Abstract

FATTY ACID COMPOSITION OF THE LIPID CLASSES OF SILYBUM MARIANUM SEED OIL

Zafar Iqbal*, Amran Waheed, Mohammad Akram and Khalid Mahmood

Abstract

Powdered seeds of two varieties of silybum marianum were subjected to soxhlet apparatus using hexane as solvent for oil extraction. Yield of oil from both categories was 33.25 % and 34.50 % respectively. Extracted oils were fractionated into hydrocarbons, wax asters, triglycerides, free fatty acids, 1,3–diglycerides, 1,2–diglycerides and monoglycerides by thin layer chromatography and identified by the comparison with Rf values of respective standards samples. The fatty acids composition of both oils was determined after conversion into their respective methyl esters. These methyl esters were analyzed by gas chromatography. Oil of category 1 silybum marianum contain oleic acid (40.12 %) as a major component followed by linoleic acid (34.70 %), palmitic acid (11.48 %), linolenic acid (4.75 %), stearic acid (4.23 %), arachidic acid (3.24 %) and lauric acid (1.48 %). Similarly in category 2 silybum marianam seed oil oleic acid (39.96 %) was the dominating fatty acid followed by linoleic acid (34.15 %), palmitic acid (12.32 %), linoleinic acid (4.48 %), arachidic acid (3.92 %), lauric acid (1.08 %) and myristic acid (0.24 %) respectively. Furthermore saturated and unsaturated fatty acids in the oil, wax esters, triglycerides, diglycerides, monoglycerides and free fatty acids were also determined.

Keywords: Silybum marianum, Soxhlet, Gas chromatography, Lipid, Oleic acid, Linoleic acid.