Compounds used in this study were purchased from ChemCruz (UK and USA) and Carbosynth (UK) with purity between 95% and 99%, unless indicated otherwise (Supplementary Table S1). Hydroxythiohomosildenafil (HTHS) (purity >98%) was purchased from Toronto Research Chemicals (Toronto, Canada).
Acetonitrile (Lot No. 1332591) and methanol (Lot. 1328761) (HPLC Supra-Gradient) were purchased from Biosolve, (Valkenswaard, The Netherlands),
acetic acid (Lot. 1.00063) (100%) and
formic acid (Lot. 1.00264) were from Merck (Darmstadt, Germany) and ammonium formate (Lot. 17843) was from Fluka, (Munich, Germany). Sterile syringe filters (0.45 mm cellulose acetate membrane) were purchased from VWR International (North America) and Whatman 0.2 mm pore size Mini-Prep TM PTFE filter media with polypropylene housing (CAT. US203NPUORG) and syringeless filter devices were from G.E Healthcare (Buckingham, UK). Ultra-pure water was prepared using a Milli-Q water purification system (Ref. A þ ). The
PDE-Glo phosphodiesterase assay kit (Promega, CAT No. V1361) was acquired from Fisher Scientific (Madison, WI, USA), Phosphodiesterase 5A1 human recombinant (CAT No. E9034) and
3-isobutyl-1-methylxanthine (IBMX) (CAT No. I5879) were purchased from Sigma-Aldrich (St. Louis, USA) and Coaster 96-well, flat bottom, non-treated, non-sterile white polystyrene assay plates from Corning (New York, USA).
Akuamoa F., Bovee T.F.H., van Dam R., Maro L., Wesseling S., Vervoort J., Rietjens I.M.C.M, & Hoogenboom R.L.A.P. (2022). Identification of phosphodiesterase type-5 (PDE-5) inhibitors in herbal supplements using a tiered approach and associated consumer risk. Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment, 39(6).
