Pergamon 0031-9422(94)00793--4 Phytochemistry, Vol. 38, No. 6, pp. 1449-1450, 1995 Copyright © 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0031 9422/95 $9.50 + 0.00 A DITERPENE FROM BIDENS PILOSA MA. CARMELITAA. ZULUETA,* MASARU TADA,~ and CONSOLACIONY. RAGASA Department of Chemistry, De la Salle University, Taft Avenue, Manila, Philippines 1004; tDepartment of Chemistry, School of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, 169 Japan (Received in revisedform 25 August 1994) Key Word lndex--Bidens pilosa; Compositae; diterpene; phytyl heptanoate. Abstract--A new diterpene, phytyl heptanoate, has been isolated from Bidens pilosa, and its structure confirmed by chemical synthesis. INTRODUCTION Bidens pilosa is found in waste places throughout the Philippines. It was investigated because of its wide range of medicinal applications. Its leaves are used as treatment for rheumatism, sore eyes, abdominal troubles, ulcers, swollen glands and toothaches, among others [1]. A number of earlier studies reported the isolation of sterols [2], monoterpenes [3], sesquiterpenes [3], flavones [4], flavonoids [5], glucosides [6] and hydrocarbons [2, 7]. We now report the isolation and identification of a novel diterpene (1) from the same species. RESULTS AND DISCUSSION The non-polar fractions of the chloroform extract of the leaves of B. pilosa afforded stigmasterol, squalene, a mixture of elaidic acid and behenic acid, and a novel diterpene, phytyl heptanoate. The structures of the first four compounds were identified by NMR, IR mass spectra and comparison with spectra obtained from authentic samples. The structure of phytyl heptanoate was elucidated by NMR, IR, mass spectrometry and, finally, synthesis of the compound from phytol and hep- tanoic acid using dicyclohexylcarbodiimide (DCC) as dehydrating agent and dimethylaminopyridine (DMAP) as catalyst [8]. The 1H NMR spectrum of phytyl heptanoate revealed the presence of an olefinic proton at 65.33 (t, d = 7.0 Hz) which was coupled to methylene protons at 64.59 (d, J = 7.0 Hz). On chemical shift grounds, the methylene may be attached to an oxygenated carbon. Possibly the com- pound had an ester functionality (C=O stretch at 1724 cm-1 and C-O-C stretch at 1203 cm-1). A methyl group attached to an olefinic carbon gave rise to a resonance at 61.69. The triplet at 62.01 suggested methyl- ene attached to an olefin, while the triplet at 62.29 and *Author to whom correspondence should be addressed. quintet at 61.62 may be assigned to methylene groups attached ct and fl, respectively, to a carbonyl, which is supported by a strong correlation in COSY. The mass spectrum of phytyl heptanoate revealed a molecular ion peak at ra/z 408. The most characteristic peak was the base peak m/z 278 which could have been generated by a McLafferty rearrangement to a diene and an acid. The acidic part of the molecule had a M, of 130 and a survey of acids with this mass revealed the possibility of heptanoic acid, C7H140 2 and a C6H1203 compound. The latter was ruled out as the NMR and IR spectra do not support the presence of alcohol or ether in the acid. The alcohol portion of the compound has a molecular formula, C2oH39OH. Among the list of alcohols with this formula, which is consistent with the 1H NMR spectral data, is phytol, a diterpene alcohol. Therefore, the peak at m/z 278 may be as shown overleaf. Based on the previously mentioned analysis it can be inferred that the compound is phytyl heptanoate, and to confirm this structure, synthesis work was carried out. Phytyi heptanoate was prepared by esterification of heptanoic acid and phytol catalysed by suiphuric acid which afforded a 2.86% yield. To obtain a higher yield, esterification was again carried out using DCC as dehy- drating agent and DMAP as catalyst which afforded a 64.8% yield. Comparison of the XH NMR, IR and mass spectra of the synthesized phytyl beptanoate and the isolated compound revealed that the two were identical. EXPERIMENTAL Isolation. A series of chromatographic separations was conducted on the first fr. collected with the following solvent systems as eluent: hexane-DCM (5: 1, 10: 1, 2:1). Final separation was accomplished by prep. TLC using hexane-DCM (2: 1) as developing solvent. Phytyl hep- tanoate (4.0 rag), an oil, was obtained. The third fr. obtained from the first column was rechromatographed 1449