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Jordan University of Science and Technology (JUST) 2011

Anti-oxidant anti-diabetic and anti-hypertensive effects of extracted phenolics from medicinal plants

Mervat Fathi Awad Rawashedh

Titre : Anti-oxidant anti-diabetic and anti-hypertensive effects of extracted phenolics from medicinal plants

Auteur : Mervat Fathi Awad Rawashedh

Université de soutenance : Jordan University of Science and Technology (JUST)

Grade : Master of Science (MS) 2011

Résumé
The presences of phenolic compounds in medicinal plants have been studied extensively due to the presence of nutraceutical, pharmaceutical and functional properties. Jordan is well known as a biodiversity environment for wild medicinal plants such as Thyme, Spearmint and Rosemary. This study was carried out to evaluate the optimum conditions for extraction phenolic compounds with anti-oxidant, anti-diabetic and anti-hypertensive properties from selected medicinal plants including Thymus vulgari, Mentha spicata and Rosmarinus officinalis. Phenolic compounds were extracted using different extraction conditions including time, temperature and solvent. Free phenolic compounds was extracted using methanol at 30°C and 50°C followed by methanol extraction after acid and base hydrolysis in order to liberate the bound phenolic compounds. The extracted phenolic compounds using different conditions were subjected to evaluate the optimum condition for content, anti-oxidant activity, and activity of Angiotensin Converting Enzyme (ACE) and α-glucosidase enzymes. Reversed Phase High Pressure Liquid Chromatography (RP-HPLC) was used to measure the contents of individual phenolic compounds in extracted phenolic compounds. Correlation coefficient between extracted phenolic compounds and biological properties were studied using statistical model system. Results revealed that the optimum contents and anti-oxidant activity of extracted phenolic compounds in Thyme, Spearmint and Rosemary were mixture of methanol and water at 60°C for 1 hr. While the best conditions for extraction of phenolic compounds with optimal inhibitory activity for ACE in Thyme, Spearmint and Rosemary were mixture of acetone and water at 40°C for 6hrs. Indicated results revealed that the optimal extraction condition of phenolic compounds with maximum inhibitory activity for α-glucosidase were methanol at 50°C for 8 hrs in Rosemary and mixture of methanol, acetone and water extraction at 40°C for 3 hrs in Spearmint. The highest ratio of phenolic was obtained as free in Thyme, Spearmint and Rosemary with values of 64, 72 and 66 % of total phenolic compounds content, respectively. Results revealed that the bound phenolic compounds have anti-oxidant, anti-hypertensive and anti-diabetic properties. A positive correlation between the content of phenolic compounds and ACE and α-glucosidase inhibitory activities were obtained in Thyme (0.71, 0.42 and 0.66, respectively) and Spearmint (0.27, 0.96 and 0.79, respectively). While the content of phenolic compounds in Rosmary was negatively correlated with ACE inhibitory activity with value of -0.97. The presence of bound phenolic compounds with carbohydrate, protein, fat and minerals showed anti-oxidant, anti-diabetic and anti-hypertensive properties. The predominant free phenolic compounds using different extraction solvents, time and temperature was thymol in Thyme and Rosemary and rutin in Spearmint. The major predominant bound phenolic compounds in Thyme, Rosemary and Spearmint were caffeic acid and chlorogenic acid which did not exist as free phenolic compounds. This study recommended Thyme, Spearmint and Rosmary to be used extensively as anti-hypertensive and anti-diabetic drink.

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Page publiée le 23 octobre 2016, mise à jour le 22 mars 2019