Chemistry and Antioxidative Activity of Lignan Glucosides in Sesame

Chapter 28

Chemistry and Antioxidative Activity of Lignan Glucosides in Sesame Seed Hirotaka Katsuzaki, Toshihiko Osawa, and Shunro Kawakishi

Downloaded by YORK UNIV on November 11, 2012 | http://pubs.acs.org Publication Date: May 5, 1994 | doi: 10.1021/bk-1994-0547.ch028

Department of Food Science and Technology, Nagoya University, Chikusa, Nagoya 464-01, Japan

Novel lipid-soluble lignans, sesamolinol, sesaminol and pinoresinol were isolated from sesame seed. While the quantity of these lignans was small, most of these lignans were found to exist as glucosides in sesame seed. Three novel lignan glucosides were isolated as the water-soluble antioxidative components from the 80% ethanol extracts of sesame seed. Their structures have been confirmed by instrumental analysis as pinoresinol 4'-O-β-D-glucopyranosyl(1—>6)β-D-glucopyranoside (KP1), pinoresinol 4'-O-β-D-glucopyranosyl(1—>2)-β-D-glucopyranoside (KP2), and the lignan triglucoside pinoresinol 4'-O-β-D-glucopyranosyl(1—>2)-0-[β-D-glucopyranosyl(1—>6)]-β-D-glucopyranoside (KP3). These lignan glucosides have unique glucosidic linkages, in particular KP3, which has branched (1—>2)- and (1—>6)-linkages. Chemistry and antioxidative activity of lignan glucosides using several in vitro systems are discussed.

Recently much attention has been focused on studies which suggest the involve ment of active oxygen and free radicals in a variety of pathological events, cancer, and even the aging process. In particular, oxygen species such as hydrogen peroxide, superoxide anion radical, singlet oxygen and other radicals, are proposed as agents that attack polyunsaturated fatty acid in cell membranes, giving rise to lipid peroxidation. Lipid peroxidation may cause oxidative damage in the living cell, and finally, that damage leads to aging and susceptiblity to cancer. Normal cell membranes do not undergo lipid peroxidation, however, because of the efficient protective mechanism against damage caused by active oxygen and free radicals. On the other hand, dietary antioxidants may effectively protect from peroxidative damage in living systems. Many natural antioxidants have been found in numerous plant and food products. We have isolated lipid-soluble lignan antioxidants, such as sesamolinol (1) and sesaminol (2), from sesame seed (Figure 1). Presently, we describe the isolation of antioxidants from sesame seed which are novel lignan glucosides. These compounds were determined by instrumental analyses (including ID and 2D NMR) and methylation analysis (3) using GC-MS (4, 5).

0097-6156/94/0547-0275$06.00/0 © 1994 American Chemical Society

In Food Phytochemicals for Cancer Prevention II; Ho, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.

FOOD PHYTOCHEMICALS II: TEAS, SPICES, AND HERBS

276


OCH

3

Sesamolinol

Sesaminol

Sesamol

OCH3

Pinoresinol

OCH3

P1

Figure 1. Structures of lipid-soluble antioxidants isolated from sesame seed

Isolation Sesame seed (500 g) was ground, defatted with n-hexane, and extracted with 80% ethanol. The extract was charged onto an Amberlite X A D - 2 column, and eluted with H2O, 50% methanol, methanol and acetone. The 50% methanol fraction has antioxidative activity. This fraction was purified by preparative H P L C (ODS column). From two active fractions, two active compounds, temporarily named KP1 (10.3 mg) and KP2 (21.3 mg), were isolated. The third active fraction was further purified by preparative H P L C (phenyl column), and two compounds, temporarily named KP3 (26.1 mg) and KP4 (25.4 mg), were isolated. Structural Determination These compounds generated the aglycone pinoresinol and D-glucose with βglucosidase digestion. FAB-MS of KP, KP2 and KP4 showed the same [M+H] at m/z 683 and m/z 705 as a [M+Na] peak, and KP3 showed [M+H] at m/z 845 and m/z 867 as a [M+Na] peak. The results of hydrolysis and F A B - M S spectroscopy indicate that KP1, KP2, and KP4 are constituted from one pinoresinol and two Dglucoses, and KP3 is constituted from one pinoresinol and three D-glucoses. +

+

+

+


28.

K A T S U Z A K I E T A L

Lignan Glucosides in Sesame Seed

277

KP4 was identified as pinoresinol di-OP-D-glucopyranoside by comparison of the U V , MS, IR, N M R and [a] data with those of an authentic sample, which was isolated from Eucommia ulmoides by Deyama (6). In the ^ - N M R spectrum, KP1 and KP2 had two anomeric protons and KP3 had three anomeric protons. The anomeric configuration of D-glucosyl residues were deduced from the homonuclear vicinal coupling constants. Values obtained for the ^-homonuclear coupling constants of D-glucose moieties (all coupling constant showed ca. 7.5 Hz) were characteristic of the β-configurations. This config uration also supported the conclusion that these four compounds can be hydrolyzed to D-glucose and pinoresinol with β-glucosidase. In the C - N M R spectrum, each C-4' signal of KP1, KP2, and KP3 showed downfield shifts in comparison with each C-4" signal. These data indicate that, for each compound, the sugar residues were linked at the C-4' positions of the aglycone. Chemical shift of C-G6 of KP1 showed a downfield shift in comparison with C-G6'; therefore, the C-G6 position was assumed to be linked with D-glucosyl residues. The methylation analysis using GC-MS gave two peaks, the first peak was determined to be l,5-di-0-acetyl-2,3,4,6-tetra-0-methyl-D-glucitol and second peak was determined to be l,5,6-tri-0-acetyl-2,3,4-tri-0-methyl-D-glucitol from the mass fragments (7). The 0-6 position of l,5,6-tri-0-acetyl-2,3,4-tri-0-methylD-glucitol was not methylated, and indicating that KP1 had a (1—»6)-linked D-glucosyl residue. From these results, the structure of KP1 was determined to be pinoresinol 4'-0^-D-glucopyranosyl(l—»6)^-D-glucopyranoside (Figure 2). Chemical shift of C-G2 of KP2 showed a downfield shift in comparison with C-G2'. From this results, glucosidic linkage of KP2 was assumed to be a (1—»2)-linkage. Two peaks given by methylation analysis using G C - M S were characteristic for sugars, and determined to be l,5-di-0-acetyl-2,3,4,6-tetra-0methyl-D-glucitol and l,2,5-tri-0-acetyl-3,4,6-tri-0-methyl-D-glucitol from the mass fragments (7). Since the 0-2 position of l,2,5-tri-0-acetyl-3,4,6-tri-0-methylD-glucitol was not methylated, a (1—>2)-glucosidic linkage was confirmed. Thus KP2 was determined to be pinoresinol 4'-0^-D-glucopyranosyl(l—>2)-β-ϋglucopyranoside (Figure 2). For the C - N M R spectrum of KP3, one of the 2 position carbon signals of D-glucosyl residues showed a downfield shift in comparison with the other 2 position carbon signals of D-glucosyl residues, and one of the 6 position carbon signal of D-glucosyl residues showed a downfield shift in comparison with the other 6 position carbon signals. These results suggest that KP3 has both (1—»2)- and (1—»6)-glucosidic linkages. Methylation analysis using GC-MS for the KP3 gave two peaks, which were determined to be l,5-di-0-acetyl-2,3,4,6-tetra-0-methyl-Dglucitol and l,2,5,6-tetra-0-acetyl-3,4-di-0-methyl-D-gluciotl from mass fragments (7). The 0-2 and 0-6 position of l,2,5,6-tetra-0-acetyl-3,4-0-dimethyl-D-glucitol were not methylated; therefore, the pinoresinol linked D-glucosyl residue had branched (l->2)- and (1—>6)-glucosidic linkages. From these results, KP3 was confirmed as pinoresinol 4'-0^-D-glucopyranosyl(l—>2)-0-$-D-glucopyranosyl(1—>6)]^-D-glucopyranoside (Figure 2). D


13

13

Antioxidative Activity KP1, KP2, and KP3 had strong antioxidative activity, but KP4 did not, using rabbit erythrocyte membrane ghost system (8) (Figure 3). Moreover, KP1, KP2, KP3, and




278


28.

KATSUZAKI ET AL.

Lignan Glucosides in Sesame Seed

279

KP4 were classified in the category of pro-antioxidant, because they produce the lipid-soluble antioxidant pinoresinol by hydrolysis with β-glucosidase of intestinal bacteria after intake as food components (9). It is thought that when we eat sesame seed, these lignan glucosides produce the lipid-soluble antioxidative lignan pinoresinol, which protects against oxidative damage in the membrane lipids.

•— · ·

control

··· ·· ι

KPl Downloaded by YORK UNIV on November 11, 2012 | http://pubs.acs.org Publication Date: May 5, 1994 | doi: 10.1021/bk-1994-0547.ch028

KP2 KP3

ι

KP4

I

Pinoresinol Z3 γ-Tocopherol Zl 0

100 Lipid peroxidation (%) (Final concentration of each compound: 80 μΜ) Figure 3. Antioxidative activity of lignan glucosides using the rabbit erythro cyte membrane ghost system

Conclusions 1. Three new lignan glucosides ( K P l , KP2, and KP3) were isolated from sesame seed. The yield of new lignan glucoside and pinoresinol 4'-di-0-P-D-glucopyranoside (KP4) from 500 g sesame seed were: K P l , 10.3 mg; KP2, 21.3 mg; KP3,26.1 mg; KP4, 25.5 mg. 2. Isolated lignan glucosides were easily hydrolyzed to pinoresinol and D-glucose by β-glucosidase. 3. The three new lignan glucosides were determined to be the follwing: K P l : pinoresinol 4'-0-p-D-grucopyranosyl(l—>6)-P-D-glucopyranoside. KP2: pinoresinol 4'-0-P-D-glucopyranosyl(l—>2)-P-D-glucopyranoside. KP3: pinoresinol 4 -0-(î-D-glucopyranosyl(l-^2)-Ô-[p-D-glucopyranosyl(l->6)]β-D-glucopyranoside. 4. K P l , KP2, and KP3 had antioxidative activity using the rabbit erythrocyte membrane ghost system, and all of the lignan glucosides formed the lipid-soluble antioxidative aglycone, pinoresinol. /

Literature Cited 1. Osawa, T.; Nagata, M.; Namiki, M.; Fukuda, Y. Agric. Biol. Chem. 1985, 49, 3351-3352. 2. Fukuda, Y.; Osawa, T.; Namiki, M.; Ozaki, T. Agric. Biol. Chem. 1985, 49, 301-306. 3. Hakomori, S. J. Biochem. 1964, 55, 205-207. In Food Phytochemicals for Cancer Prevention II; Ho, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1994.


280

4. Katsuzaki, H.; Kawasumi, M.; Kawakishi, S.; Osawa, T. Biosci. Biotech. Biochem. 1992, 56, 2087-2088. 5. Katsuzaki, H.; Kawakishi, S.; Osawa, T. Heterocycles, in press. 6. Deyama, T.; Chem. Pharm. Bull. 1983, 31, 2993-2997. 7. Bjorndal, H.; Lindberg, B.; Svenssn, S. Carbohyd. Res. 1967, 5, 433-440. 8. Osawa, T.; Ide, Α.; Su, J.-De; Namiki, M. J. Agri . Food Chem. 1987, 35, 808-812. 9. Tamura, G.; Gold, C.; Ferro-Luzzi, Α.; Ames, Β. N. Proc. Natl. Acad. Sci. USA 1980, 77, 4961-4965.


R E C E I V E D May 8, 1993


Chemistry and Antioxidative Activity of Lignan Glucosides in Sesame

Recommend Documents