Send Orders for Reprints to reprints@benthamscience.net The Natural Products Journal, 2014, 4, 43-46 43 Prenylated Flavonoids from Bark of Pithecellobium dulce Shankar D. Katekhaye * and Kirti S. Laddha 1 1 Medicinal Natural Products Research Laboratory, Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Matunga, Mumbai-400019, India Abstract: Prenylated flavonoids such as 3'prenyl-apigenin (1), 2-(4-hydroxy-3,5-bisisoprenyl)-8,8-dimethyl[2,3]pyrano) flavanone (2), 2(8'8'-dimethyl[2,3]pyrano-3,4-dehydro-cyclohexane)flavanone (3) and 2-(3'-isoprenyl)-4-oxocyclohexyl)- 4H-chromene-4,5,7(4aH,6H)-trione (4) were isolated from Pithecellobium dulce. Structures of isolated phytoconstituents were elucidated on the basis of spectroscopic analysis and physicochemical properties. Keywords: Characterization, Pithecellobium dulce, isolation, phytoconstituents, prenylated flavanoid. INTRODUCTION Pithecellobium dulce (Roxb.) Benth. (Leguminoceae) is an evergreen tree, widely distributed in the greater part of India and it is locally called as 'Vilayti chinch. The plant is reported to be used as astringent in dysentery, antidiabetic, antiulcer, larvicide and to cure indigestion and toothache [1- 3]. The leaves are applied as plasters for pain and venereal sores [4]. Fruits of the plant are consumed as food in many parts of India. The phytochemical investigation of heart wood had shown the presence of compounds like β - sitosterol, campesterol, stigmasterol, and α -spinasterol [5-7]. Various classes of chemical constituents are reported from leaves, fruits and seeds of this plant, but very few reports are available on the bark. The baek ark is reported to contain polyphenols and tannins along with other important constituents which contribute to important pharmacological activity of the plant. Therefore considering the pharmacological importance, the plant was selected for further exploration of its phytoconstituents present in the bark. EXPERIMENTAL General Experimental Procedures Melting point was determined using a Fisher Johns melting point apparatus. Ultra-Violet (UV) spectra were run in methanol on a Jasco UV-1575 spectrophotometer. Infra- Red (IR) spectra were recorded on a Shimadzu FT-IR 8400S spectrometer attenuated total reflector as sample applicator. 1 H and 13 C NMR spectra were determined in the indicated solvent on a Bruker AV 300 spectrometer. 1 H and 13 C chemical shifts (δ, ppm) were relative to the solvent signals used as references [DMSO: δC 39.98; δH 2.50]. The *Address correspondence to this author at the Medicinal Natural Products Research Laboratory, Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Matunga, Mumbai-400019; Tel: +919924462079; Fax: +917927450449; E-mail: shankar.katekhaye@gmail.com abbreviations s = singlet, d = doublet, t = triplet, and m = multiplet have been used throughout the presented analytical data. Mass spectra analysis was performed on a Thermo Scientific, LTQ-XL equipped with XCalibur 1.4 software. Silica gel (Merck) was used for column chromatography and silica gel 60 F-254 (Merck) was used for thin layer chromatography (TLC) analysis. High performance liquid chromatography (HPLC) analysis was performed with a Jasco system (Hachioji, Tokyo, Japan), using RP-18 column (5μm, 250×4.6 mm), an intelligent pump (PU-1580, PU-2080), a high-pressure mixer (MX-2080-31), a manual sample injection valve (Rheodyne 7725i), injection volume loop: 20 μL, andmonitoring by UV (UV-1575), and chromatographic data were processed with Borwin software. Plant Material P. dulce wood bark was collected from Mumbai, India in the month of October, 2010. The plant material was authenticated by Dr. G. Iyer, Ramnarain Ruia college, Mumbai. The sample specimen (ICT/2010/NP/06) was deposited in the Institute of Chemical Technology, Mumbai. Preparation of Extract The bark of P. dulce was shade dried and pulverized to powder. Powdered drug material (4 kg) was extracted sequentially with petroleum ether followed by chloroform and ethyl acetate (12 L each) using Soxhlet apparatus for 24 h each. Powder marc was dried each time before subjecting it to extraction with different solvents and all extracts were dried under vacuum to dryness. Isolation and Purification Ethyl acetate extract (100 g) was loaded on silica gel column. The column was packed and eluted with 100% chloroform , gradually increasing the concentration of methanol. Each fraction of 250 mL was collected. Fractions (Fr-A) eluted with 6% methanol were pooled together based on TLC profile. Likewise, fractions (Fr-B) eluted with 10% 2210-3163/14 $58.00+.00 © 2014 Bentham Science Publishers