Antiviral activity of five filamentous cyanobacteria against coxsackievirus B3 and rotavirus.

Coxsackievirus B3 (CVB3) and rotavirus (RV) are pathogens of some chronic human diseases. The aim of this study was to determine in vitro antiviral activity of some cyanobacteria against RV and CVB3 infections. Five cyanobacteria were collected from Egypt, identified, and analyzed biochemically. Then, the inhibition of the cytopathic effect of RV and CVB3 viruses by cyanobacterial extracts was examined. Methanol extract of the cyanobacterial isolates showed high antiviral activity against CVB3 with Therapeutic index (TI) of 50.0, 30.0, 27.6, 16.6, and 20.0 for Leptolyngbya boryana, Arthrospira platensis, Nostoc punctiforme, Oscillatoria sp., and Leptolyngbya sp., respectively. The extracts reduced CVB3 titers comparing to 50% tissue culture infectious doses (TCID50) with values 3.25-5.75 log10 of TCID50. Moreover, extracts of A. platensis, and Oscillatoria sp. exhibited high antiviral activity against RV with TI values of 45 and 42.5, respectively, and a reduction in virus titers by 5.75 log10 and 5.5 log10 of TCID50, respectively. Extracts of L. boryana, Leptolyngbya sp., and N. punctiforme had a moderate to low antiviral activity against RV with TI ranging between 2.8 and 7, respectively, and a reduction in virus titers between 0.5 log10 and 1.5 log10 of TCID50, respectively. This study concluded that extracts of five cyanobacterial isolates possess a potent antiviral effect against CVB3 and RV, making them promising sources of new safe antiviral drugs.

Biological effects of pyrimethinal on aquatic worms (Tubifex tubifex) under laboratory conditions.

Laboratory studies were conducted to determine the effects of different concentrations of pyrimethinal on protein contents, and some oxidative stress in Tubifex tubifex after an exposure of 2, 4, and 7 days. Residues of the fungicide were followed in water and in the worms. In water, pyrimethinal concentration decreased slowly (maximum -6.4 % ± 0.8 % after 2 days for 25 mg L(-1)). In the worms, it increased after 4 days and decreased thereafter. LC50 values were between 49.2 ± 0.58 and 39.5 ± 0.95 mg L(-1) depending on exposure time. The activity of catalase increased in response to the fungicide after 2 days of exposure to 25 mg L(-1) of pyrimethinal (+90 %). The highest decrease of glutathione-S-transferase activity (-29.7 %) was found after 7 days in the presence of 25 mg L(-1).

Toxic responses and antioxidative enzymes activity of Scenedesmus obliquus exposed to fenhexamid and atrazine, alone and in mixture.

Laboratory studies were conducted to determine the effects of different concentrations of fenhexamid and atrazine (25, 50 and 100 µg L(-1)) on growth and oxidative stress on Scenedesmus obliquus (microalgae) after exposure for 24, 48, and 96 h. In addition, residues of fenhexamid and atrazine were determined in the culture medium after 96 h; 52%, 44% and 43% of fenhexamid remained in the medium for the lowest, middle and highest concentrations, respectively. Atrazine concentration decreased significantly in the medium with time. The reduction was faster with the lowest concentration (-53%), than in the highest concentration (-46%), while it was intermediate with 50 µg L(-1) (-47%). The antioxidative enzyme activities were used as biomarkers to evaluate the toxic effects of fenhexamid and atrazine on the microalgae. Enzymatic activities were measured in the presence of each compound alone after 24, 48 and 96 h and also in mixture after 24h exposure. The results showed that fenhexamid and atrazine induced antioxidative enzyme activities (GST, CAT and GR) at different concentrations. Catalase activities (CAT) in both pesticides treated-algae were significantly increased. Additionally, an increase in gulathione-S-transferase (GST) was observed in algae after 24, 48 and 96 h of exposure to both fenhexamid and atrazine. Antioxidative enzymes in fenhexamid and atrazine mixture treatment showed an antagonistic interaction after 24h of exposure in algae.