311
Anti-Oxidant Activity of Dibenzocyclooctene Lignans Isolated from Schisandraceae Hua Lu' and Geng-Tao Liu 1.2 Department of Pharmacology, Institute of Materia Medica. Chinese Academy of Medical Sciences. Beijing 100050, People's Republic ofChina 2 Address for correspondence Received: June 17. 1991
The anti-oxidant activity of nine diben-
peroxidation and the generation of superoxide anion were studied. The chemical structure of schisanhenol, the most active lignan, is shown in Fig. 1.
zocyclooctene lignans isolated from Schisandra
chinensis. S. rubr(flora, and Kadsura longipedunculata, respectively, was studied. Seven of the 9 lignans (1 mM)
inhibited iron/cysteine-mnduced lipid peroxidation
(malondialdehyde, MDA, formation) of rat liver micro-
somes as well as superoxide anion production in the xanthine/xanthine oxidase system. The actions of the 7 lignans were much more potent than vitamin E at the
same concentration of 1 mM. Among the lignans. schisanhenol was the most active one. This compound
also prevented the decrease of membrane fluidity of liver microsomes induced by iron/cysteine. The results indicated that seven of the lignans such as schisanhenol have anti-oxidant activities.
OCH3
H3COL
H3CO/
H
OCH3 schisanhenol
Fig. 1 Chemical structure of schisanhenol isolated from Schisandra rubriflora Rhed et Wils.
Key words
Schisandra chinensis, Schisandra rubriflora, Kadsura longipedunculata, dibenzocyclooctene lignans, schisanhenol, lipid peroxidation, anti-oxidant activity.
Introduction The medicinal drug Fructus Schisandrae chinensis (FS) has been used as a tonic and anti-aging drug in traditional Chinese medicine (1). FS was found to improve the liver function of patients with viral hepatitis in
Materials and Methods Male Wistar rats weighing 195 SD 12.5 g were used. Nine lignans were kindly provided by Profs. Y. Y. Chen and N. L. Lee in our institute. The name of each lignan is given below: schisandrin A (Sin A), (+)-schisandrin B (Sin B), R(+)-schisandrin B lR(+)Sin B], S(—)-schisandrin B [S(—)Sin B], R(+)-schisandrin C [R(+)Sin C], S(—)-schisandrin C [S(—)Sin C], schisanhenol (Sal),
schisandrol A (Sol A), and schisandrol B (Sol B). Xanthine, xanthine oxidase. cytochrome C, cysteine, and 1.6-diphenyl-1,3, 5-hexatriene (DPH) were purchased from Sigma Chemical Co. The other reagents (A.G) were obtained from the market in Beijing.
Preparation of liver microsomes
China (2). Our previous studies demonstrated that 15 dibenzocyclooctene lignans isolated from Schisandra
capitation. The livers were perfused in situ with ice-cold 1.15 %
chinensis, S. rubriflora and Kadsura longipedunculata, respectively, reduced the liver damage and microsomal lipid
KC1 solution. Liver microsomes were prepared (6) and microsomal protein was determined by the method of Lowry (7).
peroxidation induced by Cd4 (3, 4). CCl induces lipid peroxidation by formation of the free radical methyl tnchloride ('Cd3) in liver microsomes (5). The inhibition of CC14-induced lipid peroxidation by the lignans implicated that these compounds might have an anti-oxidant activity.
To veri1' this possibility, the effects of 9 dibenzocyclooctene lignans on the iron/cysteine-induced lipid
The rats were starved overnight before de-
Measurement of iron/cysteine- induced lipid peroxidation (MDA formation) The incubation mixture contained 1 ml phosphate buffer (0.IM, pH 7.4) 1.4mg microsomal protein, 10tl of the lignan in dimethyl sulfoxide (DMSO) or only DMSO, FeSO4 5—100sM, and 2—10MM cysteine. After incubation for 30mm at
Downloaded by: NYU. Copyrighted material.
Abstract
312 Planta Med. 58(1992)
IIua Lu and Geng-Tao Liu
37°C. the reaction mixture was quenched with 20% tn-
200
chloroacetic acid (TCA) (0.5 ml). Malonic dialdehyde (MDA) in the
supernatant after centrifugation was determined by the colorimetric method using thiobarbituric acid (TBA) (8) and used as the indication for lipid peroxidation (9. 10).
150
Determination ofmembranefluidity DPI-I lipid probe was used for the determination
100
of rnicrosomal fluidity by fluorescence polarization. The incubation mixture contained 1.5 ml phosphate buffer (0.1 M. p11 7.4). microsomal protein 50g, and DPH 2MM. The amount of the lignan and Fe2' /cysteine added was the same as described in the *xperiment for lipid peroxidation. Incubation was carried out at 25°C for I h. The incubation mixture was then subjected to polarization analysis by recording the fluorescence at emission 432 nm with the excitation at 363 nm. The fluorescence polarization was calculated according to the known equation (11).
50
0
Fe2+ concentration (M
Tris-HCI buffer (0.1 M, pH 7.4) (1 ml) contained xanthine 0.2mM. cytochrome C 0.2M. lignan or DMF, and 0.02 unit of xanthine oxidase. The mixture was incubated for 5 mm at 25°C. The difference of absorbance (A) of cytochrome C at the wave length 550—557 nm was recorded with a double wavelength spectrophotometer. The amount of the reduction of cytochrome C was used to indicate 0; generation (12).
Fig. 2 Influence of schisanhenol (Sal, 0.1 mM) on Fe2 °-induced decrease of membrane fluidity of liver microsomes from rats; b, c, polarization (P); a, d, fluorescence intensity (Fl.). Each point is the mean of duplicate de-
terminations. 0—0,
Control; S—•, fl—fl Sal.
120 tOO
Results
D
80
Effect on Fe2 7cysteine-induced lipid peroxidation of liver microsomes
60
As shown in Table 1, all 9 lignans at a final concentration of 1 mM inhibited MDA production. Among the lignans, Sal was the most potent. The inhibition of MDA formation by Sal (1 mM) was 100%. With the exception of Sol A and So! B, all the lignans were more potent than vitamin E at the same concentration.
40 20
Effect on Fe2/cysteine-induced decrease of membrane fluidity of liver rnicrosomes The value of DPH fluorescence polarization increased with iron (4—20MM) in the incubation mixture, indicating a decrease of membrane lipid fluidity of liver Table 1 Effects of 9 dibenzocyclooctene lignans (1 mM) on rat liver microsomal lipid peroxidation (MDA formation) induced by Fe2° (50zM)/cysteine
(200zM) and on superoxide anion (0) generation in xanthine/xanthine oxidase system in vitro. Compound (1 mM)
Control Vit E Sal
0.84 0.80
0
inhibition
(nM/mm)
—
26.4 25.2 20.4 23.4 23.2 23.4 22.6 21.4 21.0 25.6 25.2
4.7 100 21.2
0.66 0.41
51.1
R(+)sin B S(—)sinB
0.48
42.9 25.0 67.8
R(+)sinC S(—)sinC
SolA Sol B
Fig. 3 Dose-effect relationship of schisanhenol (Sal) on Fe2° (1.67 ttM)induced decrease of the membrane fluidity of liver microsomes from rats. Each bar is the mean of duplicate determinations. Sal concentration /.LM in the presence of Fe2° (1.67zM): A, 0; B, 1; C, 5; D, 10; E, 50; F, 100; G, normal control.
%
%
SinA (±)SinB
0.63 0.27 0.20 0.78 0.80
025
0 (cytochro me C reduced)
MDA
(nM/mg) protein
0.. 0.20
76.2 7.1 4.7
Values are means of duplicate determinations.
inhibition —
4.6 22.7 11.3 12.1 11.3
14.4 18.9
20.4 3.0 4.5
microsomes. Sal (Oi mM) added to the incubation mixture
prevented the reduction of fluidity of liver microsomes induced by iron (Fig. 2). This effect of Sal on membrane fluidity was
dose-dependent (Fig. 3). The polarization was close to normal with Sal (0.1 mM). However, Sal (1—100MM) showed no influence on lipid fluidity of normal liver microsomes. So! A and Sol B, which exhibited only a weak anti-
lipid peroxidation activity, had no effect on iron-induced decrease of fluidity of liver microsomes (data not shown).
Downloaded by: NYU. Copyrighted material.
Measurement of 0; generation in xanthine/xanthine oxidase system
Planta Med. 58(1992) 313
Anti-Oxidant Activity of Dibenzocyclooctene Lz.qnans lsolatedfrom Schisandraceae
Effect on superoxide anion (O) generation in xanthine/xanthine oxidase system
References 1 Li, S. Z. (Ming dynasty) U978) Ben-Cao Gong-Mu. p. 1711. Beijing, The People's Health Publisher. China. 2 Liu, G. T. (1977) in: World Health Organization Regional Office for
the Western Pacific, Final Report, pp. 101—112, Manila,
The production of O in the xanthine I xanthine oxidase system was reduced by the 9 lignans at 1 mM. The order of activity of these lignans was Sal > S(—)sin C > R(+)sin C > (±) Sin B > S(—)sin B > R(+)sin B>
Sin A > Sol B > Sol A, similar to that in inhibiting ironinduced lipid peroxidation as shown in Table 1. Among the
lignans, Sal was also the most active in inhibiting O
'
generation, while So! A and So! B were the weakest. The compounds except So! A and Sol B were more potent than vitamin E at 1 mM in the inhibition of O production.
Discussion
l.owry, 0. II.. Hosebrough. N. J., Lewis, Farr. A., Randall. R. J. (1951)J. Biol. Chem, 193. 265—70.
'
The present data showed that 7 out of 9 lignans isolated from Schisandraceae inhibited iron-
lipid peroxidation activity of these lignans may be due to the variation of the functional group in their structures. Sal has a phenolic hydroxy group in its structure, while Sol A and So! B have a hydroxy group in their cyclooctene ring. The anti-oxidant activity of vitamin E has been considered to be due to the presence of a phenolic hydroxy group in its structure. Lipid peroxidation of membranous PUFA is accompanied by a rigidification of the membrane, i.e. a decrease of membrane fluidity (12). In the present study, the lipid fluidity of microsomal membranes was decreased by
iron/cysteine-induced lipid peroxidation. Sal with its strong anti-lipid peroxidation action was able to antagonize the reduction of membrane fluidity induced by iron, whereas Sin A exerted no influence on the reduction of iron-induced membrane fluidity of liver microsomes. It may be logical to postulate that Sal maintains the stability of the
liver microsomal membrane through inhibiting ironinduced lipid peroxidation.
The oxidation of xanthine by xanthine oxidase generated O which could be determined by measurement of the reduction of cytochrome C. The lignans added to this system also inhibited O generation. There is a good correlation between the inhibition of MDA formation and O generation, although the percentage of inhibition varied. These results further support the conclusion that certain lignans isolated from Schisandraceae possess anti-oxidant activity.
Buege. J. A., Aust. A. I). (1978) in: Methods F.nzymol., III. Biomembranes, Part C, (Fleischer, S., Packer, L.. eds.), pp. 302—3 10, Academic Press. New York. Wilson. R. I.., Searle, A. J. F. (1975) Nature 255. 498—500. Barenholz, Y.. Moore, N. F., Wagner, H. R. (1976) Biochemistry 15, 3563— 70.
induced lipid peroxidation of polyunsaturated fatty acids (PUFA) of liver microsomes. Sal was the most potent, while So! A and Sol B were the weakest. The differences in anti-
Philippines. Liu. G. 1. (1986) in: Proceedings of the International Symposium on Traditional Medicines and Modern Pharmacology, (Lei, 11. P., Song, Z. Y.. Zhang. Z. T.. Liu, G. Z.. han. H. Z.. eds.) pp. 78—86. Beijing No. I Press, Beijing. Liu. K. 1., Lesca. I'. 11982) Chem. Biol. Interact. 41. 39—47. Recknagel. H. 0.. Glende, F. A.. Jr.. llruszkewycz. A. M. (1977) in: Free Radicals in Biology. Vol. Ill, (Pryor. W. A., ed), pp. 97—132. Academic Press. New York. I.esca. P.. Lecointe, C., Paoletti, C.. Mansuy, 0. (1976) C. R. Hebd. Seances Acad Sd., Ser. I). 282, 1457—60.
12
(1981) Riochem. Biophys. Res. Dave. J. R.. Knazek, R. A., 1.iu. S Commun. 100, 45—51. Kuthan, H.. Ullrich, V., Estabrook. R. W. (1982) Biochem. J. 203. 551— 5 58.
Downloaded by: NYU. Copyrighted material.
Both Sal and Sol A (1—1OO.iM) showed no influence on lipid fluidity of normal liver microsomes.
Anti-Oxidant Activity of Dibenzocyclooctene Lignans Isolated from Schisandraceae Hua Lu' and Geng-Tao Liu 1.2 Department of Pharmacology, Institute of Materia Medica. Chinese Academy of Medical Sciences. Beijing 100050, People's Republic ofChina 2 Address for correspondence Received: June 17. 1991
The anti-oxidant activity of nine diben-
peroxidation and the generation of superoxide anion were studied. The chemical structure of schisanhenol, the most active lignan, is shown in Fig. 1.
zocyclooctene lignans isolated from Schisandra
chinensis. S. rubr(flora, and Kadsura longipedunculata, respectively, was studied. Seven of the 9 lignans (1 mM)
inhibited iron/cysteine-mnduced lipid peroxidation
(malondialdehyde, MDA, formation) of rat liver micro-
somes as well as superoxide anion production in the xanthine/xanthine oxidase system. The actions of the 7 lignans were much more potent than vitamin E at the
same concentration of 1 mM. Among the lignans. schisanhenol was the most active one. This compound
also prevented the decrease of membrane fluidity of liver microsomes induced by iron/cysteine. The results indicated that seven of the lignans such as schisanhenol have anti-oxidant activities.
OCH3
H3COL
H3CO/
H
OCH3 schisanhenol
Fig. 1 Chemical structure of schisanhenol isolated from Schisandra rubriflora Rhed et Wils.
Key words
Schisandra chinensis, Schisandra rubriflora, Kadsura longipedunculata, dibenzocyclooctene lignans, schisanhenol, lipid peroxidation, anti-oxidant activity.
Introduction The medicinal drug Fructus Schisandrae chinensis (FS) has been used as a tonic and anti-aging drug in traditional Chinese medicine (1). FS was found to improve the liver function of patients with viral hepatitis in
Materials and Methods Male Wistar rats weighing 195 SD 12.5 g were used. Nine lignans were kindly provided by Profs. Y. Y. Chen and N. L. Lee in our institute. The name of each lignan is given below: schisandrin A (Sin A), (+)-schisandrin B (Sin B), R(+)-schisandrin B lR(+)Sin B], S(—)-schisandrin B [S(—)Sin B], R(+)-schisandrin C [R(+)Sin C], S(—)-schisandrin C [S(—)Sin C], schisanhenol (Sal),
schisandrol A (Sol A), and schisandrol B (Sol B). Xanthine, xanthine oxidase. cytochrome C, cysteine, and 1.6-diphenyl-1,3, 5-hexatriene (DPH) were purchased from Sigma Chemical Co. The other reagents (A.G) were obtained from the market in Beijing.
Preparation of liver microsomes
China (2). Our previous studies demonstrated that 15 dibenzocyclooctene lignans isolated from Schisandra
capitation. The livers were perfused in situ with ice-cold 1.15 %
chinensis, S. rubriflora and Kadsura longipedunculata, respectively, reduced the liver damage and microsomal lipid
KC1 solution. Liver microsomes were prepared (6) and microsomal protein was determined by the method of Lowry (7).
peroxidation induced by Cd4 (3, 4). CCl induces lipid peroxidation by formation of the free radical methyl tnchloride ('Cd3) in liver microsomes (5). The inhibition of CC14-induced lipid peroxidation by the lignans implicated that these compounds might have an anti-oxidant activity.
To veri1' this possibility, the effects of 9 dibenzocyclooctene lignans on the iron/cysteine-induced lipid
The rats were starved overnight before de-
Measurement of iron/cysteine- induced lipid peroxidation (MDA formation) The incubation mixture contained 1 ml phosphate buffer (0.IM, pH 7.4) 1.4mg microsomal protein, 10tl of the lignan in dimethyl sulfoxide (DMSO) or only DMSO, FeSO4 5—100sM, and 2—10MM cysteine. After incubation for 30mm at
Downloaded by: NYU. Copyrighted material.
Abstract
312 Planta Med. 58(1992)
IIua Lu and Geng-Tao Liu
37°C. the reaction mixture was quenched with 20% tn-
200
chloroacetic acid (TCA) (0.5 ml). Malonic dialdehyde (MDA) in the
supernatant after centrifugation was determined by the colorimetric method using thiobarbituric acid (TBA) (8) and used as the indication for lipid peroxidation (9. 10).
150
Determination ofmembranefluidity DPI-I lipid probe was used for the determination
100
of rnicrosomal fluidity by fluorescence polarization. The incubation mixture contained 1.5 ml phosphate buffer (0.1 M. p11 7.4). microsomal protein 50g, and DPH 2MM. The amount of the lignan and Fe2' /cysteine added was the same as described in the *xperiment for lipid peroxidation. Incubation was carried out at 25°C for I h. The incubation mixture was then subjected to polarization analysis by recording the fluorescence at emission 432 nm with the excitation at 363 nm. The fluorescence polarization was calculated according to the known equation (11).
50
0
Fe2+ concentration (M
Tris-HCI buffer (0.1 M, pH 7.4) (1 ml) contained xanthine 0.2mM. cytochrome C 0.2M. lignan or DMF, and 0.02 unit of xanthine oxidase. The mixture was incubated for 5 mm at 25°C. The difference of absorbance (A) of cytochrome C at the wave length 550—557 nm was recorded with a double wavelength spectrophotometer. The amount of the reduction of cytochrome C was used to indicate 0; generation (12).
Fig. 2 Influence of schisanhenol (Sal, 0.1 mM) on Fe2 °-induced decrease of membrane fluidity of liver microsomes from rats; b, c, polarization (P); a, d, fluorescence intensity (Fl.). Each point is the mean of duplicate de-
terminations. 0—0,
Control; S—•, fl—fl Sal.
120 tOO
Results
D
80
Effect on Fe2 7cysteine-induced lipid peroxidation of liver microsomes
60
As shown in Table 1, all 9 lignans at a final concentration of 1 mM inhibited MDA production. Among the lignans, Sal was the most potent. The inhibition of MDA formation by Sal (1 mM) was 100%. With the exception of Sol A and So! B, all the lignans were more potent than vitamin E at the same concentration.
40 20
Effect on Fe2/cysteine-induced decrease of membrane fluidity of liver rnicrosomes The value of DPH fluorescence polarization increased with iron (4—20MM) in the incubation mixture, indicating a decrease of membrane lipid fluidity of liver Table 1 Effects of 9 dibenzocyclooctene lignans (1 mM) on rat liver microsomal lipid peroxidation (MDA formation) induced by Fe2° (50zM)/cysteine
(200zM) and on superoxide anion (0) generation in xanthine/xanthine oxidase system in vitro. Compound (1 mM)
Control Vit E Sal
0.84 0.80
0
inhibition
(nM/mm)
—
26.4 25.2 20.4 23.4 23.2 23.4 22.6 21.4 21.0 25.6 25.2
4.7 100 21.2
0.66 0.41
51.1
R(+)sin B S(—)sinB
0.48
42.9 25.0 67.8
R(+)sinC S(—)sinC
SolA Sol B
Fig. 3 Dose-effect relationship of schisanhenol (Sal) on Fe2° (1.67 ttM)induced decrease of the membrane fluidity of liver microsomes from rats. Each bar is the mean of duplicate determinations. Sal concentration /.LM in the presence of Fe2° (1.67zM): A, 0; B, 1; C, 5; D, 10; E, 50; F, 100; G, normal control.
%
%
SinA (±)SinB
0.63 0.27 0.20 0.78 0.80
025
0 (cytochro me C reduced)
MDA
(nM/mg) protein
0.. 0.20
76.2 7.1 4.7
Values are means of duplicate determinations.
inhibition —
4.6 22.7 11.3 12.1 11.3
14.4 18.9
20.4 3.0 4.5
microsomes. Sal (Oi mM) added to the incubation mixture
prevented the reduction of fluidity of liver microsomes induced by iron (Fig. 2). This effect of Sal on membrane fluidity was
dose-dependent (Fig. 3). The polarization was close to normal with Sal (0.1 mM). However, Sal (1—100MM) showed no influence on lipid fluidity of normal liver microsomes. So! A and Sol B, which exhibited only a weak anti-
lipid peroxidation activity, had no effect on iron-induced decrease of fluidity of liver microsomes (data not shown).
Downloaded by: NYU. Copyrighted material.
Measurement of 0; generation in xanthine/xanthine oxidase system
Planta Med. 58(1992) 313
Anti-Oxidant Activity of Dibenzocyclooctene Lz.qnans lsolatedfrom Schisandraceae
Effect on superoxide anion (O) generation in xanthine/xanthine oxidase system
References 1 Li, S. Z. (Ming dynasty) U978) Ben-Cao Gong-Mu. p. 1711. Beijing, The People's Health Publisher. China. 2 Liu, G. T. (1977) in: World Health Organization Regional Office for
the Western Pacific, Final Report, pp. 101—112, Manila,
The production of O in the xanthine I xanthine oxidase system was reduced by the 9 lignans at 1 mM. The order of activity of these lignans was Sal > S(—)sin C > R(+)sin C > (±) Sin B > S(—)sin B > R(+)sin B>
Sin A > Sol B > Sol A, similar to that in inhibiting ironinduced lipid peroxidation as shown in Table 1. Among the
lignans, Sal was also the most active in inhibiting O
'
generation, while So! A and So! B were the weakest. The compounds except So! A and Sol B were more potent than vitamin E at 1 mM in the inhibition of O production.
Discussion
l.owry, 0. II.. Hosebrough. N. J., Lewis, Farr. A., Randall. R. J. (1951)J. Biol. Chem, 193. 265—70.
'
The present data showed that 7 out of 9 lignans isolated from Schisandraceae inhibited iron-
lipid peroxidation activity of these lignans may be due to the variation of the functional group in their structures. Sal has a phenolic hydroxy group in its structure, while Sol A and So! B have a hydroxy group in their cyclooctene ring. The anti-oxidant activity of vitamin E has been considered to be due to the presence of a phenolic hydroxy group in its structure. Lipid peroxidation of membranous PUFA is accompanied by a rigidification of the membrane, i.e. a decrease of membrane fluidity (12). In the present study, the lipid fluidity of microsomal membranes was decreased by
iron/cysteine-induced lipid peroxidation. Sal with its strong anti-lipid peroxidation action was able to antagonize the reduction of membrane fluidity induced by iron, whereas Sin A exerted no influence on the reduction of iron-induced membrane fluidity of liver microsomes. It may be logical to postulate that Sal maintains the stability of the
liver microsomal membrane through inhibiting ironinduced lipid peroxidation.
The oxidation of xanthine by xanthine oxidase generated O which could be determined by measurement of the reduction of cytochrome C. The lignans added to this system also inhibited O generation. There is a good correlation between the inhibition of MDA formation and O generation, although the percentage of inhibition varied. These results further support the conclusion that certain lignans isolated from Schisandraceae possess anti-oxidant activity.
Buege. J. A., Aust. A. I). (1978) in: Methods F.nzymol., III. Biomembranes, Part C, (Fleischer, S., Packer, L.. eds.), pp. 302—3 10, Academic Press. New York. Wilson. R. I.., Searle, A. J. F. (1975) Nature 255. 498—500. Barenholz, Y.. Moore, N. F., Wagner, H. R. (1976) Biochemistry 15, 3563— 70.
induced lipid peroxidation of polyunsaturated fatty acids (PUFA) of liver microsomes. Sal was the most potent, while So! A and Sol B were the weakest. The differences in anti-
Philippines. Liu. G. 1. (1986) in: Proceedings of the International Symposium on Traditional Medicines and Modern Pharmacology, (Lei, 11. P., Song, Z. Y.. Zhang. Z. T.. Liu, G. Z.. han. H. Z.. eds.) pp. 78—86. Beijing No. I Press, Beijing. Liu. K. 1., Lesca. I'. 11982) Chem. Biol. Interact. 41. 39—47. Recknagel. H. 0.. Glende, F. A.. Jr.. llruszkewycz. A. M. (1977) in: Free Radicals in Biology. Vol. Ill, (Pryor. W. A., ed), pp. 97—132. Academic Press. New York. I.esca. P.. Lecointe, C., Paoletti, C.. Mansuy, 0. (1976) C. R. Hebd. Seances Acad Sd., Ser. I). 282, 1457—60.
12
(1981) Riochem. Biophys. Res. Dave. J. R.. Knazek, R. A., 1.iu. S Commun. 100, 45—51. Kuthan, H.. Ullrich, V., Estabrook. R. W. (1982) Biochem. J. 203. 551— 5 58.
Downloaded by: NYU. Copyrighted material.
Both Sal and Sol A (1—1OO.iM) showed no influence on lipid fluidity of normal liver microsomes.
