Analytical studies on traditional Iranian herbs

Human being has used plants for centuries for food and medicinal purposes. In recent decades, there has been a gradual revival of interest in the use of foods with plant resources due to their nutritional values and potential healing properties. This folklore reputation promotes the importance of determination of plants ingredients by scientists. Plant phenolic compounds are increasingly of interest of food industry as they retard oxidative degradation of lipids and thereby improve the quality and nutritional value of food. Carotenoids, flavonoids, polyphenols and their secondary metabolites have shown great antioxidant and anti-carcinogenic properties. Moreover, phenols have potential to act as food anti-oxidant agents. Among the vast range of plants, which are used as medicinal herbs and foods, some of them due to their taste, color and odor have been found a special place in Iranian food basket. Saffron (Crocus sativus), cardamom (Elettaria cardamomum), sumac (Rhus coriaria L.), and barberry (Berberis vulgaris) are among the most used herbs in Iranian cuisine due to their taste, color and healing properties. Saffron, the dried stigmas of Crocus sativus L., is the most expensive spice in the world. This plant is cultivated for seasoning, cosmetic, perfume and medicine over centuries. Studies on saffron are extensively evaluated the crocetin ester compounds in this plant which responsible for its color and taste. Crocetin esters are major quality indicators in saffron. Cardamom (Elettaria cardamomum) is the third most expensive spice in the world after saffron and vanilla. There are reports on medicinal properties of cardamom as stimulant, digestive and aphrodisiac. Also, according to some studies cardamom oil has anti-bacterial, anti-microbial and anti-inflammatory effects. Sumac (Rhus coriaria L.) fruits are used as seasoning spice in salads and as souring agent in foods. Sumac fruits contain poly phenols, flavonols, hydrolysable tannins anthocyanins and low molecular organic acids. Sumac extracts have been shown anti-microbial, anti-fungal and anti-viral effects. Barberry (Berberis vulgaris) belonging to the Berberidaceae family, is an evergreen shrub. The root of barberry as medicinal herb, which contains alkaloids like berberine, has showed antidepressant, neuroprotective, anti-inflammatory and anti-apoptotic effects. There were reports on antihistaminic and anticholinergic and hypotensive effects in red fruit extracts. This thesis contains three research themes. In the first study, we determined the riboflavin (vitamin B2) content of saffron by a simple, sensitive, trustable capillary electrophoresis method hyphenated with laser induced fluorescence detector. Capillary electrophoresis has superiorities over other separation techniques such as low cost, less sample and reagent consumption, ease of automation, less analyzing time and high resolution. Optimum separation was obtained with borate buffer in the concentration of 20 mM (background electrolyte) at pH= 9.5 voltage 30 kV. Calibration curve was linear in the range of 0.01-0.5 µM with correlation coefficient above 0.99. The limit of detection (LOD) and limit of quantification (LOQ) for the method were 4.15 nM (1.56 ng/L) and 13 nM (4.89 ng/mL), respectively. Five saffron samples from the biggest producers in global market, Iran and Spain were analyzed by this method and it was showed that saffron is one of the riboflavin-rich foods. In the second study low molecular organic acids and sugar contents of saffron (Crocus sativus), cardamom (Elettaria cardamomum), sumac (Rhus coriaria L.), and barberry (Berberis vulgaris) were determined by capillary electrophoresis coupled with UV/Vis detector. Separation of organic acids was made with 5 mM PDC (2,6-pyridinedicarboxylic acid) both as chromophore and background electrolyte. In order to accelerate the co-electroosmotic migration of organic acids, 0.5 mM CTAB, a positively charged surfactant, was added to the background electrolyte (BGE) as dynamic wall coating agent. Separation was made at pH=5.65, while the running voltage was set at 28 kV. Satisfactory recoveries were obtained between 84.0 and 114% for all organic acids in saffron samples, 85-108 % for barberry sample, 91-113 % for sumac and 88-109 % for cardamom sample. The limit of detections, LOD of the method were between 0.372 µg/mL and 2.80 µg/µL. Sugars were determined by indirect UV detection using 50 mM glycylglycine at pH=12.5 as background electrolyte. The separation voltage was set at 22 kV. Calibration curves were drawn in the range of 2-12 mM with regression of 0.990 and 0.997 for glucose and fructose, respectively. The limit of detections, LOD (S/N = 3) of the method were 28.2 µg/mL and 29.1 µg/mL for glucose and fructose, respectively. Recovery values were between 87-99 % for saffron samples, 96 % berberis vulgaris fruits, and 97 % for sumac sample. We could not detect any sugars in cardamom using this method. Principal component analysis and hierarchical cluster analysis classified ten saffron samples from different commercial brands according to their similarities and dissimilarities of organic acid and soluble sugar contents. The results will contribute to a better understanding of nutritional values of saffron (Crocus sativus L), cardamom Elettaria cardamomum), sumac (Rhus coriaria L.), and barberry (Berberis vulgaris) by contributing to the limited number of data on their organic acid and sugar contents. To the best of our knowledge, it is the first reports on organic acid contents of sumac and cardamom in the literature. In the third study, using the ability of high resolution liquid chromatography hyphenated with ion trap-time of flight mass spectrometry in qualitative characterization of unknown structures led to identifying new crocetin ester compounds in saffron extract. Trans and cis-crocin 4(Gn-diG), trans and cis-crocin 3 with unknown glycoside structure and also the isomer of crocin 1 were the compounds tentatively identified in this study. Principal component analysis was used for classification of saffron samples from Spain an Iran according to the country of origin.