At-Line LC-QTOF-ESI-MS/MS Fractionation of Impatiens balsamina Linn. Coupled With a Simple DPPH for Rapid Identification and Guided Isolation of Antioxidant.

Introduction: Reactive oxygen species (ROS) and ultraviolet (UV) light are significant factors to impair skin disorders. Impatiens balsamina Linn. (IB), a traditional Chinese and Thai herbal medicine, has long been used to treat skin and nail diseases, potentially due to its radical-scavenging properties. However, specific antioxidant compounds in IB have not been well defined.

Objective: This work aims to rapidly identify, target, and isolate antioxidant biomarkers in IB using at-line LC-ESI-QTOF-(MS/MS) coupled with a simple DPPH assay and comprehensively investigate the antioxidant activities of IB extract and isolated biomarker.

Methodology: Following liquid chromatography (LC), the eluent of IB extract was split into two streams (9:1 ratio). The majority was fractionated for DPPH assay in 96-well plates, whereas 10% underwent chemical identification using ESI-QTOF-MS. Antioxidants in IB were identified, targeted, and promptly isolated through transfer from analytical LC to preparative HPLC. IB and the isolated biomarkers were evaluated for antioxidant effects using various antiradical assays and in suppressing ROS induced by UV in skin cells, keratinocytes, and fibroblasts.

Results: Thirty-one chemical constituents were identified, with four tentatively identified as potent antioxidants. Kaempferol emerged as a potential antioxidant biomarker in IB, exhibiting superior antioxidant activity in various in vitro assays compared with positive controls. Both IB extract and kaempferol effectively reduced UVB-induced ROS in skin cells.

Conclusion: This study represents the first comprehensive identification of antioxidants and chemical constituents in IB, pinpointing kaempferol as a key antioxidant biomarker. Its rapid identification using at-line techniques holds promise for advancing bioactive compound discovery in herbal medicine.