Osteoarthritis (OA), caused by the long-term use of joints, is a representative degenerative disease in the elderly. However, recently, the age of onset has been decreasing owing to excessive activities among young people in their 20s and 30s. Gynostemma pentaphyllum (Thunb.) Makino (GP), a perennial herb of the Cucurbitaceae family, has been used since the Ming dynasty as a medicinal material to treat various ailments, such as rheumatism, liver disease, and diabetes. In this study, we investigated the anti-arthritic effects of heat-processed Gynostemma pentaphyllum extract (Actiponin (AP)) and its derivatives, damulin A (DA) and damulin B (DB), using in vitro (primary rat chondrocytes and SW1353 cells) and in vivo (destabilization of the medial meniscus (DMM)-induced OA model) systems. Histological analysis results from the in vivo study showed that the group that underwent DMM surgery induced degeneration by the loss of proteoglycan and the destruction of cartilage (OARSI score 14 ± 0.57), whereas the group that received AP daily for 8 weeks maintained an intact condition (OARSI score 5 ± 0.28 at 200 mg/kg, p < 0.001). In addition, cartilage thickness and chondrocytes were reduced in the DMM group, but were restored in the AP-administered group. Furthermore, the von Frey analysis results showed that the pain threshold of the DMM group was considerably low (54.5 g at 8 weeks), whereas that of the AP group was dose-dependently increased (65.5, 69.5, 70.3, and 71.8 at 8 weeks for 30, 50, 100, and 200 mg/kg, respectively). In vitro studies showed that AP, DA, and DB reduced the expression of interleukin-1β alone-induced nitrite; inducible nitric oxide synthase; cyclooxygenase-2; matrix metallopeptidase 1/3/13; and a disintegrin and metalloproteinase with thrombospondin motifs 4/5. They also restored the expression of collagen type II and aggrecan, which are components of the extracellular matrix. The anti-arthritic effects of AP, DA, and DB were confirmed to be mediated by the mitogen-activated protein kinase and nuclear factor kappa-light-chain-enhancer of activated B cell signaling pathways. Collectively, these results suggest that AP is a potential therapeutic agent for mitigating OA progression and chondroprotection.

Gynostemma pentaphyllum (GP) is a medicinal plant that has long been used as drug for the treatment of rheumatism, liver disease, and diabetes. In this study, GP was extracted with 50% ethanol extract, and then the extract was heat-processed under high pressure to analyze the anti-inflammatory potential of these extract (named actiponin (AP)) and its derived components, damulin A and damulin B, in RAW264.7 cells and carrageenan-induced rat models. Ap had no effect on RAW264.7 cells up to 180 μg/mL, but DA and DB showed cytotoxicity from 18 μM. Pretreatment with AP significantly suppressed the LPS-induced increase in nitric oxide (NO) and inducible nitric oxide synthase (iNOS) protein expression via griess reagent and Western blot analysis, and these effects were similar to those of DA and DB. AP, DA, and DB also significantly suppressed the expression of prostaglandin E2 (PGE2) and cyclooxygenase-2 (COX-2) protein, which were increased by LPS, in a concentration-dependent manner. In addition, AP, DA, and DB inhibited the LPS-induced increase in pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 in RAW264.7 cells. The anti-inflammatory activities of AP, DA, and DB are mediated by the suppression of the nuclear factor (NF)-κB and phosphorylation of mitogen-activated protein kinases (MAPKs) signaling pathways. Oral administration of 30, 50, 100, or 200 mg/kg (AP) suppressed carrageenan-induced edema in a concentration-dependent manner. Collectively, these results suggest that AP exerts potential anti-inflammatory activity by suppressing the inflammatory-mediators and pro-inflammatory cytokines via the NF-κB and MAPK pathways in vitro and by reducing the thickness of carrageenan-induced paw edema in vivo.