Immunomodulatory effect of standardized C. asiatica extract on a promotion of regulatory T cells in rats

Asiaticoside promoted ferroptosis and suppressed immune escape in gastric cancer cells by downregulating the Wnt/β-catenin pathway

BACKGROUND

Our previous study has revealed that asiaticoside (AC) promotes endoplasmic reticulum stress and antagonizes proliferation and migration of gastric cancer (GC) via miR-635/HMGA1 axis. However, the effect and mechanism of AC on other progressions of GC, such as ferroptosis and immune escape, are still unknown.

METHODS

AGS and HGC27 cells were incubated with 1, 2 and 4 μM of AC for 24 h. Mice xenografted with AGS cells were intragastrically injected with AC. The effect and mechanism of AC on GC were determined by the measurement of the ferrous iron level, the ROS level and the glutathione peroxidase (GSH) content, flow cytometry, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and western blotting assays.

RESULTS

AC increased the Fe2+ level and the ROS level, but decreased the expression of GPX4 and SLC7A11 and the GSH level. Besides, AC enhanced the percent of CD8+ T cells and the IFN-γ concentration, but reduced the PD-L1 expression and the IL-10 level. Mechanically, AC downregulated the relative levels of β-catenin, active-β-catenin, p-GSK3β/GSK3β, cyclin D1 and c-Myc in GC cells, which were rescued with the application of LiCl (an activator of Wnt/β-catenin pathway) in AGS cells. Moreover, activation of Wnt/β-catenin pathway by LiCl or the β-catenin overexpression inverted the effect of AC on ferroptosis and immune escape in GC cells. In vivo, AC treatment declined the tumor size and weight, the level of GPX4, SLC7A11, PD-L1 and IFN-γ, and the expression of Wnt/β-catenin pathway.

CONCLUSION

AC enhanced ferroptosis and repressed immune escape by downregulating the Wnt/β-catenin signaling in GC.

Sub-chronic oral toxicity of a water-soluble extract of Centella asiatica (Centell-S) in Wistar rats

BACKGROUND

Centell-S, a water-soluble extract from Centella asiatica, is predominantly composed of madecassoside and asiaticoside, exceeding 80% w/w. Pursuing its development as an herbal medicinal product, Centell-S underwent sub-chronic toxicity assessment adhering to OECD GLP 408 standards.

METHODS

In a study involving 100 Wistar rats, varying doses of Centell-S (50, 200, or 800 mg/kg/day) or a vehicle control were administered orally over 90 days. To evaluate Centell-S's safety profile, assessments included clinical observations, health examinations, clinical biochemistry analyses, and detailed anatomical pathology evaluations were conducted.

RESULTS

Over the 90 days of treatment, the administration of Centell-S did not lead to any fatalities in the test animals. Clinical observations did not reveal any signs indicative of toxic effects. Notably, an increase in total white blood cell and lymphocyte counts was observed in both sexes, yet these levels returned to normal following a two-week discontinuation period post-treatment.

CONCLUSIONS

Under the specific conditions of the OECD GLP 408, Repeated Dose 90-day Oral Toxicity Study in Rodents, the no observed adverse effect level (NOAEL) of Centell-S was 800 mg/kg/day. These findings are promising for the continued development of Centell-S as a phytopharmaceutical for clinical applications.

A review of pharmacokinetic and pharmacological properties of asiaticoside, a major active constituent of Centella asiatica (L.) Urb

ETHNOPHARMACOLOGICAL RELEVANCE

Centella asiatica (L.) Urb., a potential medicinal plant, is widely used in orient traditional medicine. Its major active constituents include asiaticoside (AS), madecassoside (MS), asiatic acid and madecassic acid. Thereinto, AS is a pentacyclic triterpenoid saponin with a variety of pharmacological effects including antitumor, neuroprotective and wound healing effects.

AIM OF THE STUDY

In this review, we summarize the pharmacokinetics, safety and pharmacological properties of AS.

MATERIALS AND METHODS

We gathered information about AS from articles published up to 2022 and listed in Google scholar, PubMed, Web of Science, Elsevier, and similar databases. The keywords used in our search included "asiaticoside", "Centella asiatica", "pharmacokinetics", "nerve", "cancer", "skin", etc. RESULTS: AS appeared to degrade through a first-order reaction and had low biotoxicity. However, the pharmacokinetic properties of AS differed according to species. AS is highly blood-brain-barrier permeable without any harmful side effect. It has a variety of pharmacological effects including anti-neural inflammation and anti-cancer properties, as well as protective properties for the skin, cardiovascular system, and pulmonary system.

CONCLUSION

This review comprehensively summarized current information regarding the pharmacokinetic and pharmacological properties of AS, and supported the pharmaceutical value of this compound. Future research should focus on improving bioavailability of AS and conducting clinical assessment.

Asiaticoside Prevents Oxidative Stress and Apoptosis in Endothelial Cells by Activating ROS-dependent p53/Bcl-2/Caspase-3 Signaling Pathway

BACKGROUND

Asiaticoside (AC) is a triterpenoid saponin found in Centella asiatica (L.) urban extract that has a wide range of pharmacological properties. Our previous study demonstrated that AC could promote angiogenesis in diabetic wounds, but the specific mechanisms remain unknown.

OBJECTIVE

This study aimed to examine the effectiveness and mechanism of AC on human umbilical vein endothelial cells (HUVECs) exposed to tert-butyl hydroperoxide (t-BHP) toxicity.

METHODS

Senescence was confirmed using senescence-associated betagalactosidase (SA-β-gal) activity and expression of the cell cycle phase markers p16 and p21. The levels of SOD, NO, MDA, GSH-Px, and ROS were tested. Furthermore, several cell death-related genes and proteins (p53, Bax, Bcl-2 and Caspase-3) were assessed with RT-qPCR and Western blotting.

RESULTS

AC significantly reduced SA-β-gal activity, with both the suppression of cellcycle inhibitors p16 and p21. We also found that the induced oxidative stress and apoptosis caused by t-BHP treatment resulted in the decrease of antioxidant enzymes activities, the surge of ROS and MDA, the up-regulation of p53, Bax and caspase-3, and the decrease of SOD, NO, GSH-Px and Bcl-2. These biochemical changes were all reversed by treatment with varying doses of AC.

CONCLUSION

AC alleviates t-BHP-induced oxidative injury and apoptosis in HUVECs through the ROS-dependent p53/Bcl-2/Caspase-3 signaling pathway. It may be a potential antioxidant applied in metabolic disorders and pharmaceutical products.