Pergamon zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Phytochemistry, Vol. 39, No.6, pp. 1399-1402, 1995 Co~wiPhl 0 1995 Elwier Science Ltd Printed -inbr&? Britain. All rights reserved 0031-9422/95 $9.50 + 0.00 zyxwvutsrqpon DITERPENOID LACTONES FROM THE ROOTS OF G YNOCARDIA ODORATA BHIM P. PRADHAN,* SATYAJIT CHAKRABORTY, RAJAT K. GHOSH and ANIMESH Rovt Department of Chemistry, University of North Bengal, P.O. North Bengal University, Darjeeling, India zyxwvutsrqponmlkjihg (Received in revised form 4 January 1995) Key Word Index-Gynocardia odorata; Flacourtiaceae; roots; entkauranoids; diterpenoid lactones; 16a-hydroxy-ent-kauran-19 + 20-olide; ent-kaur-16(17)-en-19 + 20-olide; ent-kaur-15(16)-en-19 -+ 20-olide. Abstract-Three new diterpenoid lactones, odolide iso-odolide and hydroxy odolide, isolated from the roots of Gy nocardia odorata have been characterized as ent-kaur-15(16)-en-19 + 20-olide, ent-kaur-16(17)-en-19 + 20-olide and 16a-hydroxy-ent-kauran-19 + 20-olide on the basis of spectral and chemical analysis. The higher terpenoids isolated were odolactone, trichadenic acid-A and /?-sitosterol. INTRODUCTION The isolation of three triterpenoid lactones [l] from the bark of Gy nocardia odorata [2] have been reported. The structure of odolactone was subsequently revised on the basis of carbon+arbon connectivity 2D NMR studies and this led to the revision of the structures of the series of compounds discussed in a later communication [YJ. We now report on the isolation of three new diterpenoid lactones each with an ent-kaurane skeleton along with odolactone, trichadenic acid-A and fi-sitosterol. RESULTS AND DISCUSSION The neutral part of the benzene extract of the roots of G. odorata was chromatographed over silica gel. The less polar fraction was identified as odolactone (1) [l, 33. Further elution with solvents of increasing polarity af- forded first a mixture of odolide (2a) and iso-odolide (2b) followed by hydroxy odolide (3) and /3-sitosterol. The acidic fraction of the benzene extract yielded trichadenic acid-A(4) [l, 31. The mixture of 2a and b could not be separated by column chromatography and GLC showed the ratio of these two to be components 4: 1. The mixture was cry- stallized from acetone to furnish fine flake-like crystals, C20H2s02, [M]’ m/z 300 mp 131-132”, [a]?, - 72”. The mixture showed a single spot on TLC and gave a yel- low colouration with TNM indicating the presence of double bonds. The IR spectrum showed the presence of a &lactone ring (1725 and 1150 cm- ‘) and an exocyclic (3010, 1640 and 880 cm-‘) along with a trisubstituted (810 cm-‘) double bond. The ‘H NMR spectrum showed a sharp peak at 60.90 for a tertiary methyl, and a doublet *Author to whom correspondence should be addressed. TPresent address: CFTRI, Mysore. at 6 1.71 (J = 1.7 Hz) indicating the presence of a methyl group on an olefinic double bond. An AB quartet centred at 64.1 with J = 11.5 Hz suggested the presence of methyl- ene protons attached to oxygen. Broad singlets at 64.70 and 4.78 had the same appearance and belonged to the methylinic protons and another broad singlet at 6 5.01 was due to an isolated olefinic proton. Irradiation at 65.02 collapsed the doublet at 6 1.71 but did not affect any other signals. Hence the methyl group at 61.71 had to be at- tached to the same olefinic double bond to which the proton at 6 5.02 belonged. The methylene protons at C- 15 appeared as a doublet of a doublet at 62.08 (J = 14 Hz) due to geminal coupling. Integration of the protons sug- gested that the singlet at 60.90 and the AB quartet at 64.1 contained three protons and two protons, respectively, whereas the olefinic protons at 64.70, 4.08 and 5.02 contained protons in the ratio 1: 1: 4 and integrated for 1.5 protons. This confirmed that the compound was a mixture of two isomers as observed on GC. The “CNMR data of the mixture are presented in Table 1. The structures of compounds 2a and b were further confirmed by their synthesis from 3 (see below). Thus, all of the above evidence proved that the mixture was made up of the isomeric lactones 2a and b. The most polar compound, 3, analysed for CZOHSOOJ, [M]’ m/z 318; mp 217-218”; [a]o - 50”. Its IR spectrum showed the presence of a hydroxyl group (3320- 3240 cm-‘) and a Slactone ring (1730 and 1140 cm-‘). The ‘HNMR data showed two tertiary methyls (60.87 and 1.33), one downfield due to the presence of a geminal hydroxyl group at C-16. Doublets centred at 64.05 and 4.21 (J = 14 Hz) accounted for the methylene protons at C-20 which was attached to the lactone oxygen and the doublets of a doublet centred at 62.08 were due to C-15 methylene protons, typical of kauranoids. The “C NMR data (Table 1) showed a triplet at 676.5 due to a methyl- ene carbon bearing the lactone oxygen. Two singlets at 6 174.8 and 79.3 were attributed to the 6-lactone carbonyl