Iron 2 sulfate 7 hydrate

Sodium carbonate (Na₂CO₃), Folin–Ciocaltue’s reagent, gallic acid, quercetin, aluminium chloride (AlCl₃), iron (II) sulfate 7-hydrate (FeSO₄·7H₂O), iron (III) chloride 6-hydrate (FeCl₃·6H₂O), acetic acid, 2,2,6-Tri(2-pyridyl)-s-triazine (TPTZ), and hydrochloric acid (HCl) were purchased from Sigma-Aldrich. Only analytical grade of chemicals was used throughout the experiments. Fruits of Hylocereus polyrhizus were obtained from a local farm located in Sepang, Malaysia. Seeds were separated from the pulp and washed under running tap water to remove the mucilage and dried in the laboratory. Dried seeds were ground into smaller particles and kept in air-tight bottles. Subsequently, the seeds were defatted by maceration method using n-hexane as the solvent. The defatted seeds were left overnight in a fume hood to let residual n-hexane evaporates before being used in subsequent polyphenols extraction procedures.

All reagents used were of analytical grade. Folin–Ciocalteu reagent, phenol solution, sodium carbonate (Na₂CO₃), 1,1-diphenyl-2-picrylhydrazyl (DPPH^•), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ATBS), methanol and ethanol (HPLC grade), potassium ferricyanide (K₃[Fe(CN)₆]), potassium persulfate (K₂S₂O₈), potassium hydroxide (KOH), 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), 2,4-dinitrophenylhydrazine (DNPH), guanidine HCl, iron(III) chloride 6-hydrate (FeCl₃^•6H₂O), iron(II) sulfate 7-hydrate (FeSO₄^•7H₂O), acetic acid (CH₃COOH), hydrochloric acid (HCl), sulfuric acid (H₂SO₄), sodium hydroxide (NaOH), aluminum chloride (AlCl₃), glucose, gallic acid, tetramethoxypropane (TMP), butylated hydroxytoluene (BHT), and rutin were purchased from Sigma Chemicals (St. Louis, MO, USA). Pancreatin, lipase enzymes, and Oxgall media were obtained from Merck (Darmstadt, Germany). Trichloroacetic (TCA) and 2-thiobarbituric acid (2-TBA) were supplied by JT Baker (Baker ^®, Phillipsburg, NJ, USA). POP was purchased from Aloha Medicinals, Inc.