Evaluation of the cytotoxicity, oral toxicity, genotoxicity, and mutagenicity of the latex extracted from Himatanthus drasticus (Mart.) Plumel (Apocynaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Himatanthus drasticus is a tree popularly known as janaguba. Endemic to Brazil, it is found in the Cerrado and Caatinga biomes, rock fields, and rainforests. Janaguba latex has been used in folk medicine for its antineoplastic, anti-inflammatory, analgesic, and antiallergic activities. However, studies investigating the safety of its use for medicinal purposes are limited.

AIM OF THE STUDY

This study aimed to evaluate the toxicity of the latex extracted from H. drasticus.

MATERIALS AND METHODS

The latex was extracted from H. drasticus specimens by removing a small area of bark (5 × 30 cm) and then dissolving the exudate in water and lyophilizing it. Phytochemical screening was performed by TLC and GC-MS, protein, and carbohydrate levels. Cell viability was performed by the MTT method. Acute oral toxicity, genotoxicity, and mutagenicity assays were performed in mice.

RESULTS

TLC showed the presence of saponins and reducing sugars, as well as steroids and terpenes. The GC-MS analysis of the nonpolar fraction identified lupeol acetate, betulin, and α/β-amyrin derivatives as the major compounds. The latex was toxic to S-180 cells at 50 and 100 μg/mL. No signals of toxicity or mutagenicity was found in mice treated with 2000 mg/kg of the latex, but genotoxicity was observed in the Comet assay.

CONCLUSIONS

H. drasticus latex showed toxicity signals at high doses (2000 mg/kg). Although the latex was not mutagenic to mice, it was genotoxic in the Comet assay in our experimental conditions. Even testing a limit dose of 2000 mg/kg, which is between 10 to 35-fold the amount used in folk medicine, caution must be taken since there is no safe level for genotoxic compounds exposure. Further studies on the toxicological aspects of H. drasticus latex are necessary to elucidate its possible mechanisms of genotoxicity.

Integrative analysis of proteomic and metabonomics data for identification of pathways related to Rhizoma Paridis-induced hepatotoxicity

Clinical reports on hepatotoxicity that arise from Rhizoma Paridis have recently received widespread attention. Because the hepatotoxicity mechanism is little understood, this research strived to investigate the hepatotoxicity mechanism of Rhizoma Paridis extracts based on iTRAQ quantitative proteomics and metabonomics. The extraction solutions were administrated to rats for 7 days by gavage, and the hepatotoxicity was assessed through quantification of biochemical indexes and Oil red O staining. Additionally, the mechanism of hepatotoxicity was investigated by metabonomics based upon GC-MS and iTRAQ quantitative proteomics. The biochemical and histopathological analysis stood out that Rhizoma Paridis extract could induce liver injury, which was proved by the formation of fat droplets, the changes of mitochondrial structure, and biochemical parameters. The iTRAQ proteomics and metabonomics revealed that Rhizoma Paridis-induced hepatotoxicity was chiefly connected with the abnormal activity of mitochondrion function, which brought about oxidative stress injuries and inflammation, finally causing cell apoptosis. Collectively, we have provided previously uncharacterized hepatotoxic mechanism induced by Rhizoma Paridis and a reference to ensure its safe use in the future.

Similar hepatotoxicity response induced by Rhizoma Paridis in zebrafish larvae, cell and rat

Rhizoma Paridis, as a Traditional Chinese Medicine (TCM), has been used in clinic for thousands of years. Recently, the hepatic toxicity was reported in some published articles while its hepatotoxicity mechanisms have not been well established. Therefore, the present study was performed to determine the effect of Rhizoma Paridis treatment on the lipid deposition and metabolism, oxidative stress and mitochondrial dysfunction, and explore the underlying molecular mechanism through L02 cell, rat and zebrafish larvae. Rhizoma Paridis could diminish cell activity and cell proliferation, brought on cell apoptosis and elevated the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) compared with the control group, as evaluated in cell cultures. Rhizoma Paridis could result in the change of the liver structure and the liver function in the rat model and zebrafish larvae. Our results showed that Rhizoma Paridis could increase hepatic lipid accumulation, which was similar to the previous study and probably exerted toxic effect through intensive fatty acid lipogenesis, inhibition of fat degradation. Meanwhile, this experiment highlighted the importance of the oxidative stress, mitochondrial dysfunction, ER function, and the inflammation response in Rhizoma Paridis-induced disorder of hepatic lipid metabolism, which proposed a novel mechanism for interpretation of Rhizoma Paridis exposure inducing the disorder of lipid metabolism in vertebrates. Furthermore, the result of this experiment suggested that the toxicity response of zebrafish larvae was similar to the conventional model with a significant advantage.

Hepatocellular Toxicity of Paris Saponins I, II, VI and VII on Two Kinds of Hepatocytes-HL-7702 and HepaRG Cells, and the Underlying Mechanisms

Rhizoma paridis is a popularly-used Chinese medicine in clinics, based on the pharmacodynamic properties of its saponin components. The four main saponins in Rhizoma paridis are designated saponins I, II, VI, and VII. At present, much attention is focused on the anticancer effect of Rhizoma paridis which is manifested in its cytotoxicity to various cancer cells. The purpose of this study was to investigate the hepatocellular toxicities of the four saponins in Rhizoma paridis and the relative intensities of their cytotoxic effects. It was found that the four saponins were cytotoxic to two types of hepatocytes-HL-7702 and HepaRG cells. The cytotoxicities of the four saponins to the two cell models were compared. One of the most cytotoxic saponins was Rhizoma paridis saponin I (PSI). This was used to determine the mechanism of hepatocellular toxicity. Results from MTT assays demonstrated that the four saponins induced apoptosis of the two hepatocyte models in a dose-dependent and time-dependent manner. In addition, fluorescent 4′,6-diamidino-2-phenylindole (DAPI) staining was used to observe the morphological changes of HepaRG cells after saponin administration. Further, as the concentration increased, PSI-induced lactate dehydrogenase (LDH) release from HepaRG cells increased gradually. In addition, PSI enhanced the levels of reactive oxygen species (ROS) and blocked the S and G2 phases of the cell cycle in HepaRG cells. A western blot indicated that PSI upregulated the protein expression levels of p53, p21, and Fas. Furthermore, the PSI-induced changes in the p53 protein increased the Bax/bcl-2 ratio, resulting in enhancement of the release of mitochondrial cytochrome c, activation of caspases-3, -8, and -9, poly-ADP ribose polymerase (PARP), and ultimately apoptosis. Increased Fas protein activated caspase-8, which led to the activation of caspase-3 and its downstream PARP protein, resulting in cell apoptosis. These results indicate that PSI induced apoptosis in HepaRG cells through activation of ROS and death receptor pathways. The results obtained in this study suggest that the hepatocellular toxicity of saponins in Rhizoma paridis should be considered during the clinical application of this drug. In addition, they provide a reference for future anti-cancer studies on Rhizoma paridis.

Inhibition of diethylnitrosamine-induced liver cancer in rats by Rhizoma paridis saponin

Rhizoma Paridis saponin (RPS) had been regarded as the main active components responsible for the anti-tumor effects of the herb Paris polyphylla var. yunnanensis (Franch.) Hand.-Mazz. In the present research, we set up a rat model of diethylnitrosamine (DEN) induced hepatoma to evaluate antitumor effect of RPS. After 20 weeks treatment, rats were sacrificed to perform histopathological examinations, liver function tests, oxidative stress assays and so forth. As a result, DEN-induced hepatoma formation. RPS alleviated levels of liver injury through inhibiting liver tissues of malondialdehyde (MDA) and nitric oxide (NO) formation, increasing superoxide dismutases (SOD) production, and up-regulating expression of GST-α/μ/π in DEN-induced rats. All in all, RPS would be a potent agent inhibiting chemically induced liver cancer in the prospective application.