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  3. Influence of 6-aminonicotinamide (6AN) on Leishmania promastigotes evaluated by metabolomics: Beyond the pentose phosphate pathway

Influence of 6-aminonicotinamide (6AN) on Leishmania promastigotes evaluated by metabolomics: Beyond the pentose phosphate pathway

  • Chem Biol Interact. 2018 Oct 1;294:167-177. doi: 10.1016/j.cbi.2018.08.014.
Shawgi Hago Almugadam 1,  Alessandro Trentini 2,  Martina Maritati 3,  Carlo Contini 4,  Gianluca Rugna 5,  Tiziana Bellini 6,  Maria Cristina Manfrinato 7,  Franco Dallocchio 8,  Stefania Hanau 9
Affiliations

Affiliations

  • 1 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy; Present Address: Faculty of Medical Laboratory Sciences, University of Khartoum, P.O Box 321, Khartoum, 51111, Nile Avenue, Sudan. Electronic address: shawgialmugadam@uofk.edu.
  • 2 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy. Electronic address: trnlsn@unife.it.
  • 3 Infectious Diseases and Dermatology, Department of Medical Sciences, Via Fossato di Mortara 64, University of Ferrara, 44121, Ferrara, Italy. Electronic address: martina.maritati@unife.it.
  • 4 Infectious Diseases and Dermatology, Department of Medical Sciences, Via Fossato di Mortara 64, University of Ferrara, 44121, Ferrara, Italy. Electronic address: cnc@unife.it.
  • 5 Modena Unit, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Via Bianchi 9, 25124, Brescia, Italy. Electronic address: gianluca.rugna@izsler.it.
  • 6 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy. Electronic address: blt@unife.it.
  • 7 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy. Electronic address: mmc@unife.it.
  • 8 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy. Electronic address: dlf@unife.it.
  • 9 Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialty Surgical Sciences, Via Borsari 46, University of Ferrara, 44121, Ferrara, Italy. Electronic address: hns@unife.it.
PMID: 30170107 DOI: 10.1016/j.cbi.2018.08.014
Abstract

6-Aminonicotinamide (6AN) is an antimetabolite used to inhibit the NADPH-producing pentose phosphate pathway (PPP) in many cellular systems, making them more susceptible to oxidative stress. It is converted by a NAD(P)+ glycohydrolase to 6-aminoNAD and 6-aminoNADP, causing the accumulation of PPP intermediates, due to their inability to participate in redox reactions. Some parasites like Plasmodium falciparum and Coccidia are highly sensitive but not all cell types showed a strong responsiveness to 6AN, probably due to the different targeted pathway. For instance, in bacteria the main target is the Preiss-Handler salvage pathway for NAD+ biosynthesis. We were interested in testing 6AN on the kinetoplastid protozoan Leishmania as another model to clarify the mechanisms of action of 6AN, by using metabolomics. Leishmania promastigotes, the life-cycle stage residing in the sandfly, demonstrated a three order of magnitude higher EC50 (mM) compared to P. falciparum and mammalian cells (μM), although pre-treatment with 100 μM 6AN prior to sub-lethal oxidative challenge induced a supra-additive cell kill in L. infantum. By metabolomics, we did not detect 6ANAD/P suggesting that NAD+ glycohydrolases in Leishmania may not be highly efficient in catalysing transglycosidation as happens in other Microorganisms. Contrariwise to the reported effect on 6AN-treated Cancer cells, we did not detect 6-phosphogluconate (6 PG) accumulation, indicating that 6ANADP cannot bind with high affinity to the PPP Enzyme 6 PG dehydrogenase. By contrast, 6AN caused a profound phosphoribosylpyrophosphate (PRPP) decrease and nucleobases accumulation confirming that PPP is somehow affected. More importantly, we found a decrease in nicotinate production, evidencing the interference with the Preiss-Handler salvage pathway for NAD+ biosynthesis, most probably by inhibiting the reaction catalysed by nicotinamidase. Therefore, our combined data from Leishmania strains, though confirming the interference with PPP, also showed that 6AN impairs the Preiss-Handler pathway, underlining the importance to develop compounds targeting this last route.

Keywords

6-Aminonicotinamide; Leishmania; Metabolomics; Nicotinamidase; Pentose phosphate pathway.

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