Corresponding Author:
S. B. Kalidhar]
Department of Chemistry, Haryana Agricultural University, Hisar - 125 004, India. E-mail: [email protected]
Date of Submission 22 May 2006
Date of Revision 15 February 2007
Date of Acceptance 30 July 2007
Indian J Pharm Sci, 2007, 69 (4): 576-578  

Abstract

The phytochemical studies on the leaves of Prosopis cineraria resulted in isolation of methyl docosanoate, diisopropyl-9,10-dihydroxyicosane-1,20-dioate, tricosan-1-ol and 7,24-tirucalladien-3-one. While diisopropyl-10,11-dihydroxyicosane-1,20-dioate is a hitherto unreported compound, methyl docosanoate, tricosan-1-ol and 7,24-tirucalladien-3-one are being reported for the first time from P. cineraria . These compounds have been characterized on the basis of spectral and other data.

Prosopis cineraria (L.) Druce (Syn. P. spicigera L.) (fam: Leguminosae, subfam: Mimosaceae) is prickly tree or shrub and commonly found in dry and arid regions of north-western India, southern India, Pakistan, Afghanistan, Iran and Arabia [1]. Leaves and pods are extensively used as fodder for cattle, camels and goats.

Prosopis species have also been extensively used in indigenous system of medicine as folk remedy for various ailments [1,2] like leprosy, dysentery, bronchitis, asthma, leucoderma, piles, muscular tremors and wandering of the mind. It is also known to possess anthelmintic, antibacterial, antifungal, antiviral, anticancer and several other pharmacological properties. Leaf paste of P. cineraria is applied on boils and blisters, including mouth ulcers in livestock and leaf infusion on open sores on the skin [3-6]. The smoke of the leaves is considered good for eye troubles. Jewers et al. have studied the phytochemicals in the leaves of P. cineraria and reported alkaloid namely spicigerine; steroids namely campesterol, cholesterol, sitosterol, stigmasterol; alcohols namely octacosanol and triacontan-1-ol; and alkane hentriacontane [7,8].

The present study undertakes the reinvestigations on the chemical examination of its leaves and we isolated one new ketone along with three known compounds, reported for the first time, from the methanol extract of the plant leaves.

The melting points were determined on Ganson Electrical Melting Point apparatus. 1H NMR spectra were recorded in CDCl3 using tetramethylsilane (TMS) as internal standard on Bruker AC-300F 300 MHz NMR spectrometer and chemical shifts are given in δ (ppm). Pellets were prepared in KBr and IR spectra were recorded on Hitachi 570 infra red spectrophotometer. Mass spectra were recorded on VG-70S 11-250J GC-MS-DS Mass spectrometer.

Three kilograms dried leaves of P. cineraria were obtained from the Landscape Section HAU, Hisar and extracted with hot methanol. Extractives were subjected to column chromatography over silica gel using petroleum ether, benzene, ethyl acetate, methanol and their mixtures in the eluotropic series with increasing polarity. The silica gel (60-120 mesh) column chromatography of methanol extracts afforded four compounds, compound A to D (1, 2, 3 and 4, fig. 1).

Figure

Figure 1: Structures of the four compounds (1-4) isolated from Prosopis cineraria 1. Methyl docosanoate, 2. Diisopropyl-10,11-dihydroxyicosane-1,20-dioate, 3. Tricosan-1-ol and 4. 7,24-Tirucalladien-3-one

Compound A (methyl docosanoate, 1) was obtained from the eluate petroleum ether and it crystallized from methanol as a colourless solid, 11 mg, m. p. 55°, lit. m. p. 54°. IR νmax (KBr) (cm-1): 476, 678, 735, 802, 865, 907, 1094, 1261, 1404, 1462, 1646, 1717, 2361, 2854; 1H NMR (CDCl3, δ) 3.75 (3H, s, –COOMe), 2.49 (2H, br s, –CH3–COO–), 2.03 (2H, m, –CH3– CH3–COO–), 1.26 (36H, br s, 18×–CH3–), 0.89 (3H, t, J 7.0 Hz, –CH3); MS (m/z, relative intensity) 356 (M+ + 2, 1), 326 (1.5), 295 (1.5), 281 (3.8), 197 (4.7), 183 (5.7), 169 (6.4), 155 (7.5), 141 (11.3), 125 (18.9), 111 (41.5), 97 (74.5), 83 (100). A comparison of data of compound A fully agreed with the literature data of methyl docosanoate9 which is being reported for the first time from P. cineraria leaves.

Compound B (diisopropyl-10,11–dihydroxyicosane-1,20-dioate, 2) was obtained on elution with benzenehexane (1:3) and it crystallized from methanol as a white crystalline solid, 20 mg, m. p. 88°; Found C, 68.10; H, 10.90. C26H50O6 Required: C, 68.12; H, 10.91%; IR νmax (KBr) (cm-1): 669, 722, 802, 1027, 1099, 1466, 1724, 2359, 2849, 2919, 3435; 1H NMR (CDCl3, δ) 4.20 – 3.30 (4H, m, 2×–COOCH Me2, 2×–CHOH–), 2.35 (4H, t, J 7.5 Hz, 2×–CH3–COO–), 1.60 (4H, br s, 2×–CH3–CH3–COO–), 1.26 (24H, br s, 12×–CH3–), 0.88 (12H, d, J 7.5 Hz, 2×–CH–(CH3)2); MS (m/z, relative intensity) 458 (M+, 37), 418 (4.5), 387 (7), 372 (6), 298 (4.5), 284 (7.5), 257 (20.5), 241 (7), 227 (9), 213 (16.5), 197 (9), 183 (24), 167 (16.5), 149 (50), 129 (38), 111 (51), 97 (70), 81 (100). The data suggested the compound B to be diisopropyl- 10,11-dihydroxyicosane-1,20-dioate (2). A survey of the literature reveals that this compound has not been reported earlier.

Compound C (tricosan-1-ol, 3) was obtained on elution with benzene-hexane (1:1). It crystallized from methanol as white crystalline solid, 40 mg, m. p. 75°, lit. m. p. 73.5–74.5°. IR νmax (KBr) (cm-1): 724, 1062, 1121, 1467, 2359, 2848, 2919, 3307; 1H NMR (CDCl3, δ) 3.64 (2H, t, J 7.0 Hz, –CH3–OH), 1.54 (2H, br s, –CH3–CH3–OH), 1.26 (40H, br s, 20×–CH3–), 0.86 (3H, t, J 7.0 Hz, –CH3); MS (m/z, relative intensity) 341 (M+. + 1, 6), 290 (9), 279 (11), 256 (14), 213 (11), 178 (60), 161 (33), 149 (64), 111 (41), 97 (65), 81 (100). The data suggested the compound C to be tricosan-1-ol (3). It may be mentioned that M+ (340) was not observed rather M+ + 1 (341) was observed. On comparison, the data of the compound C was found to agree fully with the literature data10 of tricosan-1-ol.

Compound D (7,24-tirucalladien-3-one, 4) was eluted with pure benzene. It crystallized from methanol as a white solid, 10 mg, m. p. 114°, lit. m. p. 115-116°. IR νmax (KBr) (cm-1): 668, 803 , 961, 1058, 1167, 1260, 1374, 1461, 1704, 2357, 2855, 2925; 1H NMR (CDCl3, δ) 5.40–5.00 (2H, m, 2×>C=CH–), 3.54 (2H, m, –CH3–CO–), 1.83 (3H, s, =C(CH3)–CH3), 1.57 (3H, s, =C(CH3)–CH3), 1.30 - 2.40 (20H, m, 8×>CH3 and 2×>CH–), 1.01 (3H, s, –CH3), 0.93 (3H, d, J 6.5 Hz, >CH–CH3), 0.90 (3H, s, –CH3), 0.86 (3H, s, –CH3), 0.82 (3H, s, –CH3), 0.67 (3H, s, –CH3); MS (m/z, relative intensity) 424 (M+, 2.6), 414 (6), 396 (5.3), 381 (5), 329 (5), 303 (5), 279 (11.5), 264 (7), 256 (22), 239 (8), 213 (19), 148 (75), 97 (82), 83 (100). The data suggested the compound D to be 7, 24-tirucalladien-3-one (4). The data of the compound D was found in full agreement with the literature data of 7, 24-tirucalladien-3-one [11].

Acknowledgements

The authors are thankful to the Landscape Section, Haryana Agricultural University, Hisar for providing the plant material and Mr. Avtar Singh, RSIC, Chandigarh for providing 1H NMR spectral data.

References