title: Comparative Study of Betacyanin Profile and Antimicrobial Activity of Red Pitahaya (Hylocereus polyrhizus) and Red Spinach (Amaranthus dubius).
abstract: Betacyanins are reddish to violet pigments that can be found in red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius). This study investigated the impact of sub-fractionation (solvent partitioning) on betacyanin content in both plants. Characterization of betacyanins and evaluation of their antimicrobial activities were also carried out. Betanin was found in both plants. In addition, isobetanin, phyllocactin and hylocerenin were found in red pitahaya whereas amaranthine and decarboxy-amaranthine were found in red spinach. Sub-fractionated red pitahaya and red spinach had 23.5 and 121.5 % more betacyanin content, respectively, than those without sub-fractionation. Sub-fractionation increased the betanin and decarboxy-amaranthine content in red pitahaya and red spinach, respectively. The betacyanin fraction from red spinach (minimum inhibitory concentration [MIC] values: 0.78-3.13 mg/mL) demonstrated a better antimicrobial activity profile than that of red pitahaya (MIC values: 3.13-6.25 mg/mL) against nine Gram-positive bacterial strains. Similarly, the red spinach fraction (MIC values: 1.56-3.13 mg/mL) was more active than the red pitahaya fraction (MIC values: 3.13-6.25 mg/mL) against five Gram-negative bacterial strains. This could be because of a higher amount of betacyanin, particularly amaranthine in the red spinach.
authors.affiliation: School of Science, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia.
authors.forename: Yi Yi
authors.initials: YY
authors.lastname: Yong
authors.affiliation: School of Public Health, Curtin University, Kent Street, Bentley, Perth, WA, 6102, Australia.
authors.forename: Gary
authors.initials: G
authors.lastname: Dykes
authors.affiliation: School of Science, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia.
authors.forename: Sui Mae
authors.initials: SM
authors.lastname: Lee
authors.affiliation: School of Science, Monash University Malaysia, 47500, Bandar Sunway, Selangor, Malaysia. choo.wee.sim@monash.edu.
authors.forename: Wee Sim
authors.initials: WS
authors.lastname: Choo
mesh_terms: D027721:Amaranthus / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000032:analysis* / Q000494:pharmacology; D050859:Betacyanins / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology; D029421:Cactaceae / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D050859:Betacyanins; D010936:Plant Extracts; C508223:hylocerenin; C508222:phyllocactin; C020228:betanin
keywords: Antimicrobial activity; Betacyanin; Red pitahaya; Red spinach; Sub-fractionation