The effect of andrographolide on equine chondrocytes viability. MTT assay and LDH assay were performed in equine primary cell cultures (a) and in equine cartilage explant cultures, respectively (b). The equine chondrocytes were incubated for 24 hours with andrographolide (0.1 to 100 µM), control, and vehicle control (0.1% DMSO in DMEM). The viability of the cells was determined using the MTT assay. The cell viability was expressed as a percentage relative to the control. The bar graphs were expressed as the mean ± SD of three independent experiments. In the equine cartilage explant culture system, the equine cartilage explants were left untreated as the control or treated with IL-1β (25 ng/mL) with or without andrographolide (12.5 to 100 µM), respectively. After three days of the treatment period, the culture media were analyzed for LDH release. The results were expressed as a percentage relative to the control. Data were expressed as the mean ± SD of three independent experiments. The significant differences were tested by one-way ANOVA at ().