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Distribution of exudate flavonoids in the genus Plectranthus
Thirty-four species of the genus Plectranthus (including species of the former genera Coleus and Solenostemon, fam. Lamiaceae) were surveyed for exudate flavonoids to see whether the distribution of these compounds would support a recent classification of the genus based on molecular and morphologic...
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Published in: | Biochemical systematics and ecology 2010-06, Vol.38 (3), p.335-341 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Thirty-four species of the genus
Plectranthus (including species of the former genera
Coleus and
Solenostemon, fam. Lamiaceae) were surveyed for exudate flavonoids to see whether the distribution of these compounds would support a recent classification of the genus based on molecular and morphological characters. In this classification two major groups had been identified, the
Coleus and
Plectranthus clades. Only about 40% of the species, predominantly from the
Plectranthus clade, were found to produce exudate flavonoids, which were mainly flavones. Flavanones were restricted to five species of the
Plectranthus clade, whereas flavonols were only found in two species of the
Coleus clade,
Plectranthus montanus Benth. (synonyms
Plectranthus marrubioides Hochst. ex Benth. and
Plectranthus cylindraceus Hochst. ex Benth.) and
Plectranthus pseudomarrubioides R.H.Willemse. Four of these flavonols were isolated from
P. montanus and identified by NMR spectroscopy as the 3,7-dimethyl ether and 3,7,4′-trimethyl ether of quercetin and the 3,6,7-trimethyl ether and 3,6,7,4′-tetramethyl ether of quercetagetin. The remaining flavonols and flavones were identified by HPLC–UV and LC–MS of crude extracts on the basis of their UV and mass spectra, retention times and comparison with standards. Most flavonols were 3-methyl ethers and many of the flavones and flavonols were oxygenated at the 6-position. The most common flavones, occurring in both clades, were cirsimaritin and salvigenin, which are methoxylated at the 6- and 7-positions. 6-Hydroxylated flavones such as scutellarein and ladanein were restricted to species of the
Plectranthus clade. |
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ISSN: | 0305-1978 1873-2925 |
DOI: | 10.1016/j.bse.2010.01.014 |