Gas chromatography-mass spectrometry (GC-MS) analysis revealed the major components in black cumin essential oils which were thymoquinone (37.6%) followed by p-cymene (31.2%), α-thujene (5.6%), thymohydroquinone (3.4%), and longifolene (2.0%), whereas the oleoresins extracted in different solvents contain linoleic acid as a major component. The antioxidant activity of essential oil and oleoresins was evaluated against linseed oil system at 200 ppm concentration by peroxide value, thiobarbituric acid value, ferric thiocyanate, ferrous ion chelating activity, and 1,1-diphenyl-2-picrylhydrazyl radical scavenging methods. The essential oil and ethyl acetate oleoresin were found to be better than synthetic antioxidants. The total phenol contents (gallic acid equivalents, mg GAE per g) in black cumin essential oil, ethyl acetate, ethanol, and n-hexane oleoresins were calculated as 11.47 ± 0.05, 10.88 ± 0.9, 9.68 ± 0.06, and 8.33 ± 0.01, respectively, by Folin-Ciocalteau method. The essential oil showed up to 90% zone inhibition against Fusarium moniliforme in inverted petri plate method. Using agar well diffusion method for evaluating antibacterial activity, the essential oil was found to be highly effective against Gram-positive bacteria.

The present study was designed to assess differences in chemical composition and antioxidant potential of essential oils and oleoresins from fresh and sun-dried Mentha longifolia L. Essential oils and oleoresins were obtained by hydrodistillation and solvent extraction (n-hexane and ethanol), respectively. The chemical profile was evaluated by using gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). Antioxidant effectiveness was examined by five different methods, namely the ferric thiocyanate (FTC) method, the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, determination of the metal chelating power, and determination of the peroxide and thiobarbituric acid values in mustard oil at 0.02% concentration. The chemical composition was dominated by the presence of piperitenone oxide, an oxygenated monoterpene whose composition varied from 23.2% to 88.5% in both essential oils and oleoresins. Based on the antioxidant potential of essential oils, oleoresins and synthetic antioxidants can be sorted in the following descending order: butylatedhydroxytoluene > dried mint essential oil > fresh mint essential oil > propyl gallate > fresh mint ethanol oleoresin > dried mint ethanol oleoresin > dried mint hexane oleoresin > fresh mint hexane oleoresin. The drying process has a significant influence on the qualitative and quantitative content of the extracted substances.

The chemical composition, antioxidant and antimicrobial potentials of essential oils and oleoresins obtained from dill (Anethum graveolens L.) seeds and leaves have been studied. The isolated essential oils and oleoresins were analyzed by gas chromatography coupled with mass spectrometry. The antioxidant activity of essential oils and oleoresins in comparison with synthetic antioxidants were evaluated using different antioxidant assays namely peroxide, thiobarbituric acid values. The antioxidant potentials were further confirmed using other methods such as ferric thiocyanate method in linoleic acid system, scavenging effect (%) on DPPH radical and metal chelating activity. Total phenolic content was also calculated using Folin-Ciocalteau method. Their antimicrobial activity was investigated using various methods on an array of microorganisms. Carvone (47.2%) was the major component in seed essential oil whereas dillapiole (90.2%) was the main component of leave essential oil. The oleoresins were mainly having a major fraction of carvone, dillapiole and oleic acid. Both essential oils have shown excellent antioxidant activity. The seed essential oil showed excellent antimicrobial activity against Aspergillus flavus and Fusarium graminearum in food poisoned method. Significant antibacterial activity was recorded for essential oils against Staphylococcus aureus and Bacillus subtilis while nominal inhibitory effects were observed against Escherichia coli and Pseudomonas aeruginosa.