Spectrophotometric and Chromatographic Determination of Alkaloids and Nicotine Contents in Lebanese Tobacco Leaves

Abstract

Nicotiana Tabacum; the annual herb; known as Tobacco from the Solanaceae family was known for its alkaloids and especially nicotine (NCT) content; smoking products, insecticides, anthelminthic activity and clinically proven therapeutics are examples of its uses. Herein two different methods were applied in an attempt to quantify the total alkaloids and NCT content in Nicotiana tabacum cultivated in Lebanon. Total alkaloids were investigated through the formation of a complex with bromocresol green under a simple spectrophotometric method. Whilst HPLC-DAD was the choice for the quantitation of NCT levels. The column was Lichrospher select B (5 µm, 250x4 mm), the temperature was set at 29 ⁰C and the wavelength at 260 nm. The mobile phase consisted of 2 M O-phosphoric acid and methanol (60:40, v/v) using isocratic elution at 1 mL/min. A linear relationship was proved under both instruments. The extraction yield of alkaloid totum ranges between 2.1 ± 0.25 and 6.8% ± 0.58 and alkaloids contents range from 12.14 ± 2.01 to 53.12 ± 4.54 mg of AE/g of extract for Ghandouriyeh and Danniye samples respectively. On the other side among the different areas which cultivated Tobacco in Lebanon, Danniye was found to have the highest NCT concentration of dry weight (2.64%) while Al-Hissa possesses the lowest content (0.75%). Even if the results were generally similar to other countries, the study showed a difference in values from one region to another.