Abstract
Vietnamese Callisia fragrans (C. fragrans) has been considered as a valuable traditional plant with various medicinal properties. In this study, polyphenols were extracted from Vietnamese C. fragrans leaves by supercritical carbon dioxide (SC-CO2) extraction method using ethanol as a cosolvent. The investigation of four factors influencing the total polyphenol content (TPC) and antioxidant activity of the extracts obtained from each single-factor experiment was conducted including ethanol concentration, CO2 flow rate, extraction temperature, and pressure. Besides, the extraction efficiency of the SC-CO2 method under the best extraction conditions, namely ethanol concentration of 14%, CO2 flow rate of 20 g/min, extraction temperature of 45°C, and pressure of 200 bar was compared to that of the Soxhlet extraction (SE) method in terms of the TPC and antioxidant activity of the extracts. The results showed that using SC-CO2 method, the TPC and the half-maximal inhibitory concentration value obtained were of 87.42 ± 1.33 mg/g and 243.83 ± 5.30 μM TE/g, respectively, with much less time and solvent amount required while that obtained using SE method were of 85.34 ± 4.27 mg/g and 236.33 ± 7.66 μM TE/g, respectively. This indicated that SC-CO2 would be suitable for the industrial production of polyphenols with high antioxidant activity of the extracts obtained due to the restrictions of using the SE method and advantages of applying SC-CO2 method. Therefore, SC-CO2 method could be regarded as a potentially upcoming extraction technique which might be employed to replace the conventional SE method.
Highlights
Over 500 species belonging to Commelinaceae family, especially Vietnamese Callisia fragrans (C. fragrans), have been widely grown in eastern Australia to have their leaves and stems harvested [1]
The influences of four single operational parameters including ethanol concentration, CO2 flow rate, extraction temperature, and pressure were determined according to the total polyphenol content (TPC) and antioxidant activity of the extracts obtained from singlefactor experiments
Experiments were conducted under extraction conditions including extraction temperature of 50°C, extraction time of 60 min, CO2 flow rate of 14 g/min, and pressure of 200 bar
Summary
Over 500 species belonging to Commelinaceae family, especially Vietnamese Callisia fragrans (C. fragrans), have been widely grown in eastern Australia to have their leaves and stems harvested [1]. Containing a great variety of bioactive components such as flavonoids, phytosteroids, vitamins, and microelements, this plant has been well known for many pharmaceutical uses including anti-inflammation, pain killers, burn treatment, and cardiovascular drugs [2, 3]. Polyphenols, known as secondary metabolites, present commonly in all higher plants with more than 8,000 phenolic structures that were identified and classified into 10 classes in association with its structures [4]. It is reported that there are more than 4,000 flavonoid structures of which 143 are proanthocyanidins that have been found [5]. E polyphenols have been widely applied for sunburn prevention because their aromatic-ring structures could affect the absorbance of the UV radiation ranging from 280 to 315 nm [8] Polyphenols have been considered as an antioxidant agent and an anticancer component owing to biological characterizations for the activation of a variety of enzymes and cell receptors [7]. e polyphenols have been widely applied for sunburn prevention because their aromatic-ring structures could affect the absorbance of the UV radiation ranging from 280 to 315 nm [8]
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