الملخص الإنجليزي
Abstract
Polyphenols are known to possess anti-inflammatory, anti-carcinogenic, and antioxidant properties. Pomegranate pericarp has a high content of polyphenols. No research has been done using pomegranate pericarp from Omani variety; Hellow. This study was undertaken to characterize the physiochemical properties of pomegranate pericarp, analyze the individual phenols present in the pericarp and investigate the effect of the pericarp extract on the azoxymethane (AOM) induced carcinogenesis and oxidative stress in rat colon. Pomegranate pericarp was dried by freeze-drying, air-drying, vacuum-drying and sun- drying. The moisture sorption isotherm was measured and modelled using the Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-De Boer (GAB) models. Two solvents (methanol and ethanol) and water were used to extract the phenolic compounds in pomegranate fruit pericarp. All drying methods reduced the extractable polyphenols irrespective of the solvent used. Freeze-drying pericarp retained the highest level of polyphenols in comparison to the other drying methods.
Thermal characteristics of pomegranate pericarp extract (PomPE) were measured as a function of moisture and temperature. A state diagram of the extract was developed by measuring the freezing curve, glass transition line and ultimate maximal-freeze-concentration conditions. The freezing point and glass transition were modelled using Chen's model based on the Clausius Clapeyron equation, and Gordon-Taylor equation, respectively.
· Total phenols, total flavonoids and total antioxidant capacity tests of pomegranate pericarp extract were assayed. The extract was subjected to ESI-MS/MS. Results revealed high contents of total phenols, total flavonoids and total antioxidant capacity. The analysis revealed the presence of 61 different polyphenols in the extract. Major compounds were tannins and flavonoids such as; ellagic acid, gallic acids, punicalin, punicalagin and malic acid.
The chemopreventive effect of pomegranate pericarp extract against AOM-induced oxidative stress and carcinogenesis. in rat colon was investigated. The colon tissues were examined microscopically for pathological changes and aberrant crypt foci development, genotoxicity, micronuclei cells enumeration, and measurement of glutathione and lipid peroxidation. Results showed that the concomitant treatment of AOM with PomPE had significantly ameliorated the observed AOM cytotoxic effects.
In conclusion, this study was able to analyze the effect of different drying methods on the retention of polyphenolic content of pomegranate pericarp extracts, develop the state diagram of the extract, characterize 61 individual polyphenols present in the pomegranate pericarp extract and reveal the anti-carcinogenic and anti-inflammatory ameliorating effect against AOM-induced. cytoxicity in rat colon
