*Corresponding author. Tel.: 01705 843593; fax: 01705 843565.

Biochemical Systematics and Ecology 26 (1998) 797—799

Danshenol-A and 15-epi-danshenol-A fromthe roots of Salvia glutinosa

Gabor Nagy!,*, Gabor Gunther", Imre Mathe!,#,Gerald Blunden$, Ming-He Yang$, Trevor A. Crabb$

!Department of Pharmacognosy and "Department of Pharmaceutical Chemistry, Albert Szent-Gyo( rgyi MedicalUniversity, H-6720, P.O. Box 121, Szeged, Hungary

#Institute of Ecology and Botany of the Hungarian Academy of Sciences, Alkotma& ny Street 15, Va& cra& to& t, H-2163,Hungary

$School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael+s Building,White Swan Road, Portsmouth, Hampshire, PO1 2DT, U.K.

Received 28 January 1998; accepted 16 March 1998

Keywords: Salvia glutinosa; Labiatae; Diterpenoids; Danshenol-A; 15-epi-danshenol-A

1. Subject and source

Salvia species are a rich source of diterpenoids (Hanson, 1993). S. miltiorhiza Bunge,the source of the traditional Chinese medicine known as dan-shen, contains manyditerpenoids, one of which is danshenxinkun-D (Luo et al., 1985). Recently, Kasimuet al. (1997) isolated danshenol-A from S. miltiorhiza, and suggested that this wasidentical to danshenxinkun-D and that the structure assigned by Luo et al. (1985) wasincorrect. Danshenol-A was shown to be a strong aldose reductase inhibitor (Tezuka etal., 1997). We now report the isolation of danshenol-A from the roots of S. glutinosa L.,along with its C-15 epimer, which, to our knowledge, is a novel compound. Thenumbering system used by Kasimu et al. (1997) has been adopted for this current work.

2. Previous work

Patudin et al. (1974) detected diterpenoids in the roots of S. glutinosa, but nocompound was characterized. Nagy et al. (1997) have reported the isolation of the

0305-1978/98/$19.00 ( 1998 Elsevier Science Ltd. All rights reserved.PII: S0305-1978(98)00043-X

tanshinone-type diterpene quinones tanshinone 1, dihydrotanshinone 1, tanshinone11A, cryptotanshinone and dihydroisotanshinone 1.

3. Present study

3.1. Plant material

S. glutinosa roots were collected in Galyateto, Hungary, in August 1994; anherbarium sample (voucher number SO22) is maintained in the Department ofPharmacognosy, Albert Szent-Gyorgyi Medical University.

3.2. Extraction, purification and characterization

The roots (930 g) were dried at room temperature, powdered and extracted bypercolation with acetone at room temperature. The extract was evaporated in vacuo togive 24.2 g residue. This material was purified by VLC (5]50 cm) on silica gel usingn-hexane and ethyl acetate (95 :5; 9 : 1; 8 :2; 6 : 4; 4 : 6) as the elution solvents. Thefractions were checked by TLC and similar fractions were combined. Further separ-ation of the diterpenoids was achieved with the use of gel filtration through SephadexLH20 gel and with acetone as the eluting solvent.

Compounds A and B were isolated together, but separation was achieved bypreparative TLC using benzene—ethyl acetate (60 : 40) as the development solvent. Themass spectral, proton (1H-) and carbon (13C-) nuclear magnetic resonance (NMR)spectroscopic data for compound A were very similar to those of danshenol-A(Kasimu et al., 1997) and NOESY experiments confirmed the structure assigned to itby Kasimu et al. (1997).

The mass, infra red (IR), 1H- and 13C-NMR spectra of compound B were verysimilar to those of danshenol-A, indicating that the two were isomers. NOESYexperiments showed that there were strong relationships between the signal at d 9.02(H-1) and those at d 3.05 and d 3.30 (H

2-20). The signal at d 1.39 (CH

3-17) showed

a NOE only with that at d 4.45 (H-16). The vicinal coupling constants between H-15and the H

2-16 methylene protons differ from those observed for danshenol-A, indicat-

ing the change in configuration of the methyl group attached at C-15. The trivial name15-epi-danshenol-A is proposed for this epimer of danshenol-A.

4. 15-Epi-danshenol-A

HR-EIMS (probe) 70 eV:m/z (rel.int.): 336.1399 [M`]; calcd for C21

H20

O4

336.1362;279 (base peak); IR lCHCl

3max cm~1: 1625, 1700; UV cMeOHmax (log &): 231.2 (4.42), 298.7

(4.00), 356.4 (3.56). 1H-NMR (400.13 MHz; CDCl3; int. standard TMS): d1.39 (3 H,

d, J"7 Hz, CH3-17), 2.00 (3 H, s, CH

3-22), 2.73 (3 H, s, CH

3-18), 3.05 (1 H, d,

J"13 Hz; H-20), 3.30 (1 H, d, J"13 Hz, H-20), 3.63 (1 H, m; H-15), 4.45 (1 H,dd, J"5, 9 Hz, H-16), 4.69 (1 H, s, OH-11), 4.94 (1 H, t, J"9,9 Hz, H-16), 7.43 (1 H,br d, J"7 Hz; H-3), 7.51 (1 H, dd, J"7,9 Hz, H-2), 7.82 (1 H, d, J"9 Hz, H-7), 8.10

798 G. Nagy et al./Biochemical Systematics and Ecology 26 (1998) 797—799

Fig. 1. R1"Me; R2"H"danshenol-A; R1"H; R2"Me"15-epi-danshenol-A.

(1 H, d, J"9 Hz, H-6), 9.02 (1 H, br d, J"9 Hz, H-1). 13C-NMR (250.63 MHz;CDCl

3; int. standard TMS): d 125.7 (C-1), 126.8 (C-2), 128.5 (C-3), 120.1 (C-4), 134.8

(C-5), 125.5 (C-6), 120.1 (C-7), 131.0 (C-8), 141.3 (C-9), 135.2 (C-10), 79.3 (C-11), 196.1(C-12), 113.6 (C-13), 171.7 (C-14), 34.7 (C-15), 81.5 (C-16), 19.4 (C-17), 20.2 (C-18),57.1 (C-20), 204.9 (C-21), 32.0 (C-22). In the numbering system used by Kasimu et al.(1997), C-19 was assigned to the carbon of a second methyl group attached at C-4 ofthe reduced ring A of danshenol-B.

5. Chemotaxonomic significance

Danshenol-A has a structure which could have been derived from aldol-typecondensation between either dihydrotanshinone 1 or cryptotanshinone and acetone.Both of these diterpenoids are constituents of S. miltiorhiza (Tezuka et al., 1997) and S.glutinosa (Nagy et al., 1997). However, Tezuka et al. (1997) did not use acetone in theisolation procedure. Moreover, when dihydrotanshinone 1 was refluxed with acetonein the presence of silica gel, no modification of the structure was detected. Tezuka et al.(1997) thus concluded that danshenol-A was a natural product.

Nagy et al. (1997) reported that from a chemotaxonomic viewpoint there wasa close relationship between S. miltiorhiza and S. glutinosa. The finding of danshenol-A in S. glutinosa strengthens this viewpoint.

References

Hanson, J. R., 1993. Nat. Prod. Rep. (R. Chem. Soc.) 10, 159.Kasimu, R., Basnet, P., Tezuka, Y., Kadota, S., Namba, T., 1997. Chem. Pharm. Bull. 45, 564.Luo, H.-W., Wu, B.-J., Wu, M.-Y., Yong, Z.-G. and Jin, Y. 1985. Acta Pharm. Sin. 20, 542.Nagy, G., Yang, M.-H., Gunther, G., Blunden, G., Crabb, T. A. and Mathe, I. 1997. Pharm. Pharmacol.

Lett., 7(4), 37.Romanova, A., Sokolov, W.S., Ribylova, P., 1974. Planta Med. 26, 201.Tezuka, Y., Kasimu, R., Basnet, P., Namba, T., Kadota, S., 1997. Chem. Pharm. Bull. 45, 1306.

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