Phenolic compounds and antioxidants from Eucalyptus camaldulensis as affected by some extraction conditions, a preparative optimization for GC-MS analysis

Abstract

Four organic solvents along with water were applied for the conventional extraction of Eucalyptus camaldulensis (Myrtaceae), phenolic contents and antioxidant activities were investigated through variable protocols and correlation coefficients were considered, the phenolic composition was also characterized by Gas chromatography-mass spectrometry (GC-MS). Using solvents with dissimilar polarities affected the phenolic yields extracted from E. camaldulensis and their related antioxidant activities varied significantly among the four investigated plant organs. The leaf extract of acetone 70% contained the highest amount of phenolic compounds (46.56 mg/g dry weight); while the bud-water boiled extract maintained the maximum value of tannins (45.68 mg/g dry weight). Correlation coefficients indicated that phenolic compounds were mostly accountable for the phosphomolybednum antioxidant potentials (0.520), followed by tannins (0.460). Also, both the reducing power activities and hydrogen peroxide scavenging of E. camaldulensis extracts positively correlated with tannins, but at different significance degrees. However, the GC-MS analysis revealed that most of the detected phenolic constituents were more abundant in the plant seed. So, the existence of some other compounds such as organic acids, along with phenolics, may have increased the antioxidant potentials of leaf and bud. Undeniably, the optimization of extraction conditions could stimulate the antioxidant capabilities of the plant extracts of E. camaldulensis.

Keywords:

• Antioxidant potentials
• Eucalyptus camaldulensis
• GC-MS analysis
• phenolic compounds
• tannins

Acknowledgments

The authors would like to express their appreciations to Dr. Ragab Amer, Faculty of Engineering, Menoufia University, Egypt for his valuable contributions to the statistical analysis of the obtained data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the National Natural Science Foundation of China [31570010], the Innovation Team of Scientific Research Platform in Anhui Universities, and the Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources.