Cycloartane Triterpenoid and Alkaloids from Ameidea SPP

Abstracts

A new triterpene 3-beta-tiglyl-24-methylcycloartanol jointly with a mixture containing 3beta-hydroxy-urs-12-ene-28-oic and 3beta-hydroxy-olean-12-ene-28-oic acids were isolated from Almeidea coerulea. In addition to the triterpenes five alkaloids were also isolated from the same plant: 7-O-acetylhaplophyllidine, dutadrupine, isodutadrupine, 7-methoxy-8-(3,3-dimethylallyl)-dictamnine and arborinine. From A. rubra, the alkaloids arborinine, methylarborinine, evolitrine, skimmianine, kokusagine and folinine were isolated. Their structures were established based on their spectral data. The alkaloids 7-methoxy-8-(dimethylallyl)-dictamnine and 7-O-acetylhaplophyllidine are described for the first time as natural products.

Almeidea coerulea; Almeidea rubra; Rutaceae; leaves; triterpenes; alkaloids

O presente trabalho descreve o isolamento do novo triterpeno 3beta-O-tiglyl-24-metilcicloartanol e uma mistura contendo os ácidos ursólico e oleanólico de Almeidea coerulea. Além dos triterpenos foram isolados cinco alcalóides da mesma planta: 7-O-acetilhaplofilidina, dutadrupina, isodutadrupina, 7-metoxi-8-(3,3-dimetilalil)-dictamina e arborinina. De A. rubra foram isolados os seguintes alcalóides: arborinina, metilarborinina, evolitrina, esquimianina, cocusagina e folinina. As estruturas das substâncias isoladas foram estabelecidas com base em dados espectroscópicos. Os alcalóides 7-metoxi-8-(3,3-dimetilalil)-dictamina e 7-O-acetilhaplofilidina estão sendo descritos pela primeira vez na literatura.

Article

Article

Cycloartane Triterpenoid and Alkaloids from Ameidea SPP

Celcione S. Santos^a, Ana H. Januário^b, Paulo C. Vieira^b*, João B. Fernandes^b, M. Fátima G.F. da Silva^b, and José R. Pirani^c

^aDepartamento de Química, Universidade Federal do Maranhão, São Luis - MA, Brazil

^bDepartamento de Química, Universidade Federal de São Carlos, C.P. 676, 13565-905 São Carlos - SP, Brazil

^cInstituto de Biociências, Departamento de Botânica, Universidade São Paulo, 05508 São Paulo - SP, Brazil

Received: April 18, 1997

O presente trabalho descreve o isolamento do novo triterpeno 3b-O-tiglyl-24-metilcicloartanol e uma mistura contendo os ácidos ursólico e oleanólico de Almeidea coerulea. Além dos triterpenos foram isolados cinco alcalóides da mesma planta: 7-O-acetilhaplofilidina, dutadrupina, isodutadrupina, 7-metoxi-8-(3,3-dimetilalil)-dictamina e arborinina. De A. rubra foram isolados os seguintes alcalóides: arborinina, metilarborinina, evolitrina, esquimianina, cocusagina e folinina. As estruturas das substâncias isoladas foram estabelecidas com base em dados espectroscópicos. Os alcalóides 7-metoxi-8-(3,3-dimetilalil)-dictamina e 7-O-acetilhaplofilidina estão sendo descritos pela primeira vez na literatura.

A new triterpene 3-b-tiglyl-24-methylcycloartanol jointly with a mixture containing 3b-hydroxy-urs-12-ene-28-oic and 3b-hydroxy-olean-12-ene-28-oic acids were isolated from Almeidea coerulea. In addition to the triterpenes five alkaloids were also isolated from the same plant: 7-O-acetylhaplophyllidine, dutadrupine, isodutadrupine, 7-methoxy-8-(3,3-dimethylallyl)-dictamnine and arborinine. From A. rubra, the alkaloids arborinine, methylarborinine, evolitrine, skimmianine, kokusagine and folinine were isolated. Their structures were established based on their spectral data. The alkaloids 7-methoxy-8-(dimethylallyl)-dictamnine and 7-O-acetylhaplophyllidine are described for the first time as natural products.

Keywords: Almeidea coerulea, Almeidea rubra, Rutaceae, leaves, triterpenes, alkaloids

Introduction

The genus Almeidea, belonging to the tribe Cusparieae, is almost unknown from the chemical point of view. Few reports have been found in the literature and those that exist describe only the occurrence of flavones¹ and 2-quinolone alkaloids². We have been interested in the chemistry of the South American Cusparieae for a better understanding of the circumscription of the tribe^3-6. Here, we report the isolation and identification of triterpenoids and alkaloids from two species from the genus Almeidea.

Experimental

Isolation of the constituents from A. coerulea

The leaves of A. coerulea collected in Espirito Santo State, southeast of Brazil, were extracted with hexane and CH₂Cl₂ yielding after evaporation of the solvent respectively 6.1 g and 8.5 g of the crude extracts. These extracts were chromatographed separately over silica gel using as eluent hexane:CH₂Cl₂:EtOAc in increasing polarity. From the hexane extract were isolated compounds 1 (178 mg), 3 (86 mg), 2 (120 mg) and 5 (98 mg). From the CH₂Cl₂ extract were isolated compounds 3 (220 mg), 6 (680 mg) and 4 (105 mg). In a similar way the petrol extract obtained from the stems yielded a mixture of triterpenes 3b-hydroxy-urs-12-ene-28-oic and 3b-hydroxy-olean-12-ene-28-oic acids (58 mg), which were first methylated with diazomethane and then isolated as a mixture by TLC.

Isolation of alkaloids from A. rubra

A. rubra was collected in Espirito Santo State, southeast of Brazil. The leaves were extracted with CH₂Cl₂ and MeOH successively. The CH₂Cl₂ extract was chromatographed on a silica gel column deactivated with 10% water, followed by column chromatography on silicagel, using as eluent mixtures of CH₂Cl₂:acetone to get increasing polarities. The fractions collected were further purified yielding compounds 10 (6 mg), a mixture of 6 and 10 (45 mg), 6 (385 mg), 7 (21 mg), and a mixture of 9 and 11 (198 mg). The MeOH extract was submitted to solvent partition MeOH/H₂0/CH₂Cl₂. The MeOH fraction was chromatographed on a silica gel column using as eluent mixtures of CH₂Cl₂/acetone of increasing polarities affording 6 (21 mg) and 7 (15 mg). A second CH₂Cl₂ extract from the same plant was submitted to filtration chromatography using CH₂Cl₂, EtOAc and MeOH successively. The CH₂Cl₂ fraction after column chromatography yielded 8 (135 mg), 11 (7 mg) and a mixture of 8 and 10 (2 mg). The EtOAc fraction after chromatography afforded 8 (8 mg) and 11 (9 mg). The MeOH fraction was submitted to DCCC, using as stationary phase the aqueous layer of the mixture petroleum eter/MeOH/H₂O/ EtOAc (5:4:1:2) and the organic layer as mobile phase, affording 8 (69 mg) and 11 (4 mg).

3b-Tiglyl-24-methyl-cycloartenol (1)

Amorphous solid, IR n_max (cm^-1): 2980, 1730, 1460, 1370. ¹H-NMR (CDCl₃, 80 MHz, d): 6.8 (m, H-3’), 4.65 (dd, J 11.0, 4.0 Hz, H-3), 1.82 (s, Me-5’), 0.50 and 0.20 (d, J 5.0 Hz, 2H-19). ¹³C-NMR (CDCl₃, 20 MHz, d): 167.7 (s, C-1’), 136.1 (s, C-2’), 129.1 (d, C-3’), 78.5 (d, C-3), 52.1 (d, C-17), 48.8 (d, C-14), 46.8 (d, C-5), 46.6 (d, C-8), 45.2 (s, C-13), 41.6 (s, C-4), 38.4 (d, C-24), 36.9 (d, C-20), 35.2 (t, C-12), 33.1 (t, C-22), 32.7 (t, C-15), 31.8 (t, C-1), 31.3 (t, C-23), 30.9 (d, C-25), 26.4 (t, C-2), 29.4 (t, C-19), 28.1 (t, C-7), 26.9 (s, C-10), 26.4 (t, C-16), 26.4 (t, C-11), 25.1 (q, C-29), 20.9 (t, C-6), 20.9 (d, C-9), 19.1 (q, C-26), 19.0 (q, C-4’), 18.5 (q, C-28), 18.5 (q, C-21), 17.7 (q, C-18), 17.6 (q, C-5’), 17.4 (q, C-27), 14.2 (q, C-31), 14.1 (q, C-30). EIMS m/z (rel. int.): 524 (8), 424(100), 409(65), 283(80), 43 (70). Hydrolysis of 1 under basic conditions afforded 24-methylcicloartenol (1a): amorphous solid. ¹³C-NMR (CDCl₃, 20 MHz, d): 76.6 (d, C-3), 52.5 (d, C-17), 49.0 (s, C-14), 46.7 (d, C-5), 46.6 (d, C-8), 44.9 (s, C-13), 39.8 (d, C-24), 39.8 (s, C-4), 36.5 (s, C-20), 35.4 (t, C-12), 33.1 (t, C-22), 32.9 (s, C-15), 30.8 (d, C-25), 30.9 (t, C-1), 30.9 (t, C-2), 30.6 (t, C-23), 29.6 (t, C-19), 28.4 ( t, C-7), 26.9 (t, C-16), 26.2 (t, C-11), 26.1 (s, C-10), 25.5 (q, C-29), 20.6 (t, C-6), 20.9 (q, C-26), 19.9 (d, C-9), 19.0 (q, C-28), 18.5 (q, C-21), 17.6 (q, C-27), 17.3 (q, C-18), 14.4 (q, C-31), 14.0 (q, C-30).

7-O-Acetylhaplophyllidine ( 2 )

Mp. 144-7°, IR n_max (cm^-1): 2990, 1730, 1600, 1550, 1380. ¹H-NMR (CDCl₃, 80 MHz, d): 7.55 (d, J 3Hz, H-2), 6.95 (d, J 3Hz, H-3), 5.20 (m, H-2’, H-7), 4.28 (s, OMe-4), 3.13 (s, OMe-8), 1.98 (s, OAc-7), 1.66, 1.60 (s, Me-4’, Me-5’). EIMS m/z (rel. int.): 359 (5), 344 (20), 328 (37), 311 (56), 248 (100), 69 (98). ¹³C-NMR: Table 1.

7-Methoxy-8-(3,3-dimethylallyl)-dictamnine ( 5 )

Mp.86-88^o IR n_max (cm^-1): 3100, 1595, 1450, 1260. ¹H-NMR (CDCl₃, 80 MHz, d): 8.12 (d, J 9.0 Hz, H-5), 7.52 (d, J 3.0 Hz, H-2), 7.15 (d, J 9.0 Hz, H-6), 7.00 (d, J 3.0 Hz, H-3), 5.32 (br.t, J 6.0 Hz, H-2’), 4.38 (s, OMe-4), 3.92 (s, OMe-7), 1.90, 1.65 (s, Me-4’, Me-5’). ¹³C-NMR (CDCl₃, 20 MHz, d): 142.4 (d, C-2), 104.5 (d, C-3), 157.3 (s, C-4), 120.9 (d, C-5), 110.8 (d, C-6), 145.4 (s, C-7), 124.1 (s, C-8), 156.9 9 (s, C-9), 101.3 (s, C-10), 163.9 (s, C-11), 113.9 (s, C-12), 23.7 (t, C-1’), 123.5 (d, C-2’), 130.7 (s, C-3’), 17.9 (q, C-4’), 25.6 (q, C-5’), 58.7 (q, OMe-4), 56.2 (q, OMe-7).

Results and Discussion

Working separately on two species A. coerulea and A. rubra we have isolated from the leaves of the first a new triterpenoid 3b-O-tiglyl-24-methylcycloartanol (1), together with the alkaloids 7-O-acetylhaplophyllidine (2), dutadrupine (3), isodutadrupine (4), 7-methoxy-8-(3,3-dimethylallyl)-dictamnine (5) and arborinine (6). A. rubra has yielded the alkaloids arborinine (6), methylarborinine (7), evolitrine (8), skimmianine (9), kokusagine (10) and folinine (11).

Compound 1 is an amorphous solid and was identified as 3b-O-tiglyl-24-methylcycloartanol (1). The IR spectrum of 1 showed a characteristic carbonyl band (1730 cm^-1). From the mass spectrum the parent peak (m/z 524) allowed us to propose the following elementary formula C₃₆H₆₀O₂ for compound 1, as well as, the fragment (m/z 424, M-100) indicating the loss of a tiglic acid or angelic acid (C₅H₈O₂ = 100 daltons). The ¹H-NMR of 1 showed two doublets at d 0.70 and 0.48 (J 5.0Hz) attributed to two protons in a cyclopropane ring, as well as, 42H in the region between d 0.80 and 1.65 characterizing 18H and 8Me. Furthermore, a singlet at d 1.82 attributed to the vinylic dimethyl in the tiglate moiety. Two other signals at d 4.65 and 6.80 were assigned to the carbinolic and an olefinic protons respectively. The ¹³C-NMR showed besides the characteristic high field signals of the triterpene skeleton, three signals (d 167.7, 136.1, 129.1) indicating the presence of a carbonyl and two other C-sp². Compound 1 was hydrolyzed under basic conditions, affording one acid and the known 24-methylcycloartanol 1a⁷. The ¹³C-NMR of the alcoholic moiety did not show the signals at low field indicating that the acidic moiety should contain one double bond. The mass spectrum obtained for 1a showed a parent peak (m/z 424), which corresponds to the loss of a fragment C₅H₇O₂ from 1. These results lead us to propose the structure of 3-O-tiglyl-24-methylcycloartanol (1) to compound 1. The corresponding isomer angeloyl was excluded based on the ¹H-NMR of 1 which showed a signal for the olefinic proton (d 6.80) indicating the presence of tigloyl moiety. The same signal would be expected at d 5.90 in the case of angeloyl group.

7-O-Acetylhaplophyllidine (2) showed to be a furoquinoline alkaloid, however it has a reduced tetrahydroquinoline ring. ¹H-NMR of 2 showed a pair of doublets (d 7.53 and 6.87) referring to the furan ring, two overlapping signals due to a vinylic and O-acetylcarbinolic proton signal (d 5.10-5.30), two methoxyl groups (d 4.28 and 3.13) and one acetyl group (d 1.98). The presence of the 3,3-dimethylallyl moiety linked to C-8 was also deduced from ¹H-NMR (d 5.15, 1.66 and 1.60). Compound 2 was hydrolyzed in basic conditions yielding the corresponding alcohol haplophyllidine (2a). The most significant differences between the ¹H NMR of both compounds 2a and 2 was the shielding observed for the carbinolic proton signal (d 4.15) and the lack of the acetyl (d 1.98) signal in the former. The ¹³C-NMR also confirmed the presence of the prenyl chain for compound 2 (d 118.3, 132.6, 28.5, 25.2 and 17.3) and two methoxyl groups (d 57.7 and 49.8). The similarity between the chemical shifts observed for all carbons when compared with the model compound haploplyllidine⁸ and the data reported for haplophyllidine and its epimer at C-7⁹ (Table 1) led us to propose a cis relationship between the acetoxy and prenyl groups.

The ¹H-NMR of compound 5 showed signals due to a prenyl (3,3-dimethylallyl) substituent (d 5.32, t, H-2’ and 1.90, 1.65, br s, H-4’/H-5’), two methoxy groups ( 4.38, 3.92), two ortho hydrogens in a quinoline system (d 8.12, 7.15) and a 2,3-substituted furan ring (d 7.52, 7.00) leading to a furoquinoline alkaloid structure. The ¹³C-NMR confirmed the structure of a furoquinoline alkaloid for 5, which was identified as 7-methoxy-8-(3,3-dimethylallyl)-dictamnine (5). The possibility of the isomer 7-(3,3-dimethylallyl)-8-methoxydictamnine for compound 5 was ruled out on the basis of the chemical shift for the methoxyl (d 56.2), this methoxy group at C-8 would display a downfield chemical shif (d ~60)¹¹.

The other alkaloids dutadrupine (3)¹⁰, isodutadrupine (4)¹⁰, arborinine (6), methylarborinine (7)^11,12, evolitrine (8)¹³, skimmianine (9)¹¹, kokusagine (10)¹⁴ and folinine (11)¹⁵ had their structures determined through comparison of their ¹H- and ¹³C-NMR data with the literature. Isodutadrupine has already been known as a reaction product obtained from dutadrupine, however this is the first time that it has been isolated as natural product.

The chemical evidence to hand for Almeidea, strongly reinforces its position as a member of the Cusparieae. However, up to now, the occurrence of dihydro and tetrahydrofuroquinoline alkaloids has been only described for the genus Haplophyllum belonging to the allied tribe Ruteae.

Acknowledgments

The authors are grateful to FAPESP, CNPq and CAPES for the financial support. C.S.S. and A.H.J. thank CAPES (PICD) and CNPq for the award of a scholarship.

FAPESP helped in meeting the publication costs of this article

• 1. Jay, M.; Gleye, J.; Bouillant, M.L.; Stanislas, E.; Moretti, C. Phytochemistry 1979, 18, 184.
• 2. Moulis, C.; Wirasutisna, K.R.; Gleye, J.; Loiseau, P.; Stanislas, E.; Moretti, C. Phytochemistry 1983, 22, 2095.
• 3. Müller, A.H.; Vieira, P.C.; Silva, M.F.G.F.; Fernandes, J.B. Phytochemistry 1995, 40, 1797.
• 4. Sargenti, S.R.; Fernandes, J.B.; Silva, M.F.G.F.; Vieira, P.C.; Salatino, A.; Pirani, J.R. Biochem Syst Ecol 1993, 21, 723.
• 5. Arruda, A.C.; Vieira, P.C.; Fernandes, J.B.; Silva, M.F.G.F. J Braz Chem Soc 1993, 4, 80.
• 6. Müller, A.H.; Degaspari, L.R.O.; Vieira, P.C.; Silva, M.F.G.F.; Fernandes, J.B.; Pirani, J.R. Phytochemistry 1993, 34, 585.
• 7. Wherli, F.W.; Nishida, T. Fortsch. Chem. Org. Naturst 1979, 36, 1.
• 8. Yagudaev, M.P.; Besonova, I.A. Khim. Prir. Soedin. 1989, 20 (Engl. Ed.).
• 9. Zs. Róza, R.M.; Rabik, M.; Szendrei, K.; Aynechi, M.; Pelczer, I. Phytochemistry 1988, 27, 2369.
• 10. Baudouin, G.; Tillequin, F.; Koch, M. J. Nat. Prod 1981, 44, 546.
• 11. Ahond, A.; Picot, F.; Potier, P.; Poupat, C.; Sévenet, T. Phytochemistry 1978, 17, 166.
• 12. Bousquet, M.B.; Tillequin, F.; Koch, M.; Sévenet, T. Planta Medica 1985, 536.
• 13. De Silva, L.B.; De Silva, U.L.L.; Mahendran, M.; Jennings, R. Phytochemistry 1979, 18,1255.
• 14. Yajima, T.; Kato, N.; Munakata, K. Agric. Biol. Chem 1977, 41, 1263.
• 15. Nadzan, A.M.; Rinehart Jr., K.L. J. Am. Chem. Soc 1977, 99, 4647.

Publication Dates

• Publication in this collection
  17 Mar 2008
• Date of issue
  Feb 1998

History

• Accepted
  18 Apr 1997
• Received
  18 Apr 1997