Euphorbia tirucalli is a medicine plant possessing many bioactive properties. This paper focused on phytochemical screening (alkaloid, flavonoid, saponin, tannin, and anthraquinone), quantification of polyphenol and flavonoids, and activating evaluation of antioxidants and antimicrobial properties against Xanthomonas axonopodis of different extracts from Euphorbia tirucalli grown in Binh Thuan, Vietnam. The best activity fraction was used for purification and determining bioactive ingredients. The results showed that the phytochemical study revealed the presence of alkaloids, flavonoids, tannins, and terpenoids in the ethyl acetate fraction. Saponin and anthraquinone did not present in all extracts. The content of polyphenol and flavonoid of Euphorbia tirucalli stem was in the range of 16.65–106.32 mg EqAG/g and 97.97–450.83 μg QE/g. The ethyl acetate fraction showed higher amounts of polyphenol and flavonoids and antimicrobial activity against X. axonopodis than other fractions. The antioxidant (SC50) activity of Euphorbia tirucalli stem was in the range of 12.91 ± 0.70 and 528.33 ± 25.15 μg/mL. At concentrations of 5.0 and 7.5 mg/mL, the diameter of inhibition of the ethyl acetate fraction was 14.33 ± 0.76 mm and 17.87 ± 0.57 mm, respectively. The MIC (minimum inhibitory concentration) was 0.156 mg/mL. Scopoletin, gallic acid, and piperic acid got MICs corresponding to 78, 312, and 312 μg/mL, respectively. Scopoletin, gallic acid, and piperic acid were found in the ethyl acetate fraction of Euphorbia tirucalli and exhibited the treatment of citrus bacteria canker and plant diseases.

Xanthomonas axonopodis pv. citri (X. axonopodis pv. citri) is the cause of canker disease on lime trees that negatively affect plant health and fruit quality. This study focused on the comparison of the extraction yield and antibacterial properties of Euphorbia tirucalli against X. axonopodis pv. citri, phytochemical screening, quantifcation of phenolic and flavonoid contents of the fraction extract. The results showed that the ethyl acetate fraction (EA) (7.5 mg/mL) of E. tirucalli from Dak Nong province had the best activity against bacteria with diameter of inhibition zone determined 15.50 ± 0.50 mm, and the minimum inhibition concentration was 0.312 mg/mL. Alkaloids, flavonoids, tannins, and terpenoids were found in the EA fraction extract of E. tirucalli, whereas saponin did not appear in the extract. The phenolic and flavonoid content was in the range of 14.46 - 98.63 mg GEA/g and 90.34 - 408.86 µg QE/g, respectively. Column chromatography followed Nuclear Magnetic Resonance spectra were performed and the three compounds were identifed as scopoletin, gallic acid, and 3,3’,4’-tri - O - methylellagic acid. This study suggests that the extract from E. tirucalli and the isolated compounds can be used for managing of citrus canker disease.