Comparison of the brine shrimp nauplii bioassay and the ToxScreen-II Test for the detection of toxicity associated with Aloe vera (Aloe barbadensis

This study assessed the performance of a bioluminescent bacterial assay, the ToxScreen-II Test (Photobacterium leiognathi), in comparison to the brine shrimp (Artemia franciscana) nauplii lethality assay for the detection of toxicity associated with Aloe vera leaf gel extract and the organophosphate pesticide Mevinphos. In both bioassays, clear dose-response relationships were demonstrated for these two test substances. Sensitivity to the Aloe vera leaf extract was similar for both bioassays, with 1 h IC50 of 2 994 μg/ml in the the ToxScreen-II Test and 2 h LC50 of 3 940 μg/ml in the brine shrimp nauplii bioassay. In contrast, the ToxScreen-II Test was approximately 10 fold more sensitivity towards Mevinphos (1 h IC50 113 μg/ml) than the brine shrimp nauplii test (24 h LC50 1 316). While the ToxScreen-II Test was developed as a tool primarily for the detection of anthropogenic chemicals in water, this study showed that it can also be used for the screening of bioactivity in a complex plant extract. The advantages of this bioluminescent bacterial assay, over the traditionally used brine shrimp test, included a quicker turn around time, reduced preparation of the test organism and other materials, and the acquisition of test results within 1 hour.