A new aromatic ester from the mangrove plant Lumnitzera racemosa willd +

Chemical examination of the Indian-mangrove plant Lumnitzera racemosa Willd has resulted in the isolation of a new aromatic ester besides the known triterpenoids, friedelin, betulin and betulinic acid. The structure of the new compound was established as 3-(4-hydroxyphenyl)- propyl-3 1 -(3,4-dihydroxyphenyl)-propionate by a study of its spectral data.


Introduction
Lumnitzera racemosa Willd (Fam: Combretaceae) is a handsome shrub or a small tree found on the coast of India and on the Andaman and Nicobar Islands.The wood of L. racemosa is used as a fuel for its calorific value and the leaves of the plant are eaten in South Pacific Island during periods of scarcity.The reddish brown bark contains 15-19% tannin while the leaves and wood contain smaller quantities.A fluid obtained from incisions made in the stem was reported to be employed as an external application for the treatment of herpes and itches 1 .Antihypertensive activity has been recently reported for the aqueous acetone extract of the plant 2 .Chemical examination of this plant occurring in various parts of the world was reported to give a large number of compounds, long chain rubber like polyisoprenoid alcohols in leaves 3 , flavonoids and long chain fatty acids 4 and low molecular weight carbohydrates 5 .Chemical examination of the Indian species was reported to give friedelin, β-amyrin, taraxerol, betulin, β-sitosterol and triacontanol 6 .The presence of trace elements was also reported 7 .In our continuing interest on the chemical constituents of Indian mangrove plants [8][9][10][11][12][13][14][15][16][17] we have examined this species collected from the Bhiravapalem Island in the Godavary estuary and the results are reported herein.

Results and Discussion
The air dried and powdered stem of L. racemosa was exhaustively extracted with CH 2 Cl 2 : MeOH (1:1

Experimental Section
General experimental procedures.Melting points were determined on a VEB-analytic Dreader HMK hot plate and are uncorrected.IR spectra were recorded on a Perkin-Elmer-841 IR spectrometer in CHCl 3 solution. 1H NMR spectra were measured on a Bruker Advance DRX 300 and Jeol JNM EX-90 spectrometers. 13C NMR spectra were measured on a Bruker Advance DRX 300 spectrometers at 75 MH z and Jeol JNM EX-90 spectrometer at 22.5 MH z using CDCl 3 as a solvent and tetramethylsilane as an internal reference.Elemental analyses were determined on a Carlo Ebra 1108 instrument.Mass spectra were obtained on a Jeol JMS-300 spectrometer.
Plant material.The stems of Lumnitzera racemosa were collected at the Bhiravapalem Island in the Godavari estuary ( 16 0 58 1 N Latitude and 82 0 15 1 E Longitude) in March 1998.The plant material was identified by Prof. B.KondalaRao Dept of Marine Living Resourses, Andhra University and the voucher specimens of the material have been kept in the museums of Organic chemistry, School of Chemistry, Andhra university and NIO Goa as AU1-166.
Extraction and isolation.The air-dried and powdered stem of Lumnitzera racemosa (4Kg) was exhaustively extracted with CH 2 Cl 2 : MeOH (1:1) (8X8L).Removal of the solvent from the combined CH 2 Cl 2 : MeOH extracts gave a residue (20 g) which was extracted with EtOAc (3 X 500 mL).Removal of the solvent under reduced pressure gave a residue (15 g) which was subjected to column chromatography over a column of silica gel (Acme brand , 100-200 mesh, 400 g) using solvents of increasing polarity from n-hexane through EtOAc.In all, 260 fractions (750 mL) were collected .The fractions showing similar spots were combined and the residues from therein were subjected to chromatography over silica gel or silver nitrate (20%) impregnated silica gel columns to yield four pure compounds as given below.
Fraction I.The residue (800 mg) from the column fractions 95-125 (n-hexane: EtOAc,8.75:1.25)was rechromatographed over a small column of silica gel using n-hexane and ethyl acetate mixtures as eluant to afford pure compound  1 Fraction II.The residue (2 g) from the column fractions 35-60 ( n-hexane : EtOAc, 9.5:5 ) was chromatographed through a small column of silica gel using n-hexane and ethyl acetate as Comparison of the physical and spectral data of 4 with the literature values 19,20 of betulinic acid confirmed the characterization.Alkaline hydrolysis of compound 1.To compound 1 (25 mg) dissolved in methanol (10 ml) was added methanolic KOH (10%, 5 ml) and the mixture refluxed on a steam bath for 1 hour.
The mixture was diluted with water (20 ml) and then extracted into ether.The ether solution after evaporation gave 3-(4-hydroxyphenyl)-1-propanol m.p 52 0 C identical with the literature compound 21 (m.p, 1 HNMR taken on 90MH Z instrument in CDCl 3 with TMS as internal standard).The alkaline aqueous solution from the reaction was acidified with dil H 2 SO 4 and the acid liberated was extracted into ether.The ether solution after evaporation left a residue which on crystallization from chloroform-methanol gave 3,4-dihydroxydihydrocinnamic acid m.p 136-38 0 identical with the literature compound 22 ( m.p, 1 HNMR taken on 90MH Z instrument in CDCl 3 with TMS as internal standard).
). Removal of the solvent from the combined CH 2 Cl 2 : MeOH extracts gave a residue which was extracted with EtOAc.Removal of the ethyl acetate under reduced pressure gave a residue which on repeated chromatographic separations over silica gel columns furnished a new aromatic ester 1, in addtion to the known triterpenoids, friedelin, betulin and betulinic acid.