The chemical constituents of the root extracts and the evolutionarily neutral DNA base sequences were studied for 28 samples of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia collected in Sichuan and Yunnan Provinces of China. The samples could be classified into four chemotypes (1-4). Sesquiterpenoids having eremophilane and oplopane skeletons were isolated from two (Chemotype 1) and three (Chemotype 2) samples, respectively. Two new oplopane derivatives were isolated and their structures were determined. In 18 samples, phenylpropenoids were the major components (Chemotype 3). In five samples, neither phenylpropenoids nor sesquiterpenoids were found (Chemotype 4). Despite this large chemical variety, no correlation was found between the chemotype and the morphological criteria of species identification. The analysis of the evolutionarily neutral DNA regions also indicated that the samples were not separated into distinct clades and that introgression was extensive.

Dedicated to Professor Emeritus Takeyoshi Takahashi on the occasion of his 83rd birthdayRoot chemicals and evolutionarily neutral DNA regions in L. cyathiceps samples collected in the Zhongdian (Shangrila) County of Yunnan, P. R. China, were examined. Twenty compounds were isolated, including three new ones, 1b,10b-epoxy-6b-(propionyloxy)furanoeremophilan-9-one (6), 1b,10b-epoxy-8a-ethoxyeremophila-6,11-diene (14), and 11aH-6b-isobutyryloxy-1b,10b,7b,8b-diepoxyeremophilan-12,8a-olide (15). The chemical diversity was found to be limited, with cacalol (1) and 6-(acyloxy)furanoeremophilan-9-ones (4 and/or 5) being major components in all the samples. The nuclear ribosomal RNA gene was also found to harbor little variation, although two distinct sequence types were found for the plastid atpB-rbcL intergenic region.

From the roots of Ligularia oligonema and an unidentified sample of Ligularia collected in Yunnan Province of China, two new sesquiterpenoids, 3β-acetoxy-6β-(2-methylbutyryloxy)furanoeremophilan-10β-ol and 3β-acetoxy-6β-isobutyryloxyfuranoeremophilan-10β-ol, were isolated. DNA sequencing showed that the unidentified sample was likely to be L. oligonema. In addition, the DNA data suggested that the chemical evolution among L. oligonema and related Ligularia species is rather complex.