Optimizing Conditions for Microwave-Assisted Extraction of Polyphenolic Content and Antioxidant Activity of Barleria lupulina Lindl

Noor Wahida Ismail-Suhaimy; Siti Salwa Abd Gani; Uswatun Hasanah Zaidan; Mohd Izuan Effendi Halmi; Paiman Bawon

doi:10.3390/plants10040682

Optimizing Conditions for Microwave-Assisted Extraction of Polyphenolic Content and Antioxidant Activity of Barleria lupulina Lindl

Plants (Basel). 2021 Apr 1;10(4):682. doi: 10.3390/plants10040682.

Authors

Noor Wahida Ismail-Suhaimy¹, Siti Salwa Abd Gani^{1

2}, Uswatun Hasanah Zaidan³, Mohd Izuan Effendi Halmi⁴, Paiman Bawon⁵

Affiliations

¹ Halal Products Research Institute, Universiti Putra Malaysia, Putra Infoport, Serdang 43400, Selangor, Malaysia.
² Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
³ Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
⁴ Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
⁵ Department of Forest Production, Faculty of Forestry, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.

Abstract

Barleria lupulina Lindl. (Acanthaceae) as an ornamental plant has been widely used in folklore medicine due to its abundancy in polyphenolic compounds. The present study examined conditions for optimal extraction of antioxidants from B. lupulina leaf extracts by using the microwave-assisted extraction (MAE) method. The effects of ethanol concentrations, microwave power, and extraction time on total phenolic content (TPC), total flavonoid content (TFC), 1-diphenyl-2-picrylhydrazyl (DPPH), and 2,20-azino-bis (3-ethylbenzothizoline-6-sulfonic acid) (ABTS) were investigated by single-factor experiments. Response surface methodology (RSM) was applied to observe interactions of three independent variables (ethanol concentrations, microwave power, and extraction time) on the dependent variables (TPC, TFC, DPPH, and ABTS) to establish optimal extraction conditions. Quadratic polynomial equations in all experimental models yielded favorably with fitted models with R² and R²_adj of more than 0.90 and a non-significant lack of fit at p > 0.05. The optimal conditions for the extraction of antioxidant activity were established at 80% (v/v) ethanol, 400 W, and 30 s with TPC (238.71 mg gallic acid equivalent (GAE)/g sample), TFC (58.09 mg QE/g sample), DPPH (87.95%), and ABTS (89.56%). Analysis by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) successfully identified four new phenylethanoid glycoside compounds in the species.

Keywords: 1-diphenyl-2-picrylhydrazyl (DPPH); 2,20-azino-bis (3-ethylbenzothizoline-6-sulfonic acid) (ABTS); Barleria lupulina Lindl.; microwave-assisted extraction (MAE); response surface methodology (RSM); total flavonoid content (TFC); total phenolic content (TPC).

Grants and funding

9688800/Geran Putra Berimpak