Optimization of the Processing with Decoction of Millet Technology of Gastrodia elata and Its Anti-inflammatory Efficacy

To optimize the processing technology of Gastrodia elata by water in which millet had been cooked and investigate the effects of LPS-induced microglia (BV2) inflammatory responses. Determination of gastrodin, p-hydroxybenzyl alcohol, parishin A, parishin B, parishin C, parishin E in the extract of Gastrodia elata by high-performance liquid chromatography (HPLC), and the content of six components were used as evaluation index, the volume ratio of water in which millet had been cooked to water, cooking time and drying temperature were selected as single factor variables. The designation of orthogonal test was based on single factor on three indicators, then optimization of the preparation technology. Comparison of the content of six components in different processed product. The neuroinflammatory cell model was induced by LPS and the cell viability was evaluated after treatment with the extract of processed products by a Cell Counting kit 8 (CCK-8) assay. The levels of TNF-α, IL-6, IL-1β in the cell culture medium were measured with ELISA kits. The protein expressions of TLR4, MYD88, P65, INOS, COX-2, IL-1β in LPS-induced BV2 cells were detected by Western blot. The results showed that the cooking time and the volume ratio of water in which millet had been cooked to water had a significant effect on the test results. The water in which millet had been cooked of Gastrodia elata processing technology: The ratio of the volume water in which millet had been cooked to water was 1:3, the boiling time was 25 min and the temperature of drying was 75 ℃. The comprehensive score of the six components in processing with water in which millet had been cooked products was higher than that of steamed products. The extract of Gastrodia elata had exhibited varying degrees of protective activity on LPS-induced BV2 cells. The results showed that the secretion of TNF-α, IL-6, IL-1β was significantly increased in BV2 microglial cells induced by LPS compared with the normal control group (P<0.001). Compared with the LPS group, the two extract of Gastrodia elata significantly decreased the expression level of TNF-α (P<0.05), IL-6 (P<0.05, P<0.001), IL-1β (P<0.05, P<0.001) in LPS-induced BV2 microglial cells. The result of Western blot showed that PZH significantly inhibited the LPS-induced TLR4/MYD88/NF-κB signaling pathway activation, and decreased the protein expressions of TLR4 (P<0.01), MYD88 (P<0.01, P<0.05), P65 (P<0.01), INOS (P<0.05), COX-2 (P<0.05, P<0.001), IL-1β (P<0.001). The optimized processing technique is simple, stable and feasible. The mechanism of processed drugs of Gastrodia elata may reduce inflammatory factor expression by inhibiting the TLR4/MYD88/NF-κB signaling pathway.