Study on the Component Analysis, Antioxidant and Antibacterial Activities of Rosemary Essential Oil from Jiangxi
Rosemary (Rosmarinus officinalis L.) is a sub shrub of the genus Rosmarinus in the family Lamiaceae, native to the Mediterranean region and now grown worldwide. It contains abundant aromatic oil components. Rosemary has a strong aroma and is commonly used in cooking spices, natural preservatives in the food industry, as well as ornamental and medicinal plants. Research has found that rosemary and other herbs have good antioxidant activity among a wide range of herbs and spices.
Essential oil is a secondary product formed during plant metabolism, which is a substance with high concentration of aroma and volatility. It exists in certain special organs of plants and plays various ecological functions. Due to the diverse biological activities of essential oils, their applications in many fields such as food industry, cosmetics industry, plant therapy, medicine, etc. are constantly growing. Although synthetic antioxidants and preservatives have been widely used in the food industry, their long-term use can pose certain risks to human health. Therefore, many recent studies have been searching for natural active ingredients. Plant essential oils, as a natural extract, have been proposed as a potential alternative to synthetic antioxidants. Rosemary essential oil is a colorless or light yellow liquid extracted from its stems, leaves, flowers, etc., with a plant specific odor, mainly containing α – pinene, 1,8-cineole, camphene, camphor, borneol, caryophyllene and other terpenoids. Rosemary essential oil has antioxidant, bacteriostatic and antiseptic effects, and is widely used in medicine, food industry and aromatherapy. In this study, the essential oil of rosemary leaves from Jiangxi Province was extracted by steam distillation, and its components were analyzed by gas chromatography-mass spectrometry (GC-MS).

The chemical composition of rosemary essential oil was identified by steam distillation combined with gas chromatography-mass spectrometry (GC-MS). The high content components of rosemary essential oil were α – pinene (39.05%) and 1,8-cineole (16.86%), followed by camphene (4.22%), D-limonene (3.87%), borneol (3.74%), β – caryophyllene (3.11%), geraniol (2.92%), β – pinene (2.23%), camphor (2.16%), etc. According to ISO international standards, Jiangxi rosemary essential oil belongs to Spanish type. Rosemary is a commonly used spice in Western cuisine, characterized by a mixed aroma of ingredients such as camphora, camphora esters, and camphor, as well as a sweet and woody aroma and flavor, with a rich aroma. It is speculated that this may be related to the four main components of rosemary, alpha pinene, 1,8-eucalyptol, camphora, and camphora, which account for 61.80% of the total component content. Camphor has a strong pungent aroma, and 1,8-eucalyptol and camphene have a camphor like aroma. The taste of camphora is tough and slightly cold; Rosemary has camphor and pine wood aromas, while alpha pinene has pine, needle, and resin like aromas, resulting in a strong pine wood aroma.

The antioxidant activity of rosemary essential oil was analyzed by the determination of DPPH free radical, hydroxyl free radical scavenging and total reducing power. The IC50 values of DPPH free radical, hydroxyl free radical scavenging capacity and reducing power of rosemary essential oil are 76.42, 51.40 and 49.15 μ L/mL, respectively. It can be seen that rosemary essential oil has good antioxidant activity and good scavenging effect on free radicals. Ra Š kovic ‘and other studies have shown that rosemary essential oil has good antioxidant activity. The composition of rosemary essential oil from different habitats varies greatly, leading to different IC50 values. It can be seen from the inhibition circle size of rosemary essential oil against Bacillus subtilis, Staphylococcus aureus and Escherichia coli of 14.40 ± 0.66, 11.41 ± 0.19, 11.70 ± 0.27 mm and the minimum inhibitory concentration (MIC) of 2.50, 10.00, 10.00 μ L/mL that rosemary essential oil has good bacteriostasis against the three tested bacteria, and has broad-spectrum bacteriostasis. The inhibitory effect of essential oil on Bacillus subtilis is significantly stronger than that of Staphylococcus aureus and Escherichia coli. Jiang et al. reported that the antibacterial activity of rosemary essential oil was better than α – pinene and 1,8-cineole. It was inferred that the antibacterial activity of rosemary essential oil was the synergistic effect of its chemical components. According to the above GC-MS results, the content of α – pinene and linalool is higher than that of other domestic producing areas, and the content of 1,8-cineole in rosemary essential oil is higher, which is the main reason why rosemary essential oil has good antioxidant and antibacterial activities. It can be seen from this experiment that rosemary essential oil has good antioxidant and antibacterial activities, and has great development value as a natural antioxidant and antibacterial agent.