In vitro anti-oxidant, anti-inflammatory, anti-bacterial, and cytotoxic effects of extracted colorants from two species of dragon fruit (Hylocereus spp.)

Abstract

To evaluate the medicinal value of natural colorants derived from dragon fruit, this research measures the antioxidant, anti-inflammatory, antibacterial, and cytotoxic activities of extracted colorant from two species (Hylocereus polyrhizus and Hylocereus undatus) of dragon fruit at different concentrations. The cold extraction method was used for extraction. Anti-oxidant, anti-inflammatory, antibacterial, and cytotoxic assay were measured using free radical scavenging, denaturation, and hemolytic inhibitory, disk diffusion, liquid microdilution assay, brine shrimp lethality and 3-(4,5-dimethyl-2- thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, respectively. The aqueous extract showed high levels of phytochemicals (phenolics and flavonoids) in contrast to the other two (ethanol and ethyl acetate) extracts. Aqueous extract colorants exhibited better antioxidant and anti-inflammation activity than other two extracts (p<0.05; <0.001). Promising antibacterial activity was observed in a range of concentrations (50–200 mg/mL) of the aqueous extract colorants against tested bacteria; the inhibiting zone ranged from 6.00±0.50 to 8.54±0.23 mm. The both species of dragon fruits extract could inhibit the selected microorganism under study with variable minimal inhibitory concentration (MIC). Lack of cytotoxic activity was evident in the aqueous extract colorant relative to the other (LC50 for the aqueous extracts ranged from 748.78 to 886.63 µg/mL). Subsequently, the aqueous extract colorant from the two dragon fruit species could be an excellent source of color for food additive purposes, and as an ingredient in pharmaceutical medications.