Antidiabetic and biochemical effects of new flavonols extracted from Justicia ghiesbreghtiana stem

Background and objective The main aim of this study was to examine the biochemical effects of two new natural flavonoid compounds isolated from Justicia ghiesbreghtiana stem extract on diabetes mellitus type II. Materials and methods One kilogram air-dried stems of J. ghiesbreghtiana were exhaustively extracted with 75% aqueous ethanol several times by heat treatment. The resulting extract was fractionated on a Sephadex LH-20 column using water and water/ethanol mixtures as eluents to yield six fractions, from which two new pure natural compounds 1 and 2 were isolated. The antidiabetic effect of compounds 1 and 2 was investigated in this study using 40 adult male rats. Results and conclusion Phytochemical investigation of the ethanolic extract of J. ghiesbreghtiana stem has led to the isolation of nine pure flavonoid compounds of quercetin type; two of them are new and have been identified as quercetin 3- O -α-l-arabinofuranoside-7- O -α-l-rhamnopyranoside-4′- O -β-d-galactopyranoside (1) and quercetin 3- O -α-l-arabinofuranoside-7- O -β-d-glucopyranoside-4′- O -β-d-galactopyranoside (2); in addition, two quercetin diglycosides, four quercetin monoglycosides, and aglycone quercetin were obtained. Their chemical structures have been established by conventional methods of chemical and physical analysis and confirmed by nuclear magnetic resonance spectroscopy. The biochemical study of compounds 1 and 2 on diabetic rats indicated improvement in kidney functions shown by reductions in both urea and creatinine levels. Moreover, glutathione peroxidase and superoxide dismutase concentrations were increased. Also, albumin and total protein levels were reduced, with an increase in liver functions, aspartate aminotransferase, and alanine aminotransferase levels, with a mild decrease in both cholesterol and triglyceride concentrations.