. vaginalis) is a flagellated protozoan that inhabits the human vagina [1]. It is one of the most common STDs, with an estimated incidence of 248 million new cases annually [2,3]. Trichomoniasis usually presented clinically with vaginitis and cystitis [4]. It can be complicated by preterm birth, cervical erosion, and infertility [5]. Additionally, trichomoniasis was reported with HIV acquisition [6]. Trichomoniasis is mostly treated with metro- nidazole (MTZ) [7]. Which is activated inside the cell by anaerobic reduction forming cytotoxic nitro radical anion [8]. Unfortunately, increased MTZ resistance augments the refractory cases, which are usually treated with higher doses, leading to toxicity in some pa- tients [9,10]. FDA listed MTZ as B risk factor in pregnancy for possible teratogenicity [11]. Also, increased preterm rates in preg- nant females were reported with MTZ [12]. The aforementioned, poses many therapeutic dilemmas. Other nitroimidazoles, have been tried, but because of a similar mode of action, resistance has to be considered [13]. Other non-nitroimidazole drugs were tested, but they had limited effect [13,14]. Lately, attention was drawn to minor groove binders (MGBs), they bind to DNA minor groove, inhibiting DNA synthesis [15]. MGBs display a broad spectrum of antiviral, antibacterial, anti- tumor and antiprotozoal activity [16]. They are divided GC (Gua- nine-Cytosine) and the AT (Adenine-Thymine) classes [16]. Most of AT-specific MGBs were synthesized based on naturally occurring netropsin [15]. Netropsin binds to specific AT-base sequence; blocking DNA helicase, topoisomerase, endonuclease, interfering * All authors meet the ICMJE authorship criteria * Corresponding author. E-mail address: hayamezz@hotmail.com (H.M. Ezz Eldin). 1 All authors contributed equally to this work. Contents lists available at ScienceDirect Journal of Infection and Chemotherapy journal homepage: http://www.elsevier.com/locate/jic https://doi.org/10.1016/j.jiac.2019.05.015 1341-321X/© 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved. J Infect Chemother xxx (xxxx) xxx Please cite this article as: Abou Gamra MM et al., Efficacy of netropsin dihydrochloride against the viability, cytopathogenicity and hemolytic activity of Trichomonas vaginalis clinical isolates, J Infect Chemother, https://doi.org/10.1016/j.jiac.2019.05.015