Glucocorticoids are effective anti-inflammatory drugs, but their clinical use is complicated due to the wide range of side effects they induce. Patients requiring glucocorticoid therapy would benefit from more selective glucocorticoid receptor (GR) agonists, capable of attenuating the immune response without causing these side effects. Ginsenosides, such as the compound Rg1, are natural plant compounds with structural similarity to classical glucocorticoids and well-documented anti-inflammatory effects. Here, we have investigated the activity of the ginsenoside Rg1 using a zebrafish larval model, in which amputation of the tail fin allows us to assess drug effects on inflammation, while the ability to regenerate the wounded tissue serves as a readout for side effects. We found that Rg1 attenuates neutrophilic inflammation at the amputation site, similarly to a classical glucocorticoid, beclomethasone. Mutation of the Gr abolishes this anti-inflammatory effect of Rg1. Rg1 and beclomethasone differentially modulate gene expression, suggesting that Rg1 induces transrepression, but not transactivation, activity of Gr. Interestingly, we found no effect of Rg1 on tissue regeneration, whereas beclomethasone inhibits tissue regeneration entirely. We conclude that Rg1 is a promising candidate for development as a selective glucocorticoid drug, and that zebrafish larvae provide a useful model system for screening of such GR agonists.

Ginsenoside extracts are often used as raw materials for various pharmaceutical, cosmetic and food supplement products. Development of a direct, rapid, cheap, and comprehensive measurement tool for the quality assessment of ginsenoside extracts, and indeed all herbal extracts, is urgently needed. In addition, a bioactivity-based assessment should be linked with quality control. In this report, we try to develop a novel quality control tool using ginsenoside extracts as an example. High-performance liquid chromatography (HPLC) was used to detect nine principal ginsenosides in 11 batches of ginsenoside extracts. Delayed luminescence (DL) was used to analyze the same ginsenoside extract samples. DL measurements showed the same results in terms of differentiating 11 ginsenoside extract samples compared with chemical analysis, and DL properties could be closely linked to index ginsenosides in the quality control of ginsenoside extracts. Next, a zebrafish tail-fin amputation model was used to study differences in anti-inflammatory effect between the ginsenoside extract batches. The results indicate that both chemical analysis and DL measurements could partially reflect biological activity. Thus, DL may serve as a rapid, direct, sensitive, and systemic tool for studying the overall properties of ginsenoside extracts. Our proposal for linking bioactivities as a tool for evaluation of the quality of ginsenoside extracts opens a new direction for quality control.

The collagen antibody-induced arthritis (CAIA) model is highly effective in inducing arthritis, making it an attractive model for screening therapeutic compounds such as glucocorticoids (GCs). The severity of discomfort in this model makes it desirable to administer analgesics, but it is a prerequisite that these do not interfere with the model or tested therapeutics. In the present study, we studied the effect of 1 mg/mL tramadol and 3.5 mg/mL paracetamol (TP) on CAIA in male BALB/cAnNCrl mice and the possible interference of TP analgesia with the activity of the GC drug prednisolone (Pred). Our results showed that TP abolished the Pred-induced amelioration of CAIA, as well as several other Pred-induced effects, such as the reduction in thymus weight and the increase in insulin level. This most likely results from the effects of TP on the hepatic metabolism of this drug, since it strongly increased the Cyp3a11 expression in the liver. Altogether, we conclude that TP analgesia is not suitable for the CAIA model in male BALB/cAnNCrl mice, in particular when evaluating the effects of GCs such as Pred.