Many methods for the evaluation of the antioxidant activity of natural product extracts have been developed, such as active oxygen species (e.g., superoxide anion, peroxy radical, and hydroxyl radical) scavenging capability determination, radical (not a natural free radical found in the body) scavenging activity determination, including 1,1-diphyl-2-picrylhydrazyl (DPPH) radical and 2,2'-azinobis-(3-ethyl- benzothiazline)-6-sulfonate radical cation (ABTS.+
), and enzymatic or nonenzymatic measurements of LPO-inhibiting effects [1
Antioxidative traditional Chinese medicine (TCM) is an attractive target for the study as a model of antioxidant-based composite therapy against cerebral oxidative damage, as TCM has been used as an alternative medicine for treating complex pathophysiological conditions, even for diseases that Western medicine has failed to allocate a specific diagnostic name.
In view of increasing environmental and health concern about traditional organic solvent extraction, supercritical fluid extraction (SFE) has received much attention in the past several years. The advantages of SFE using carbon dioxide compared with ethanol extraction are that it is relatively rapid and environmentally friendly, such as low operating temperature (hence no thermal degradation of most of the active compounds ocurrs); high selectivity in the extraction compounds; no solvent residue. However, the drawback in the use of SFE-CO2
is the cost of supplementary equipment and its low polarity, making the extraction of polar components difficult. Even small amounts of polar modifiers, such as methanol or ethanol, can enhance the efficiency of extraction, the polar solvent extraction provide a higher efficiency on the separation of polar active components [2
]. The disadvantages of solvent extraction are: low yield, loss of volatile compounds, long extraction time, toxic solvent residues and degradation of active compounds, due to heat.
The main classes of bioactive compounds from plants include flavonoids, terpenes, alkaloids, and coumarins [3
]. Favonoids are polyphenolic compounds that produce the flavor of fruits and vegetable as well as the red and blue pigments of plants, and have been used in taxonomic studies of angiosperms. Terpenes are responsible for the fragrance of essential oils, and they consist of repeating isoprene units with monoterpenes having two isoprene units. Coumarins are most abundant in grasses and have been found to have wide-ranging activity, including antimicrobial, antiviral, antithrombotic and anti-inflammatory properties. Alkaloids are compounds that consist of a heterocyclic ring with a nitrogen atom. They include caffeine, morphine, and nicotine.
has a long history of use as preservative and for medicinal purposes in the East. In our previous studies, we examined the antibacterial activities of 58 herbal plants extracted by 95% ethanol. The results revealed that C. cassia
sticks exhibited obvious broad-spectrum antimicrobial activity against clinical drug-resistant Pseudomonas aeruginosa
]. Following the study, we extracted C. cassia
sticks by supercritical fluid extraction (SFE) under various extraction conditions to determine the best SFE conditions. The extraction conditions were examined in the range of 4,000–6,000 psi and 40–50 °C [2
]. The results showed that the highest yield of the antimicrobial substance, (E
)-cinnamaldehyde, can be isolated at 4,500 psi and 45 °C. In addition to our previous studies, there are many literature reports that barks and leaves of Cinnamon
present various bioactive functions, such as the anti-diabetic effects presented by C. cassia
], the antibacterial and antioxidant activities of C. zeylanicum
barks and leaves [6
], the anti-inflammation and anti-proliferation of tumor cell activities presented by C. osmophloeum
]. C. osmophloeum
leaves have antifungal activities [8
]. However, regarding to the antioxidant activities of various parts of Cinnamon
, not much related research has been reported.
In this study, we aimed to compare the antioxidant activities of extracts of various parts of C. cassia (barks, buds and leaves) obtained by supercritical carbon dioxide extraction and ethanol extraction. The total flavonoid and phenolic contents in each extract were also determined. The results of this study not only provided a better technique for bioactive substance extraction from C. cassia, but also revealed the best parts of C. cassia to isolate the active constituents.