Table 6.

Phenolic content and antioxidant activity for walnut flower extracts (WMFs) and type of extraction method.

Area	Extraction Conditions	TPC (GAE)	TFC	CTC	DPPH	FRAP	TEAC	Ref
Iran	Percolation in methanol (24 h)	71.7 ± 3.2 mg/g extract	61.7 ± 2.7 mg QE/g extract	-	IC50 = 674 ± 27.6 μg/mL	-	-	[17,18]
China	US in methanol (40%, v/v), 50 min at 50 °C for TPC and AA; ethanol (30%, v/v), 1 h at 70 °C in water bath for TFC	24.3 ± 0.5 mg/g dw WMF (in EFS)	21.5 ± 0.4 mg RE/g WMF (in FS)	-	84.3% ± 0.1% inhibition (in EFS)	2.1 ± 0.1/100 g dw WMF (in EFS)	-	[15]
China	US in methanol (40%, v/v), 50 min at 50 °C for TPC and AA; ethanol (30%, v/v), 1 h at 70 °C in water bath for TFC	3.6 mg/100 g fresh WMF; 2.1 mg/100 g dried WMF	3.2 mg RE/100 g fresh WMF; 1.8 mg RE/100 g dried WMF	-	86% for fresh WMF; 78%–79% for dried WMF	3.8/100 g fresh WMF; 2.1–2.2/100 g dried WMF	-	[16]
China	UE in 70% methanol	1350.8 ± 44.6 mg/g	385.0±16.5 mg CE/g	38.3 ± 1.2 mg CE/g	IC50 = 57.3 ± 1.4 μg/mL	IC50 = 56.3 ± 1.5 μg/mL	IC50 = 42.4 ± 1.2 μg/mL	[43]
India	95% methanol (1:6, w/v) for 48 h at 20 °C	129.8 ± 3.1 mg/g dried material	144.6 ± 2.4 QE mg/g dried material	-	IC50 = 66.8 ± 2.1 μg/mL	46.6 ± 4.8 g extract	IC50 = 53.9 ± 6.5 μg/mL	[20]
Italy	MAE, DoE 50% ethanol in water (v/v), for 30 min at 60 °C	3.2 ± 0.5 mg/g fresh WF (one cycle); 5.9 ± 0.2 mg/g fresh WF (3 cycles)	-	-	-	-	-	[40]

AA—antioxidant activity; DoE, design of experiments.