Tetracyclic triterpenoids from the leaves of Azadirachta indica Bina S. Siddiqui * , Farhana Afshan, Tahsin Gulzar, Muddasar Hanif International Center for Chemical Sciences, H.E.J. Research Institute of Chemistry, University of Karachi, Karachi, 75270, Pakistan Received in revised form 30 March 2004 Available online 30 July 2004 Abstract Two new tetracyclic triterpenoids zafaral [24,25,26,27-tetranorapotirucalla-(apoeupha)-6a-methoxy-7a-acetoxy-1,14-dien-3,16- dione-21-al] (1) and meliacinanhydride [24,25,26,27-tetranorapotirucalla-(apoeupha)-6a-hydroxy,11a-methoxy-7a,12a-diacet- oxy,1,14,20(22)-trien-3-one] (2) have been isolated from the methanolic extract of neem leaves along with two known constituents nimocinol and isomeldenin. Their structures and the relative configurations were determined by spectroscopic methods ( 1 H and 13 C NMR, IR, and MS) and 2D NMR experiments. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Azadirachta indica; Meliaceae; Fresh leaves; Triterpenoids; Zafaral; Meliacinanhydride 1. Introduction In view of enormous therapeutic and economical importance (Fujiwara et al., 1982, Okpanyi and Eze- ukwu, 1981. Kraus, 1995) attributed to Azadirachta in- dica (neem), studies undertaken by several groups of workers on its various parts have led to the isolation of a host of new constituents (Lavie et al., 1971, Kraus et al., 1981, Siddiqui et al., 1986, Akhila and Rani, 1999). In continuation of our investigations on the terpenoidal constituents of the leaves of neem (Siddiqui et al., 1999, 2001), two new tetracyclic triterpenoids zafaral (1) and meliacinanhydride (2) along with two known constitu- ents nimocinol and isomeldenin have been isolated from the methanolic leaves extract. Their structures have been elucidated as 24,25,26,27-tetranor apotirucalla-(apoeu- pha)-6a-methoxy-7a-acetoxy-1,14 dien-3,16-dione-21-al (1) and 24,25,26,27-tetranor-apotirucalla-(apoeupha)- 6a-hydroxy,11a-methoxy,7a,12 a-diacetoxy,1,14,20(22)- trien-3-one (2). 2. Results and discussion Zafaral (1) showed the molecular ion peak at m=z 484 in the EIMS and at m=z 484.2795 in the HREIMS, corresponding to the molecular formula C 29 H 40 O 6 re- quiring ten degrees of unsaturation. The IR spectrum showed characteristic absorption bands at 2850 cm 1 (aldehydic C–H stretching), 1735, 1725, 1720, 1680 cm 1 (ester, aldehyde and a,b-unsaturated carbonyl moieties) and 1370 cm 1 (geminal methyls), while the UV spec- trum exhibited maximum at 225.0 nm. The 1 H NMR spectrum (300 MHz, CDCl 3 Table 1) showed a pair of AB doublets at d 7.05 (H-1) and 5.90 (H-2) with cou- pling constant J ¼ 10:2 Hz indicating the presence of 1-en-3-one system (Siddiqui et al., 1984). It was also supported by the 13 C NMR spectral values for C-1, C-2, and C-3 (Table 1) and significant mass fragment a at m=z 137.0919 (C 9 H 13 O) (vide experimental and structure) in the EI-HRMS spectrum. The 1 H NMR spectrum fur- ther showed two doublets at d 5.29 (J ¼ 2:8 Hz) and 2.11 (J ¼ 11:3 Hz) attributable to H-7 and H-5, re- spectively, while a double doublet at d 4.24 (J ¼ 11:3, 2.8 Hz) was due to H-6. Their crossed peaks in the HMQC spectrum appeared at d c 82.0 (C-7), 48.5 (C-5), and 67.5 (C-6). These NMR signals were suggestive of two a-oriented oxygen substituents at C-6 and C-7. * Corresponding author. Tel.: +92-21-9243199; fax: +92-21-9243190. E-mail address: bina@khi.comsats.net.pk (B.S. Siddiqui). 0031-9422/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.phytochem.2004.04.031 Phytochemistry 65 (2004) 2363–2367 PHYTOCHEMISTRY www.elsevier.com/locate/phytochem