Optimization of preparation process and antioxidant activity of gardenia extract
Gardenia jasminoides Ellis and double petaled Gardenia jasminoides Ellis var. fortuniana (Lindl.) Hara, both belonging to the Rubiaceae family, are the dried flowers of Gardenia jasminoides Ellis and Gardenia jasminoides var. fortuniana (Lindl.) Hara. They are included in books such as “Chinese Materia Medica” and “Dictionary of Traditional Chinese Medicine”. They have a bitter taste and a cold nature, and when used as medicine, they have the effects of clearing the lungs, stopping cough, cooling blood, and stopping bleeding. Gardenia has a long history of consumption, medicinal use, and cosmetic use. According to “Dian Nan Ben Cao”, it can “stop lung heat cough, stop nosebleeds, and eliminate phlegm”; The Thousand Golden Wings Formula and the Compendium of Materia Medica both refer to it as “pleasing to color”. Modern research has shown that gardenia contains various components such as essential oils, triterpenoids, flavonoids, phenolic acids, alkaloids, etc. Gardenia has a fragrant aroma, and the essential oil extracted from it has the effects of soothing the body and mind, anti anxiety, etc., but it is extremely precious due to its low content and difficulty in extraction; Research has shown that gardenia flowers and their essential oils can eliminate various free radicals and have good antioxidant beauty effects. Flavonoids are plant active ingredients with strong antioxidant properties. The gardenia flower and the commonly used Chinese medicinal herb gardenia come from the same plant, which is widely planted and has abundant resources. Its extract has been included in the 2021 edition of the “Catalogue of Used Raw Materials in Cosmetics”. However, due to limited research, the utilization rate of gardenia flower in China is not high, resulting in a significant waste of gardenia resources.
The traditional extraction method for plant essential oils is steam distillation, which has simple equipment but low extraction rate, and can easily lead to impure aroma of the extracted essential oils. Supercritical CO2 extraction is an extraction method that uses CO2 fluid as a solvent to separate components from a mixture. Compared with steam distillation, this method has higher extraction efficiency and can more effectively preserve the natural aroma of essential oils. Moreover, CO2 is recyclable, non-toxic, and does not produce waste or pollution. There are literature reports that the essential oil of gardenia obtained by this extraction method is not affected by the high temperature of water vapor, and some volatile aromatic components are retained, possessing the characteristic aroma of fresh gardenia flowers. In addition, studies have also investigated the extraction process of flavonoids from gardenia flowers. Due to the strong biological activity and wide application range of essential oils and flavonoids in plants, their comprehensive extraction has been applied in various traditional Chinese medicines and plants containing essential oils, such as purple clover, loquat flower, rose, lavender, etc. At present, the extraction of Gardenia jasminoides flower essential oil (GJFEO) or Gardenia jasminoides flower flavonoids extract (GJFFE) is based on the single extraction of Gardenia jasminoides flower as the raw material. Comprehensive deep processing research on Gardenia jasminoides flower can improve its utilization rate and provide reference for the development and utilization of non medicinal parts of traditional Chinese medicine resources.
According to literature reports, GJFEO has shown good scavenging effects on DPPH, ABTS, and OJH free radicals in vitro chemical experiments, and plant flavonoids are also a hot topic in the research of natural antioxidant active ingredients. At present, there is relatively little research on the antioxidant activity of gardenia at the cellular and animal levels. Further pharmacological activity research on gardenia can provide technical support and theoretical basis for the development of related antioxidant cosmetics and daily products. This study aims to optimize the comprehensive extraction process of essential oil and total flavonoids in gardenia flowers, and investigate their antioxidant activity, in order to solve the above problems and provide reference for the comprehensive utilization of non medicinal parts of traditional Chinese medicine.

This study optimized the optimal extraction process of GJFEO using single factor and orthogonal experiments, with extraction temperature of 38 ℃, extraction pressure of 32MPa, and separation pressure of 12MPa; The optimal extraction process for GJFEO was optimized using a single factor experiment, with an ethanol concentration of 50%, a liquid to material ratio of 25:1, an extraction time of 50 minutes, and a total of 2 extractions. Both processes have simple conditions and easy operation. On the one hand, they avoid the heating operation in the traditional extraction process of essential oils and overcome the defects of impure aroma and low extraction rate of essential oils by distillation method; On the other hand, re extracting the residue after extracting the essential oil can obtain the total flavonoid components, which improves the utilization rate of gardenia raw materials.
The experimental results of this study indicate that GJFEO, GJFEE, and GJFCE all have a certain protective effect on HaCaT cells damaged by H2O2, and the combination of GJFEO and GJFEE can produce a synergistic effect, suggesting that GJFCE can be developed or further studied as a high antioxidant extract of gardenia. According to the experiment, the mass ratio of GJFEO and GJFEE in Gardenia jasminoides was 1:24. In order to improve the utilization rate of raw materials, the GJFCE studied in this article was compounded according to this ratio. Later, further activity evaluation can be conducted on GJFCE compounded in different ratios to select the optimal ratio. At present, due to weak development technology, there is a significant waste of gardenia resources. The results of this study can provide technical support and theoretical basis for the development of gardenia related antioxidant cosmetics and daily chemical products, and provide reference and guidance for the comprehensive utilization of non medicinal parts of traditional Chinese medicine.