Solvent polarity mediates phytochemical yield and antioxidant capacity of Isatis tinctoria

Abdul Wakeel; Sohail Ahmad Jan; Ikram Ullah; Zabta Khan Shinwari; Ming Xu

doi:10.7717/peerj.7857

Solvent polarity mediates phytochemical yield and antioxidant capacity of Isatis tinctoria

PeerJ. 2019 Oct 9:7:e7857. doi: 10.7717/peerj.7857. eCollection 2019.

Authors

Abdul Wakeel^{1

2}, Sohail Ahmad Jan³, Ikram Ullah², Zabta Khan Shinwari², Ming Xu^{1

4}

Affiliations

¹ Key Laboratory of Geospatial Technology for Middle and Lower Yellow River Regions, School of Environment and Planning, Henan University, Kaifeng, Henan, China.
² Molecular Systematics and Applied Ethnobotany Lab (MoSAEL), Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan.
³ Department of Biotechnology, Hazara University, Dodhial, Mansehra, Khyber Pakhtunkhwa, Pakistan.
⁴ Department of Ecology, Evolution and Natural Resources, Rutgers University, New Jersey-Camden, United States of America.

Abstract

Secondary metabolites have been extensively used in the treatment of various health problems. The role of solvent polarity on the phytochemical isolation and antioxidant capacity of Isatis tinctoria (woad) is elusive. In the present study, 14 solvents with different polarity were used in the extraction and total phenolic and flavonoid content (TPC and TFC) investigation. Ferricyanide, phosphomolybdenum, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods were used to calculate and compare the antioxidant/free radical scavenging capacity. Our results showed that solvent polarity greatly affects TPC and TFC yield, which is mainly increasing with increasing solvent polarity index and suddenly decreasing at very high polarity. The comparative results showed that TPC is directly correlated with reducing power, antioxidant, and free radical scavenging capacity. Taken together, we conclude that different woad plant parts contain different level of secondary metabolites with a specific polarity that requires a particular solvent with an appropriate polarity index for the extraction. The identification of these biologically active crude extracts and fractions are very important for the basic biological sciences, pharmaceutical applications, and future research for HPLC based active compounds isolation.

Keywords: Antioxidant activity; Flavonoid content; Isatis tinctoria; Phenolic content; Solvent polarity.

Grants and funding

This work was funded by the National Key Research and Development Program of China (2017YFA0604300, 2018YFA0606500). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.