The chemical composition of the extracted fixed oil (total fatty acid composition) and volatile oil of Nigella sativa L. seeds grown in Iran were determined by GC and GC/MS. Eight fatty acids (99.5 %) and thirty-two compounds (86.7 %) have been identified in the fixed and volatile oils, respectively. The main fatty acids of the fixed oil were linoleic acid (55.6 %), oleic acid (23.4 %), and palmitic acid (12.5 %). The major compounds of the volatile oil were trans-anethole (38.3 %), p-cymene (14.8 %), limonene (4.3 %), and carvone (4.0 %).

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Thymus species are known to have significant amounts of phenolic and flavonoid compounds and exhibit strong antioxidant activities. This work was designed to evaluate the antioxidant activities of three endemic Iranian Thymus species (including T. daenensis, T. kotschyanus, and T. pubescens) in different test systems [namely DPPH() (2,2'-diphenyl-1-picrylhydrazyl), ABTS(+) [2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid], and linoleic acid/β-carotene bleaching assays] to determine the total phenolic and flavonoid contents of the species (assayed by colorimetric techniques) and to study the possible composition-activity relationship. All the tested plants exhibited concentration-dependent antioxidant and free radical scavenging activities. T. pubescens showed the highest free radical scavenging activities in both DPPH() and ABTS(+) methods, while T. daenensis and T. kotschyanus were the most active species in the β-carotene bleaching inhibition test. Alternatively, T. pubescens exhibited a significantly higher level of the total flavonoid content compared with those of the other species, while no significant statistically differences were found among the tested plants regarding the total phenolic content. In addition, significant correlations were found between the flavonoid content and DPPH()/ABTS(+) radical scavenging activities, but not between the β-carotene bleaching inhibition system and the flavonoid content.

Inhibitors of carbohydrate hydrolyzing enzymes such as a-amylase play an important role for the control of diabetes mellitus especially in patients with type 2 diabetes. In this study we selected ten antidiabetic medicinal plants, because they have been recommended to treat diabetes in traditional Iranian medicine, and screened them for a-amylase inhibitory activities. Among the tested samples, Camellia sinensis (Theaceae) leaf (IC 50 = 1.54 mg/mL), Trigonella foenumgraecum (Leguminosae) seed (IC 50 = 1.87 mg/mL) and leaf (IC 50 = 1.92 mg/mL), and Urtica dioica (Urticaceae) leaf (IC 50 = 1.89 mg/mL) revealed appreciable a-amylase inhibitory activities in a concentration-dependent manner. Furthermore, the most active sample, Camellia sinensis leaf, was partitioned by stepwise solvent-solvent extraction process and the inhibitory effect of each fraction on the a-amylase was tested. According to the results, the ethyl acetate fraction (IC 50 = 0.53 mg/mL) and the residue (IC 50 = 0.52 mg/mL) had the highest a-amylase inhibitory activities.

The composition of the hydrodistilled essential oils from the fruits and leaves of Thuja orientalis L. grown in Iran was analyzed by GC/MS. Nineteen and twenty-eight compounds have been identified in the volatile oils of the fruit and leaf, respectively. While the fruit oil contained α-pinene (52.4%), Δ-3-carene (14.2%), α-cedrol (6.5%) and β-phellandrene (5.1%), the leaf oil contained α-pinene (21.9%), α-cedrol (20.3%), Δ-3-carene (10.5%) and limonen (7.2%) as the main components.

The smoke of Peganum harmala seeds is traditionally used in Iran as a disinfectant agent. The aim of this study was to determine the antimicrobial activity of two smoke condensates from Peganum harmala seeds. Furthermore the composition of smoke preparations was studied using gas chromatography and mass spectroscopy analysis. The most prevalent compound detected in a dichloromethane extract was harmine. Standard harmine as well as the dichloromethane extract showed antimicrobial activity against all test strains. Harmine was not detected in an n-hexane extract and we did not observe antimicrobial activity from this smoke preparation at the tested concentrations.

The management of postprandial hyperglycemia is an important strategy in the control of diabetes mellitus and complications associated with the disease, especially in the diabetes type 2. Therefore, inhibitors of carbohydrate hydrolyzing enzymes can be useful in the treatment of diabetes and medicinal plants can offer an attractive strategy for the purpose. Vaccinium arctostaphylos leaves are considered useful for the treatment of diabetes mellitus in some countries. In our research for antidiabetic compounds from natural sources, we found that the methanol extract of the leaves of V. arctostaphylos displayed a potent inhibitory activity on pancreatic α-amylase activity (IC50 = 0.53 (0.53 – 0.54) mg/mL). The bioassay-guided fractionation of the extract resulted in the isolation of quercetin as an active α-amylase inhibitor. Quercetin showed a dose-dependent inhibitory effect with IC50 value 0.17 (0.16 – 0.17) mM.