Physico-chemical Identification of THIAN DAENG

Abstract

       THIAN DAENG is the dried mature seed of Lepidium sativum L. (Garden Cress). Ithas been prescribed in over 80 traditional medicines registered in Thailand. Various chemical identification tests have been conducted and the following tests were found applicable as methods for identification of THIAN DAENG: swelling test of mucilage in water; color tests with ruthenium red, with nitric acid, with sodium hydroxide, and with ninhydrin; precipitation test with acetic potassium iodobismuthate; tests forcyanide and sulfide ions using paper strip method; and Thin-layer chromatographic fingerprint of THIAN DAENG extract compared to that of sinapic acid. To confirm the presence of lepidine in THIAN DAENG as reported in the previous studies, the Thin-layer chromatography technique was applied. By comparing the chromatogram of the sample extract with that of lepidine, it showed that lepidine was absent in the studied samples. It was also found that the chemical structure of lepidine reported in the previous studies belonged to imidazole alkaloid group which was different from the chemical structure of lepidine existing in Merck index.