title: Human Cytochrome P450 Enzyme Modulation byGymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS.
abstract: BACKGROUND
  Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported.
  
  
  OBJECTIVE
  To evaluate thein-vitromodulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform andn-hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM.
  
  
  METHODS
  Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values.
  
  
  RESULTS
  GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol >n-hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml).
  
  
  CONCLUSIONS
  The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactionsin vivo.Abbreviations used:GS:Gymnema sylvestre, GSE:Gymnema sylvestreextract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE-n-hexane extract, AE: aqueous extract, ME: methanol extract.
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Bera
authors.initials: B
authors.lastname: Rammohan
authors.affiliation: Dept. of Physiology, Bankura Sammilani Medical College & Hospital, Kenduadihi, Bankura, West Bengal, India.
authors.forename: Karmakar
authors.initials: K
authors.lastname: Samit
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Das
authors.initials: D
authors.lastname: Chinmoy
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Saha
authors.initials: S
authors.lastname: Arup
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Kundu
authors.initials: K
authors.lastname: Amit
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Sarkar
authors.initials: S
authors.lastname: Ratul
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Karmakar
authors.initials: K
authors.lastname: Sanmoy
authors.affiliation: Department of Botany, Hooghly Mohsin College, Chinsurah, Hooghly, West Bengal, India.
authors.forename: Adhikari
authors.initials: A
authors.lastname: Dipan
authors.affiliation: Division of Pharmacology, Dept.of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India.
authors.forename: Sen
authors.initials: S
authors.lastname: Tuhinadri
keywords: CYPs inhibition; Gymnema sylvestre; LC-MS/MS; drug–herb interaction; human liver microsomes