الفهرس 
Phytochemical investigation of the aqueous methanolic leaf extract of M. lutea (Fam. BignoniaceaeaOnly 14 pages are availabe for public view
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Abstract
General summary
In accordance with the recent world-wide interest in plant phenolics which emerges from their broad range of biological activities, particular emphasis has been focused, in the present thesis, on the constitutive phenolics and triterpenic acids of the extract of Markhamia lutea (Family bignoniaceae).
The present study is divided into three parts in two chapters
Part I: Phytochemical investigation of the aqueous methanolic leaf extract of Markhamia lutea Family Bignoniaceae.
Part II: Phytochemical investigation of the hexane extract of Markhamia lutea including the isolation of different triterpenic acids.
Part III: Biological investigation of the antidiabetic activity of the hydroalcoholic leaf extract of Markhamia lutea Family Bignoniaceae.
1. Part I: Phytochemical investigation of the aqueous methanolic leaf extract of Markhamia lutea Family Bignoniaceae
This includes HR-ESI-MS profiling of the total extract and its fractions beside the isolation of verbascoside (the major compound) which exist in the extract and may be responsible for its antidiabetic activity.
1.1. HR-MS analysis: This analysis was performed to the total hydroalcoholic extract of M. lutea and its main fractions so as to profile and track the major constituents that may be responsible for the hypoglycemic effect of the extract. The mass analysis resulted in the tentative identification of 29 compounds from different phytochemical classes mainly phenyl propanoids and flavonoids with verbascoside (m/z 623) being the major compound in the earlier fractions (1, 2 and 3) however luteolin-7-O-glucuronide (m/z 923 being in dimer form) being the major constituent in the latter fraction (4).
1.2. Verbascoside isolation from fraction 2: As verbascoside (m/z 623) is the major compound in M. lutea fractions (1, 2 and 3) so it was isolated according to the scheme illustrated below (Fig 72).
1.3. Standardization of the hydromethanolic extract of Markhamia lutea using verbascoside standard.
2. Part II: Phytochemical investigation of the hexane extract of Markhamia lutea
This includes the isolation and identification of three triterpenic acids (musambin A, B & C) and their xyloside derivatives beside 2-epitormentic acid. The compounds show a reported antiparasitic activity (musambins) however 2-epitormentic acid showed reported anti-inflammatory & anti-tumor activity.
3. Part III: Antidiabetic activity of Markhamia lutea hydroalcoholic extract
Diabetes mellitus is a chronic metabolic disease resulted from abnormal carbohydrate metabolism caused by either abnormal blood insulin levels or insensitivity of target organs to insulin. The current study aim at evaluating the potential antidiabetic activity of M. lutea leaves aqueous methanolic extract in streptozotocin (STZ) induced diabetic rats. Furthermore, the present study aimed also at investigating the underlying mechanisms for the anti-hyperglycemic activity by assessing fasting blood glucose (FBG) levels, serum insulin levels, oral glucose tolerance test (OGTT), glucose utilization by isolated rat psoas muscle, rat gut glucose absorption, Glucose-6-Phosphatase (G-6-Pase) activity in isolated hepatic microsomes and determination of DPP-IV (Dipeptidyl peptidase-4) inhibitory activity.
3.1. In-vivo study to investigate the anti-hyperglycemic activity of M. lutea aqueous methanolic extract which is subdivided into three main experiments
3.1.1. Experiment 1. Determination of LD50 of M. lutea hydroalcoholic leaf extract: oral LD50 of M. lutea extract was assessed and was found to be GHS (Globally Harmonized System of Classification and Labeling of Chemicals) unclassified with LD50 cut-off >5000 mg/kg. Then, behavioral and body weight changes were monitored weekly for 14 days resulting in no significant changes as compared to control group.
3.1.2. Experiment 2. Screening the potential anti-hyperglycemic activity of three oral doses (50, 100, 200 mg/kg) of M. lutea leaves aqueous methanolic extract in normoglycemic rats using OGTT: A pilot study was then conducted to assess the effect of the extract on Oral
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Glucose Tolerance Test (OGTT) in normoglycemic rats after single oral dose treatment of the extract at doses 50, 100 and 200 mg/kg.
3.1.3. Experiment 3. The uprising promising effect of M. lutea leaves aqueous methanolic extract on OGTT in normoglycemic rats needed to be further vindicated in STZ-induced diabetic rats. Investigating the antidiabetic potential of three oral doses of M. lutea hydroalcoholic extract (50, 100 and 200 mg/kg) in STZ-induced diabetic rats to assess:
3.1.3.1. FBG levels: The extract was administered orally for 4 consecutive weeks by STZ-induced diabetic rats at three dose levels; 50, 100 or 200 mg/kg/day. The FBG-lowering effect of 200 mg/kg dose of the extract was by 75.9% after 4weeks of treatment as compared to baseline. As a whole the anti-hyperglycemic effect of M. lutea on FBG was observed to be time and dose related.
3.1.3.2. Serum insulin levels: The highest dose of M. lutea extract (200 mg/kg) significantly increased insulin release by 52.02% as compared to the control group and by 47.98% and 38.68% for the other two doses 100 and 50 mg/kg.
3.1.3.3. OGTT: Treatment of STZ-induced diabetic rats with M. lutea extract at doses of 100 and 200 mg/kg significantly reduced the AUC of serum glucose and time curve by 39.13% and 41.3%, respectively as compared to the untreated diabetic group after 120 min.
3.2. In-vitro study for investigating the possible anti-hyperglycemic mechanisms of M. lutea hydroalcoholic extract by studying the effect of the extract on:
3.2.1. Glucose absorption by rat gut preparation: Assessment of glucose absorption by rat gut preparation proved that in the presence of M. lutea leaves aqueous methanolic extract at concentration of 50, 100 and 200 μg/ml produced significant decrease in glucose absorption after 120 min. by 5.5%, 10.31% and 13.01% respectively as compared to control group.
3.2.2. Glucose uptake by rat isolated psoas muscle: Assessment of glucose uptake by rat isolated psoas muscle demonstrated that M. lutea extract at concentration 200 μg/ml made a significant increase in glucose utilization by 27.14% as compared to control group mean while the other two concentrations 50 and 100 μg/ml made increase in glucose uptake after 120 min by 5.13% and 13.96% as compared to control group.
3.2.3. G-6-Pase activity in rat isolated hepatic microsomes: The activity of G-6-Pase in isolated rat microsomes was significantly decreased using concentration 200 μg/ml by 17.34% compared to control group.
3.2.4. DPP-IV inhibitory activity: Assessment of DPP-IV activity for M. lutea leaves aqueous methanolic extract at five different concentrations (0-104ng/ml) resulted in inhibition with IC50 value of 5.7