M. Zeynali; B. Maleki Zanjani; P. Moradi; F. Shekari; S.M. Niazkhani
Abstract
Biological stresses such as drought affect the production of secondary metabolites, especially plant sterols (phytosterols). Among the phytoestrols found in pumpkin seeds, betasitosterol is one of the most important components which also have many medicinal properties. In this study, the effect of five ...
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Biological stresses such as drought affect the production of secondary metabolites, especially plant sterols (phytosterols). Among the phytoestrols found in pumpkin seeds, betasitosterol is one of the most important components which also have many medicinal properties. In this study, the effect of five levels of drought stress on seed oil production and its phytosterols was studied in three genotypes and Styriaca variety of pumpkin (Cucurbita pepo L.). Analysis of phytosterols using GC/MS showed that increasing drought stress had a negative effect on oil production from pumpkin ripe seeds, but oil phytosterols, especially betasitosterol, increased and this increase was higher in Styriaca than other genotypes. To confirm these results, the seeds were harvested 15-30 days after flowering and the expression of SQS, PP2A, SMT2, ERG26 and Cycloartenol synthase genes involved in the phytosterol biosynthesis pathway was investigated. The results indicated that, among the different levels of drought stress and genes studied, highest expression level was observed at the rainfed level and at that time, betasitosterol and stigmasterol pathway had the main activity in steroid biosynthesis pathway in pumpkin.
S. Abbaszadeh; T. Radjabian; M. Taghizadeh
Abstract
Phytosterol, a general term applied to a large number of plant-derived sterols, is found exclusively in all organs of higher plants and are often enriched in oilseeds. Phytosterols have wide bioactivity in humans, in particular as an efficacious cholesterol-lowering agent and consequently may have a ...
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Phytosterol, a general term applied to a large number of plant-derived sterols, is found exclusively in all organs of higher plants and are often enriched in oilseeds. Phytosterols have wide bioactivity in humans, in particular as an efficacious cholesterol-lowering agent and consequently may have a preventive role against cardiovascular disease and also a variety of cancers. Phytosterols occur in high concentrations in vegetable oils such as the Echium (Boraginaceae family). In Iran, four species of Echium have been identified so far. In respect of unique roles of phytosterols in human health, the aim of the present study was determination and quantification of sterols in seeds of two Iranian Echium. Seeds were collected from six populations of two Iranian Echium species (E. italicum and E. amoenum) from their natural habitats. After extraction with appropriate solvents, the existence of sterols in seeds was characterized by TLC and then their contents were measured using GC and spectrophotometeric methods. Total phytosterol contents were determined using the standard curve equation obtained from the changes in the absorption of solutions at a wavelength of 640 nm. Results from GC analyses showed that total phytosterol contents based on total seed dry weight were also significant, as the highest amount (399/4 mg/100g D.W) was detected in seeds of E. italicum (Alamute Qazvin population) and the lowest (112 mg/100g D.W) was measured in seeds of E. amoenum species (Hezarjarib population). Also, campesterol (20-50% of total phytosterol) and β-sitosterol (more than 50% of total phytosterol) were the main constituents of the phytosterols in all seeds. Accordingly, seeds of E.amoenum (Behshahr population) with 141 mg/100g β-sitosterol and seeds of E. italicum (Alamute Qazvin population) with 212 and 141/4 mg/100g campesterol and β-sitostanol were respectively identified as the richest samples.
