Hepatoprotective activity and standardization of the bioactive lignan fraction of Linum usitatissimum L.

 

Hepatoprotective efficiency of linseed (Linum usitatissimum L.) was in-vitro and in-vivo, assessed using silymarin (S) as positive control. Linseed was defatted with petroleum ether (PE) then extracted with 70% ethanol (E). Lignan fractions (LAl and LAc) were, respectively, obtained from alkaline and acid hydrolysates of (E). In-vitro evaluation on CCl₄-injured human hepatoma cell-line (Huh7), revealed that all samples (at 10,100,1000 µg/ml for samples & 100 µg/ml for S), significantly ameliorated AST, ALT and GSH; meanwhile, highest increase in SOD was recorded for LAl, which was in-vivo tested (at 100, 200, 400 mg/kg b.wt.) on CCl₄ liver-injured rats beside its parent extract E (at 200, 400, 800 mg/kg, relative to S at100 mg/kg). Biochemical (AST, ALT and total bilirubin) and histopathological changes were recorded. In vivo testing showed significant inhibition for ALT, AST and total bilirubin. Histological examination revealed the efficiency of linseed in preventing CCl₄-induced inflammation, necrosis and vacuolation. The lignan fraction of alkaline hydrolysate (LAl) showed the highest hepatoprotective activities. Secoisolariciresinol diglucoside, (SDG) was isolated from LAl and was assessed, in-vitro and in-vivo (15, 30, 60 mg/kg), by adopting the same previous experimental protocols where it exerted a significant protection (93 – 129% that of S) against CCl₄-induced liver injury. A simple and reliable RP-HPLC method was developed and validated for the quantification of SDG (the major bioactive constituent, 33%) in LAl. The recovery of the method was 100.9% and a high degree of precision (relative standard deviation values < 5%) was achieved. The limit of detection and quantitation were 3.11 µg/ml and 10.36 µg/ml, respectively. The method is sensitive and valuable for the commercial quality control of linseed extract and its preparations.

Keywords: Linseed, hepatoprotective, lignan, validation, SDG, Linum usitatissimum.