Phytochemicals, Antioxidant Activities, and Toxicological Screening of Native Australian Fruits Using Zebrafish Embryonic Model

Abstract

Phytochemicals play a pivotal role in human health and drug discovery. The safety evaluation of plant extracts is a prerequisite to ensure that all phytochemicals are safe before translational development and human exposure. As phytochemicals are natural, they are generally considered safe, although this is not always true. The objective of this study was to investigate and compare the phytochemical composition, antioxidant potential, and safety evaluation of native Australian Muntries (Kunzea pomifera), Kakadu plum (Terminalia ferdinandiana), Davidson plum (Davidsonia) and Quandong peach (Santalum acuminatum) through the in vivo vertebrate zebrafish embryonic model. The highest total phenolic content (TPC; 793.89 ± 22.27 μg GAE/mg) was quantified in Kakadu plum, while the lowest TPC (614.44 ± 31.80 μg GAE/mg) was quantified in Muntries. Developmental alterations, mortality, and morbidity were assessed for toxicological screening of these selected native Australian fruit extracts. In this study, muntries were quantified as having the least LC50 value (169 mg/L) compared to Davidson plum (376 mg/L), Kakadu plum (>480 mg/L), and Quandong peach (>480 mg/L), which indicates that muntries extract was more toxic than other fruit extracts. Importantly, we found that adverse effects were not correlated to the total phenolic content and antioxidant potential of these native Australian fruits and cannot simply be predicted from the in vitro analysis. Conclusively, these selected native Australian fruit extracts are categorized as safe. This study could explore the use of these native Australian fruits in cosmetics, pharmaceuticals, and drug discovery.

Keywords: bioactive compounds; davidson plum; flavonoids; kakadu plum; molecular docking; muntries; quandong peach; safety evaluations.

Figure 1

Quantification of phenolic contents and antioxidant activities of native Australian Muntries (Mu), Kakadu plum (KP), Davidson plum (DP), and Quandong peach (QP). Values with the letters (a–d) are significantly different from each other (p < 0.05).

Figure 2

Heatmap hierarchical clustering of quantified phenolic compounds in Davidson plum (DP), Quandong peach (QP), Kakadu plum (KP), and Muntries (Mu).

Figure 3

Venn diagram distribution of the total number of phytochemicals (A), the total number of phenolic acids (B), the total number of flavonoids (C), and the total number of other polyphenols (D) in Muntries (Mu), Kakadu plum (KP), Davidson plum (DP) and Quandong peach (QP).

Figure 4

Heatmaps of the changes in zebrafish embryos during the exposure of Australian muntries, Davidson plum, Kakadu plum, and Davidson plum extracts at 96 h.

Figure 5

Percentage of mortality observed in zebrafish embryos exposed during 96 h to different concentrations of native Australian fruits. The colors represent the time at which mortality was observed. Significant differences are observed for muntries at 240 and 480 mg/L compared to controls (0), both values represented by *** p < 0.001. Davidson plum: ** p < 0.01 for 240 and 480 mg/L compared to controls (0). Kakadu plum: ** p < 0.01 for 480 mg/L compared to controls (0). Quandong peach: * p ≤ 0.05 at 480 mg/L compared to controls (0).

Figure 6

The graph shows the developmental alterations and morbidity in zebrafish embryos exposed for 96 h to different concentrations of native Australian fruits. Bars represent the mean ± SEM compared to the control group (p < 0.0001). Statistical significance represented by ** p ≤ 0.01, and **** p ≤ 0.0001.

Figure 7

Malformations were observed in zebrafish exposed during 96 h post-fertilization to different concentrations of Kakadu plum, Davidson plum, quandong peach, and muntries. No statistically significant difference was observed, and the data represent the mean ± SEM.