title: Variation in secondary metabolite production as well as antioxidant and antibacterial activities of Zingiber zerumbet (L.) at different stages of growth.
abstract: BACKGROUND
  Zingiber zerumbet (L.) is a traditional Malaysian folk remedy that contains several interesting bioactive compounds of pharmaceutical quality.
  
  
  METHODS
  Total flavonoids and total phenolics content from the leaf, stem, and rhizome of Z. zerumbet at 3 different growth stages (3, 6, and 9 months) were determined using spectrophotometric methods and individual flavonoid and phenolic compounds were identified using ultra-high performance liquid chromatography method. Chalcone Synthase (CHS) activity was measured using a CHS assay. Antioxidant activities were evaluated by ferric reducing antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. The antibacterial activity was determined against Gram-positive and Gram-negative bacteria using the disc diffusion method.
  
  
  RESULTS
  Highest content of total flavonoid [29.7 mg quercetin equivalents (QE)/g dry material (DM)] and total phenolic (44.8 mg gallic acid equivalents (GAE)/g DM) were detected in the rhizome extracts of 9-month-old plants. As the plant matured from 3 to 9 months, the total flavonoid content (TFC) and total phenolic content (TPC) decreased in the leaf, but increased significantly in the rhizomes. Among the secondary metabolites identified, the most abundant, based on the concentrations, were as follows: flavonoids, catechin > quercetin > rutin > luteolin > myricetin > kaempferol; phenolic acids, gallic acid > ferulic acid > caffeic acid > cinnamic acid. Rhizome extracts from 9-month-old plants demonstrated the highest CHS activity (7.48 nkat/mg protein), followed by the 6-month-old rhizomes (5.79 nkat/mg protein) and 3-month-old leaf (4.76 nkat/mg protein). Nine-month-old rhizomes exhibited the highest DPPH activity (76.42 %), followed by the 6-month-old rhizomes (59.41 %) and 3-month-old leaves (57.82 %), with half maximal inhibitory concentration (IC50) of 55.8, 86.4, and 98.5 μg/mL, respectively, compared to that of α- tocopherol (84.19 %; 44.8 μg/mL) and butylated hydroxytoluene (BHT) (70.25 %; 58.6 μg/mL). The highest FRAP activity was observed in 9-month-old rhizomes, with IC50 of 62.4 μg/mL. Minimal Inhibitory Concentration (MIC) of Z. zerumbet extracts against Gram-positive and Gram-negative bacteria ranged from 30 to >100 µg/mL. Among the bacterial strains examined, Staphylococcus aureus was sensitive to the leaf extract of Z. zerumbet, with MIC of 30.0 μg/mL and other strains were sensitive to the rhizome extracts.
  
  
  CONCLUSIONS
  Three- and 9-month-old plants are recommended when harvesting the leaf and rhizome of Z. zerumbet, respectively, in order to obtain effective pharmaceutical quality of the desired compounds.
authors.affiliation: Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. alighasemzadeh@upm.edu.my.
authors.forename: Ali
authors.initials: A
authors.lastname: Ghasemzadeh
authors.affiliation: Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Hawa Z E
authors.initials: HZ
authors.lastname: Jaafar
authors.affiliation: Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.|Department of Agronomy and Plant Breeding, Shahr-e- Rey Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Sadegh
authors.initials: S
authors.lastname: Ashkani
authors.affiliation: Department of Nutrition & Dietetics, Faculty of Medicine & Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
authors.forename: Asmah
authors.initials: A
authors.lastname: Rahmat
authors.affiliation: Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Abdul Shukor
authors.initials: AS
authors.lastname: Juraimi
authors.affiliation: Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Adam
authors.initials: A
authors.lastname: Puteh
authors.affiliation: Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Mahmud Tengku
authors.initials: MT
authors.lastname: Muda Mohamed
mesh_terms: D000217:Acyltransferases / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D010636:Phenols / Q000032:analysis; D010936:Plant Extracts / Q000494:pharmacology*; D030521:Zingiberaceae / Q000737:chemistry* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D000217:Acyltransferases; C020141:flavanone synthetase
keywords: Antibacterial; Chalcone synthase enzyme; DPPH; FRAP; Flavonoids; Phenolic acids; Zingiber zerumbet (L.)