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Triterpenoids from the resin of Shorea robusta
Pergamon
Phytahmusrry.
Vol
35. No. 4, pp. 1073-1074. Sacna 0 1994 Elxvrr
1994 Lld
rnntcd~1GUI tuiti. ,411 mu -cd m-9422/%
TRITERPENOIDS
FROM THE RESIN OF
$6.00+0.00
SHOREA ROBUSTA*
Rlu K.HOTA and MARINGANI-IBAPU~~ Regional Research Laboratory, Bhubaneswar-751013, Orissa, India (Received in revised form 23 June 1993)
Key Word Index-Shorea nor-urs-12ene.
robusta; Dipterocarpaceae;
resin; ursane triterpenoids; new 3/?-acetoxy-2%
Abstract-From the resin of Shorea robusta, in addition to three known triterpenoids, a new nor-triterpene 3/?acetoxy-28-nor-urs-12-ene has been isolated. The structure of the new triterpene was established by photochemical conversion and spectroscopic studies.
INTRODUCTION
‘Raal’, the resin of Shoreu robusta Gaertn (Dipterocarpaceae) is abundantly available in India and has been widely used in the indigenous system of medicine as an astringent and an ingredient in ointments for skin diseases, and in ear troubles [l]. Earlier work on this resin reported the isolation of several known triterpenoids [2]. In our previous communication, from sal resin we have reported the occurrence of six more triterpene acids; ursolic acid; 2a,3Bdihydroxy-urs-12-en-28-oic acid; 2z,3a-dihydroxyurs-12en-28-oic acid; 3/?,23-dihydroxy-olean-12cn-28oic acid; 2a,3/?, 23-trihydroxy-urs-12en-28-oic acid; and 2&3B,23-trihydroxy-1 l/?-methoxy-urs-12-en-28-oic acid [3]. We now report the isolation of four more triterpenes; 28-nor-urs- 12-en-3B-ol, 1; ursaldehyde, 4; ursaldehyde acetate, 2; a 3/?-acetoxy-28-nor-urs-12ene, 3, and acetate of 1, hitherto not reported from nature. Of the three known triterpenes, 1 was earlier isolated from the fruit of Symphoricarpus albus and was identified by GC-MS [4].
R' 1 2 3 4
BOH BOAC BOAC BOH
R2 H
R3 H
H
CHO
H H
H CHO
RESULTS AND DWXJS!SION
The chromatographically pure 3 was obtained as an amorphous powder, which responded to the Liebertnann-Burchard test. (EI) mass spectrum (M+454) and elemental analysis support the molecular formula C3,H5002 for the compound. The IR spectrum of 3 showed carbonyl absorption at 1720 cm- 1 and acetate (C-G) at 1240 cm- ‘. The major fragment ion peaks at m/z 250 and m/z 204 in the mass spectrum indicated a typical retro Diels-Alder cleavage of either a- or Bamyrin skeleton, lacking one angular methyl group of ring D or E [S]. The olefinic carbon signals (123.5, C-12, 138.0, C-13) supported the ursane skeleton [6]. The *H NMR spectrum of 3 revealed signals for five tertiary methyls at 60.85,0.91,0.97, 1.10, 1.25 and two secondary *Part 2, for Part 1 see ref. [3]. TAuthor to whom correspondence should be addressed.
mlz 204
AC0
methyls as doublets at 60.89 (5=6 Hz) and 0.91 (J = 6 Hz). The peak observed downfield at 6 1.25 could be readily ascribed to the 27-methyl group [7J The ‘HNMR spectrum of 3 was very similar to that of 2 1073
Short
1074
(ursaldehyde acetate) except for the absence of the aldehyde signal and the presence of a multiplet at 6 1.90 due to the C-18 proton [8]. The signals at 62.08 (3H, s) and 5.18 (1 H, t, J = 3.4 Hz) showed the presence of an acetoxy proton and a vinylic proton, respectively. A one proton dd observed at 64.64 (J = 6 and 10 Hz) could be assigned to the C-3 a-proton. The “C NMR signals of 3 were in good agreement with those of 2 (ursaldehyde acetate), except that the signal due to the C-28 aldehydic carbon is missing in the former. Further, while comparing the 13C NMR spectrum of 3 with that of r-amyrin [9] it clearly showed that the molecule lacked C-28, because the methyl resonance at 627.3 was missing. Interestingly, 2, when kept for six-seven days in diffused sunlight yielded 3 in appreciable quantities (z 15%). When exposed to direct sunlight for 3-4 hr, 2 is partially converted to 3 as confirmed by comparison of spectroscopic data. The spectroscopic and photochemical data thus indicate that 3 is the decarbonylation product of 2. All the data given above support the structure of 3 to be 3p-acetoxy-28-nor-urs-12-ene. The co-occurrence of aamyrin. ursaldehyde, urosolic acid and 28-nor-urs- 12-en3/I-01 in sat resin is parallel to what is reported from the resin of Pistacia lent&us by Marner et al. [IO]. EXPERIMENTAL
Optical rotations were measured in CHCI, at 25” mps are uncorr. ‘H NMR spectra were recorded in CDCI, at 400 MHz. 13C NMR spectrum was recorded in CDCI, at 100 MHz. Chemical shifts are given on the 6 (ppm) scale with TMS as int. standard. MS: 70eV, EI, IR: CHCI,; TLC and CC: silica gel GF,,, (aSC) and silica gel (6C- 120 mesh aSC), respectively. The spots on TLC were visualized by spraying with H,SO, (10% in MeOH) and heating at 120”. Plant material. The resin of S. robusta was collected from the Tribal Development Co-op, Corporation of Orissa in January 1990. The trees in the area have been identified and voucher specimens kept with Dr M. Brahmam, Taxonomist, Aromatic and Medicinal Plant Division, RRL-Bhubaneswar. The seedlings raised are maintained in the experimental gardens of the laboratory. Extraction. The resin (100 g) was extracted with MeOH. The MeOH extract was coned under red. pres. to give a gummy material (63 g) which was extracted with petrol and C,H,, successively. The petrol extract (log) was chromatographed on a silica gel column with petrol-&H, (1: I) and C6H, as eluent, yielding 4 frs a-d. Fr. a showed A at 3525 cm- ‘, indicating the presence of a hydroxyl group, and no ester carbonyl was observed. It resisted purification by normal chromatography, so it was acetylated with Ac,O-pyridine and the acetylated product on prep. TLC afforded a compound (7 mg) whose IR, mass, ‘H, 13CNMR were identical with 3. Thus, the compound was identified as 28-nor-urs-12-en-3/&ol, 1. Prep. TLC of un-acetylated frs b-d afforded 2 (15 mg), 3 (5 mg), 4(20 mg). Compounds 2 (ursaldehyde acetate) and 4 (ursaldehyde) were identified by spectroscopic data (IR,
Reports
‘H NMR, mass, 13C NMR) and comparison with available literature. Ursaldehyde acetate (2). Mp 209-210”. IR v::~‘J cm- I: 1730, 1380, 1370, 1240, ‘HNMR (4OOMHz, CDCI,); SO.75,0.82,0.84,0.94, 1.13 (each s, 3H), 0.85 (d, 5=6 Hz), 0.95 (d, 5=6Hz), 2.10 (s, 3H, Me-CO,), 1.98 (IH, d, ./ =lOHz,H-18),4.62(1H,dd,5=6and lOHz,H-3r),5.20 (lH, t, J=3.3 Hz, H-12). 9.30 (lH, s, H-CO). EIMS (70 eV) m/z (rel. int.), 482 [M]’ (4). 422 (3). 232 (18). 203 (100). 3/I-acetoxy-28-nor-urs- 12-ene (3). Amorphous powder. [a]$‘+31” (CHCI,; c 0.47), (Found: C, 81.49; H, 11.01. C,,H,,O, requires: C, 81.53; H, 11.03%). IR vEF’3 cm-‘: 1720, 1240, ‘HNMR (400 MHq CDCI,); 60.85, 0.91, 0.97, 1.10, 1.25 (each s, 3H), 0.89 (d, 5=6 Hz), 0.91 (d, J =6 Hz), 2.08 (3H, s, Me-CO,), 5.18 (IH, t, J=3.4Hz), 1.90(1H,m),4.64(1H,dd,J=6and10Hz).EIMS(70eV) m/z (rel. int.) 454 [M]’ (lo), 394 (4), 379 (4), 250 (3), 204 (100). 13C NMR (100 MHz, CDCI,); 638.4 (C-l), 23.7 (C2). 78.3 (C-3), 37.8 (C-4), 53.2 (C-5), 18.3 (C-6). 32.4 (C-7), 40.1 (C-8),47.5(C-9),37.1 (C-lo), 17.7(C-ll), 123.5(C-12), 138.O(C-13), 40.9 (C-14), 29.7 (C-15), 27.1 (C-16). 50.2 (C17). 58.0 (C-18), 39.7 (C-19). 39.8 (C-20), 31.3 (C-21), 40.1 (C-22), 27.9 (C-23). 17.1 (C-24), 15.4 (C-25). 16.8 (C-26), 23.1 (C-27), 22.8 (C-29), 22.0 (C-30). Ursaldehyde (4). Amorphous powder. IR vZ’!.‘F~ cm- l: 3520, 2900, 1730, ‘H NMR (400 MHz, CDCl,): 60.74, 0.81,0.84,0.93, 1.13 (each s, 3H),0.85 (d,J=6 Hz), 0.95(d, 5=6 Hz), 1.98 (lH, d, .I= IO Hz), 3.4 (lH, dd, H-3a), 5.34 (lH, t, H-12), 9.3 (lH, s, H-CO). EIMS (70eV) m/z (rel. int.) 440 [M]’ (8), 232 (l5), 203 (100). Acknowledgements-We thank IICT-Hyderbad, RSIC, CDRI, Lucknow, CCMB, Hyderabad, for the spectral facilities; Director, RRL-Bhubaneswar, for providing laboratory facilities and support. One of us (R.K.H.) thanks CSIR for a Senior Research Fellowship. REFERENCES
1. (1972) in The Wealth of India Raw Materials, Vol. 4, p. 313. CSIR Publication, New Delhi. 2. Purushothaman, K. K., Saraswathy, A. and Sasikala, E. (1988) Indian Drugs 26, 146. 3. Hota, Raj. K. and Bapuji, M. (1993) Phytochemistry 32, 466. 4. Merfort, I. and Willuhn, G. (1985) Pharm. Ztg 30, 2467. 5. Budzikiewicz, H., Wilson, J. M. and Djerassi, C. J. (1963) J. Am. Chem. Sot. 85, 3688. 6. Doddrell, D. M., Khong, P. W. and Lewis, K. G. (1974) Tetrahedron Letters 2381. 7. Cheung, H. T. and Williamson, D. G. (1969) Tetrahedron 25, 119. 8. Katai, Masaaki, Terai, Tadamasa and Meguri Haruo (1983) Chem. Pharm. Bull. 31, 1567. 9. Seo, S., Tomita, Y. and Tori, K. (1975) Tetrahedron Letters 7. 10. Marner, F. J., Freyer, A. and Lex, J. (1991) Phytochemistry 30, 3709.
Phytahmusrry.
Vol
35. No. 4, pp. 1073-1074. Sacna 0 1994 Elxvrr
1994 Lld
rnntcd~1GUI tuiti. ,411 mu -cd m-9422/%
TRITERPENOIDS
FROM THE RESIN OF
$6.00+0.00
SHOREA ROBUSTA*
Rlu K.HOTA and MARINGANI-IBAPU~~ Regional Research Laboratory, Bhubaneswar-751013, Orissa, India (Received in revised form 23 June 1993)
Key Word Index-Shorea nor-urs-12ene.
robusta; Dipterocarpaceae;
resin; ursane triterpenoids; new 3/?-acetoxy-2%
Abstract-From the resin of Shorea robusta, in addition to three known triterpenoids, a new nor-triterpene 3/?acetoxy-28-nor-urs-12-ene has been isolated. The structure of the new triterpene was established by photochemical conversion and spectroscopic studies.
INTRODUCTION
‘Raal’, the resin of Shoreu robusta Gaertn (Dipterocarpaceae) is abundantly available in India and has been widely used in the indigenous system of medicine as an astringent and an ingredient in ointments for skin diseases, and in ear troubles [l]. Earlier work on this resin reported the isolation of several known triterpenoids [2]. In our previous communication, from sal resin we have reported the occurrence of six more triterpene acids; ursolic acid; 2a,3Bdihydroxy-urs-12-en-28-oic acid; 2z,3a-dihydroxyurs-12en-28-oic acid; 3/?,23-dihydroxy-olean-12cn-28oic acid; 2a,3/?, 23-trihydroxy-urs-12en-28-oic acid; and 2&3B,23-trihydroxy-1 l/?-methoxy-urs-12-en-28-oic acid [3]. We now report the isolation of four more triterpenes; 28-nor-urs- 12-en-3B-ol, 1; ursaldehyde, 4; ursaldehyde acetate, 2; a 3/?-acetoxy-28-nor-urs-12ene, 3, and acetate of 1, hitherto not reported from nature. Of the three known triterpenes, 1 was earlier isolated from the fruit of Symphoricarpus albus and was identified by GC-MS [4].
R' 1 2 3 4
BOH BOAC BOAC BOH
R2 H
R3 H
H
CHO
H H
H CHO
RESULTS AND DWXJS!SION
The chromatographically pure 3 was obtained as an amorphous powder, which responded to the Liebertnann-Burchard test. (EI) mass spectrum (M+454) and elemental analysis support the molecular formula C3,H5002 for the compound. The IR spectrum of 3 showed carbonyl absorption at 1720 cm- 1 and acetate (C-G) at 1240 cm- ‘. The major fragment ion peaks at m/z 250 and m/z 204 in the mass spectrum indicated a typical retro Diels-Alder cleavage of either a- or Bamyrin skeleton, lacking one angular methyl group of ring D or E [S]. The olefinic carbon signals (123.5, C-12, 138.0, C-13) supported the ursane skeleton [6]. The *H NMR spectrum of 3 revealed signals for five tertiary methyls at 60.85,0.91,0.97, 1.10, 1.25 and two secondary *Part 2, for Part 1 see ref. [3]. TAuthor to whom correspondence should be addressed.
mlz 204
AC0
methyls as doublets at 60.89 (5=6 Hz) and 0.91 (J = 6 Hz). The peak observed downfield at 6 1.25 could be readily ascribed to the 27-methyl group [7J The ‘HNMR spectrum of 3 was very similar to that of 2 1073
Short
1074
(ursaldehyde acetate) except for the absence of the aldehyde signal and the presence of a multiplet at 6 1.90 due to the C-18 proton [8]. The signals at 62.08 (3H, s) and 5.18 (1 H, t, J = 3.4 Hz) showed the presence of an acetoxy proton and a vinylic proton, respectively. A one proton dd observed at 64.64 (J = 6 and 10 Hz) could be assigned to the C-3 a-proton. The “C NMR signals of 3 were in good agreement with those of 2 (ursaldehyde acetate), except that the signal due to the C-28 aldehydic carbon is missing in the former. Further, while comparing the 13C NMR spectrum of 3 with that of r-amyrin [9] it clearly showed that the molecule lacked C-28, because the methyl resonance at 627.3 was missing. Interestingly, 2, when kept for six-seven days in diffused sunlight yielded 3 in appreciable quantities (z 15%). When exposed to direct sunlight for 3-4 hr, 2 is partially converted to 3 as confirmed by comparison of spectroscopic data. The spectroscopic and photochemical data thus indicate that 3 is the decarbonylation product of 2. All the data given above support the structure of 3 to be 3p-acetoxy-28-nor-urs-12-ene. The co-occurrence of aamyrin. ursaldehyde, urosolic acid and 28-nor-urs- 12-en3/I-01 in sat resin is parallel to what is reported from the resin of Pistacia lent&us by Marner et al. [IO]. EXPERIMENTAL
Optical rotations were measured in CHCI, at 25” mps are uncorr. ‘H NMR spectra were recorded in CDCI, at 400 MHz. 13C NMR spectrum was recorded in CDCI, at 100 MHz. Chemical shifts are given on the 6 (ppm) scale with TMS as int. standard. MS: 70eV, EI, IR: CHCI,; TLC and CC: silica gel GF,,, (aSC) and silica gel (6C- 120 mesh aSC), respectively. The spots on TLC were visualized by spraying with H,SO, (10% in MeOH) and heating at 120”. Plant material. The resin of S. robusta was collected from the Tribal Development Co-op, Corporation of Orissa in January 1990. The trees in the area have been identified and voucher specimens kept with Dr M. Brahmam, Taxonomist, Aromatic and Medicinal Plant Division, RRL-Bhubaneswar. The seedlings raised are maintained in the experimental gardens of the laboratory. Extraction. The resin (100 g) was extracted with MeOH. The MeOH extract was coned under red. pres. to give a gummy material (63 g) which was extracted with petrol and C,H,, successively. The petrol extract (log) was chromatographed on a silica gel column with petrol-&H, (1: I) and C6H, as eluent, yielding 4 frs a-d. Fr. a showed A at 3525 cm- ‘, indicating the presence of a hydroxyl group, and no ester carbonyl was observed. It resisted purification by normal chromatography, so it was acetylated with Ac,O-pyridine and the acetylated product on prep. TLC afforded a compound (7 mg) whose IR, mass, ‘H, 13CNMR were identical with 3. Thus, the compound was identified as 28-nor-urs-12-en-3/&ol, 1. Prep. TLC of un-acetylated frs b-d afforded 2 (15 mg), 3 (5 mg), 4(20 mg). Compounds 2 (ursaldehyde acetate) and 4 (ursaldehyde) were identified by spectroscopic data (IR,
Reports
‘H NMR, mass, 13C NMR) and comparison with available literature. Ursaldehyde acetate (2). Mp 209-210”. IR v::~‘J cm- I: 1730, 1380, 1370, 1240, ‘HNMR (4OOMHz, CDCI,); SO.75,0.82,0.84,0.94, 1.13 (each s, 3H), 0.85 (d, 5=6 Hz), 0.95 (d, 5=6Hz), 2.10 (s, 3H, Me-CO,), 1.98 (IH, d, ./ =lOHz,H-18),4.62(1H,dd,5=6and lOHz,H-3r),5.20 (lH, t, J=3.3 Hz, H-12). 9.30 (lH, s, H-CO). EIMS (70 eV) m/z (rel. int.), 482 [M]’ (4). 422 (3). 232 (18). 203 (100). 3/I-acetoxy-28-nor-urs- 12-ene (3). Amorphous powder. [a]$‘+31” (CHCI,; c 0.47), (Found: C, 81.49; H, 11.01. C,,H,,O, requires: C, 81.53; H, 11.03%). IR vEF’3 cm-‘: 1720, 1240, ‘HNMR (400 MHq CDCI,); 60.85, 0.91, 0.97, 1.10, 1.25 (each s, 3H), 0.89 (d, 5=6 Hz), 0.91 (d, J =6 Hz), 2.08 (3H, s, Me-CO,), 5.18 (IH, t, J=3.4Hz), 1.90(1H,m),4.64(1H,dd,J=6and10Hz).EIMS(70eV) m/z (rel. int.) 454 [M]’ (lo), 394 (4), 379 (4), 250 (3), 204 (100). 13C NMR (100 MHz, CDCI,); 638.4 (C-l), 23.7 (C2). 78.3 (C-3), 37.8 (C-4), 53.2 (C-5), 18.3 (C-6). 32.4 (C-7), 40.1 (C-8),47.5(C-9),37.1 (C-lo), 17.7(C-ll), 123.5(C-12), 138.O(C-13), 40.9 (C-14), 29.7 (C-15), 27.1 (C-16). 50.2 (C17). 58.0 (C-18), 39.7 (C-19). 39.8 (C-20), 31.3 (C-21), 40.1 (C-22), 27.9 (C-23). 17.1 (C-24), 15.4 (C-25). 16.8 (C-26), 23.1 (C-27), 22.8 (C-29), 22.0 (C-30). Ursaldehyde (4). Amorphous powder. IR vZ’!.‘F~ cm- l: 3520, 2900, 1730, ‘H NMR (400 MHz, CDCl,): 60.74, 0.81,0.84,0.93, 1.13 (each s, 3H),0.85 (d,J=6 Hz), 0.95(d, 5=6 Hz), 1.98 (lH, d, .I= IO Hz), 3.4 (lH, dd, H-3a), 5.34 (lH, t, H-12), 9.3 (lH, s, H-CO). EIMS (70eV) m/z (rel. int.) 440 [M]’ (8), 232 (l5), 203 (100). Acknowledgements-We thank IICT-Hyderbad, RSIC, CDRI, Lucknow, CCMB, Hyderabad, for the spectral facilities; Director, RRL-Bhubaneswar, for providing laboratory facilities and support. One of us (R.K.H.) thanks CSIR for a Senior Research Fellowship. REFERENCES
1. (1972) in The Wealth of India Raw Materials, Vol. 4, p. 313. CSIR Publication, New Delhi. 2. Purushothaman, K. K., Saraswathy, A. and Sasikala, E. (1988) Indian Drugs 26, 146. 3. Hota, Raj. K. and Bapuji, M. (1993) Phytochemistry 32, 466. 4. Merfort, I. and Willuhn, G. (1985) Pharm. Ztg 30, 2467. 5. Budzikiewicz, H., Wilson, J. M. and Djerassi, C. J. (1963) J. Am. Chem. Sot. 85, 3688. 6. Doddrell, D. M., Khong, P. W. and Lewis, K. G. (1974) Tetrahedron Letters 2381. 7. Cheung, H. T. and Williamson, D. G. (1969) Tetrahedron 25, 119. 8. Katai, Masaaki, Terai, Tadamasa and Meguri Haruo (1983) Chem. Pharm. Bull. 31, 1567. 9. Seo, S., Tomita, Y. and Tori, K. (1975) Tetrahedron Letters 7. 10. Marner, F. J., Freyer, A. and Lex, J. (1991) Phytochemistry 30, 3709.