However, the red ginseng total extract and GTF did not significantly inhibit MMP-13 induction. In addition, GDF/F4 was also found to give considerable protection of cartilage degradation in rabbit cartilage culture, although this was not statistically significant. Previously, it was found that selleck chemical ginsenosides Rc, Rd, Rf, F4, Rg1, and Rg3 possess MMP-13 downregulatory activity against IL-1β-treated chondrocytes at concentrations of 1–50μM . The most prominent inhibitors are ginsenosides Rg3 and F4. In this study, GDF/F4 was newly prepared from Panax ginseng leaves because the leaves contain higher amounts
of F4 and Rg3 than ginseng roots on a weight basis. However, the total ginseng extract (the ethanol extract) did not exert MMP-13 downregulation. The inactive result of the total extract is possibly explained by the fact
that the contents of these active ginsenosides in the extract might be too low to exert MMP-13 downregulation, as shown in Fig. 2. Otherwise, it is reasonable to think that if these active ginsenosides are enriched in certain fractions, they may possess meaningful inhibitory action. Indeed, the n-BuOH fraction (total ginsenoside-enriched fraction, Fig. 2) having higher amounts of ginsenosides strongly inhibited MMP-13 induction. In this learn more case, however, some cytotoxicity was observed on SW1353 cells at the concentrations of 50 μg/mL or higher. The cytotoxic property of the n-butanol fraction could be, at least partly, explained by the previous findings that ginsenosides such as Rg3, Rg5, and Rk1
exert considerable cytotoxicity on SW1353 cells and several other cells at high concentrations ,  and . Because the major active ginsenosides are diol-type and F4 , we designed a new preparation that contains high amounts of the diol-type ginsenosides and F4, i.e., GDF/F4. As expected, the most prominent active preparations for MMP-13 downregulation are GDF and GDF/F4, with GDF/F4 being the strongest. It is understood that the MMP-13 downregulatory action of these preparations might rely on the major ginsenosides of GDF (Rc and Rd) and GDF/F4 (Rc, Rd, Rg3, and F4). By contrast, the ginsenoside triol-type-enriched fraction (GTF) did not inhibit MMP-13 expression. Non-specific serine/threonine protein kinase Actually, among ginsenoside triol-type derivatives, Rf and Rg1 were found to inhibit MMP-13 expression weakly at high concentrations . It was previously found that MAPKs, NF-κB, AP-1, and STAT-1/-2 are important to induce MMP-13 in IL-1β-treated SW1353 cells  and . GDF/F4 blocked the activation of MAPKs, including p38 MAPK and JNK and transcription factors STAT-1/2. However, one prominent MMP-13 downregulating ginsenoside, F4, was previously found to block only p38 MAPK activation under the same experimental conditions . These differences may be because GDF/F4 contains several different ginsenosides in addition to F4.