Bioactivity studies of porphyrinoids against microsporidia isolated from honeybees

Abstract

Microsporidian infections are dangerous to honeybees due to the absence of an efficient treatment for nosemosis. in the present work, the abilities of several porphyrins to directly inactivate microsporidia derived from Nosema-infected honeybees were studied in vitro. Amide derivatives of protoporphyrin iX (ppiX) conjugated with one and two amino acid moieties were synthesized, and their activities were compared with those of two cationic porphyrins, tMepyp and ttMepp. the most active porphyrins, pp[Lys-Asp] 2 , pp[Lys-tfA] 2 , pp[Asp(ona) 2 ] 2 and pp[Lys-Lys] 2 at concentrations as low as 10-50 µM exerted significant effects on microsporidia, reducing the number of spores by 67-80% compared to the control. Live-cell imaging of the spores treated with porphyrins showed that only 1.6% and 3.0% of spores remained alive after 24 h-incubation with 50 µM PP[Asp(ONa) 2 ] 2 and pp[Lys-Asp] 2 , respectively. The length of the amino acid side chains and their identity in the PPIX molecules affected the bioactivity of the porphyrin. importantly, the irradiation of the porphyrins did not enhance their potency in destroying Nosema spores. We showed that the porphyrins accumulated inside the living spores but not inside dead spores, thus the destruction of the microsporidia by non-metallated porphyrins is not dependent on photosensitization, but is associated with their active transport into the spore cell. When administered to honeybees in vivo, ppiX[Lys-tfA] 2 and ppiX[Lys-Lys] 2 reduced spore loads by 69-76% in infected individuals. They both had no toxic effect on honeybees, in contrast to zinc-coordinated porphyrin. Microsporidia are a large group of eukaryotic obligatory intracellular parasites that form single-cell spores and can complete their life cycle only within an infected host cell. So far, ~ 1400 microsporidian species representing 200 genera have been reported 1. Microsporidia are in the kingdom Fungi, and chitin is a major component of the inner layer of their spore wall. An electron-dense outer exospore comprises the second layer of the cell wall 2-4. Microsporidia are characterized by their unique metabolism and the absence of certain elements common to eukaryotic cells, i.e., mitochondria, peroxisomes, and the classic Golgi apparatus 3-5. The interior of the spore is filled with sporoplasm and a mass of vesicular tubules, which are structurally homologous to the Golgi apparatus. Microsporidia contain a unique invasion apparatus that consists of a polar tube that coils around the sporoplasm and ends at an anchoring disc in the apical part of the spore. A polar tube is required for cell invasion, which occurs via injection of the spore content into the host cell 6. All of these features are associated with adaptation to the parasitic lifestyle 3. Microsporidia are able to survive outside a host cell but can exist only as metabolically inactive spores 7. Microsporidia cause many contagious diseases commonly known as microsporidiosis, and they can infect a wide range of organisms from invertebrates to vertebr...

Novel Cationic Meso-Arylporphyrins and Their Antiviral Activity against HSV-1

“…and their chemical and thermal stability [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Natural porphyrins and their synthetic analogues are widely used as photosensitizers for the photodynamic therapy (PDT) of neoplasms [ 25 , 26 , 27 , 28 , 29 ] and the photodynamic inactivation (PDI) of microorganisms, such as viruses [ 30 , 31 , 32 , 33 , 34 ], bacteria [ 35 , 36 , 37 , 38 ] and fungi [ 39 , 40 ].…”

Impact of Protoporphyrin Lysine Derivatives on the Ability of Nosema ceranae Spores to Infect Honeybees

“…In addition, these compounds showed cytotoxicity to IPL-LD 65Y cells [65]. Porphyrin compounds, in contrast, have not induced any adverse effects in our studies so far [43,66], showing that they could be effective against nosemosis without causing harm to the host. Our recent studies [66] confirmed that the protoporphyrin lysine derivatives are not toxic to honeybees in contrast to the zinc-coordinated porphyrin.…”

“…Porphyrin compounds, in contrast, have not induced any adverse effects in our studies so far [43,66], showing that they could be effective against nosemosis without causing harm to the host. Our recent studies [66] confirmed that the protoporphyrin lysine derivatives are not toxic to honeybees in contrast to the zinc-coordinated porphyrin. The latter, despite its high activity in the reduction of the spore numbers (both in vitro and in vivo), also increased the mortality of honeybees within 23 d post infection.…”

Assessing the In Vitro Activity of Selected Porphyrins in Human Colorectal Cancer Cells

“…Experiments were conducted in two separate conditions: a lack of light (for the duration of the experiment) and a short exposure to white light (3 min). Six fluorescent lamps (Osram Lumilux Cool White, Wilmington, MA, USA, with a total power of 90 W) were used as the source of visible light, in accordance with the method described by Lipke et al [ 24 ] and Buczek et al [ 25 ]. Each well of the culture plates was irradiated with a vertical array 20 cm from the plate.…”