Evaluation of antibacterial and antioxidant properties of Coriander seed essential oil and investigation of oxidative stability of soybean oil containing Coriander essential oil

One of the most important challenges facing medical science is infectious diseases and poisoning, which in turn increases the production and consumption of new and common antibiotics. With theover use of common antibiotics, we are witnessing the spread of antibiotic-resistant microbial species, which makes the treatment of infectious diseases long and costly. Natural compounds of plant origin (essential oils and extracts) have been used to kill or at least prevent the growth of pathogenic microorganisms. These compounds, which are naturally present in plant tissues, are probably produced as part of their defense mechanisms against microbial invasion. Plant-based antimicrobials have therapeutic potential and are not only effective in treating infectious diseases, but also reduce the large number of side effects that are often associated with synthetic antimicrobials. Essential oils are complex mixtures of volatile, aromatic, low molecular weight and hydrophobic compounds present in various parts of aromatic plants, including leaves, flowers, seeds, sprouts and shoots. Among these plants, we can mention the coriander plant. Coriander (Coriandrum sativum L.) is an annual, herbaceous, aromatic plant belonging to the Apiaceae family. Coriander has a long history of nutritional and therapeutic use. This plant is a rich source of aromatic compounds and essential oils that have antibacterial, antifungal and antioxidant effects and is used in the preparation of various foods as a spice.
 
The tested coriander seeds were obtained from Khorasan Razavi province, Mashhad city. Antioxidant-free soybean oil was obtained from the Seh Gol Khorasan vegetable oil factory. Total phenolic content (TPC), Radical scavenging ability (DPPH assay), Oxidative stability index (OSI), Peroxide value (PV), Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of essential oil were measured on a number of bacteria causing infection and food poisoning. The compositions of essential oils were identified by Gas Chromatography-Mass Spectrometry (GC-MS).
 
Most of the constituents of coriander seed essential oil were oxygen monoterpene compounds. Essential oils that have a higher percentage of oxygenated compounds are more important than other compounds in terms of aroma, strong odor, as well as antimicrobial and antioxidant power, so they are considered more valuable essential oils. Analysis of microbial test results showed that coriander seed essential oil had a relatively strong and good effect against the studied Gram-positive bacteria, so that the essential oil inhibited the growth of Staphylococcus aureus even at low concentrations. This essential oil had good antioxidant activity in the thermal stability of soybean oil. Coriander seed essential oil as an antioxidant compound was able to increase the oxidative stability of soybean oil under oxidative acceleration conditions. The results showed that total phenolic compounds were 0.161 mg GAE/100g, IC50 for essential oil was 30.981 mg/ml and thermal stability of soybean oil treated with coriander seed essential oil was 5.17 h. The results of microbial tests showed that Gram-positive bacteria was more sensitive to Coriander seed oil than Gram-negative bacteria. The most important constituents of coriander seed essential oil were Linalool (49%), Terpinolene (7%) and α-Pinene (6.8%).