Lawsonia inermis from the Algerian Sahara: Quantitative Analysis of Lawsone in Leaves with Special Attention to their Drying Conditions

Introduction: The continuously growing number of commercial Lawsonia inermis (henna) powders and the wide variability of their quality necessitate verifying as well as controlling their level of lawsone, the main active ingredient. The purpose of this study is to examine the effect of drying on the level of lawsone. Method: The leaves of henna were dried at different temperatures (40°C, 50°C, and 60°C) with both modes (air and ulrasons). We extracted lawsone from leaves by a Soxhlet extractor using methanol and water as solvents, respectively. This natural pigment was isolated, purified, and analyzed by thin-layer chromatography (TLC), high-pressure liquid chromatography (HPLC), and ultra-violet (UV) spectrophotometer. Result: The drying temperature highly affected the extraction yield (Re). Therefore, drying henna leaves at low temperatures allows for a higher yield of lawsone extracts. Conclusion: We recommend ultrasonically assisted drying of henna leaves to facilitate both the reduction of drying temperatures in order to conserve energy as well as the increase of the yield of lawsone extraction.