Determination of phenolic substance content and antioxidant capacity of Brassica elongata (Brassicaceae) plants

The Brassicaceae family is among the most widely consumed plant groups worldwide. Due to its various phenolic compounds, research is increasingly focused on their potential pharmacological applications. This study aimed to investigate the total phenolic and flavonoid content and antioxidant properties of methanol extracts obtained from leaf, flower and fruit tissues of Brassica elongata. Four tests were used to test the antioxidant capacity of the extracts, including radical scavenging ability (DPPH), metal ion reduction potential (CUPRAC and FRAP) and total antioxidant capacity (phosphomolybdenum) tests. Furthermore, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was utilized to identify the phenolic compounds present. The findings revealed that leaf extracts exhibited the highest total content of polyphenols and flavonoids, with highest content obtained from leaf (61,4 mg GAE/g extract and 53,2 mg QE/g extract, respectively), flower (31,7 mg GAE/g extract ve and 29,6 mg QE/g extract, respectively), and fruit (21,2 mg GAE/g extract and 44,1 mg QE/g extract). Leaf extract (221,1 mg AAE/g extract) exerted significantly higher total antioxidant activity than those of flower (162,3 mg AAE/g extract) and fruit (165,8 mg AAE/g extract) extracts. Highest DPPH scavenging activity was obtained from flower (58,6 mg TE/g extract) and leaf (56,9 mg TE/g extract) extracts. The highest FRAP values were determined in flower extracts (17,3 mg TE/g extract), followed by fruit (14,8 mg TE/g extract) and leaf extracts (10,9 mg TE/g extract). On the other hand, the highest CUPRAC value was determined in leaf extracts (0,48 mM TE/g extract), while these values were determined as 0,37 mM TE/g extract and 0,33 mM TE/g extract in flower and fruit extracts, respectively. While hyperoside was determined as the most dominant phenolic compound in all tissues, the highest concentration (897,7 g/g extract) was determined in leaf tissues. The current study demonstrated that B. elongata plants possesses significant antioxidant capabilities and could be uesd asa novel natural antioxidant for therapeutic purposes.