Introduction. Perseaamericana (avocado) fruit is known to be a rich sourceof proteins and minerals, as well as vitamins. Although many biologicalactivities have been reported for avocado fruit, far less attentionhas been paid to the biological properties of its lipid-solublebioactive substances. The aim of this study was to evaluate theantioxidant and antihemolytic activity of lipid-soluble bioactivecompounds of avocado fruit. Materials and methods.Antioxidant and antihemolytic activity of lipid-soluble bioactivecompounds of avocado fruit was assessed by employing different methods.Also, the ability of avocado fruit to protect fluorescein againstoxidant-induced bleaching was evaluated. Results and discussion.The tested sample showed good antioxidant and antihemolytic activities. Therewas no significant difference between the reducing power of lipid-soluble bioactivesubstances in avocado fruits and ascorbic acid (p <0.05). The tested sample showed weak ferrous ion-chelating activity.The sample exhibited moderate hydrogen peroxide scavenging activity, butexhibited good antioxidant activity. Avocado fruit showed very good activityagainst 2,2′-azobis(2-amidinopropane) dihydrochloride- and hydrogenperoxide-induced hemolysis in erythrocytes. Furthermore, it showed goodprotective effects against peroxyl radical-induced bleaching in fluorescein. Conclusion. Lipid-soluble bioactive substances of avocado fruitshowed good activity in all of the studied models.

Introduction. Pomegranate fruit is a good source of bioactive compounds.Although data about the importance of pomegranates in human nutrition has increasedextensively in the last years, the fruit physical and chemical characteristics of someIranian pomegranate cultivars during fruit ripening have not been investigated in detailyet. Therefore, the evaluation of physicochemical characteristics of pomegranate fruit cv.‘Rabbab-e-Fars’ at three different stages, from fruit set to ripening, was the aim of thepresent study. Materials and methods. Fruit fresh weight and volume, andpeel, aril, juice and seed percentage were measured as physical features and total solublesolids, pH, titrable acidity, ascorbic acid, total sugars, anthocyanins, phenolics andtannins, condensed tannins, and antioxidant activity in the juice were evaluated as thechemical properties. Results. The highest percentage of aril (57.86%) andjuice (48.01%) and lowest percentage of peel (42.13%) and seed (10.49%) were observed in140-day-old fruits. A significant increase in concentrations of total soluble solids andtotal sugars were recorded during fruit ripening. The ascorbic acid content decreasedsignificantly, while the amount of total anthocyanins increased significantly with fruitmaturity. Ripe fruit, which had a low titratable acidity (1.35 g·100 g-1 offruit juice), showed a correspondingly high pH (3.23). The levels of total phenolics,total tannins, condensed tannins and antioxidant activity declined significantly duringfruit ripening. Conclusion. Our results provide important information on thechanges in physical and chemical properties of pomegranate fruit during ripening, which isvery useful for determination of the fruit quality.

Introduction. Pomegranate fruits (Punica granatum L.) arechilling-sensitive crops. Materials and methods. Pomegranate fruits weretreated with calcium chloride and spermidine, alone or in combination, by normal dip andvacuum infiltration methods. The treated fruits were stored at 2 °C for 4 months. At theend of the storage period, samples were held for 3 days at 20 °C, then the qualitativeconstituents were evaluated. Results and discussion. Treated fruits exhibitedless weight loss and higher juice content than control fruits. Non-treated fruitsdeveloped chilling injury manifested as an increase in K+ leakage andpolyphenol oxidase activity. Calcium chloride and spermidine treatments resulted in lowersoluble solid content, but some fruits showed higher titratable acidity. All treatmentssignificantly increased ascorbic acid content. The pH of aril juice in treated fruits waslower than that of non-treated fruits, probably due to higher titratable acidity. Totalantioxidant activity and total phenolic content increased in treated fruits. In our study,a correlation was observed between total phenolic content and total antioxidant activity.Conclusion. The treatments applied in our experiments maintained overallquality of pomegranate fruits during long-term storage. Postharvest application of calciumand spermidine either alone or in combination could ameliorate adverse effects of lowtemperature on pomegranate fruit quality during cold storage. Vacuum infiltration was aseffective as the normal dip method. However, normal dip is a simpler and faster treatmentmethod.

Introduction. Drought stress is the major factor affecting growth,development and production of walnut trees. In Iran, approximately 33 Mha of land isaffected by salinization and drought stress. Finding genetic resources tolerant to droughtstress at different growth stages is important for such semi-arid regions. Our aim was tounderstand better the adaptive mechanisms that enable different genotypes of walnutpopulation to survive under drought stress, and to provide some useful clues for walnuttree breeding toward improved drought tolerance with utilization of existingdrought-tolerant genetic resources. Materials and methods. To study themechanism(s) involved in drought tolerance of some Persian walnut genotypes, droughtstress was induced using polyethylene glycol-6000 to produce water potentials of 0 Mpa(control), –0.10 MPa, –0.50 MPa, –0.75 MPa, –1.00 MPa, –1.50 MPa and –2.00 MPa. The amountof proline and soluble sugar accumulation in four walnut genotypes(‘Panegine20’, ‘Lara’, ‘Serr’ and ‘Chandler’) were determined after beingexposed to the various water potential levels. Results. The rates of seedgermination in all genotypes were significantly reduced by low external water potentials.Plants exposed to water stress had a higher amount of soluble sugars in roots and shootsof tolerant genotypes (‘Panegine20’ and ‘Chandler’) and a lower amount ofstarch in their tissues. These results imply the important roles of soluble sugars assolutes conferring resistance to drought in these genotypes. The free proline levels werealso increased in response to drought stress. They were higher in drought-tolerantgenotypes than in sensitive ones (‘Lara’ and ‘Serr’). Proline increased more in shootsthan in roots. However, the soluble sugar and starch fluctuations were higher in theroots. Conclusion. Our results support a direct correlation between thedegree of drought stress and proline content. As a consequence, proline concentrationscould be used as a biochemical marker of drought stress level in walnut plants.