Abstract: Objective： To compare the contents of the alkaloid marker components scopolamine and L-hyoscyamine in different parts of Hyoscyamus niger L.，and to provide a scientific basis for defining its rational medicinal part. Methods： Scopolamine and L-hyoscyamine contents in various parts of Hyoscyamus niger L. (root， stem， leaf， flower， fruit， and seed) were quantified by HPLC and comparatively analyzed. Results： Both scopolamine and L-hyoscyamine were detected in all tested parts of Hyoscyamus niger L.， but their contents varied significantly. In terms of the total content of the two alkaloids， the order from high to low was： seed > flower > fruit > root > leaf > stem and the content in seeds was substantially higher than that in other parts. Conclusion： These findings support the inclusion of only the seeds of Hyoscyamus niger L. (known as Tianxianzi) as the official medicinal material in the Chinese Pharmacopoeia， based on their superior content of pharmacologically active alkaloids.

Key words: font-size:medium, "> , Hyoscyamus niger L.； Different parts； Content determination； Scopolamine； L-hyoscyamine