Acaricide activity of organo-modified siloxane and acaricide associations in Rhipicephalus microplus.

Search to a new alternative to control bovine ticks (Rhipicephalus microplus), the present study aimed to evaluate the acaricidal activity of organo-modified siloxane alone and in association with different commercial products or with piperonyl butoxide (BPO). Engorged females were subjected to an in vitro immersion test and 10 groups were used: control, 0.5% siloxane, 1% siloxane, 2% siloxane, 0.5% siloxane + 5% BPO, 1% siloxane + 5% BPO, 2% siloxane + 5% BPO, commercial product, 0.5% siloxane + commercial product, and 1% siloxane + commercial product. After immersion, engorged females were incubated for 14 days for oviposition and hatchability tests. Another immersion test was performed with 5% siloxane and 2.5% siloxane + 10% BPO to evaluate the histopathological changes. Then, engorged females were incubated for 0, 2, 4, 8, 12, 24, 36, 48, 60, 72, 84, 96, 120, 144, and 168 h and immersed in 10% formaldehyde for later analyses. The unassociated siloxane showed an acaricide efficacy of 93.88% at 2% concentration, and when associated with 5% BPO, it reached 100% efficacy at all tested concentrations. The tested commercial products showed enhanced efficacy when associated with siloxane. Histopathological analysis showed cell changes in both treatments and total cell disintegration after 120 h in the 5% siloxane group and after 96 h in the 2.5% siloxane + 10% BPO group. Therefore, siloxane alone or in combination is an alternative against R. microplus, and siloxane enhances the efficacy of available commercial products.

Water-soluble tetra-cationic porphyrins display virucidal activity against Bovine adenovirus and Bovine alphaherpesvirus 1.

Porphyrins are photoactive compounds that can absorb the energy of light and transfer it to oxygen molecules, producing reactive oxygen species (ROS). Once produced, ROS may alter biological molecules and cellular mechanisms, leading to cell apoptosis or inactivation of microorganisms, such as bacteria, fungi, and viruses. Therefore, the objective of this study was to evaluate the in vitro virucidal activity of six tetra-cationic porphyrins against two bovine viruses (Bovine alphaherpesvirus 1, BoHV-1, enveloped; and Bovine adenovirus, BAV, non-enveloped). For this, viral suspensions were incubated with each porphyrin (H2TMeP, ZnTMeP, and CuTMeP at 4.0 µM, NiTMeP at 5.0 µM, and CoClTMeP and MnClTMeP at 1.0 µM) and exposed to white-light irradiation for 0, 60, 120, and 180 min (BAV) or 0, 30, 60, 90, and 120 min (BoHV-1). Then, the remaining viral titers were determined by limiting dilution and compared with the control (virus + porphyrins without light exposition). The porphyrins H2TMeP and ZnTMeP showed the highest virucidal activity against both viruses. ZnTMeP inactivated BoHV-1 after 30 min of photoactivation and H2TMeP after 60 min. The BAV was photo-inactivated by both porphyrins at 180 min of white-light exposition. CuTMeP, NiTMeP, and CoClTMeP porphyrins had weak virucidal activity against BoHV-1 and MnClTMeP showed no virucidal activity against both viruses. These results indicated that free-base H2TMeP and ZnTMeP porphyrins present virucidal activity against non-enveloped and enveloped viruses, opening the possibility for their use to inactivate viruses on surfaces, biological substrates, and solutions.