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Deubiquitinating enzymes (DUBs) are conserved in Schistosoma mansoni and may be linked to the 26S proteasome. Previous results from our group showed that b-AP15, an inhibitor of the 26S proteasome DUBs UCHL5 and USP14 induced structural and gene expression changes in mature S. mansoni pairs. This work suggests the use of the nonselective DUB inhibitor PR-619 to verify whether these enzymes are potential target proteins for new drug development. Our approach is based on previous studies with DUB inhibitors in mammalian cells that have shown that these enzymes are associated with apoptosis, autophagy and the transforming growth factor beta (TGF-β) signaling pathway. PR-619 inhibited oviposition in parasite pairs in vitro, leading to mitochondrial changes, autophagic body formation, and changes in expression of SmSmad2 and SmUSP9x, which are genes linked to the TGF-β pathway that are responsible for parasite oviposition and SmUCHL5 and SmRpn11 DUB maintenance. Taken together, these results indicate that DUBs may be used as targets for the development of new drugs against schistosomiasis.

Schistosomiasis continues to be a huge challenge for researchers, pharmaceutical companies, and governments in developing countries. Diterpene compounds are good source for the development of novel potential leading compounds to treat schistosomiasis. We are reporting herein the schistosomicidal activity of ent-kaurenoic acid, ent-copalic acid, ent-hardwickiic acid, isolated from oleoresins of Copaifera spp, and of their derivatives obtained by fungal transformation with strains of Aspergillus fumigatus, A. terreus, A. phoenicis and A. ochraceus, and of Cunninghamella echinulata e C. elegans. The in vitro antiparasitical assays were performed using adult worm pairs of Schistosoma mansoni for the evaluation of the worm pairing, egg production, and eggs development. Ten kaurane, labdane and clerodane-type diterpenes were obtained by fungal transformation and 7α-acetoxy-ent-kaur-16-en-19-oic acid and ent-hardwickiic acid were the most active ones by causing mortality of 100 % of the parasites within 24 h (concentrations of 100.0 and 200.0 μM) and displaying respective IC50 values for 24, 48 and 72 h of 56.7, 37.6 and 29.2 μM and 29.6, 30.8 and 25.7 μM. Additionally, 7α-acetoxy-ent-kaur-16-en-19-oic acid and ent-hardwickiic acid highly reduced the number of laid eggs at 6.25 and 12.5 μM, respectively. These diterpenes should be further investigated as potential candidates for antiparasitic drug discovery.

The proteasome is the key player in the cellular protein degradation machinery and is pivotal for protein homeostasis and Schistosoma mansoni (S. mansoni) survival. Our group study provides insights into proteasome inhibitors and reveals that selective schistosomiasis agents represent an interesting branch of proteasome research linked to the development of new drugs for this neglected disease. Here, we explored the phenotypic response of S. mansoni to b-AP15, a bis-benzylidine piperidone that inhibits 26S proteasome deubiquitinases (DUBs), ubiquitin-specific protease 14 (USP14), and ubiquitin carboxyl-terminal hydrolase 5 (UCHL5). b-AP15 induces a modest decrease in egg production in vitro and reduces viability, leading to the death of parasite couples. This inhibitor also induces a twofold increase in the accumulation of polyubiquitinated proteins in S. mansoni adult worms and causes tegument changes such as disintegration, wrinkling, and bubble formation, both throughout the length of the parasite and in the oral sucker. b-AP15 alters the cell organelles of adult S. mansoni worms, and we specifically observed mitochondrial alterations, which are suggestive of proteotoxic stress leading to autophagy. Taken together, these results indicate that the deubiquitinase function of the proteasome is essential for the parasite and support the hypothesis that the proteasome constitutes an interesting drug target for the treatment of schistosomiasis.

Made available in DSpace on 2020-12-10T19:55:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This paper reports the synthesis of (+/-)-licarin A 1, a dihydrobenzofuran neolignan, resultant of an oxidative coupling reaction of isoeugenol and horseradish peroxidase (HRP) enzyme. Following, three semi-synthetic derivatives from this compound were obtained: benzylated (+/-)-licarin A 2, methylated (+/-)-licarin A 3 and acetylated (+/-)-licarin A 4. After structural elucidation and assignment by Nuclear Magnetic Resonance of H-1, C-13 and DEPT, all compounds were evaluated in vitro against Trypomastigote forms of Trypanosoma cruzi (T. cruzi), the etiologic agent of Chagas disease, and Schistosoma mansoni (S. mansoni) worms, the etiologic agent of schistosomiasis. Compound (4) was the most active against S. mansoni adult worms, displaying worm viability reduction at 25 mu M and mortality of all worms at 100 and 200 mu M within 24 h. Compound 1 was the second most active, showing worm viability reduction at 50 mu M and mortality of 25% and 100% of worms in 24h at concentrations of 100 and 200 mu M, respectively. In addition, theoretical calculations aiming at finding molecular properties that showed the correlation for schistosomicidal and trypanocidal activities of (+/-)-licarin A and three of its semi-synthetic derivatives were also performed. Univ Franca, Nucleo Ciencias Exatas & Tecnol, Grp Pesquisa Produtos Nat, Ave Dr Armando Salles de Oliveira 201, BR-14404600 Franca, SP, Brazil Univ Sao Paulo, Escola Ciencias Farmaceut Ribeirao Preto, Ave Cafe S-N, BR-14040903 Ribeirao Preto, SP, Brazil Univ Mississippi, Sch Pharm, Dept Pharmacognosy, University, MS 38677 USA Univ Mississippi, Sch Pharm, Res Inst Pharmaceut Sci, Natl Ctr Nat Prod Res, University, MS 38677 USA Univ Estadual Paulista, Fac Engn, Dept Fis & Quim, Ilha Solteira, SP, Brazil IF Suldeminas, Ave Maria da Conceicao Santos,900 Parque Real, BR-37550000 Pouso Alegre, MG, Brazil Univ Estadual Paulista, Fac Engn, Dept Fis & Quim, Ilha Solteira, SP, Brazil FAPESP: 1998/14956-7 FAPESP: 2009/05049-2 FAPESP: 2011/07623-8 FAPESP: 2017/24856-2