Preventive chemotherapy with praziquantel is the mainstay of schistosomiasis control. However, drug resistance is an imminent threat, particularly with large-scale administration of praziquantel, in addition to much less efficacy against young schistosomes. Several biological activities of limonin have been explored such as insecticidal, insect antifeedant, and growth-regulating activity on insects as well as antimalarial, antiviral, anticancer, cholesterol-lowering, and antioxidant activities. This study investigates limonin as an alternative antischistosomal compound using two novel, single, oral dose regimens. In the current work, the therapeutic efficacy of different limonin dosing protocols was evaluated in experimentally infected mice harboring Schistosoma mansoni (Egyptian strain) juvenile or adult stages. Oral administration of limonin in a single dose of 50 or 100 mg/kg on day 21 post-infection (p.i.) resulted in a significant worm burden reduction of 70.0 and 83.33 %, respectively. The same dose given on day 56 p.i. reduced total worm burdens by 41.09 and 60.27 %, respectively. In addition, significant reductions of 34.90 and 47.16 % in the hepatic and 46.67 and 56.1 % in the intestinal tissue egg loads, respectively, associated with significant alterations in the oogram pattern with elevated dead egg levels. Limonin produced ameliorations of hepatic pathology with reduction in dimensions and number of granulomas. Limonin also produced a variety of tegumental alterations in treated worms including tubercular disruption, edema, blebbing, and ulcerations. Results obtained by this work elucidated promising limonin bioactivity against S. mansoni juvenile and adult stages and provided a basis for subsequent experimental and clinical trials.

Background: Continuous attempts are being made to develop new and more effective drugs for treatment of schistosomiasis. Curcuma longa is a medicinal plant that contains yellow pigments known as curcuminoids (curcumin, bidesmetoxi-curcumin and monodesmetoxi-curcumin), with curcumin as the highest component. The main biological effect depends on curcumin content. Curcumin has low bioavailability and poor-water solubility. Preparation of C. longa (Cl) nanoemulsion was attempted to enhance solubility and bioavailability of curcumin. Objective: The production of Cl nanoemulsion, and study of its pharmacokinetic properties (namely solubility and intestinal bioavailability) and anti-helminthic effects on Schistosoma mansoni cercariae, schistosomules and adults. Methodology: Cl nanoemulsion was prepared from ethanol extract of crude powder of Cl rhizome. Characterization was done by transmission electron microscope (TEM), testing solubility and intestinal bioavailability. Schistosomicidal effects were performed by in vitro assay. Results: Cl nanoemulsion showed increased solubility and bioavailability compared to ethanol extract of the tested plant; as well as time and dose dependent schistosomicidal effects on cercariae and 24h-old schistosomules of S. mansoni. In addition, it exhibited an optimal activity against the adult stage with decreased motor activity of the worms. Conclusion: This study proves that Cl nanoemulsion has enhanced solubility and bioavailability, as well as schistosomicidal activity.

Background: The common house mosquito, Culex pipiens, is abundant in Egypt and act as a vector of pathogens of medical and veterinary importance. Aim: The present study aimed to compare the toxic effect of rose bengal a photosensitizer to that of chlorpyrifos, a commercially available larvicide against the early 3 rd larval instar of Cx. pipiens. Methods: We compare the toxic effect of rose Bengal exposed to sunlight from 10 am to 4 pm to that of chlorpyrifos, against the early 3 rd larval instar of Cx. pipiens. Results: Treatments revealed dose-dependent mortality, reaching 100% after treatment with rose bengal for 6 hrs and 90.6% for chlorpyrifos for 24 hrs. Six hours post-treatments, the LC50 of rose bengal and chlorpyrifos were 4.9x10-6 and 4.9x10-4 , respectively; while the LC95 were 2.0x10-3 and 4.0x0-3 , respectively. Based on the LC50 values of chlorpyrifos as a reference substance, rose bengal was found 100 times more potent than chlorpyrifos. The LT50 of rose bengal ranged from 34.8 to 1.1 hrs post-treatment with1×10-6 M and 1×10-2 , respectively. The LT50 values of chlorpyrifos ranged from 3065.9 to 6.1 hrs after subjecting to 1×10-4 M and 1×10-3 , respectively. Conclusion: It could be concluded that rose bengal could be used to prevent mosquito bites and their associated diseases as an alternative to traditional insecticides and an eco-friendly larvicide.

There is renewed interest in natural products as a starting point for discovery of drugs for schistosomiasis. Recent studies have shown that phytol reveals interesting in vivo and in vitro antischistosomal properties against Schistosoma mansoni adult worms. Here, we report the in vitro antischistosomal activity of phytol against Schistosoma haematobium juvenile and adult worms and alterations on the tegumental surface of the worms by means of scanning electron microscopy. The assay, which was carried out with 6 concentrations (25, 50, 75, 100, 125, and 150 μg/ml) of phytol, has shown a promising activity in a dose and time-dependent manner. There was a significant decline in the motility of the worms and a mortality rate of 100% was found at 48 hr after they had been exposed to phytol in the concentration of 150 μg/ml. Male worms were more susceptible. On the ultrastructural level, phytol also induced tegumental peeling, disintegration of tubercles and spines in addition to morphological disfiguring of the oral and ventral suckers. This report provides the first evidence that phytol is able to kill S. haematobium of different ages, and emphasizes that it is a promising natural product that could be used for development of a new schistosomicidal agent.

Abstract. CC-BY 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/347278 doi: bioRxiv preprint first posted online Jun. 14, 2018; 26Schistosomiasis is one of the most socioeconomically exhausting parasitic 27 infection in tropical and subtropical areas. Praziquantel (PZQ), the only common 28 schistosocidal drug in use, is not efficient enough for treatment of immature infection. 29Arabic gum (AG) is a complex polysaccharide acts as anti-oxidant which modulates the Author summary 46Schistosomiasis is a major public health threat in many parts of the world, it 47 affects more than 240 million people in more than 70 countries and almost 800 million 48 people are at risk of acquiring this disease. Serious consequences and disabilities might . CC-BY 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/347278 doi: bioRxiv preprint first posted online Jun. 14, 2018;