Effects of Two Antiretroviral Drugs on the Crustacean Daphnia magna in River Water

Abstract

Antiretroviral (ARVs) drugs are used to manage the human immunodeficiency virus (HIV) disease and are increasingly being detected in the aquatic environment. However, little is known about their effects on non-target aquatic organisms. Here, Daphnia magna neonates were exposed to Efavirenz (EFV) and Tenofovir (TFV) ARVs at 62.5-1000 µg/L for 48 h in river water. The endpoints assessed were mortality, immobilization, and biochemical biomarkers (catalase (CAT), glutathione S-transferase (GST), and malondialdehyde (MDA)). No mortality was observed over 48 h. Concentration- and time-dependent immobilization was observed for both ARVs only at 250-1000 µg/L after 48 h, with significant immobilization observed for EFV compared to TFV. Results for biochemical responses demonstrated that both ARVs induced significant changes in CAT and GST activities, and MDA levels, with effects higher for EFV compared to TFV. Biochemical responses were indicative of oxidative stress alterations. Hence, both ARVs could potentially be toxic to D. magna.

Keywords: Daphnia magna; Efavirenz; HIV antiretroviral drugs; Tenofovir; antioxidant enzymes; biochemical markers.

Figure 1

Immobilization of D. magna exposed to (A) EFV (p-value = 0.004025) and (B) TFV (p-value = 0.3313) for 48 h in ER water. Asterisks (*) represent significant difference between treatments (concentrations) from Kruskal-Wallis Test (* p <0.05). All data are the average of 4 replicates ± standard deviation.

Figure 2

Catalase activity levels in D. magna exposed to (A) EFV, and (B) TFV for 48 h. Values are presented as mean ± standard deviation (n = 3); (Asterisks (*) denote significant differences (one-way ANOVA followed by Dunnett’s multiple comparisons test (** p ≤ 0.01, *** p ≤ 0.001)) between ARVs-exposed samples and the controls.

Figure 3

GST levels in D. magna exposed to (A) EFV, and (B) TFV for 48 h. Values are presented as mean ± standard deviation (n = 3); (Asterisks (*) denote significant differences (one-way ANOVA followed by Dunnett’s multiple comparisons test (* p <0.05, *** p ≤ 0.001)) between ARVs-exposed samples and the controls.

Figure 4

MDA levels in D. magna exposed to (A) EFV, and (B) TFV for 48 h. Values are presented as mean ± standard deviation (n = 3); (Asterisks (*) denote significant differences (one-way ANOVA followed by Dunnett’s multiple comparisons test (* p < 0.05, ** p ≤ 0.01, *** p ≤ 0.001)) between ARVs-exposed samples and the controls.