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Glaucolides and related sesquiterpene lactones from Vernonia incana
Phytochemistrj, Vol29.No I.pp 313315, 1990 Prmted m Great Brltdln
GLAUCOLIDES
AND RELATED SESQUITERPENE FROM VERNONIA INCANA
ALICIA BARD~N,C&AR btltuto
dk @uhca
0031-9422/90 $300+0.00 Q 1989Pergamon Press plc
LACTONES
A N CATALAN, ALICIA B.GUTIBRREZ* and WERNER
(%ga’mca, l%cultad.dk ISoqmmtca, Qmmtca Argentma, *Department of Chemistry,
y Farmacta,
4000S M de Tucumin,
The Florlda
HERZ*
Untverstdad’ Ngctonaide hcum;in,
State Umverslty,
Tallahassee,
Ayacucho
4Yi,
FL 32306, U S.A
(Received 4 May 1989) Key Word Index--Vernonm
Abstract-Chemtcai
new glaucolide
rncuna, Composltae,
Vernomeae,
of Vhwm~a zncana resulted-m isolation as well as common plant constituents.
mvestigatlon
precursors
glaucohdes,
sesqmterpene
ofglaucohdti
lactones
A, two ester analogues
and-two
INTRODUCTION In continuation of our work on Argentine Vernonia species [l-4] we have studied a collection of V. incana Less, a species found m southern Brazil, Paraguay, Uruguay and northern Argentina. Previous work on the species is limited to a mention that glaucohde A (la) [S] was detected m a sample from Argentina [S]. Our own work on a collection of V. mcana from near TucumPn resulted in the isolation from the aerial parts of glaucohde A, its analogues lb and lc and two dlepoxides 2a and b Other substances identified m the extract were lupeol, taraxerol, a- and fl-amyrm, germamcol, stlgmasterol, pand y-sltosterol
OAc
la b c d
RESULTSANDDISCUSSION Like la and other la&ones of this type, the NMR spectra of lb and c m deuterated chloroform at room temperature exhibited broad signals due to conformational equilibrium, hence measurements including spin decoupling were carried out at elevated temperature (Tables 1 and 2). Comparison with the ‘H and 13C NMR spectra of glaucohde A and the mass spectra clearly established the gross structure and the relative stereochemistry as (4R *, 8S*, 5R *, 6s *, 10R *). For comparison 13C NMR spectra of la and d the previously unreported (glaucohde B) are also listed in Table 2 We have prevlously identified lc as a contaminant m a fraction containing mainly la from Vernoma squamulosa [2]. It has also been mentioned as a constituent of V. lettermanit Engelm. ex Gray x V.fusc~ulata but was not described further [7] Lactone 2a is a new analogue of lactones 2&e previously isolated from several Vernonra species [ 1,3,8] as shown by the ‘H and 13C NMR spectra (Tables 1 and 2)
R=MeAcr R=Sen R=Ang R=Ac
OAc
2a b c d e
R=Sen R=iBu R=Ac R=MeAcr R=Ang
graph with RI detector and Rheodyne injector with 5 ml loop were used The column employed was ALLTECH R Sil Cl8 (10 p, 10 mm mner diameter x 50 cm) Retention times were measured from the solvent peak Plantmated Aenai~parts of ~ernonih mcana L. were coilected at the flowermg stage m January 1987 m Bella Vista.
EXPERIMENTAL General For separation of mixtures Waters HPLC equipment (M45 pump, U6K Injector with 2 ml loop and R-4Ul dlfirentlai refractometer) and a KONIK KNC-500-A hqmd chromato113
Short Report\ -I able
1 ‘H NMR spectra
of compounds
la*
lb*
11 5 5)
2 95 2 4x 2 48 _ I 70 2 73
and Za (270 MHz
CDCI,)
IC
-
-
2 93 rldd (17, 2 so m 2 so 111 _ 1 70 2 74 d (9 5) ,189 d (9 5) 493ii(?5) 2X2cfd(l~S,7S) ?Jlhrt/(l55)
la-c
______
2 80 m
ddtl rn w,
230m 2 30 ,?I 1 70 ,,, 2 75 111
d
490d
495d
4 86 tl 2 76 (id 273 hrd
4 Pi m
490 dd (13.1)
4 90 d
4 87 hrd (13)
483 dd (13 1)
484d
3 XI hrd (13)
167 5
161,
1 hl
161,
159 ';
(95)
2 7 ,H 7 30 ,,I
\ 167 ,
566qy(l) h Ihhl I (I).56Y hrr (1) 196q (1)
2 16 d (1) 194d(l)
*Run
at 57
Flntensllsthree protons
Table
2
la. b, d and 2a (67 X9 MHz, CDCI,
‘%I NMR Tpectra of compounds
c
la
_-
20707 hrc 33331t 3248
r
61 03, S939d
x 9
10 11 12 I? 14 --OAc
Xl 10d 16278s 64 54 d 41 90 hr tt X447 hi 5 1159x \ I 60 44 , 55 2x t 19 08 qt 190Xqf
> j ‘0 80 yi 20 50qt
170 57 16990
166301
2’ 3' 4' 5'
* Multlphcltles t Assgnments $ Assignment\
135 17 ( 12723r 1780yT
lb
___--
Id
2a
-
207 15 hr F 33 35 t 3249 t 61 05 5 59 53 i/t Xl 15d 163 56 s 63 24 d+ 41 x9 hi t x4 53 tw ', 125665
169.00 5533r: 1899 qf 1x99 i/t 17083 5 16996 v 20 83 yi_ 20 51 qt
206 X9 h, s 3303
r
32 X7 I 6124s 5X 96 d X0 96 d 167547 63 96 d 40 35 hrt X488hrF 12.5 41 s 16964 \ 5s 24 r-l lX9Ul) IX 90 y 17073 \ 170 14 \ 17006 s 20 93 I, 70 82 y 20 2x q
165 18 ,s 11399d 161 01 \ 20 51 q+ 27 41 q
estnbhshed by DEPT pulse sequence by heteronuclear decoupling may be mterchanged
57 )*
Short Reports Tucuman Provmce, Argentina. A voucher specimen (C.A.N. Catalan No 26) 1s deposited at the Instltuto Miguel Llllo, Tucuman Extractton ofV mcana Flowerheads and leaves (1 1 kg) were extracted with CHCI, (2 x 15 1) at room temp for 7 days to give 108 5 g of crude extract which was suspended m 930 ml of EtOH at 5t&55”, diluted with 700 ml of H,O and extracted successively with hexane (3 x 1 1) and CHCl, (3 x 1 1) Evapn of the hexane extract gave 52 g of residue. A portion (12 g) of the residue from the hexane extract was sapomtied with dd. KOH The unsaponifiable material (8 g) was chromatographed on silica gel usmg hexane and increasmg amounts of Et,0 (lCrSO%) to give 1.3 g of tnterpenes and 31 mg of sterols Reverse phase HPLC of a portlon (50 mg) of the trlterpene fraction (MeOH), flow rate 2 5 ml/mm) gave several peaks which were purified further by HPLC using MeCN-EtOAc (3.1) at 4 5 ml/mm to yield 10 mg of crystalline lupeol, 2 2 mg of crystallme taraxerol, 5 5 mg of Bamyrm, 5 mg of a mixture contammg mainly a-amynn and 4 4 mg of crystalline shghtly contammated germamcol. The sterol fraction separated as descrtbed for the pentacychc tnterpenes gave 4 mg of crystalline stigmasterol, 1 mg of crystalline Bsltosterol and 1 mg of y-sltosterol Evapn of the CHCl, extract furmshed a residue (34 g) a portion of which was chromatographed on silica gel using CHCl, and mcreasmg amounts of Et,0 (o-60%), 57 fractions being collected and monitored by TLC. Fractions 4-7 (900 mg) rechromatographed on silica gel (n-hexane-EtOAc, 2: 1) followed by HPLC (MeOH-H,O, flow rate 2.5 ml/mm) afforded 4 1 mg of Impure (R, 28 mm) and 11 mg of pure la (R, 28.5 min) Frs 8&22 (1 8 g) were rechromatographed by CC over silica gel packed m CHCl, with mcreasmg amounts of Et,0 (10-50X) These fractions decomposed extenstvely during work-up but final punficatlon by HPLC (MeOH-H,O 3 2 at 3 ml/mm) gave 4 5 mg of 2b (R, 19 mm) MeOH-H,O 10.7 at 20 ml/mm gave 12 4 mg 2a (R, 51 mm), 15 3 mg la (R, 60 mm) and 2 3 mg la (R, 67 5 mm) MeOH-H,O 10 7 at 3.2 ml/min gave 28.3 mg of 2b (R, 50.5 mm) and 3 mg of lc (R, 55 mm) which decomposed on standing before the 13CNMR spectrum could be run (4R*, 5R*, 6S*, 8S*, lOR*)-1-Oxo-4,5-epoxy-8-senecloyloxy10,13-dracetoxygermacr-7(1 l)-en-6,12-oItde (lb) Gum; IR v~~;crn-’ 1765, 1730 br, 1640, 1440, 1375, 1230 ‘H and 13CNMR m Tables 1 and 2 PCIMS m/z (rel. mt ) 479 ([C,,H,,O,,+H] +, 71 l), 419 (34 8), 379 (29 3), 359 (19 4), 321 (16 8), 277 (167), 261 (40 l), 259 (39 8), 101 (lOO), 83 (267);
315
EIMS m/z (rel mt.) 216 (6 7), 188 (6.7), 164 (19 0), 122 (17 l), 99 (10 4), 83 (lOO), 55 (8 4). (4R,5R*,6S*,8S*,10R*)-l-Oxo-4,5-epoxy-8-angef~~oxy-lO,l3dracetoxy-germacr-7(1 l)-en-6, lbollde (lc) Gum, ‘H NMR spectrum in Table 1, PCIMS (rel mt ) 479 ([C,,H,,O,,+H]+, 51 5), 419 (76.2), 377 (40.0), 359 (720), 321 (16 5), 319 (25 8) 277 (37 2), 261 (53.7), 259 (100) (55 2), EIMS (rel. mt ) 276 (8 6), 259 (7 l), 234 (15 l), 216 (10 6), 188 (10.4), 164 (24 3), 153 (6 3), 141 (7 8), 122 (29 5), 113 (7.1), 99 (22 8), 83 (100) (lR*,4R*,5R*,6S*,8S*,lOR*)-1(10),4,5-D~epoxy-8-senec~oyloxy13-acetoxygermacr 7(1 l)-en-6,12-olzde (2a) Gum, IR v!$i cm-’ 1760-1715 (very broad), 1640, 1440, 1380, 1225. ‘H 13CNMR spectra m Tables 1 and 2 PCIMS (rel mt ) 421 ([C,,H,,O, +H]+, IOO), 361 (46), 321 (15 1). 261 (12 l), 223 (76), 177 (24), 101(34.2), 83 (8 9), EIMS (ret. mt ) 260 (5 1). 231 (6 l), 218 (5 4), 189 (9.4). 175 (6 2), 161 (8 4), 149 (7 3), 122 (7 2), 107 (6 7), 97 (15 9), 83 (100). 55 (29 1)
Acknowledgements-Work m TucumHn was supported by grants from CONICET and ConseJo de Investigaciones de la Umverstdad de Tucumin
REFERENCES
4. 5
6 7. 8.
CatalBn, C A N , Legname, P , Cnst, B. V and de Igleslas, D I A (1985) Phytochemlstry 24, 2113 CatalLn, C A N, de Igleslas, D I A, Kavka, J., Sosa, V. E. and Herz, W (1986) J Nat. Prod. 49, 351 CatalAn, C A. N., de Igleslas, D I. A, Kavka, J., Sosa, V. E. and Herz, W. (1988) Phytochemtstry 27, 197. Bardbn, A, CatalBn, C. A. N, Gutttrrez, A B and Herz, W (1988) Phytochemlstry 27, 2989 Padolma, W G, Yoshloka, H., Nakatani, N., Mabry, T. J., Mont], S A, Davis, R. E, Cox, P J , Slm, G A, Watson, W H. and Wu, I B (1974) Tetrahedron 30, 1161. Mabry, T J , Abdel-Baset, Z H , Padohna, W G and Jones, S B (1975) Bzochem Syst Eco/ 2, 185. Jakupovq J, Zdero, C , Boeker, R., Warmng, V., Bohlmann, F and Jones, S B. (1987) Lteblgs Ann 111 Jakupovtc, J., Schmedta-Hlrschmann, G., Schuster, A., Zdero, C., Bohlman, F , King, R M , Robinson, H. and Rckardt, J. (1986) Phytochemlstry 25, 145
GLAUCOLIDES
AND RELATED SESQUITERPENE FROM VERNONIA INCANA
ALICIA BARD~N,C&AR btltuto
dk @uhca
0031-9422/90 $300+0.00 Q 1989Pergamon Press plc
LACTONES
A N CATALAN, ALICIA B.GUTIBRREZ* and WERNER
(%ga’mca, l%cultad.dk ISoqmmtca, Qmmtca Argentma, *Department of Chemistry,
y Farmacta,
4000S M de Tucumin,
The Florlda
HERZ*
Untverstdad’ Ngctonaide hcum;in,
State Umverslty,
Tallahassee,
Ayacucho
4Yi,
FL 32306, U S.A
(Received 4 May 1989) Key Word Index--Vernonm
Abstract-Chemtcai
new glaucolide
rncuna, Composltae,
Vernomeae,
of Vhwm~a zncana resulted-m isolation as well as common plant constituents.
mvestigatlon
precursors
glaucohdes,
sesqmterpene
ofglaucohdti
lactones
A, two ester analogues
and-two
INTRODUCTION In continuation of our work on Argentine Vernonia species [l-4] we have studied a collection of V. incana Less, a species found m southern Brazil, Paraguay, Uruguay and northern Argentina. Previous work on the species is limited to a mention that glaucohde A (la) [S] was detected m a sample from Argentina [S]. Our own work on a collection of V. mcana from near TucumPn resulted in the isolation from the aerial parts of glaucohde A, its analogues lb and lc and two dlepoxides 2a and b Other substances identified m the extract were lupeol, taraxerol, a- and fl-amyrm, germamcol, stlgmasterol, pand y-sltosterol
OAc
la b c d
RESULTSANDDISCUSSION Like la and other la&ones of this type, the NMR spectra of lb and c m deuterated chloroform at room temperature exhibited broad signals due to conformational equilibrium, hence measurements including spin decoupling were carried out at elevated temperature (Tables 1 and 2). Comparison with the ‘H and 13C NMR spectra of glaucohde A and the mass spectra clearly established the gross structure and the relative stereochemistry as (4R *, 8S*, 5R *, 6s *, 10R *). For comparison 13C NMR spectra of la and d the previously unreported (glaucohde B) are also listed in Table 2 We have prevlously identified lc as a contaminant m a fraction containing mainly la from Vernoma squamulosa [2]. It has also been mentioned as a constituent of V. lettermanit Engelm. ex Gray x V.fusc~ulata but was not described further [7] Lactone 2a is a new analogue of lactones 2&e previously isolated from several Vernonra species [ 1,3,8] as shown by the ‘H and 13C NMR spectra (Tables 1 and 2)
R=MeAcr R=Sen R=Ang R=Ac
OAc
2a b c d e
R=Sen R=iBu R=Ac R=MeAcr R=Ang
graph with RI detector and Rheodyne injector with 5 ml loop were used The column employed was ALLTECH R Sil Cl8 (10 p, 10 mm mner diameter x 50 cm) Retention times were measured from the solvent peak Plantmated Aenai~parts of ~ernonih mcana L. were coilected at the flowermg stage m January 1987 m Bella Vista.
EXPERIMENTAL General For separation of mixtures Waters HPLC equipment (M45 pump, U6K Injector with 2 ml loop and R-4Ul dlfirentlai refractometer) and a KONIK KNC-500-A hqmd chromato113
Short Report\ -I able
1 ‘H NMR spectra
of compounds
la*
lb*
11 5 5)
2 95 2 4x 2 48 _ I 70 2 73
and Za (270 MHz
CDCI,)
IC
-
-
2 93 rldd (17, 2 so m 2 so 111 _ 1 70 2 74 d (9 5) ,189 d (9 5) 493ii(?5) 2X2cfd(l~S,7S) ?Jlhrt/(l55)
la-c
______
2 80 m
ddtl rn w,
230m 2 30 ,?I 1 70 ,,, 2 75 111
d
490d
495d
4 86 tl 2 76 (id 273 hrd
4 Pi m
490 dd (13.1)
4 90 d
4 87 hrd (13)
483 dd (13 1)
484d
3 XI hrd (13)
167 5
161,
1 hl
161,
159 ';
(95)
2 7 ,H 7 30 ,,I
\ 167 ,
566qy(l) h Ihhl I (I).56Y hrr (1) 196q (1)
2 16 d (1) 194d(l)
*Run
at 57
Flntensllsthree protons
Table
2
la. b, d and 2a (67 X9 MHz, CDCI,
‘%I NMR Tpectra of compounds
c
la
_-
20707 hrc 33331t 3248
r
61 03, S939d
x 9
10 11 12 I? 14 --OAc
Xl 10d 16278s 64 54 d 41 90 hr tt X447 hi 5 1159x \ I 60 44 , 55 2x t 19 08 qt 190Xqf
> j ‘0 80 yi 20 50qt
170 57 16990
166301
2’ 3' 4' 5'
* Multlphcltles t Assgnments $ Assignment\
135 17 ( 12723r 1780yT
lb
___--
Id
2a
-
207 15 hr F 33 35 t 3249 t 61 05 5 59 53 i/t Xl 15d 163 56 s 63 24 d+ 41 x9 hi t x4 53 tw ', 125665
169.00 5533r: 1899 qf 1x99 i/t 17083 5 16996 v 20 83 yi_ 20 51 qt
206 X9 h, s 3303
r
32 X7 I 6124s 5X 96 d X0 96 d 167547 63 96 d 40 35 hrt X488hrF 12.5 41 s 16964 \ 5s 24 r-l lX9Ul) IX 90 y 17073 \ 170 14 \ 17006 s 20 93 I, 70 82 y 20 2x q
165 18 ,s 11399d 161 01 \ 20 51 q+ 27 41 q
estnbhshed by DEPT pulse sequence by heteronuclear decoupling may be mterchanged
57 )*
Short Reports Tucuman Provmce, Argentina. A voucher specimen (C.A.N. Catalan No 26) 1s deposited at the Instltuto Miguel Llllo, Tucuman Extractton ofV mcana Flowerheads and leaves (1 1 kg) were extracted with CHCI, (2 x 15 1) at room temp for 7 days to give 108 5 g of crude extract which was suspended m 930 ml of EtOH at 5t&55”, diluted with 700 ml of H,O and extracted successively with hexane (3 x 1 1) and CHCl, (3 x 1 1) Evapn of the hexane extract gave 52 g of residue. A portion (12 g) of the residue from the hexane extract was sapomtied with dd. KOH The unsaponifiable material (8 g) was chromatographed on silica gel usmg hexane and increasmg amounts of Et,0 (lCrSO%) to give 1.3 g of tnterpenes and 31 mg of sterols Reverse phase HPLC of a portlon (50 mg) of the trlterpene fraction (MeOH), flow rate 2 5 ml/mm) gave several peaks which were purified further by HPLC using MeCN-EtOAc (3.1) at 4 5 ml/mm to yield 10 mg of crystalline lupeol, 2 2 mg of crystallme taraxerol, 5 5 mg of Bamyrm, 5 mg of a mixture contammg mainly a-amynn and 4 4 mg of crystalline shghtly contammated germamcol. The sterol fraction separated as descrtbed for the pentacychc tnterpenes gave 4 mg of crystalline stigmasterol, 1 mg of crystalline Bsltosterol and 1 mg of y-sltosterol Evapn of the CHCl, extract furmshed a residue (34 g) a portion of which was chromatographed on silica gel using CHCl, and mcreasmg amounts of Et,0 (o-60%), 57 fractions being collected and monitored by TLC. Fractions 4-7 (900 mg) rechromatographed on silica gel (n-hexane-EtOAc, 2: 1) followed by HPLC (MeOH-H,O, flow rate 2.5 ml/mm) afforded 4 1 mg of Impure (R, 28 mm) and 11 mg of pure la (R, 28.5 min) Frs 8&22 (1 8 g) were rechromatographed by CC over silica gel packed m CHCl, with mcreasmg amounts of Et,0 (10-50X) These fractions decomposed extenstvely during work-up but final punficatlon by HPLC (MeOH-H,O 3 2 at 3 ml/mm) gave 4 5 mg of 2b (R, 19 mm) MeOH-H,O 10.7 at 20 ml/mm gave 12 4 mg 2a (R, 51 mm), 15 3 mg la (R, 60 mm) and 2 3 mg la (R, 67 5 mm) MeOH-H,O 10 7 at 3.2 ml/min gave 28.3 mg of 2b (R, 50.5 mm) and 3 mg of lc (R, 55 mm) which decomposed on standing before the 13CNMR spectrum could be run (4R*, 5R*, 6S*, 8S*, lOR*)-1-Oxo-4,5-epoxy-8-senecloyloxy10,13-dracetoxygermacr-7(1 l)-en-6,12-oItde (lb) Gum; IR v~~;crn-’ 1765, 1730 br, 1640, 1440, 1375, 1230 ‘H and 13CNMR m Tables 1 and 2 PCIMS m/z (rel. mt ) 479 ([C,,H,,O,,+H] +, 71 l), 419 (34 8), 379 (29 3), 359 (19 4), 321 (16 8), 277 (167), 261 (40 l), 259 (39 8), 101 (lOO), 83 (267);
315
EIMS m/z (rel mt.) 216 (6 7), 188 (6.7), 164 (19 0), 122 (17 l), 99 (10 4), 83 (lOO), 55 (8 4). (4R,5R*,6S*,8S*,10R*)-l-Oxo-4,5-epoxy-8-angef~~oxy-lO,l3dracetoxy-germacr-7(1 l)-en-6, lbollde (lc) Gum, ‘H NMR spectrum in Table 1, PCIMS (rel mt ) 479 ([C,,H,,O,,+H]+, 51 5), 419 (76.2), 377 (40.0), 359 (720), 321 (16 5), 319 (25 8) 277 (37 2), 261 (53.7), 259 (100) (55 2), EIMS (rel. mt ) 276 (8 6), 259 (7 l), 234 (15 l), 216 (10 6), 188 (10.4), 164 (24 3), 153 (6 3), 141 (7 8), 122 (29 5), 113 (7.1), 99 (22 8), 83 (100) (lR*,4R*,5R*,6S*,8S*,lOR*)-1(10),4,5-D~epoxy-8-senec~oyloxy13-acetoxygermacr 7(1 l)-en-6,12-olzde (2a) Gum, IR v!$i cm-’ 1760-1715 (very broad), 1640, 1440, 1380, 1225. ‘H 13CNMR spectra m Tables 1 and 2 PCIMS (rel mt ) 421 ([C,,H,,O, +H]+, IOO), 361 (46), 321 (15 1). 261 (12 l), 223 (76), 177 (24), 101(34.2), 83 (8 9), EIMS (ret. mt ) 260 (5 1). 231 (6 l), 218 (5 4), 189 (9.4). 175 (6 2), 161 (8 4), 149 (7 3), 122 (7 2), 107 (6 7), 97 (15 9), 83 (100). 55 (29 1)
Acknowledgements-Work m TucumHn was supported by grants from CONICET and ConseJo de Investigaciones de la Umverstdad de Tucumin
REFERENCES
4. 5
6 7. 8.
CatalBn, C A N , Legname, P , Cnst, B. V and de Igleslas, D I A (1985) Phytochemlstry 24, 2113 CatalLn, C A N, de Igleslas, D I A, Kavka, J., Sosa, V. E. and Herz, W (1986) J Nat. Prod. 49, 351 CatalAn, C A. N., de Igleslas, D I. A, Kavka, J., Sosa, V. E. and Herz, W. (1988) Phytochemtstry 27, 197. Bardbn, A, CatalBn, C. A. N, Gutttrrez, A B and Herz, W (1988) Phytochemlstry 27, 2989 Padolma, W G, Yoshloka, H., Nakatani, N., Mabry, T. J., Mont], S A, Davis, R. E, Cox, P J , Slm, G A, Watson, W H. and Wu, I B (1974) Tetrahedron 30, 1161. Mabry, T J , Abdel-Baset, Z H , Padohna, W G and Jones, S B (1975) Bzochem Syst Eco/ 2, 185. Jakupovq J, Zdero, C , Boeker, R., Warmng, V., Bohlmann, F and Jones, S B. (1987) Lteblgs Ann 111 Jakupovtc, J., Schmedta-Hlrschmann, G., Schuster, A., Zdero, C., Bohlman, F , King, R M , Robinson, H. and Rckardt, J. (1986) Phytochemlstry 25, 145