[Quantitative variation of total alkaloids contents in Dendrobium officinale]

To investigate the total alkaloid content and find out the variation of total alkaloids content in Dendrobium officinale with different germplasms and harvesting ages with the aim of providing scientific basis for the authenticity identification and the breeding of D. officinale.

Forty one samples with 1-3 ages were collected from cultivated fields of Zhejiang and Yunnan provinces and 11 samples were collected from markets. The total alkaloid contents of samples were determined using acid-dye colorimetry method.

The determined total alkaloid contents in D. officinale ranged 0.0190%-0.0430%. The averages of total alkaloid contents were 0.0253%, 0.0270% and 0.0326% in 1-year-old, 2-year-old and 3-year-old samples of Zhejiang province, respectively. The average of total alkaloid content was 0.034 3% in 1-year-old samples of Yunnan province.

The total alkaloid content of D. officinale with different germplasms and physiological ages existed significant discrepancy, and it increased with the growth of ages. The total alkaloid content of cultivated D. officinale in Yunnan province was higher than that in samples from Zhejiang province. But the authentic D. officinale had certain range of total alkaloid content. Samples whose total alkaloids content divagates from this range must be counterfeit; Samples whose total alkaloid content is in this range still need to combines with other active chemical groups like polysaccharides content to identify the authenticity and quality of medicinal materials.