Planta Med 2009; 75 - SL25
DOI: 10.1055/s-0029-1234280

Authentication of skullcap (Scutellaria lateriflora L.) – a commonly adulterated medicinal plant

H Wohlmuth 1, 2, 3, B Aulton 2, 3, K Penman 4, R Lehmann 4, R Upton 5
  • 1Centre for Phytochemistry and Pharmacology, Southern Cross University, PO Box 157, Lismore NSW 2480, Australia
  • 2Medicinal Plant Herbarium, Southern Cross University, PO Box 157, Lismore NSW 2480, Australia
  • 3School of Health and Human Sciences, Southern Cross University, PO Box 157, Lismore NSW 2480, Australia
  • 4MediHerb Research Laboratories, Eight Mile Plains QLD 4113, Australia
  • 5American Herbal Pharmacopoeia, Scotts Valley, California 95067, USA

INTRODUCTION: The North American herb skullcap (Scutellaria lateriflora) is widely used as a mild sedative, but it has been plagued by adulteration and substitution problems for more than a century.

Aims: To identify reliable HPLC and HPTLC methods for the authentication of S. lateriflora raw material.

Methods: A total of 45 samples were analysed by LC-MS, HPLC and HPTLC, including commercial raw material (genuine and substituted) and authentic herbarium material of S. lateriflora, five other Scutellaria taxa, and the potentially hepatotoxic substitute Teucrium chamaedrys. Four flavonoids (baicalein, baicalin, scutellarin and chrysin) were quantified and several others identified in the samples. The dataset was also subjected to principal components analysis.

Results: Genuine S. lateriflora was shown to possess a characteristic chemical profile and was readily distinguishable from the other taxa examined, both by HPLC and HPTLC. S. lateriflora had a high content of baicalin (1790±550µg/g) and a low content of scutellarin (100±70µg/g). S. galericulata had a somewhat similar profile, but also contained chrysin (39±4µg/g), whereas S. baicalensis (leaf), S. altissima and S. barbata contained scutellarin as the main flavonoid. T. chamaedrys contained teucrioside but none of the flavonoids typical of Scutellaria. Four lots of commercial raw material offered as S. lateriflora in the global market in 2007 were found to consist of a different species of Scutellaria.

CONCLUSION: Genuine S. lateriflora can readily be identified from likely adulterants by either HPTLC or HPLC, but adulteration still occurs and rigorous authentication of raw materials is essential.