Biochemical Systematics and Ecology 35 (2007) 392e396www.elsevier.com/locate/biochemsyseco

Lignans, neolignans and sesquilignans fromCestrum parqui l’Her.

Antonio Fiorentino a,*, Marina DellaGreca b, Brigida D’Abrosca a, Palma Oriano a,Annunziata Golino a, Angelina Izzo a, Armando Zarrelli b, Pietro Monaco a

a Dipartimento di Scienze della Vita, Seconda Universita degli Studi di Napoli, via Vivaldi 43, 81100 Caserta, Italyb Dipartimento di Chimica Organica e Biochimica, Universita degli Studi di Napoli ‘‘Federico II’’, via Cintia 4, 80126 Napoli, Italy

Received 24 July 2006; accepted 6 December 2006

Keywords: Solanaceae; Cestrum parqui; Lignans; Neolignans; Sesquilignans; Phytotoxic activity

1. Subject and source

Cestrum parqui l’Her. 1788 (Solanaceae) is a shrub, indigenous to South America, widely distributed in theMediterranean area and known as ‘green Cestrum’. Plants of C. parqui were collected in Sant’Agata de’ Goti,near Caserta (Italy) in the spring 2004, and identified by Dr Assunta Esposito of the Second University of Naples.A voucher specimen (CE125) has been deposited at the Herbarium of the Dipartimento di Scienze della Vita ofthe Second University of Naples.

2. Previous works

Not many papers are reported on the lignan composition of Cestrum species. Recently we have reported theisolation, characterization and the phytotoxicity of three new compounds, a sesquilignan, an oxyneolignan and a nor-lignan, from the aqueous fraction of C. parqui (D’Abrosca et al., 2006). Other class of chemicals has been isolatedfrom this plant such as saponins (Chaieb et al., 2005; Baquai et al., 2001; Abdel-Gwad et al., 1997; Torres et al.,1988), terpenoids (Pearce et al., 1992; D’Abrosca et al., 2004a) and phenols (D’Abrosca et al., 2004b).

3. Present study

The phytochemical study of the hydroalcoholic extract of green Cestrum has led to the isolation ofthe 18 compounds with lignan skeletons, which have been identified as four diepoxylignans 1e3 and 18, four epox-ylignans 4e7, three neolignans 8e10, five sesquilignans 11, 12 and 15e17, an oxyneolignan 13 and a norlignan 14, onthe basis of their spectroscopic features (NMR spectra were recorded at 300 MHz for 1H and 75 MHz for 13C on

* Corresponding author. Tel.: þ39 (0) 823274576; fax: þ39 (0) 823274571.

E-mail address: antonio.fiorentino@unina2.it (A. Fiorentino).

0305-1978/$ - see front matter � 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.bse.2006.12.009

393A. Fiorentino et al. / Biochemical Systematics and Ecology 35 (2007) 392e396

a Varian 300 Spectrometer Fourier transform NMR and at 500 MHz for 1H and 125 MHz for 13C on a Varian 500Spectrometer Fourier transform NMR).

O

O

H H

OR2

HO

H3CO

R1

OCH3

R

1

2

3

18

R = R1 = R2 = H R = R2 = H; R1 = OCH3R2 = H; R = R1 = OCH3R2 = glc; R = R1 = OCH3

O

RHO

HO

OH

OCH3

R1

H3CO

R2

4

5

6

7

R = R1 = R2 = H R = R2 = H; R1 = OCH3 R = R1 = H; R2 = OCH3 R = OH; R1 = R2 = H

1

3

7

91'

3'

7'

9'9'

7' 1'3'

13

7

8

HO

O

OH

OCH3

OH

OCH3

R

O

OH

H3CO

OCH3

O

OH

OCH3

OH

8

9

10

cis R = Htrans R = Htrans R = OCH3

1

3

79 1'

3'

7'

8'9' 1

3

7

1'

3'3"

7'

9'

1"7"

9"

11

12

cis

trans

HO

O

O

O

OCH3

OCH3

H3CO

13

1'

7'9'

4'4

1

7

9

OCH3

OHO

H3CO

OCH3

OHHO

O1

4

78

9

1'

3'5'

7'8'

14

O

O

HH

OH

OCH3

OCH3

OOCH3

OH

HO

OHOCH3

15

16

17

threo R = Herythro R = Herythro R = OCH3

R1

3

7 9'

9"

1"

1'7'

Fresh leaves of C. parqui (30 kg) were frozen at�80 �C, powdered and extracted with MeOHeH2O (1:9) for 48 h.The solution, after the evaporation of the MeOH, was extracted in a separator funnel first using CH2Cl2 and then withEtOAc, yielding 8.0 g and 9.2 g of residual material, respectively.

The CH2Cl2 extract was chromatographed on silica gel, with CHCl3 and EtOAc solutions, to give three frac-tions AeC. Fraction A, eluted with CHCl3, was fractionated by FCC (EtOAcePet) to have compounds: 1 (1 mg),2 (6 mg) and 3 (70 mg). Fraction B, eluted with CHCl3eEtOAc (9:1), was rechromatographed by SephadexLH-20� eluting with n-hexaneeCHCl3eMeOH (3:1:1) to obtain three fractions: the first, after further purificationon HPLC, RP-8 column semipreparative eluting with MeOHeMeCNeH2O (1:1:3), gave pure compounds

394 A. Fiorentino et al. / Biochemical Systematics and Ecology 35 (2007) 392e396

4 (1 mg), 5 (2 mg) and 6 (3 mg); the second fraction was purified on HPLC, in the same condition, to give pure 14(6 mg); the third fraction was also purified on HPLC using an RP-18 preparative column, and eluting withMeOHeMeCNeH2O (3:2:5) to give pure 15 (7 mg), 16 (3 mg) and 17 (3 mg). The sesquilignan 17 showed a mo-lecular formula C32H38O12, on the basis of the ESI-MS experiment and of the 13C NMR spectrum. The NMRdata indicated the presence of a sesquilignan constituted by a guaiacylglycerol and a syringaresinol unity. Inthe aromatic region the 1H NMR showed two signals, each integrated for two protons, at d 6.76 and 6.67 dueto the H-2/H-6 and H-20/H-60 protons of two sinapylic moieties, three protons at d 7.03, 9.91 and 6.75 due toa guaiacyl group, as well as five methoxyls and 12 other hydrogens in the aliphatic region. These data, togetherwith those deriving by two-dimensional experiments, were in accordance with the erythro-40,400,700,900-tetrahy-droxy-3,30,300,5,50-pentamethoxy-4,800-oxy-7,90:70,9-diepoxylignan structure. This compound has been previouslydescribed as a product of the polymerization of mixtures of coniferyl and sinapyl alcohols (Landucci et al.,1998) and was isolated for the first time from natural sources such as Caragana rosea (Cui et al., 2003). FractionC, eluted with CHCl3eEtOAc (1:4), was rechromatographed by Sephadex LH-20� eluting with n-hexaneeCHCl3eMeOH (4:1:1) to give two fractions: the first one was purified by HPLC [RP-18, MeOHeMeCNeH2O(1:1:3)], to give 10 (2 mg); also the second fraction was chromatographed on HPLC using an RP-18 semiprepar-ative column, and eluting with MeOHeMeCNeH2O (1:1:3) to give pure 7 (2 mg), 9 (1 mg) and 11 (3 mg).

The EtOAc extract was chromatographed on silica gel, with CHCl3 and EtOAc solutions to give three fractionsDeF. Fraction D, eluted with CHCl3eEtOAc (9:1), gave pure 13 (4 mg). Fraction E, eluted with CHCl3eEtOAc(1:4) was chromatographed by Sephadex LH-20� eluting with EtOH, increasing the percentage of H2O, to obtainone fraction. By further purification on HPLC using an RP-18 preparative column, and eluting with MeOHeMeCNeH2O (1:1:3), pure 12 (2 mg) and 8 (1 mg) were obtained. Compound 8 showed a molecular formulaC20H22O6 in accordance with the mass spectrum and the 13C NMR. The 1H NMR spectrum showed the H-70 andH-80 protons of the dihydrofuran ring as a doublet at d 5.53 (J¼ 6.4 Hz), and a multiplet at d 3.60; the H-7, H-8and H-9 protons of the propenyl chain were also evident as a doublet (J¼ 11.7 Hz) at d 6.49, a double triplet(J¼ 6.0 and 11.7 Hz) at d 5.72 and a doublet (J¼ 6.0 Hz) at d 4.72, respectively, besides five aromatic protons asa singlet at d 6.78 (H-2 and H-6), a doublet (J¼ 8.1 Hz, H-50) at d 6.77, a double doublet (J¼ 2.2 and 8.1 Hz,H-60) at d 6.84, and a doublet (J¼ 2.2 Hz, H-20) at d 6.85. The coupling constants of the double bond D7 were con-sistent with a cis configuration. This compound was previously obtained from the biotransformation of the coniferylalcohol by Caldariomyces fumago (Sih et al., 1976). Fraction F, eluted with Me2COeEtOAc (1:1), was chromato-graphed on Sephadex LH-20� eluting with EtOH:H2O (1:3), to obtain one fraction. Further purification on HPLC,using an NH2 semipreparative column, and eluting with MeCNeH2O (91:9), was obtained pure 18 (4 mg).

Pure lignans, with the exception of 5, 10 and 13, were assayed on three wild species growing in the same habitat ofC. parqui: Amaranthus retroflexus, Chenopodium album and Portulaca oleracea (Table 1). The effects on seedgermination and seedling growth were measured in accordance with Macıas et al. (2000).

Significative effects on the germination were observed for A. retroflexus and P. oleracea: the furofurans 1e3 and 18were the most active compounds on the first species, while compounds 6 and 7 were the most toxic on P. oleracea.These latter, together with syringaresinol 3 inhibited the root development of A. retroflexus. Finally, all the compoundsresulted slowly stimulant on the shoot elongation of C. album and P. oleracea.

4. Chemotaxonomic significance

The diepoxylignans were identified as (þ)-pinoresinol (1) (Pelter et al., 1982), (þ)-mediaresinol (2) (Zhuang et al.,1982) and (þ)-syringaresinol (3) (Ratnayake et al., 1992) by comparing their spectral data with those reported in theliterature. Compounds 4 and 5 were, respectively, identified as (þ)-lariciresinol (Katayama et al., 1992) and (þ)-justiciresinol, already isolated from Justicia glauca (Subbaraju et al., 1991), respectively. The furanoid lignan 6was identified as 50-methoxylariciresinol, a constituent of Rubia yunnanensis (Tao et al., 2003) and compound 7was identified as (�)-berchemol, already isolated from Berchemia racemosa (Sakurai et al., 1989).

Compound 9, the trans isomer of 8, was identified as dehydrodiconiferyl alcohol (Shiba et al., 2000). Compound 10was identified as (�)-simulanol, isolated by Yang et al. (2002) from the stem wood of Zanthoxylum simulans.

The sesquilignans were identified as the isomeric structures 11 and 12. This latter had already been isolated fromHerpetospermum caudigerum and named herpetotriol (Favre-Bonvin et al., 1978), while compound 11 has beendescribed as C. parqui together with the oxylignan 13 and the norlignan 14 (D’Abrosca et al., 2006).

395A. Fiorentino et al. / Biochemical Systematics and Ecology 35 (2007) 392e396

Compounds 15 and 16 have been identified as threo and erythro-40,400,700,900-tetrahydroxy-3,30,300,50-tetramethoxy-4,800-oxy-7,90:70,9-diepoxylignan, respectively (Li and Kuo, 2000).

Appendix A. Supplementary data

Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.bse.2006.12.009.

Table 1

Effects of the lignans from C. parqui on the germination and growth of A. retroflexus, C. album, and P. oleracea

1 2 3 4 6 7 8 9 11 12 14 15 16 17 18

Amaranthus retroflexus

Germination

10�4 M �24.0a nt �33.3a �3.0 nt �10.0 �4.0 �20.0a nt nt �9.0 �19.0 �8.0b nt �26.0a

10�6 M �25.0 �20.0a �16.7 �6.0 �13.0b �10.0 �8.0 �15.0a �25.0a �16.0 2.2 �4.0 �7.0 �11.0b �6.0

10�8 M �6.7 �8.0 �5.0b �2.1b �11.0 �2.0 �12.0 6.7 �25.0a �18.9a 3.0 �6.0 �7.0 �12.5a �4.3a

Root elongation

10�4 M �6.3 nt �37.9a �5.4 nt �27.1a �10.0 �2.4 nt nt 5.3 �8.3 �5.0 nt �13.2

10�6 M �4.9 �14.9 �10.1 �6.3 �35.2a �26.8a �17.3b 2.5 �19.7 �11.9 7.1 �6.2b �3.4 �8.9 �6.8

10�8 M �4.8 �14.9 1.3 �7.7 8.5 1.7 �18.1b 11.5 �19.1b �18.7b 6.7 �10.0 �3.5 �4.5 �13.5a

Shoot elongation

10�4 M 3.0 nt �6.1 �12.9 nt �9.0 �2.0 9.2 nt nt 2.5 �7.6 �6.9 nt �4.5

10�6 M 3.3 �14.1 1.7 3.6 �6.6 2.5 �1.8 12.0 �8.1 �7.7 0.7 �10.0 �5.2 �2.2 �7.0

10�8 M 0.5 �6.5 8.0 0.3 �6.1 1.6 6.0 2.6 2.0 �12.3 0.2 �6.4 �3.0 3.8 �4.3

Chenopodium album

Germination

10�4 M �8.0 nt �9.0 �10.0 nt �10.0 �7.0 �15.0b nt nt 4.0 �8.7a �15.0b nt �11.0

10�6 M �9.0b �3.0 �11.0 �9.0 �6.4 �7.0 �10.0 �14.0b �7.0 �4.0 1.3 �10.0b �12.0b �8.0 �10.0

10�8 M �2.0 �1.0 �11.0 �5.3b �8.0b �4.0 �3.0 �2.0 �6.0 �3.0 1.3 �7.0b �12.0 �9.0 �11.1b

Root elongation

10�4 M 10.8 nt �9.2 �5.9 nt 5.9 �17.5 �9.4 nt nt �19.4 �1.6 2.1 nt 7.6

10�6 M 15.6 7.8 �10.3 1.9 5.5 12.5 �16.0 �12.3 2.5 14.5 �7.0 �2.7 4.9 10.3 7.2

10�8 M 3.9 10.2 �4.7 9.7 12.5 13.2 6.6 �7.8 10.7 27.1 5.5 3.6 2.3 6.4 6.9

Shoot elongation

10�4 M 2.1 nt �9.7 9.4 nt 6.5 �0.8 10.2 nt nt �13.4 5.0 16.7 nt 9.4

10�6 M 8.4 �2.5 15.7b 8.6 10.8 10.7 �2.8 10.7 �8.2 11.7 �14.8 7.4 11.8 2.7 11.1

10�8 M 8.0 �1.6 7.0 6.1 13.5 2.6 �1.6 5.6 �3.3 3.1 �6.1 4.2 6.3 1.2 13.0

Portulaca oleracea

Germination

10�4 M �6.0 nt �21.0a 1.1b nt �20.0b �5.0 �17.0 nt nt �9.0 �14.0 �9.0b nt �22.0a

10�6 M �10.0 �16.0b �11.0 2.0 �17.0a �24.0a �4.0 �19.0b �16.0 �18.0b �7.0 �14.0 �9.0 �14.0b �9.0

10�8 M �9.0a �9.0 �9.0 4.0 �20.0a �23.0a �5.0 �12.0b �12.0 �21.0a �5.0a �15.0a �5.0b �2.0 �10.0b

Root elongation

10�4 M 0.3 nt 11.2 16.9 nt 3.6 �12.7 0.0 nt nt 14.7 10.1 7.3 nt �27.2

10�6 M 14.7 0.6 �0.4 16.8 �22.1 �12.2 2.9 32.2 11.8 1.0 �0.5 20.5 �3.3 36.0 16.7

10�8 M 0.7 9.8 1.2 �4.7 14.3 �14.9 7.3 �0.1 25.9 14.6 20.5 8.6 52.6 8.4 0.5

Shoot elongation

10�4 M �0.1 nt 3.1 �9.2 nt 3.1 6.7 7.3 nt nt �2.2 7.8 9.2 nt �6.2

10�6 M 4.9 �1.6 4.4 24.9 5.5 �7.5 6.3 9.2 �12.3 0.9 �5.8 6.6 �1.7 15.9 5.8

10�8 M 2.3 �0.1 4.3 3.4 �3.6 8.3 10.0 9.1 1.2 6.0 7.8 10.0 4.6 3.6 4.6

Values are presented as percentage differences from control and they are significantly different with P> 0.05 for Student’s t-test; nt¼ not tested.a P< 0.01.b 0.01< P< 0.05. Positive percentages represent stimulation while negative values represent inhibitions.

396 A. Fiorentino et al. / Biochemical Systematics and Ecology 35 (2007) 392e396

References

Abdel-Gwad, M.M., El-Amin, S.M., El-Sayed, M.M., Refahy, L.A., Sabry, W.A., 1997. J. Pharm. Sci. 20, 80.

Baquai, F.T., Ali, A., Ahmad, V.Q., 2001. Chim. Acta 84, 3350.

Chaieb, I., Ben Halima-Kamel, M., Ben Hammouda, M.H., 2005. Commun. Agric. Appl. Biol. Sci. 70, 809.

Cui, Y., Mu, Q., Hu, C., 2003. Tianran Chanwu Yu Kaifa 15, 277.

D’Abrosca, B., DellaGreca, M., Fiorentino, A., Monaco, P., Oriano, P., Temussi, F., 2004a. Phytochemistry 65, 497.

D’Abrosca, B., DellaGreca, M., Fiorentino, A., Monaco, P., Zarrelli, A., 2004b. J. Agric. Food Chem. 52, 4101.

D’Abrosca, B., DellaGreca, M., Fiorentino, A., Golino, A., Monaco, P., Zarrelli, A., 2006. Nat. Prod. Res. 20, 293.

Favre-Bonvin, J., Kaouadji, M., Mariotte, A.M., 1978. Tetrahedron Lett. 43, 4111.

Katayama, T., Davin, L.B., Lewis, N.G., 1992. Phytochemistry 31, 3875.

Landucci, L.L., Ralph, S.A., Hammel, K.E., 1998. Holzforschung 52, 160.

Li, Y.-C., Kuo, Y.-H., 2000. Chem. Pharm. Bull. 48, 1862.

Macıas, F.A., Castellano, D., Molinillo, J.M.G., 2000. J. Agric. Food Chem. 48, 2512.

Pearce, C.M., Skelton, N.J., Naylor, S., Kanaan, R., Kelland, J., Oelrichs, P.B., Sanders, J.K.M., Williams, D.H., 1992. J. Chem. Soc. Perkin Trans.

1, 593.

Pelter, A., Ward, E.S., Watson, D.J., Collins, P., Kai, I.T., 1982. J. Chem. Soc. Perkin Trans. 1, 175.

Ratnayake, S., Fang, X., Anderson, J.E., McLaughlin, J.L., Evert, D.E., 1992. J. Nat. Prod. 55, 1462.

Sakurai, N., Nagashima, S., Kawai, K., Inoue, T., 1989. Chem. Pharm. Bull. 37, 3311.

Shiba, T., Xiao, L., Miyakoshi, T., Chen, C.L.J., 2000. Mol. Catal. B-Enzim. 10, 605.

Sih, C.J., Ravikumar, P.R., Huang, F., Buckner, C., Whitlock Jr., H., 1976. J. Am. Chem. Soc. 98, 5412.

Subbaraju, G.V., Kumar, K.K.K., Raju, B.L., Pillai, K.R., Reddy, M.C., 1991. J. Nat. Prod. 54, 1639.

Tao, J., Morikawa, T., Ando, S., Matsuda, H., Yoshikawa, M., 2003. Chem. Pharm. Bull. 51, 654.

Yang, Y.P., Cheng, M.J., Teng, C.M., Chang, Y.L., Tsai, I.L., Chen, I.S., 2002. Phytochemistry 61, 567.

Torres, R., Modak, B., Faini, F., 1988. Bol. Soc. Chil. Quim. 33, 239.

Zhuang, L., Seligmann, O., Jurcic, K., Wagner, H., 1982. Planta Med. 45, 172.