Effect of growth stages, culture media, and processing methods on the component variations of Bletilla formosana and comparison of its component contents to commercial Rhizoma Bletillae crude drugs

Rhizoma Bletillae, a traditional Chinese medicine (TCM), and Bletilla formosana (Hayata) Schltr. (endemic to Taiwan) is widely distributed throughout the island. This study used militarine, cinnamic acid, 1,8-bi(4-hydroxybenzyl)-4-methoxyphenanthrene-2,7-diol (BHMD), and 4,7-dihydroxy-1-p-hydroxybenzyl-2-methoxy-9,10-dihydrophenanthrene (DHMD) as marker compounds along with high pressure liquid chromatography (HPLC) for quantitative analysis of B. formosana. Through mass reproduction by tissue culture, B. formosana was analyzed according to different growth stages, culture media, drying methods, and processing treatments, and then compared with different commercial Rhizoma Bletillae crude drugs. The results showed that the levels of almost all component contents in the vegetative phase were higher than those in the flowering phase. The militarine content in the mature tuber was higher than that in other components and plant sections. The results of this study indicated that the ideal harvest time for B. formosana is from September to October. In the different culture media, Medium 2 (peat soil: snake wood: nacrite: vermiculite = 1:2:1:1) and Medium 3 (sandy loam: snake wood: nacrite: vermiculite = 5:2:2:1) offered higher productivities and provided the best growth conditions. However, Medium 4 (snake wood: nacrite: vermiculite = 3:1:1) gave the highest content of the four compounds in its tuber. The processing treatment applied to fresh tubers was steam heating for a short time (10 minutes or 45 minutes) and then drying at 50 °C. This study also revealed that B. formosana had higher component contents than the commercial crude Rhizoma Bletillae drugs.