Two Novel Trimeric Resveratrol Derivatives from Cotylelobium lanceolatum

Two Novel Trimeric Resveratrol Derivatives from Cotylelobium lanceolatum

by Tetsuro Ito*a), Zulfiqar Alib), Miyuki Furusawaa), Ibrahim Iliyab), Toshiyuki Tanakaa),Ken-ichi Nakayaa), Jin Muratac), Dedy Darnaedid), Masayoshi Oyamab), and Munekazu Iinumab)

a) Gifu Prefectural Institute of Health and Environmental Sciences, 1-1 Naka-fudogaoka,Kakamigahara 504-0838, Japan

(phone: � 81-583-80-2100; fax: � 81-583-71-5016; e-mail : [email protected])b) Department of Pharmacognosy, Gifu Pharmaceutical University, 5-6-1, Mitahora-higashi, Gifu 502-8585,

Japanc) Botanical Gardens, Koishikawa, Graduate School of Science, University of Tokyo, 3-7-1, Hakusan,

Bunkyo-Ku, Tokyo, 112-0001, Japand) Indonesian Institute of Sciences, Jalan Ir. H. Juanda 13, Bogor 16122, Indonesia

Two new resveratrol (� 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol) trimers, cotylelophenols A(1) and B (2), were isolated from the stem of Cotylelobium lanceolatum (Dipterocarpaceae), together with tenknown resveratrol oligomers (3 ± 12). The structures of the isolates were established on the basis ofspectroscopic analyses, including a detailed NMR spectroscopic investigation of 1 under different conditions.Compound 1 is the first resveratrol trimer with a rearranged 4-hydroxyphenyl group. Four possible biogeneticpathways towards resveratrol oligomers are proposed (Scheme).

Introduction. ± Stilbenoids represented by resveratrol (� 5-[(E)-2-(4-hydroxyphe-nyl)ethenyl]benzene-1,3-diol) have drawn much attention from the chemical com-munity due to their roles in food and beverage, and because of their diverse biologicalactivities. These compounds, either in glycosylated or non-glycosylated form, aretypically found as oligomers in limited plant families such as Dipterocarpaceae [1],Vitaceae [2], Cyperaceae [3], and Gnetaceae [4]. High structural diversity andmultifunctional bioactivity make stilbenoid oligomers interesting targets for detailedphytochemical investigations. Dipterocarpaceaous plants are well-known to containresveratrol oligomers, and their occurrences in Vatica [5], Vateria [6], Shorea [7],Upuna [8], Dipterocarpus [9], and Hopea [10] genera have been disclosed in ourprevious works.The genus Cotylelobium, which belongs to the tribe Dipterocarpeae in the largest

subfamily Dipterocarpoideae, comprises six species, and is distributed mainly inSoutheast Asia [11]. Although structural elucidations of resveratrol oligomers havebeen made in some of the above-mentioned related genera, no examination ofCotylelobium has been reported yet. In our current phytochemical studies ofDipterocarpaceae, the chemical constituents of C. lanceolatum were examined, andtwo new resveratrol oligomers, named cotylelophenols A (1) and B (2), were isolated,together with ten known resveratrol derivatives (3 ± 12) [5]. The structure elucidationsof 1 and 2, and their NMR characteristics are described in this paper. Also, thebiogenetic relationship of all the isolates is discussed according to structural similaritiesand differences.

CHEMISTRY & BIODIVERSITY ± Vol. 2 (2005)1200

¹ 2005 Verlag Helvetica Chimica Acta AG, Z¸rich

Results and Discussion. ± 1. Structure Elucidation. Cotylelophenols A (1) and B (2)were isolated from the acetone extract of the stem of C. lanceolatum by columnchromatography (CC), preparative thin-layer chromatography (TLC), and medium-pressure liquid chromatography (MPLC).Cotylelophenol A (1), a pale yellow solid, had the molecular formula C42H30O10, as

deduced by HR-FAB-MS ([M�H]� at m/z 693.1773) and 13C-NMR spectroscopy. An

CHEMISTRY & BIODIVERSITY ± Vol. 2 (2005) 1201


IR absorption band at 1777 cm�1 and a 13C-NMR signal at �(C) 176.2 (in (D6)DMSO at25�) indicated the presence of a C�O group (C(7b))1). The 1H- and 13C-NMR spectraof 1 (Tables 1 and 2), and the corresponding 1H,1H- and 13C,1H-COSY, as well asHMBC spectra (Table 3 and Fig. 1) were recorded at various temperatures and in twodifferent solvents.

Data analysis revealed the presence of three 4-hydroxyphenyl groups (rings A1�C1), a 3,5-dioxygenated 1,2-disubstituted benzene ring (A2), a 3,5-dioxygenated 1,2,6-trisubstituted benzene ring (B2), and a 3,5-dihydroxyphenyl group (C2). The presenceof a sequence of four aliphatic H-atoms (H�C(7b), H�C(8b), H�C(7c), andH�C(8c)) was also evident (Fig. 1). An NMR signal at �(C) 56.9 (in (D6)DMSO at25�) was assigned to a quaternary aliphatic C-atom (C(8b)). The 1H-NMR spectrum(same conditions) exhibited signals for eight phenolic OH groups at �(H) 8.11 ± 9.87,which disappeared upon addition of D2O. Considering the molecular formula, one O-atom could be allotted to an ester linkage.The connection of partial structures was established as follows. The significant 3J

long-range correlations observed between H�C(14a)/C(8a), H�C(7b)/C(11a),

Table 1. 1H-NMR Data of Cotylelophenol A (1). At 300 MHz; � in ppm, J in Hz. N.o.� not observed.

Atom Temperature

80�a) 25�a) 25�b) � 25�b)H�C(2a) 6.06 (br. d, J� 8.6) N.o. N.o. 6.56 (br. d, J� 8.6)H�C(3a) 6.11 (br. d, J� 8.6) N.o. N.o. 6.48 (br. d, J� 8.6)H�C(5a) 6.11 (br. d, J� 8.6) N.o. N.o. 5.90 (br. d, J� 8.6)H�C(6a) 6.06 (br. d, J� 8.6) N.o. N.o. 5.70 (br. d, J� 8.6)H�C(12a) 6.50 (d, J� 2.4) 6.49 (d, J� 2.4) 6.63 (d, J� 2.4) 6.80 (br. s)H�C(14a) 7.24 (d, J� 2.4) 7.18 (d, J� 2.4) 7.43 (d, J� 2.4) 7.40 (br. s)H�C(2b,6b) 5.94 (d, J� 8.6) 5.89 (d, J� 8.6) 6.05 (d, J� 8.6) 6.02 (br. d, J� 8.6)H�C(3b,5b) 5.44 (d, J� 8.6) 5.39 (d, J� 8.6) 5.52 (d, J� 8.6) 5.50 (br. d, J� 8.6)H�C(7b) 5.49 (d, J� 3.8) 5.46 (d, J� 3.7) 5.69 (d, J� 3.7) 5.69 (br. d, J� 3.7)H�C(8b) 3.76 (dd, J� 7.7, 3.8) 3.67 (dd, J� 7.7, 3.7) 3.89 (dd, J� 7.7, 3.7) 3.86 (br. s)H�C(12b) 6.66 (s) 6.69 (s) 6.75 (s) 6.64 (br. s)H�C(2c,6c) 6.76 (d, J� 8.6) 6.73 (d, J� 8.6) 6.87 (d, J� 8.6) 6.97 (br. d, J� 8.6)H�C(3c,5c) 6.25 (d, J� 8.6) 6.24 (d, J� 8.6) 6.32 (d, J� 8.6) 6.33 (br. d, J� 8.6)H�C(7c) 3.47 (d, J� 7.7) 3.42 (d, J� 7.7) 3.62 (d, J� 7.7) 3.62 (br. d, J� 7.7)H�C(8c) 4.68 (s) 4.63 (s) 4.86 (s) 4.86 (br. s)H�C(10c,14c) 5.71 (d, J� 2.0) 5.64 (d, J� 2.0) 5.86 (d, J� 2.0) 5.83 (br. s)H�C(12c) 5.97 (t, J� 2.0) 5.95 (t, J� 2.0) 6.14 (t, J� 2.0) 6.14 (br. s)��C(4a) 8.67 (br. s) 8.99 (br. s) 7.97 (br. s) 8.30 (br. s)��C(4b) 7.79 (br. s) 8.11 (br. s) 7.10 (br. s) 7.45 (br. s)��C(4c) 8.49 (br. s) 8.78 (br. s) 7.77 (br. s) 8.14 (br. s)��C(11a) 9.31 (br. s) 9.66 (br. s) 8.74 (br. s) 9.10 (br. s)��C(11c) 8.65 (br. s) 8.95 (br. s) 8.03 (br. s) 8.40 (br. s)��C(13a) 9.02 (br. s) 9.31 (br. s) 8.38 (br. s) 8.71 (br. s)��C(13b) 9.51 (br. s) 9.87 (br. s) 8.82 (br. s) 9.21 (br. s)��C(13c) 8.65 (br. s) 8.95 (br. s) 8.03 (br. s) 8.40 (br. s)

a) In (D6)DMSO. b) In (D6)acetone.


1) Arbitrary atom numbering, for systematic names, see Exper. Part.


Table 3. HMBC and NOESY NMR Data of 1. In (D6)DMSO.

H-Atom 1H,13C-HMBC 1H,1H-NOESY

H�C(12a) C(10a), C(11a), C(13a), C(14a) HO�C(11a), HO�C(13a)H�C(14a) C(8a), C(10a), C(12a), C(13a) HO�C(13a)H�C(2b,6b) C(4b), C(7b) H�C(7b), H�C(2c,6c)H�C(3b,5b) C(1b), C(4b) HO�C(4b)H�C(7b) C(9a), C(10a), C(11a), C(1b),

C(2b,6b), C(8b), C(9b)HO�C(11a), H�C(2b,6b),H�C(8b), H�C(2c,6c), H�C(7c)

H�C(8b) C(10a), C(1b), C(7b), C(9b),C(14b), C(1c), C(7c)

H�C(7b), H�C(7c), H�C(10c,14c)

H�C(12b) C(10b), C(11b), C(13b), C(14b) HO�C(13b)H�C(2c,6c) C(4c), C(7c) H�C(2b,6b), H�C(7b), H�C(7c),

H�C(8c), H-C(10c,14c)H�C(3c,5c) C(1c), C(4c) HO�C(4c)H�C(7c) C(8b), C(9b), C(14b), C(1c),

C(2c,6c), C(8c)H�C(7b), H�C(8b), H�C(2c,6c),H�C(10c,14c)

H�C(8c) C(8b), C(9b), C(14b), C(1c),C(7c), C(9c), C(10c,14c)

H�C(2c,6c), H�C(10c,14c)

H�C(10c,14c) C(8c), C(11c,13c), C(12c) H�C(8b), HO�C(13b), H�C(2c,6c),H�C(7c), H-C(8c), HO�C(11c,13c)

H�C(12c) C(9c,14c), C(11c,13c) HO�C(11c,13c)HO�C(4a) C(3a,5a), C(4a) ±HO�C(11a) C(10a), C(11a), C(12a) H�C(12a), H�C(7b)HO�C(13a) C(12a), C(13a), C(14a) H�C(12a), H�C(14a)HO�C(4b) C(3b,5b), C(4b) H�C(3b,5b)HO�C(13b) C(12b), C(13b), C(14b) H�C(12b), H�C(10c,14c)HO�C(4c) C(3c,5c), C(4c) H�C(3c,5c)HO�C(11c,13c) C(10c,14c), C(11c,13c), C(12c) H�C(10c,14c), H�C(12c)

Table 2. 13C-NMR Data for Cotylelophenol A (1). At 75 MHz; � in ppm. N.o.�not observed.

Atom Temperature Atom Temperature

80�a) 25�a) 25�b) 80�a) 25�a) 25�b)

C(1a) 129.3 129.2 131.0 C(7b) 36.7 36.7 38.1C(2a) 126.0c) N.o. N.o. C(8b) 48.4 48.4 49.4C(3a) 114.5 114.8c) 115.7c) C(9b) 143.7 143.9 145.3C(4a) 155.8 156.2 157.0c) C(10b) 114.0 114.2 116.2C(5a) 114.5 114.8c) 115.7c) C(11b) 152.9 153.2 154.8d)C(6a) 126.0c) N.o. N.o. C(12b) 95.6 95.9 96.6C(7a) 175.7 176.2 176.9 C(13b) 154.5 154.9 155.7d)C(8a) 56.7 56.9 58.1 C(14b) 124.2e) 124.3g) 125.1C(9a) 135.9 136.1 137.7 C(1c) 132.7 132.9 134.4C(10a) 124.23e) 124.2g) 125.7d) C(2c.6c) 128.6 129 130.1C(11a) 155.1 f) 155.4h) 156.3d)i) C(3c.5c) 113.8 114 114.9d)C(12a) 102.6 102.5 103.2d) C(4c) 155.0 f)l) 155.4h) 156.4e)j)C(13a) 155.0l) 155.3 156.1d) C(7c) 58.3 58.6 60.0C(14a) 106.6 106.5 108.1d) C(8c) 53.2 53.3 54.2C(1b) 128.5j) 128.7k) 130.2 C(9c) 145.5 145.7 146.8C(2b.6b) 128.5j) 128.7k) 129.9 C(10c.14c) 104.5 104.6 105.9d)C(3b.5b) 111.7 111.8 112.8 C(11c,13C) 157.9 158.3 159.2d)C(4b) 152.3 152.6 153.6d) C(12c) 100.3 100.4 101.2d)

a) In (D6)DMSO. b) In (D6)acetone. c) Broad signals. d) Duplicated signals. e) ± l) Interchangeable.

H�C(7b)/C(2b,6b), H�C(8b)/C(14b), H�C(7c)/C(2c,6c), H�C(8c)/C(13b), andH�C(8c)/C(10c,14c) (see Fig. 1) indicated C�C bonds between C(8a)/C(9a), C(7b)/C(10a), C(7b)/C(1b), C(8b)/C(9b), C(7c)/C(1c), C(8c)/C(14b), and C(8c)/C(9c),respectively. Although no long-range correlation regarding C(7a) and C(8a) wasobserved, the C�C bonds between C(1a)/C(8a), C(7a)/C(8a), and C(8a)/C(10b), andthe presence of a five-membered lactone ring (C(7a)�C(8a)�C(10b)�C(11b)�O)were proposed after consideration of the molecular formula. The spatial neighboringrelation between the C(7a)�O group and H�C(14a) at �(H) 7.18 rationalized thedown-field shift of the latter. From these data, the constitution of cotylelophenol Acould be drawn.The relative configuration of 1 was determined by a NOESY experiment (Table 3

and Fig. 2). The orientation of the four methine H-atoms H�C(7b), H�C(8b),


Fig. 1. Selected 2D-NMR correlations for cotylelophenol A (1)

Fig. 2. Selected NOEs observed for 1

H�C(7c), and H�C(8c) was concluded to be the same as those in pauciflorol A (5)[5a], not only from NOEs (H�C(2b,6b)/H�C(2c,6c), H�C(7b)/H�C(2c,6c),H�C(7b)/H�C(7c), H�C(8b)/H�C(10c,14c)), but also based on the similarity ofthe signal patterns in both the 1H- and 13C-NMR spectra. Although the C1 ring andH�C(7b) in 1 are located on opposite sides of the molecular reference plane, both areclose to one another, similar as in 5. The A1 ring was also found to be �-oriented, asdeduced from NOEs observed at � 20�, where correlations of H�C(2b,6b)/H�C(2a)and H�C(2b,6b)/H�C(3a) were observed. The remaining stereogenic C-atom, C(8a),thus, had to have the relative (S*)-configuration.In the 1H-NMR spectra of 1 measured under different conditions (see Table 1 and

Figs. 3 and 4), very complicated signal patterns were observed for H�C(2a,6a) andH�C(3a,5a) due to different degrees of immobilization of ring A1 by steric hindrance.At room temperature, the four H-atoms were scarcely observed because of extremesignal broadening, both in (D6)DMSO (Fig. 3,a) and (D6)acetone (Fig. 4,a). When thetemperature was raised to 80 and 100� in (D6)DMSO, the equivalent H-atoms ofH�C(2a,6a) and H�C(3a,5a) appeared as a d (Fig. 3,b ± 3,d). Under these conditions,ring A1, thus, rotates freely. In contrast, when the temperature was lowered in(D6)acetone, the four H-atoms H�C(2a), H�C(6a), H�C(3a), and H�C(5a) wereobserved as separated, broad signals at 0�, which became a broad d below � 20�(Fig. 4,b ± f). At such low temperature, steric hindrance, thus, prevents ring A1 fromfree rotation, which means that these H-atoms are located in different chemicalenvironments. Similar phenomena have been reported in some related stilbeneoligomers of vaticanols G and H [5b], vateriaphenol A [6], and amurensins D±F [2b].

In addition to ring A1, rings C1 and B1 of 1 were also found to be rotationallyrestricted (Fig. 4,d ± f). Four H-atoms on C1, H�C(2c,6c) and H�C(3c,5c), started todisappear at � 60�, and were clearly observed as four separated signals at � 90�. Also,the ring B1 H-atoms, H�C(2b,6b) and H�C(3b,5b), disappeared at � 90�, while thoseof ring A1 did so at room temperature. The mutual couplings of H�C(2a)/H�C(6a),H�C(3a)/ H�C(5a), H�C(2c)/H�C(6c), and H�C(3c)/H�C(5c) were confirmedby 1H,1H-COSYexperiments at � 20 and � 90�. These results indicate that the three 4-

Fig. 3. 300-MHz 1H-NMR Spectra of 1 in (D6)DMSO recorded at 25� (a), 60� (b), 80� (c) , and 100�(d). 2a(6a)�H�C(2a,6a) etc.


hydroxylphenyl rings in 1 are rotationally restricted in the order A1�C1�B1 due todifferential steric hindrance by neighboring substituent(s) and/or other factors.The conclusion that H�C(2a) and H�C(6a), and H�C(3a) and H�C(5a), are

located in different chemical environments at � 20� was further supported by NOESYresults. As can be seen in Fig. 4,c, H�C(2a) and H�C(3a) are separated from theother signals. NOEs were observed between H�C(2a)/H�C(2b,6b) and H�C(3a)/H�C(2b,6b), respectively, but never between H�C(6a)/H�C(2b,6b) and H�C(5a)/H�C(2b,6b), respectively (Fig. 2). If ring A1 rotated freely at � 20�, these NOEsshould have been observed.In the 13C-NMR spectrum of 1, the ring-A1 signals first broadened, and then

disappeared (Table 2). The shifts of the aromatic H-atoms on rings A1 ±C1 to higherfield are well-explained by the anisotropic effects caused by the neighboring rings(Fig. 5). For example, at � 20�, where H�C(5a) and H�C(6a) were observed at �(H)5.90 and 5.70 respectively, these shifts must be caused by the anisotropic effect of ringB1. The anisotropic effects of both rings A1 and C1 resulted in upfield shifts ofH�C(2b,6b) (�(H) 6.02) and H�C(3b,5b) (�(H) 5.50). At � 90�, where the aromaticH-atoms of ring C1 were observed as four separate signals (see Fig. 4, f), H�C(3c) wasshifted upfield to �(C) 6.08 due to the neighboring ring B1. The dibenzobicyclo[5.3.0]-decadiene framework and the configuration at C(8a) causes the additional anisotropy.As mentioned above, such upfield chemical shifts due to anisotropic effects areessential to exactly understand the stereochemistry of stilbenoid oligomers.Certain 13C-NMR signals of 1, e.g., C(11c,13c), C(4c), or C(11a), were found to be

split (−duplicated×) in (D6)acetone (see Table 2 and Fig. 6), but −collapsed× to −first-


Fig. 4. 300-MHz 1H-NMR Spectra of 1 recorded in D6(acetone) at 25� (a), 0� (b), � 20� (c), � 40� (d), � 60�(e), and � 90� (f)

order× signals in (D6)DMSO. The reason for this phenomenon is not clear yet. A similarobservation has been reported for some procyanidins biflavonoids. Fletcher et al. [12]interpreted an observed signal splitting as the result of rotational isomerism [12]. In thecases reported, all signals were observed with multiple features in the occupation ratioof the rotamers, namely a so called −compact× and an −extended× form [13]. Thesemultiple forms were caused by hindered rotation of the asymmetric frames of a flavoneskeleton. However, in the case of compound 1, this rationalization does not hold. First,


Fig. 5. Upfield chemical shifts (�(H)) of aromatic H-atoms of 1 caused by anisotropic effects at low temperature(in brackets)

Fig. 6. 75-MHz 13C-NMR Spectrum of 1 in (D6)acetone at room temperature

not all pertinent signals behaved this way, and second, there are no asymmetric rotatingframes in the molecule. We rather tend to assume that our observation has to do with aconformational exchange and/or a conformational instability. Further detailed analysisof related compounds will provide a clue for these phenomena.Cotylelophenol B (2) was obtained as a yellow solid. The composition was deduced

to be C42H30O10 from the HR-FAB-MS pseudo-molecular ion peak at m/z 693.1754([M�H]� ) and the 13C-NMR spectrum (Table 4). An IR absorption band at1655 cm�1 and an NMR signal at �(C) 185.3 (in (D6)acetone) indicated the presence ofan �,�-unsaturated C�O group (C(13b)). In addition, seven phenolic OH groups weredetected in the 1H-NMR spectrum (Table 4).Acetylation of 2 yielded the octaacetate 2a, suggesting that 2 bore, apart from seven

phenolic OH groups, an additional OH function. The remaining O-atom was, thus,attributed to an ether linkage. 2D-NMRAnalysis of 2 (Table 5) showed that the partialstructures were composed of rings A2 , B1, C1, and C2, and that the four methinesH�C(7b), H�C(8b), H�C(7c), and H�C(8c) were connected in the same manner asin compounds 1, 4, and 5 (Fig. 7, partial structure A). The presence of ring A1 and thebonds C(1a)�C(7a) and C(8a)�C(9a) were also supported by these data (partialstructures A and B).Atoms C(7a) and C(8a) were identified to be quaternary. The remaining ring

system of 2 and the connectivities were determined as follows. The presence of a six-membered ring system was substantiated by the 13C-NMR signals of ring B2 (Table 4),with five quaternary sp2 atoms (C(9b), C(10b), C(11b), C(13b), C(14b)), and ahydrogenated sp2 atom (C(12b)). The proposed partial structures of the five aromaticrings A1 ±C1, A2, and C2 accounted for 20 out of 28 degrees of unsaturation. Thepresence of a C�O group and five sp2 signals on ring B2 suggested a fused quinoid ringsystem (Fig. 7, partial structure C), with the following important HMBC correlations:H�C(7b)/C(9b), H�C(8b)/C(14b), and H�C(8c)/C(9b), which supported connec-tions between C(8b), C(9b), C(14b), and C(8c), in this order. Finally, the bondsC(7a)�C(8a) and C(8a)�C(10b) were assumed after consideration of the molecularskeleton (Fig. 7, partial structure D). The remaining O-atom was assigned to the etherlinkage C(7a) ±O�C(11b). The location of the non-phenolic OH group was deducedto be at C(7a) (structure D). Thereby, the alternative structure D� could be excludedbased on NOESY results, in which a correlation between H�C(2a,6a)/H�C(2b,6b)was observed (Fig. 8). If both C(7a) and C(8a) were olefinic C-atoms (which would bethe case in the partial structure D�), rings A1 and B1 would be much more distant, andthe above correlation would not have been observed.The location of the 7a-OH group was further supported by consideration of the

chemical shifts of the peracetate 2a (Fig. 9). Acetylation generally induced shifts tolower field in the aromatic H-atom signals due to deshielding and/or electron-withdrawing effects of the Ac group(s). On acetylation, stronger shifts were observedfor the ortho H-atoms (�� ca. 0.3 ± 0.4) compared to the para ones (0.1 ± 0.2 ppm),which is a known tool for positional determination of OH group(s) on aromatic rings.These general rules can be applied to rings B1, C1, and C2 in 2a, and to rings A1, A2 , B2 ,and C2 of the acetate 3a, respectively.On acetylation, an aliphatic H-atom also tends to be shifted to lower field due to the

deshielding effect of Ac groups. In the case of 2a, H�C(8b), H�C(7c), and H�C(8c)



Table 4. NMR Data for Cotylelophenol B (2) and Its Peracetate 2a. At 300/75 MHz, resp.; � in ppm, J in Hz.

Atom/Group �(H) �(C)

2a) 2b) 2aa) 2a) 2b)

C(1a) ± ± ± 129.7 128.5H�C(2a,6a) 7.08 (d, J� 8.6) 6.97 (d, J� 8.6) 7.38 (d, J� 8.4) 128.1 127.2H�C(3a,5a) 6.63 (d, J� 8.6) 6.58 (d, J� 8.6) 7.00 (d, J� 8.4) 115,1 114.5C(4a) ± ± ± 158.3 157.6C(7a) ± ± ± 116.4 116.1C(8a) ± ± ± 150.3 150.3C(9a) ± ± ± 131.7 130.5C(10a) ± ± ± 127.2 125.7C(11a) ± ± ± 155.3 154.8H�C(12a) 6.51 (d, J� 2.4) 6.43 (d, J� 2.3) 7.11 (d, J� 2.4) 106.2 105.8C(13a) ± ± ± 156.0 155.2H�C(14a) 7.26 (d, J� 2.4) 7.03 (d, J� 2.3) 7.63 (d, J� 2.4) 110.9 109.8C(1b) ± ± ± 133.1 131.6H�C(2b,6b) 6.61 (d, J� 8.6) 6.43 (d, J� 8.6) 6.76 (d, J� 8.4) 130.0 129.0H�C(3b,5b) 6.37 (d, J� 8.6) 6.32 (d, J� 8.6) 6.68 (d, J� 8.4) 114.3 113.7C(4b) ± ± ± 155.4 154.9H�C(7b) 5.16 (d, J� 2.7) 4.96 (d, J� 2.7) 4.68 (d, J� 2.7) 38.4 37.8H�C(8b) 4.28 (dt, J� 10.2, 2.7) 4.28 (dt, J� 10.2, 2.7) 4.56 (dt, J� 10.2, 2.7) 51.7 50.8C(9b) ± ± ± 144.8 144.1C(10b) ± ± ± 125.9 124.4C(11b) ± ± ± 169.5 168.6H�C(12b) 5.58 (s) 5.60 (s) 5.73 (s) 99.9 98.9C(13b) ± ± ± 185.3 184.5C(14b) ± ± ± 141.4 140.0C(1c) ± ± ± 131.6 129.9H�C(2c,6c) 7.00 (d, J� 8.6) 6.96 (d, J� 8.6) 7.18 (d, J� 8.4) 130.6 129.7H�C(3c,5c) 6.54 (d, J� 8.6) 6.52 (d, J� 8.6) 6.95 (d, J� 8.4) 114.7 114.2C(4c) ± ± ± 156.1 155.3H�C(7c) 3.97 (dd, J� 10.2, 4.8) 3.87 (dd, J� 10.2, 4.8) 4.27 (dd, J� 10.2, 4.8) 57.7 56.3H�C(8c) 4.58 (dd, J� 4.8, 2.7) 4.41 (dd, J� 4.8, 2.7) 5.01 (dd, J� 4.8, 2.7) 56.1 54.6C(9c) ± ± ± 147.9 146.8H�C(10c,14c) 6.19 (d, J� 2.0) 6.01 (d, J � 2.0) 6.93 (d, J� 2.0) 106.1 105.1C(11c,13c) ± ± ± 158.8 158.1H�C(12c) 6.16 (t, J� 2.0) 6.04 (t, J � 2.0) 6.84 (t, J� 2.0) 101.0 100.4HO�C(4a) ± 9.59 (br. s)c) ± ± ±HO�C(7a) ± 4.60 (br. s)c) ± ± ±HO�C(11a) ± 9.60 (br. s)c) ± ± ±HO�C(13a) ± 9.40 (br. s)c) ± ± ±HO�C(4b) ± 8.86 (br. s)c) ± ± ±HO�C(4c) ± 9.12 (br. s)c) ± ± ±HO�C(11c,13c) ± 9.05 (br. s)c) ± ± ±HO (3�) 7.94 (br. s), 8.27 (br. s),

8.61 (br. s)± ± ±

Ac (8�) ± ± 2.37 (s), 2.33 (s), 2.24 (s),2.21 (s), 2.20 (s), 2.20 (s),2.20 (s), 2.20 (s)

± ±

a) In (D6)Acetone. b) In (D6)DMSO. c) Assigned by NOESY.

were shifted by �� 0.28 ± 0.43 to lower field. However, H�C(7b) was shifted upfield by0.48 ppm. These shifts can be rationalized by the anisotropic effect of the neighboringC�O groups, since H�C(7b) is located in a shielding region of the Ac group atC(11a). A similar situation is found for H�C(7b) in 3a, which is shifted upfield by0.24 ppm due to the anisotropy effect of the Ac group at C(13a). On the basis of theseresults, the −abnormal× shifts of H�C(2a,6a) and H�C(14a) in 2a were rationalized asfollows. While the H�C(2a,6a) signals were deshielded, the H�C(14a) signal wasshielded by the Ac group at C(7a). This observation strongly supported the location ofthe aliphatic OH group at C(7a). Also, the NOESY spectrum of 2 (Fig. 8) was inaccordance with a three-dimensional structure in which the four-methine sequence(H�C(7b), H�C(8b), H�C(7c), H�C(7b)) was arranged in the same manner as in 1and pauciflorol A (5).In addition to the two new resveratrol trimers 1 and 2, the ten known stilbene-type

oligomers 3 ± 12 [5] were isolated, and identified as vaticanols G (3), A (4), B (7), C(8), D (9), H (10), I (11), and J (12), pauciflorol A (5), and (�)-�-viniferin (6).2. Biogenetic Considerations. The resveratrol oligomers 1 ± 12 isolated from C.

lanceolatum are presumed to be produced by successive oxidative couplings of aresveratrol monomer and/or an �-viniferin (dimer). Plausible coupling modes via


Table 5. HMBC and NOESY 75-MHz NMR Data of 2. Correlations were observed both in (D6)acetone and(D6)DMSO, unless noted otherwise.

H-Atom 1H,13C-HMBC 1H,1H-NOESY

H�C(2a,6a) C(4a), C(7a) H�C(14a), H�C(2b,6b)H�C(3a,5a) C(1a), C(4a) HO�C(4a)H�C(12a) C(10a), C(11a), C(13a), C(14a) HO�C(11a), HO�C(13a)H�C(14a) C(8a), C(9a), C(10a), C(12a), C(13a) H�C(2a,6a), HO�C(13a)H�C(2b,6b) C(4b), C(7b) H�C(2a,6a), H�C(7b), H�C(8c)H�C(3b,5b) C(1b), C(4b) HO�C(4b)H�C(7b) C(9a), C(10a), C(11a), C(1b),

C(2b,6b), C(8b), C(9b), C(7c)H�C(2b,6b), H�C(8b), H�C(2c,6c)

H�C(8b) C(1b), C(7b), C(9b), C(14b) H�C(7b), H�C(7c), H�C(10c,14c)H�C(12b) C(10b), C(11b), C(14b)H�C(2c,6c) C(4c), C(7c) H�C(7b), H�C(7c), H�C(8c)H�C(3c,5c) C(1c), C(4c) HO�C(4c)H�C(7c) C(7b), C(8b), C(9b), C(14b), C(1c),

C(2c,6c), C(8c), C(9c)H�C(8b), H�C(2c,6c), H�C(8c),H-C(10c,14c)

H�C(8c) C(9b), C(14b), C(1c), C(7c),C(9c), C(10c,14c)

H�C(2b,6b), H�C(2c,6c), H�C(7c),H�C(10c,14c)

H�C(10c,14c) C(8c), C(11c,13c), C(12c) H�C(8b), H�C(7c), H�C(8c),HO�C(11c,13c)

H�C(12c) C(9c,14c), C(11c,13c) ��C(11c,13c)HO�C(4a)a) C(3a,5a), C(4a) H�C(3a,5a)HO�C(11a)a) C(10a), C(11a), C(12a) H�C(12a)HO�C(13a)a) C(12a), C(13a), C(14a) H�C(12a), H�C(14a)HO�C(4b)a) C(3b,5b), C(4b) H�C(3b,5b)HO�C(4c)a) C(3c,5c), C(4c) H�C(3c,5c)HO�C(11c,13c)a) C(10c,14c), C(11c,13c), C(12c) H�C(10c,14c), H�C(12c)a) In (D6)DMSO)

radicals species are shown in the Scheme. Two pathways are suggested for theproduction of vaticanol-A-type trimers: vaticanols A (4) and E, and pauciflorols A (5)and B. One involves a step-by-step coupling of three resveratrol units via the


Fig. 7. Selected 2D-NMR correlations for the partial structures A ±D of cotylelophenol B (2)

Fig. 8. Spatial structure and NOEs observed for 2

hypothetical radical E, followed by formation of a dihydrobenzofuran ring in the laststep (Scheme, Path 1). The other route involves coupling of a dimer of �-viniferin (6),which has a dihydrobenzofuran ring, with a resveratrol (Path 2).

Sotheeswaran et al. [1a] proposed that resveratrol oligomers can be classifiedbiogenetically into two groups, I and II, depending on whether they have dihydro-benzofuran rings (group I) or not (group II). In group-I compounds, the dihydro-benzofuran ring is attributed to that of 6. However, we propose here that group-Icompounds involve the biogenetic Paths 1 and 2 (Scheme). That is, the intermediary,trimeric radical E participates in formation of furan rings in addition to �-viniferin (6),for the following reasons: 1) A partial structure of E has been commonly identified innatural resveratrol hexamers or a heptamer, and E is apt to couple with otherresveratrol units. In the case of the resveratrol oligomers in C. lanceolatum, radical Ecoupled with vaticanols G (3) and B (7) results in the formation of vaticanols H (10)and J (12). When E is coupled with pauciflorol B, which has not been isolated from thisplant, vaticanols D (9) and I (11) are produced. 2) Vaticanol G (3) is a majorconstituent of this plant, and is biosynthesized via the trimeric radical E. It is a rareexample of a resveratrol trimer lacking a dihydrobenzofuran ring.From a stereochemical standpoint, the presence of the trimeric radical E is also

supported. The relative configuration of the four methines in E is commonlymaintained in the resulting oligomers. If E had a different, not fixed configuration,the resulting oligomers would exhibit high structural diversity. Although pauciflorol A(5) is the only vaticanol-A-type trimer, and has the same relative configuration as E, itis not clear whether 5 is biosynthesized either via Paths 1 or 2. However, the majorpathway for the vaticanol-A-type trimer is preferable to Path 2, when the configurationof the pertinent methine groups is considered.In addition to Paths 1 and 2, two other routes (Paths 3 and 4) may be proposed for

the formation of resveratrol oligomers. Vaticanol B, which is a major resveratroltetramer, comprises a characteristic indane moiety. The latter would be constructed


Fig. 9. Changes in NMR chemical shifts (��(H)) for the acetates 2a and 3a relative to the non-acetylatedcompounds


Scheme.

Plausible

Biogenetic

Pathw

aysof

Resveratrol

Olig

omers

through a hypothetical radical F during biogenesis (Path 3), which includes thecondensation of a pair of �-viniferins. In Path 4, coupling of pauciflorol B (a vaticanol-A-type trimer) with a resveratrol takes place. When the co-existence of vaticanols B (7)and C (8) as major product is considered, the preferable route for 7 would be Path 3.Among vaticanol-A-type trimers, pauciflorol A (5) could be regarded as a

precursor of 1 and 2. Although the mechanism is not clear, 2 is produced through 5, andthe skeleton of 1 is accomplished by rearrangement of ringA1 after several conversions,including oxidation of 5. These considerations reasonably rationalize the biogenesis ofthree different bicyclic systems: dibenzobicyclo[3.2.1]octadiene (for 8), dibenzobicy-clo[3.3.0]octadiene (for 1, 2, 4, 5, 7, and 9 ± 12), and tribenzobicyclo[3.3.2]octatriene(for 3 and 10).The phylogenetic relationships in Dipterocarpaceaeous plants have been addressed

using both morphological [11] and chloroplast-gene analytical data [14]. The twogeneraCotylelobium andVatica have been reported to bear a close relationship in theseexaminations. When the chemical constituents are additionally compared, all theisolates of C. lanceolatum, except for 1, 2, and 5, match those of Vatica rassak. They alsobear a resemblance in the major constituents of vaticanols B (7), C (8), and G (3).Thus, Cotylelobium and Vatica seem to be closely related genera based on phylogeneticresults.

We are grateful to Mr. Y. Doke, Gifu Prefectural Institute of Industrial Product Technology, for technicalsupport regarding NMR experiments. We also express our appreciation to Mrs. M. Hosokawa and Mrs. M.Hayashi, Gifu Pharmaceutical University, for measurements of FAB mass spectra.

Experimental Part

General. Anal. and prep. TLC: Kieselgel F254 (0.25 mm;Merck). Column chromatography (CC): silica gel60 (70± 230 mesh; Merck), ODS (100 ± 200 mesh; Fuji Silysia Chemical), or Sephadex LH-20 (Pharmacia).Optical rotation: Jasco P-1020 polarimeter. UV Spectra: Shimadzu UV-2200 spectrophotometer; �max (log �) innm. IR spectra: Jasco FT-IR-8000 spectrophotometer; KBr microplate; in cm�1. 1H- and 13C-NMR Spectra: JeolJNM-LA-300 spectrometer; in (D6)acetone; �(H) in ppm rel. to Me4Si (�0 ppm) as internal standard, �(C)in ppm rel. to residual solvent signals (C�O at 206.0 ppm); coupling constants J in Hz. FAB-MS: Jeol JMS-DX-300 spectrometer; in m/z.

Plant Material. Cotylelobium lanceolatum ��. was cultivated at Bogor Botanical Garden, Bogor,Indonesia. The stem was collected inMay 2000, and identified byD. D.Avoucher specimen was deposited at theGifu Prefectural Institute of Health and Environmental Sciences, Gifu, Japan.

Extraction and Isolation. The dried and well-ground stem of C. lanceolatum (800 g) was successivelyextracted with acetone (3� 3 l), MeOH (3� 3 l), and 70% MeOH (2� 3 l) at r.t., and the extracts wereevaporated to afford 70 g (from acetone), 15 g (from aq. MeOH), and 14 g (from aq.MeOH) of rawmaterial. Apart (65 g) of the acetone extract was subjected to CC (SiO2; CHCl3/MeOHmixtures of increasing polarity): Fr.1 ± 13. Compound 6 (650 mg) was obtained from Fr. 2 (CHCl3/MeOH 10 :1; 3.5 g) after purification by repeatedCC (Sephadex LH-20 ; MeOH). Fr. 4 (CHCl3/MeOH 8 :1; 1.2 g) was re-subjected to CC (Sephadex LH-20 ;MeOH) to afford the subfractions Fr. 4a ± c. Compounds 4 (8 mg) and 5 (12 mg) were obtained from Fr. 4c afterpurification by CC (RP, 40% MeOH; then Sephadex LH-20, MeOH) and prep. TLC (AcOEt/CHCl3/MeOH/H2O 15 :8 : 4 : 1). Compounds 1 (6 mg) and 2 (40 mg) were obtained from Fr. 5 (CHCl3/MeOH 8 :1; 1.1 g) afterpurification by CC (RP; 40% MeOH) and repeated prep. TLC (AcOEt/CHCl3/MeOH/H2O 15 :8 :4 :1).Compounds 7 (550 mg) and 8 (80 mg) were isolated from Fr. 6 (CHCl3/MeOH 7 :1; 5.5 g) after purification byCC (Sephadex LH-20 ; MeOH). Purification of Fr. 7 (CHCl3/MeOH 6 :1; 6 g) by CC (Sephadex LH-20 ; MeOH)resulted in 3 (4.8 g). Compound 9 (5 mg) was obtained from Fr. 10 (CHCl3/MeOH 5 :1; 4.5 g) after purificationby CC (Sephadex LH-20, MeOH; then RP, 30% MeOH) and prep. TLC (AcOEt/CHCl3/MeOH/H2O6 :3 : 3 : 1). Compounds 10 (15 mg), 11 (10 mg), and 12 (20 mg) were obtained from Fr. 12 (CHCl3/MeOH 5 :1;3.6 g) after purification by CC (RP, 30% MeOH) and prep. TLC (AcOEt/CHCl3/MeOH/H2O 6 :3 :3 :1).


Colylelophenol A (� (3S*,4S*,4aS*,5S*,9bS*)-3-(3,5-Dihydroxyphenyl)-4,4a,5,9b-tetrahydro-2,6,8-trihy-droxy-4,5,9b-tris(4-hydroxyphenyl)-11-oxabenzo[5,6]cyclohepta[1,2,3,4-jkl]-as-indacen-10(3H)-one ; 1). Paleyellow solid. [�]25D ��150 (c � 0.1, MeOH). UV: 208 (4.93), 224 sh (4.72), 281 (3.99). IR: 3387, 1777, 1611,1450. 1H- and 13C-NMR: see Tables 1 ± 3. FAB-MS (neg.): 693 ([M�H]�). HR-FAB-MS (neg.): 693.1773([M�H]� , C42H29O�

10 ; calc. 693.1760).Colylelophenol B (� (3S*,4S*,4aS*,5S*,10R*)-3-(3,5-Dihydroxyphenyl)-3,4a,5,10-tetrahydro-6,8,10-trihy-

droxy-4,5,10-tris(4-hydroxyphenyl)-11-oxabenzo[5,6]cyclohepta[1,2,3,4-jkl]-as-indacen-2(4H)-one ; 2). Yellowsolid. [�]25D � 527 (c � 0.1, MeOH). UV: 213 (4.74), 275 sh (4.03), 388 (4.31). IR: 1655, 1613, 1543, 1512, 1456.1H- and 13C-NMR: see Tables 4 and 5. FAB-MS (neg.): 693 ([M�H]� . HR-FAB-MS (neg.): 693.1754 ([M�H]� , C42H29O�

10 ; calc. 693.1760).Cotylelophenol Heptaacetate (2a). A soln. of 2 (3 mg) in pyridine (0.5 ml) andAc2O (0.1 ml) was kept at r.t.

for 24 h. Workup in the usual manner and purification of the resulting crude product (3 mg) by prep. TLC(hexane/AcOEt 1 :1) afforded 2a (3 mg). Pale yellow solid. 1H-NMR: see Table 4. FAB-MS (neg.): 987 ([M�H]�).

REFERENCES

[1] a) S. Sotheeswaran, V. Pasupathy, Phytochemistry 1993, 32, 1083; b) J. Gorham, M. Tori, Y. Asakawa, −TheBiochemistry of the Stilbenoids×, Chapman & Hall, London, 1995.

[2] a) K.-S. Huang, M. Lin, G.-F. Cheng, Phytochemistry 2001, 58, 357; b) K.-S. Huang, M. Lin, L.-N. Yu, M.Kong, Tetrahedron 2000, 56, 1321.

[3] J. Kawabata, M. Mishima, H. Kurihara, J. Mizutani, Phytochemistry 1995, 40, 1507.[4] I. Iliya, Z. Ali, T. Tanaka, M. Iinuma, M. Furusawa, K. Nakaya, J. Murata, D. Darnaedi, N. Matsuura, M.

Ubukata, Phytochemistry 2003, 62, 601.[5] a) T. Ito, T. Tanaka, M. Iinuma, I. Iliya, K. Nakaya, Z. Ali, Y. Takahashi, R. Sawa, Y. Shirataki, J. Murata, D.

Darnaedi, Tetrahedron 2003, 59, 5347; b) T. Ito, T. Tanaka, K. Nakaya, M. Iinuma, Y, Takahashi, H.Naganawa, M. Ohyama, Y. Nakanishi, K. F. Bastow, K.-H. Lee, Tetrahedron 2001, 57, 7309; c) T. Tanaka, T.Ito, K. Nakaya, M. Iinuma, S. Riswan, Phytochemistry 2000, 54, 63.

[6] T. Ito, T. Tanaka, M. Iinuma, K. Nakaya, Y. Takahashi, R. Sawa, H. Naganawa, V. Chelladurai, Tetrahedron2003, 59, 1255; T. Ito, T. Tanaka, K. Nakaya, M. Iinuma, Y. Takahashi, H. Naganawa M. Ohyama, Y.Nakanishi, K. F. Bastow, K.-H. Lee, Tetrahedron Lett. 2001, 42, 5909.

[7] T. Ito, M. Furusawa, I. Iliya, T. Tanaka, K. Nakaya, R. Sawa, Y. Kubota, Y. Takahashi, S. Riswan, M.Iinuma, Tetrahedron Lett. 2005, 46, 3111; T. Ito, T. Tanaka, M. Iinuma, K. Nakaya, Y. Takahashi, H.Nakamura, H. Naganawa, S. Riswan, Helv. Chim. Acta 2003, 86, 3394.

[8] T. Ito, Z. Ali, I. Iliya, M. Furusawa, T. Tanaka, K. Nakaya, Y. Takahashi, R. Sawa, J. Murata, D. Darnaedi,M. Iinuma, Helv. Chim. Acta 2005, 88, 23.

[9] T. Ito, T. Tanaka, M. Iinuma, K. Nakaya, Y. Takahashi, R Sawa, J. Murata, D. Darnaedi, Helv. Chim. Acta2004, 87, 479.

[10] T. Tanaka, T. Ito, Y. Ido, K. Nakaya, M. Iinuma, V. Chelladurai, Chem. Pharm. Bull. 2001, 49, 785.[11] P. S. Ashton, −Flora Malesiana. Ser. I: Spermatophyta× ; Ed. C. G. G. J. Steenis, Martivus Nijhoff Publishers,

Leiden, 1982, Vol. 9, p. 341.[12] A. C. Fletcher, L. J. Porter, E. Haslam, R. K. Guta, J. Chem. Soc., Perkin Trans. 1 1977, 1628.[13] T. Hatano, R. W. Hemingway, J. Chem. Soc., Perkin Trans. 2 1997, 1035.[14] Y. Tsumura, T. Kawahara, R. Wickneswari, Theor. Appl. Genet. 1996, 93, 22.; S. Dayanandan, P. S. Ashton,

S. M. Williams, R. B. Primack, Am. J. Bot. 1999, 86, 1182.

Received March 29, 2005


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Two Novel Trimeric Resveratrol Derivatives from Cotylelobium lanceolatum