Genotoxicity and 28-day repeated dose oral toxicity study of ovatodiolide in rats

Ovatodiolide induces autophagy-mediated cell death through the p62-Keap1-Nrf2 signaling pathway in chronic myeloid leukemia cells

Ovatodiolide is a macrocyclic diterpenoid compound with various biological activities that displays considerable anticancer potential in different tumor models. However, the underlying mechanism for this antineoplastic activity remains unclear. The aim of the present study was to investigate the anticancer effect and possible molecular mechanism of ovatodiolide in human chronic myeloid leukemia (CML). Ovatodiolide suppressed cell colony formation and induced apoptosis in the K562 and KU812 cells. We also observed that ovatodiolide enhanced the production of reactive oxygen species (ROS), activated Nrf2 signaling, and inhibited mTOR phosphorylation. Autophagic flux was shown to be enhanced after treatment with ovatodiolide in K562 cells. Furthermore, autophagy inhibition alleviated ovatodiolide-induced cell apoptosis, whereas autophagy promotion aggravated apoptosis in CML cells. These results demonstrated that ovatodiolide activates autophagy-mediated cell death in CML cells. Additionally, ovatodiolide transcriptionally activated the expression of p62, and the p62 levels were negatively regulated by autophagy. Moreover, p62-Keap1-Nrf2 signaling was confirmed to be involved in ovatodiolide-induced cell death. Accordingly, LC3B knockdown augmented the ovatodiolide-induced p62 expression, increased the p62-Keap1 interaction, and enhanced the translocation of Nrf2 into the nucleus. In contrast, p62 inhibition abolished the effects that were induced through ovatodiolide treatment. Nrf2 inhibition with ML385 diminished the protective effect of autophagy inhibition in CML cells. Collectively, our results indicate that ovatodiolide induces oxidative stress and provokes autophagy, which effectively decreases the expression of p62 and weakens the protective effect of Nrf2 signaling activation, thus contributing to apoptosis in CML cells.

Identification and semisynthesis of (-)-anisomelic acid as oral agent against SARS-CoV-2 in mice

(-)-Anisomelic acid, isolated from Anisomeles indica (L.) Kuntze (Labiatae) leaves, is a macrocyclic cembranolide with a trans-fused α-methylene-γ-lactone motif. Anisomelic acid effectively inhibits SARS-CoV-2 replication and viral-induced cytopathic effects with an EC50 of 1.1 and 4.3 μM, respectively. Challenge studies of SARS-CoV-2-infected K18-hACE2 mice showed that oral administration of anisomelic acid and subcutaneous dosing of remdesivir can both reduce the viral titers in the lung tissue at the same level. To facilitate drug discovery, we used a semisynthetic approach to shorten the project timelines. The enantioselective semisynthesis of anisomelic acid from the naturally enriched and commercially available starting material (+)-costunolide was achieved in five steps with a 27% overall yield. The developed chemistry provides opportunities for developing anisomelic-acid-based novel ligands for selectively targeting proteins involved in viral infections.

Comparative Study of the Aftereffect of CO2 Inhalation or Tiletamine–Zolazepam–Xylazine Anesthesia on Laboratory Outbred Rats and Mice

CO2 inhalation is currently the most common method of euthanasia for laboratory rats and mice, and it is often used for further terminal blood sampling for clinical biochemical assays. Lately, this method has been criticized due to animal welfare issues associated with some processes that develop after CO2 inhalation. The stress reaction and the value of the clinical laboratory parameters significantly depend on the used anesthetics, method, and the site of blood sampling. Especially in small rodents, an acute terminal state followed by a cascade of metabolic reactions that can affect the studied biochemical profile may develop and cause unnecessary suffering of animals. The aim of this study was to compare the stability of biochemical parameters of outbred Sprague Dawley rats and CD-1 mice serum collected after CO2 inhalation or the intramuscular injection of tiletamine–zolazepam–xylazine (TZX). The serum content of total protein and albumin, cholesterol, triglycerides, aspartate aminotransferase (AST), alanine aminotr ansferase (ALT), alkaline phosphatase (ALP), total bilirubin, and creatinine was decreased by the injection of TZX in comparison with CO2 inhalation. In addition, the levels of calcium, phosphates, chlorides and potassium were lowered by TZX vs. CO2 administration, while the level of sodium increased. Finally, the level of the majority of serum clinical biochemical parameters in rats and mice tend to be overestimated after CO2 inhalation, which may lead to masking the possible effect of anti-inflammatory drugs in animal tests. Injection anesthesia for small rodents with TZX is a more feasible method for terminal blood sampling, which also reduces the suffering of animals.

Innovative Purification Method of Ovatodiolide from Anisomeles indica to Induce Apoptosis in Human Gastric Cancer Cells

Ovatodiolide (Ova), found in the plant Anisomeles indica (AI), has been reported to have an anti-proliferation effect in various cancer cells. However, little information is available regarding the anti-cancer effect of Ova in human gastric cancer cells. In this study, we investigated the inhibitory effects and the mechanisms of action responsible for these effects on human AGS cell lines from a newly developed purification technique for Ova from AI extract. Extract obtained at the optimum condition of 95% ethanol extraction of AI was sequentially partitioned by using different polarity solvents. Enriched content of Ova (35.9% purity) from the n-hexane fraction was then applied to the purification by using centrifugal partition chromatography (CPC) in a two-phase solvent system consisting of n-hexane:ethyl acetate:methanol:water (1.0:1.0:1.0:1.0, v/v/v/v) to reach purity over >95.0%. In evaluation of the anti-proliferation effect on AGS cells, Ova induced cell apoptosis with IC₅₀ values of 13.02 and 6.18 μM at 24 and 48 h, respectively, and arrested the cells at the G2/M phase. Quantification of Bax/Bcl2 mRNA expressions using qPCR showed a 2.5-fold increase in the Ova (5 μM)-treated cells at 48 h than in the control group. Specific protein expression data warrant further research to further confirm the proposed Ova-induced apoptotic pathway in AGS cells.