Limits...
Antioxidant activity and free radical-scavenging capacity of Gynura divaricata leaf extracts at different temperatures.

Wan C, Yu Y, Zhou S, Liu W, Tian S, Cao S - Pharmacogn Mag (2011)

Bottom Line: However, TPC and TFC were not significantly different (P > 0.05) at the extraction temperatures 90°C and 100°C.Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05).The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Food Science & Technology, Nanchang University, Nanchang - 330 047, Jiangxi,, China.

ABSTRACT

Background: Extraction temperature influences the total phenolic content (TPC), total flavonoid content (TFC) of medicinal plant extracts to a great extend. TPC and TFC are the principle activity constituents present in the plant. The effects of extraction temperature on TPC, TFC and free radical-scavenging capacity of Gynura divaricata leaf extracts are worth to study.

Materials and methods: Folin-Ciocalteu and aluminum chloride colorimetric assay were used to determine the TPC and TFC of Gynura divaricata leaf extracts at different temperatures. The antioxidant and free radical-scavenging activity were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and phosphomolybdenum methods.

Results: TPC and TFC were significantly elevated with increasing extraction temperature (from 40°C to 100°C). However, TPC and TFC were not significantly different (P > 0.05) at the extraction temperatures 90°C and 100°C. Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05). The TPCs (13.95-36.68 mg gallic acid equivalent/g dry material) were highly correlated with DPPH (R(2) = 0.9229), ABTS (R(2) = 0.9951) free radical-scavenging capacity, and total antioxidant activity (R(2) = 0.9872) evaluated by phosphomolybdenum method.

Conclusion: The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

No MeSH data available.


Relationship between (a) extraction temperature and total phenolic contents, (b) extraction temperature and total flavonoid contents
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3065156&req=5

Figure 0002: Relationship between (a) extraction temperature and total phenolic contents, (b) extraction temperature and total flavonoid contents

Mentions: The present study was focused on TPC and TFC, in addition to the antioxidant activity of G. divaricata leaf extracts obtained at different temperatures. The influence of extraction temperature on TPC, TFC, and antioxidant activity of the 45% ethanol extracts was investigated. For all the extraction temperatures surveyed, the highest TPC, TFC, and antioxidant activities were observed in the extracts obtained at 100°C followed by extraction at 90°C. Significant lower levels of TPC and TFC were demonstrated by extractions at temperatures below 80°C. The TPC and TFC of extracts have strong positive correlation with the extraction temperature, with the correlation coefficient (R2) 0.9925 and 0.9928, respectively [Figure 2]. The results of the present study also indicate that there was a significant reduction in the total antioxidant activity and free radical-scavenging capacity of the extracts obtained at temperatures below 80°C compared to those extracted at 90°C or 100°C. This was expected due to the elevation the TPC and TFC of extracts at higher temperatures. Our findings are in contrast to Akowuah et al.’s study[13] on G. procumbens, indicating that TPC and free radical scavenging activities decreased with increasing extraction temperatures. Also our findings implied that extraction temperatures will have different effects on the bioactive components of identical genus plants, although they may share some uniform constituents. It is generally considered that extraction at a high temperature will lead to a degradation of some bioactive compounds, whereas recently some researches have demonstrated that this is not always true, especially with regard to the polyphenols with antioxidant activity. Increasing the extraction temperature has been found to enhance the recovery of phenolic compounds as described in previous reports.[2526] The mechanism maybe is that increasing extraction temperature promotes solvent extraction by enhancing both diffusion coefficients and the solubility of polyphenol content.[2728] Also, increasing extraction temperature will contribute to the release of bound polyphenols in plants with the breakdown of cellular constituents of plant cells which leads to increased cell membrane permeability. Moreover, release of these bound polyphenols could further reduce the chances of those polyphenols coagulating with lipoprotein. Thereby enhancing solubility of the polyphenols and inhibiting coagulation with lipoprotein will increase polyphenols yield.[29]


Antioxidant activity and free radical-scavenging capacity of Gynura divaricata leaf extracts at different temperatures.

Wan C, Yu Y, Zhou S, Liu W, Tian S, Cao S - Pharmacogn Mag (2011)

Relationship between (a) extraction temperature and total phenolic contents, (b) extraction temperature and total flavonoid contents
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3065156&req=5

Figure 0002: Relationship between (a) extraction temperature and total phenolic contents, (b) extraction temperature and total flavonoid contents
Mentions: The present study was focused on TPC and TFC, in addition to the antioxidant activity of G. divaricata leaf extracts obtained at different temperatures. The influence of extraction temperature on TPC, TFC, and antioxidant activity of the 45% ethanol extracts was investigated. For all the extraction temperatures surveyed, the highest TPC, TFC, and antioxidant activities were observed in the extracts obtained at 100°C followed by extraction at 90°C. Significant lower levels of TPC and TFC were demonstrated by extractions at temperatures below 80°C. The TPC and TFC of extracts have strong positive correlation with the extraction temperature, with the correlation coefficient (R2) 0.9925 and 0.9928, respectively [Figure 2]. The results of the present study also indicate that there was a significant reduction in the total antioxidant activity and free radical-scavenging capacity of the extracts obtained at temperatures below 80°C compared to those extracted at 90°C or 100°C. This was expected due to the elevation the TPC and TFC of extracts at higher temperatures. Our findings are in contrast to Akowuah et al.’s study[13] on G. procumbens, indicating that TPC and free radical scavenging activities decreased with increasing extraction temperatures. Also our findings implied that extraction temperatures will have different effects on the bioactive components of identical genus plants, although they may share some uniform constituents. It is generally considered that extraction at a high temperature will lead to a degradation of some bioactive compounds, whereas recently some researches have demonstrated that this is not always true, especially with regard to the polyphenols with antioxidant activity. Increasing the extraction temperature has been found to enhance the recovery of phenolic compounds as described in previous reports.[2526] The mechanism maybe is that increasing extraction temperature promotes solvent extraction by enhancing both diffusion coefficients and the solubility of polyphenol content.[2728] Also, increasing extraction temperature will contribute to the release of bound polyphenols in plants with the breakdown of cellular constituents of plant cells which leads to increased cell membrane permeability. Moreover, release of these bound polyphenols could further reduce the chances of those polyphenols coagulating with lipoprotein. Thereby enhancing solubility of the polyphenols and inhibiting coagulation with lipoprotein will increase polyphenols yield.[29]

Bottom Line: However, TPC and TFC were not significantly different (P > 0.05) at the extraction temperatures 90°C and 100°C.Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05).The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Food Science & Technology, Nanchang University, Nanchang - 330 047, Jiangxi,, China.

ABSTRACT

Background: Extraction temperature influences the total phenolic content (TPC), total flavonoid content (TFC) of medicinal plant extracts to a great extend. TPC and TFC are the principle activity constituents present in the plant. The effects of extraction temperature on TPC, TFC and free radical-scavenging capacity of Gynura divaricata leaf extracts are worth to study.

Materials and methods: Folin-Ciocalteu and aluminum chloride colorimetric assay were used to determine the TPC and TFC of Gynura divaricata leaf extracts at different temperatures. The antioxidant and free radical-scavenging activity were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and phosphomolybdenum methods.

Results: TPC and TFC were significantly elevated with increasing extraction temperature (from 40°C to 100°C). However, TPC and TFC were not significantly different (P > 0.05) at the extraction temperatures 90°C and 100°C. Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05). The TPCs (13.95-36.68 mg gallic acid equivalent/g dry material) were highly correlated with DPPH (R(2) = 0.9229), ABTS (R(2) = 0.9951) free radical-scavenging capacity, and total antioxidant activity (R(2) = 0.9872) evaluated by phosphomolybdenum method.

Conclusion: The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

No MeSH data available.