Determination of gymnemagenin in rat plasma using high-performance liquid chromatography-tandem mass spectrometry: application to pharmacokinetics after oral administration of Gymnema sylvestre extract - Bhagyashree, K; Ankur, G; Dada, P; Laxman, K; Shirish, J; Ismail, M; Basavan, D (Biomed Chromatogr, 2013)