LC-QTOF-MS Characterization, Antioxidant Activity, and In Vitro Toxicity of Medicinal Plants from the Tri-Than-Thip Remedy

BACKGROUND: The world population has exhibited increased trust in folk medicine, including Thai folk medicine, for the treatment of various illnesses. However, the comparative antioxidant and cytoprotective activities against oxidative damage of Tri-Than-Thip (Tri-TT), a Thai folk remedy, have not been reported. OBJECTIVES: The purpose of this study was to evaluate the antioxidant capacities of Tri-TT and its herbal constituents, Cassia fistula, Pithecellobium dulce, and Ficus benjamina. METHODS: Extracts were obtained from Tri-TT and its herbal constituents. The free radical scavenging activities, cytotoxicity, ferric-reducing antioxidant power (FRAP), metal chelating activities, total phenolic compound (TPC) contents, and total flavonoid (TF) contents of Tri-TT extract were investigated, and qualitative analysis of the chemical composition of Tri-TT extract was performed by LC-QTOF-MS. RESULTS: Tri-TT extract exhibited remarkable scavenging activities toward DPPH, ABTS, and superoxide anion radicals, with IC(50) values of 0.081 ± 0.00, 0.021 ± 0.00, and 0.205 ± 0.057 mg/mL, respectively. The oxygen radical antioxidant capacity (ORAC) and FRAP values of Tri-TT were 6.499 ± 0.67 μM TE/g extract and 1,919.71 ± 63.14 mM FeSO(4)/mg sample, respectively. P. dulce had the highest scavenging activities and antioxidant capacity followed by C. fistula and F. benjamina. The TPC and TF content of Tri-TT extract were 287.87 mg equivalence/g extract and 225.62 mg catechin equivalent/g extract, respectively. The highest TPC was obtained from P. dulce, and TF content was observed in C. fistula. Using LC-QTOF-MS, a total of 25 compounds were tentatively identified in Tri-TT, including polyphenols such as luteolin, gallic acid, baicalein, apigenin, epicatechin, and ellagic acid. In addition, Tri-TT extract demonstrated nontoxicity (cell viability >90%) to Vero cells at the highest tested concentration of 80 μg/mL. CONCLUSION: This study demonstrated that the Tri-TT remedy is a promising candidate as a natural source of antioxidant activity, suggesting that the polyphenol content of plants may contribute to antioxidant activities.