Bioactive Compounds and Biological Properties of Thunbergia laurifolia Leaf Extract and Its Potential Use as Functional Drink

Abstract

The phytochemical screening including phenolic and flavonoid profiling and antioxidant activity in the aqueous crude extract of Thunbergia laurifolia leaves were evaluated. The crude extract contained phenols, flavonoids, tannins and sterols groups and exhibited the highest in DPPH antioxidant activity. The liquid chromatography-mass spectrometry (LC-MS) analyses indicated the presence of caffeic acid, rosmarinic acid, catechin, rutin, isoquercetin, quercetin and apigenin compounds. The antioxidant enzyme improvement of the crude extract was tested with murine macrophage (RAW264.7), human embryonic kidney cells (HEK293) and human hepatocellular carcinoma (HepG2) as a tested cell model. The crude extract increased catalase (CAT) and glutathione peroxidase (GPx) activities and decreased malondialdehyde (MDA) levels in HEK293 and HepG2 cells. The results indicated that cytotoxicity of the crude extract when treated with those cell lines was quite low (>100 μg/ml). In addition, the crude extract could reduce nitric oxide production in RAW 264.7 cells induced by lipopolysaccharide (LPS) which 50% of inhibitory concentration (IC50) value of the crude extract was 25.74+1.51 μg/ml. Effect of the crude extract on anti-cadmium (Cd) toxicity in RAW264.7, HEK293 and HepG2 were investigated. The experiment was designed as 3 groups; combined, pre- and post-treatments and cell viability were determined with MTT test (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). It was found that the crude extract showed the protective against Cd agent in all cell types and more improved therapeutic efficacy when using combined with a chelating agent (CaNa EDTA). To evaluate the anti-insecticides toxicity (chlorpyrifos, CP, and methomyl, MT), the experiment were tasted in similar ways as Cd toxicity assay. The results indicated that the crude extract provided protection and healing effect on CP and MT insecticides better than using atropine sulfate (AS) standard drug especially in HepG2 and HEK293 cells, respectively. The outcome of this experiment indicated that the aqueous crude extract of T. laurifolia leaves at proper dose could be anti-inflammatory agent by NO inhibition process and improved antioxidant enzymes activity including healing and protection functions against Cd heavy metal, CP and MT insecticides. This results supported the Thai folklore wisdom for using T. laurifolia leaves, however, to be safe for health claims, the clinical trial still needed and more investigated.