title: Crispene A, B, C and D, Four New Clerodane Type Furanoid Diterpenes from Tinospora crispa (L.).
abstract: BACKGROUND
  Tinospora crispa (L.) is used to alleviate the symptoms of diabetes mellitus in folk medicine. It is also used for hypertension and to treat malaria, remedy for diarrhea, and as vermifuge.
  
  
  METHODS
  Stems of T. crispa were collected, sun dried for several days followed by oven dried for 24 h at a considerably low temperature and then ground into coarse powder. The powdered stems were soaked in methanol at room temperature for 14 days with occasional shaking. The extract was collected by filtration, and the solvent was evaporated under reduced pressure in a rotary evaporator to obtain a solid residue which was then subjected to fractionation using the modified Kupchan partitioning method into n-hexane, CCl4, CHCl3 and aqueous soluble fractions. The n-hexane soluble fraction was chromatographed over sephadex (LH-20) and the column was eluted with n-hexane: CH2Cl2:MeOH (2:5:1) followed by CH2Cl2:MeOH (9:1) and MeOH (100%) in order to increase the polarities. The column fractions were then concentrated and subjected to thin layer chromatography screening and the fractions with a satisfactory resolution of compounds were rechromatographed over silica gel to isolate the pure compounds.
  
  
  RESULTS
  Four new furanoid diterpenes of clerodane types, Crispene A, B, C, and D (1-4), including one known furanoid diterpene glucoside, borapetoside E (5), were isolated from the stems of T. crispa. The structures of these compounds were elucidated by means of extensive spectroscopic analysis and by comparison of their spectral data with closely related compounds.
  
  
  CONCLUSIONS
  We have reported four new furanoid diterpenes of clerodane types, including one known furanoid diterpene glucoside. This is the first report of any clerodane diterpene having olefinic bond between C-6 and C-7.
  
  
  CONCLUSIONS
  Crispene A, B, C, and D, four new furanoid diterpenes of clerodane types from Tinospora crispaCrispene C, an unusual furanoid diterpene with olifinic bond between C-6 and C-7First report of Crispene D as a free aglycone, though it was earlier reported as an enzymatic hydrolysis product. Abbreviation used: TLC: Thin layer chromatography, NMR: Nuclear magnetic resonance, COSY: Correlation spectroscopy, NOE: Nuclear overhauser effect, HPLC: High-performance liquid chromatography, ESI-MS: Electrospray ionization mass spectroscopy.
authors.affiliation: Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Farhad
authors.initials: F
authors.lastname: Hossen
authors.affiliation: Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Rubaida
authors.initials: R
authors.lastname: Ahasan
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Mohammad Rashedul
authors.initials: MR
authors.lastname: Haque
authors.affiliation: Department of Clinical Pharmacy and Pharmacology, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Bilkis
authors.initials: B
authors.lastname: Begum
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Choudhury Mahmood
authors.initials: CM
authors.lastname: Hasan
keywords: Clerodane; Crispene; Menispermaceae; Tinospora crispa; furanoid diterpene