Tetramethylmurexide

All chemicals used were of analytical grade. Thiobarbituric acid (TBA), trichloroacetic acid (TCA), 1,1,3,3-tetramethoxypropane, Brij-L23, tetramethylmurexide, and L-β-(3,4 dihydroxyphenyl) alanine (L-DOPA) were procured from Sigma Aldrich (St. Louis, MO, USA). Potassium carbonate and copper (II) sulfate were purchased from Thermo Fisher Scientific (Auckland, New Zealand). The microbial media (eosin methylene blue agar (EMB), Pseudomonas isolation agar (PIA), plate count agar (PCA), triple sugar iron agar, and Mueller–Hinton broth (MHB) were acquired from Himedia (Mumbai, India).

ACE enzyme (from rabbit lung), hippuryl-histidyl-leucine (HHL), hippuric acid (HA), captopril, zinc chloride, tetramethylmurexide and hexamine/HCl were purchased from Sigma-Aldrich (Subang Jaya, Selangor, Malaysia). Rosmarinic acid (RA), Sinensetin (SIN), eupatorin (EUP) and 3′-hydroxy-5,6,7,4′-tetramethoxy flavone (TMF) standards were purchased from Indofine (Hillsborough, NJ, USA). Acetonitrile (HPLC grade), formic acid (HPLC grade) methanol (HPLC grade), orthophosphoric acid (HPLC grade), methanol (AR grade), ethanol (AR grade) and ammonium dihydrogen phosphate, monobasic dihydrogenphosphate and dibasic monohydrogen phosphate were obtained from Merck (Petaling Jaya, Selangor, Malaysia). Deionized water for HPLC was prepared using ultra-pure water purifier system (Elgastat, Bucks, UK).