Pharmacognostic Specifications and Lawsone Content of Lawsonia inermis Leaves

BACKGROUND: Lawsonia inermis L. has been used as a traditional or folk medicine for the treatment of a wide range of skin infectious diseases. OBJECTIVE: The objective of this study was to determine the pharmacognostic specifications and lawsone contents of L. inermis leaves. MATERIALS AND METHODS: The pharmacognostic specifications of L. inermis leaves from 12 sources were evaluated according to the WHO guideline of quality control method for medicinal plant materials. The lawsone contents were analyzed by thin-layer chromatography (TLC) coupled with densitometry and image analysis. RESULTS: Microscopic evaluation of L. inermis powders showed the fragment of mesophyll, fragment of parenchyma, epidermis layer with stomata, and the rosette crystal of calcium oxalate. Physicochemical parameters revealed that total ash, acid-insoluble ash, loss on drying, and water content should be not <6.98, 1.12, 8.08, and 9.86% of dried weight, respectively, whereas ethanol and water extractive values should be not < 19.67 and 23.06% of dried weight, respectively. The content of lawsone in L. inermis leaves by TLC-densitometry was found to be 0.76 ± 0.05 g/100 g of dried crude drug, whereas the lawsone content evaluation by TLC image analysis was found to be 0.87 ± 0.11 g/100 g of dried crude drug. The validation of the methods revealed that both TLC-densitometry and TLC image analysis showed a good sensitivity and accuracy for lawsone quantitation in L. inermis. CONCLUSION: The pharmacognostic specifications could be used as the standardization data of L. inermis leaves, and the development of TLC method could be applied to determine lawsone content in this plant material. SUMMARY: The pharmacognostic specification of Lawsonia inermis leaves could be used as the standardization data of L. inermis leaves in Thailand. Both TLC-densitometry and TLC image analysis showed a good sensitivity and accuracy for lawsone quantitation. Abbreviations Used: LOD: Limit of detection; LOQ: Limit of quantitation; RSD: Relative standard deviation; TLC: Thin layer chromatography; UV: Ultraviolet; Rf value: Relative to front value