Apoptosis and Necrosis are Involved in the Toxicity of Sauropus androgynus in an In Vitro Study

Background/Purpose

The raw juice of the young sticks and leaves of Sauropus androgynus (SA) has been widely used as a natural food for body weight reduction and vision protection in Taiwan and Southeast Asia. But as has been reported, SA-associated obliterative bronchiolitis can develop after taking SA for more than 3 months. Lung transplantation was carried out in severe cases.

Methods

To study the toxic effect, we separated the SA extract into three parts, namely CHCl₃, EtOAc and n-BuOH fractions, using polarity dissection. NIH3T3 fibroblasts were treated with the SA fractions 300 μg/mL and subjected to a series of cytotoxic assays.

Results

The EtOAc fraction exhibited the strongest effect of cell growth inhibition, followed by the CHCl₃ and n-BuOH fractions. Features of condensed chromatin and apoptosis were observed in cells exposed to n-BuOH and EtOAc fractions using fluorescence microscopy. Formation of DNA ladders was also observed in the above cells. Instead, the CHCl₃ fraction induced DNA smearing. In bivariate dot plots of annexin V and propidium iodide double staining, necrosis and apoptosis appeared in cells treated with CHCl₃ and n-BuOH fractions, respectively, and a mixed type of necrosis and apoptosis appeared in EtOAc fraction-treated cells.

Conclusion

Our results indicate that necrosis and apoptosis are involved in the toxic effect of SA in NIH3T3 fibroblasts. More evidence is needed to clarify if necrosis and apoptosis are also related to the pathogenesis of SA-associated obliterative bronchiolitis.

Key Words:  apoptosis , lung obstruction , necrosis , Sauropus androgynus

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