Pro-apoptotic and anti-inflammatory effects of araloside A on human rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis fibroblast-like synoviocytes play an essential role in the occurrence and progression of rheumatoid arthritis. As the main pharmacologically active components of Aralia taibaiensis, total saponins, particularly triterpenoid saponins, have been shown to possess multiple pharmacological activities including relieving rheumatism. However, the effect of araloside A, a triterpenoid saponin extracted from the root bark of Aralia taibaiensis, on rheumatoid arthritis remains unknown. Cell counting kit-8 assay was employed to determine cell viability. Flow cytometry analysis, caspase-3/7 activity assay and Western blot analysis of cytochrome c and B-cell lymphoma 2 were conducted to evaluate cell apoptosis. Inflammation was assessed by detecting the production of inflammatory cytokines including interleukin-6 and interleukin-8, as well as inflammatory mediators including nitric oxide and prostaglandin E₂. The changes of the nuclear factor kappa B pathway were examined by Western blot. Results showed that araloside A concentration-dependently inhibited the proliferation of MH7A cells. Meanwhile, araloside A dose-dependently augmented the apoptotic rate and caspase-3/7 activity, increased cytochrome c level and decreased B-cell lymphoma 2 level in MH7A cells. Araloside A concentration-dependently curbed the production of interleukin-6, interleukin-8, prostaglandin E₂ and nitric oxide in MH7A cells. In addition, we found that araloside A inhibited the nuclear factor kappa B pathway and inhibition of the nuclear factor kappa B pathway by BAY11-7082 and PDTC showed a similar role to araloside A in MH7A cells. Taken together, araloside A exerted pro-apoptotic and anti-inflammatory effects in rheumatoid arthritis fibroblast-like synoviocytes via inhibition of the nuclear factor kappa B pathway.

Gastroprotective effect of araloside A on ethanol- and aspirin-induced gastric ulcer in mice: involvement of H+/K+-ATPase and mitochondrial-mediated signaling pathway

The aim of this study was to elucidate the gastroprotective activity and possible mechanism of involvement of araloside A (ARA) against ethanol- and aspirin-induced gastric ulcer in mice. The experimental mice were randomly divided into control, model, omeprazole (20 mg/kg, orally) and ARA (10, 20 and 40 mg/kg, orally). Gastric ulcer in mice was induced by intragastric administration of 80% ethanol (10 mL/kg) containing 15 mg/mL aspirin 4 h after drug administration on day 7. The results indicated that ARA could significantly raise gastric juice volume and acidity; ameliorate gastric mucosal blood flow, gastric binding mucus volume, ulcer index and ulcer inhibition rate; suppress H⁺/K⁺-ATPase activity, which was confirmed by computer-aided docking simulations; inhibit the release of mitochondrial cytochrome c into the cytoplasm; inhibit caspase-9 and caspase-3 activities and down-regulate mRNA expression levels; down-regulate the mRNA and protein expressions of apoptosis protease-activating factor-1 and protein expression of cleaved poly(ADP ribose) polymerase-1; and up-regulate Bcl-2 mRNA and protein expressions and down-regulate Bax mRNA and protein expressions, thus elevating the Bcl-2/Bax ratio in a dose-dependent manner. Histopathological observations further provided supportive evidence for the aforementioned results. The results demonstrated that ARA exerted beneficial gastroprotective effects on alcohol- and aspirin-induced gastric ulcer in mice, which was related to suppressing H⁺/K⁺-ATPase activity as well as pro-apoptotic protein expression, and promoting anti-apoptotic protein expression, thus alleviating gastric mucosal injury and cell death.

Intestinal absorption mechanisms of araloside A in situ single-pass intestinal perfusion and in vitro Caco-2 cell model

Araloside A is a triterpenoid saponin,which exhibits a broad spectrum of pharmacological activities, such as stimulating fibrinolysis, preventing coagulant, inhibiting renin, and decreasing blood pressure. Our previous report found that the compound exhibits a poor absolute bioavailability. However the underlying mechanisms of its absorption have not been investigated in the small intestine or in a Caco-2 cell model. In this study, the absorption mechanisms of araloside A were investigated in a Caco-2 cell monolayer and in a single-pass intestinal perfusion in situ model with Sprague-Dawley rats. The effects of basic parameters, such as compound concentration, time, temperature, paracellular pathway, different intestinal segments were analyzed, and the susceptibility of araloside A absorption process to treatment with various inhibitors, such as the P-gp inhibitor verapamil, the multidrug resistance protein2 inhibitors (MRP2) MK571 and indomethacin, the breast cancer resistance protein (BCRP) inhibitors Ko143 and reserpine, and endocytosis inhibitor chlorpromazine were assessed. It can be found that the mechanisms of intestinal absorption of araloside A may involve multiple transport pathways, such as passive diffusion, the paracellular pathway, as well as the participation of efflux transporters.