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Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20
Antioxidant activity and mechanism of the abietane-type diterpene ferruginol a
a
H. Saijo , H. Kofujita , K. Takahashi
ab
ab
& T. Ashitani
a
The United Graduate School of Agricultural Sciences, Iwate University, 18-8, Ueda-3 chome, Morioka 020-8550, Japan b
Faculty of Agriculture, Yamagata University, 1-23, Wakabamachi, Tsuruoka 997-8555, Japan Published online: 14 Jan 2015.
Click for updates To cite this article: H. Saijo, H. Kofujita, K. Takahashi & T. Ashitani (2015): Antioxidant activity and mechanism of the abietane-type diterpene ferruginol, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2014.997233 To link to this article: http://dx.doi.org/10.1080/14786419.2014.997233
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2014.997233
SHORT COMMUNICATION Antioxidant activity and mechanism of the abietane-type diterpene ferruginol H. Saijoa*, H. Kofujitaa, K. Takahashiab and T. Ashitaniab
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
a
The United Graduate School of Agricultural Sciences, Iwate University, 18-8, Ueda-3 chome, Morioka 020-8550, Japan; bFaculty of Agriculture, Yamagata University, 1-23, Wakaba-machi, Tsuruoka 9978555, Japan (Received 6 October 2014; final version received 6 December 2014) OH
OH Free radical OH
L LOO H Dehydroferruginol
OH
Quinone methide
H
O Sugiol
H Ferruginol
LH LOOH
OH H 7-Hydroxyferruginol Antioxidation step of ferruginol
The antioxidant activity of the abietane-type diterpene ferruginol was evaluated by comparison with that of carnosic acid, (^ )-a-tocopherol and dibutylhydroxytoluene using 2,2-diphenyl-1-picrylhydrazyl, b-carotene bleaching and linoleic acid assays. Ferruginol had the lowest antioxidant activity of this group using the 2,2-diphenyl-1picrylhydrazyl and b-carotene methods in polar solvent buffer. However, ferruginol exhibited stronger activity than carnosic acid and a-tocopherol for linoleic acid oxidation under non-solvent conditions. Five peaks corresponding to ferruginol derivatives were detected through GC-MS analysis of the reaction between ferruginol and methyl linoleate. The three reaction products were identified as dehydroferruginol, 7b-hydroxyferruginol and sugiol, and the other two peaks were assumed to be 7ahydroxyferruginol and the quinone methide derivative of ferruginol. The time course of the reaction suggests that the quinone methide was produced early in the reaction and reacted further to produce dehydroferruginol, 7-hydroxyferruginol and sugiol. Thus, we inferred that quinone methide formation was a key step in the antioxidant reaction of ferruginol. Keywords: word; ferruginol; abietane-type diterpene; antioxidant mechanism; quinone methide
1. Introduction The abietane-type diterpene ferruginol is a component of herbaceous and woody plants and is considered a useful natural product because of its various biological effects, including antioxidant (Wang et al. 2002; Cheng & Chang 2014), anti-fungal (Kofujita et al. 2006; Kusumoto et al. 2010), anti-termite (Chang et al. 2001; Kusumoto et al. 2009) and anti-ulcerogenic
*Corresponding author. Email: [email protected] q 2015 Taylor & Francis
H. Saijo et al.
activities (Rodrıguez et al. 2006) and algal growth inhibition properties (Saijo et al. 2013). Several plantation trees are known to produce ferruginol. Japanese cedar (Japanese name ‘Sugi’; Cryptomeria japonica) is one of the primary forested trees in the Japanese wood industry. Sugi contains ferruginol in its heartwood (Shibutani et al. 2007) and bark (Ashitani et al. 2001; Kofujita et al. 2006); its bark contains a substantial amount of ferruginol. Sugi bark is discarded in large quantities during the production of woody material; thus, a large amount of a potential ferruginol source is wasted. Various natural resources derived from plants are used as antioxidants (Brewer 2011), particularly sage (Salvia officinalis) and rosemary (Rosmarinus officinalis), which are used as antioxidants in the food industry worldwide (Tena et al. 1997). Masuda et al. (2001, 2002) reported the antioxidant activity of sage extracts and demonstrated the antioxidant mechanism of the primary active component, carnosic acid, and its derivatives. Carnosic acid is a commercially available antioxidant and, similar to ferruginol, is an abietane-type diterpene. However, the antioxidant mechanisms of ferruginol have not yet been examined. To efficiently utilise this resource, the detailed characterisation and examination of the antioxidant activity of ferruginol from plantation trees are needed. 2. Results and discussion 2.1. Assays for antioxidant activity a-Tocopherol and carnosic acid exhibited the highest activities in the DPPH and b-carotene methods, respectively. Ferruginol, as reported by Kolak et al. (2009), showed the lowest activity than any commercial reagent (Table S1). However, Wang et al. (2002) and Cheng and Chang (2014) reported that ferruginol had comparatively high antioxidant activity in diterpene components. Although the reference compounds dissolved completely in the buffer solution at every concentration, an emulsion was observed at high concentrations (greater than 200 mM) of ferruginol. Thus, the solubility of ferruginol in the buffer solution for both methods was less than the solubility of the other three compounds. Figure 1 shows the antioxidant activities from the linoleic acid method. This experiment was performed to directly estimate the ability of the
120 100 Linoleic acid (%)
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
2
80 60 40 20 0 0
5
10 15 Time (h)
20
Linolic acid
BHT+Linolic acid
α-Tocopherol+Linolic acid
Carnosic acid+Linolic acid
Ferruginol+Linolic acid
Figure 1. Antioxidant activities of ferruginol and reference compounds by the linoleic acid method. Note: The antioxidant activity was evaluated based on the amount of residual linoleic acid.
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Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
samples to suppress the oxidation of unsaturated oil. The sample was added directly into the oil. Suppression of oil oxidation was evaluated over a short time period of 1 day at 858C. The activity of ferruginol was weaker than dibutylhydroxytoluene (BHT) but stronger than carnosic acid and a-tocopherol in this method. Thus, the hydrophobic compound ferruginol was able to protect linoleic acid under non-solvent conditions. This result suggests that ferruginol possesses antioxidant activity against the oxidation of linoleic acid.
2.2. Analysis of ferruginol derivatives in methyl linoleate by GC-MS The mixture of ferruginol and methyl linoleate was analysed by GC-MS. Peaks 1 –5 were detected in the MS spectra and were presumed to be ferruginol derivatives (Figure S1). Other peaks were regarded as fragments formed from methyl linoleate by its MS spectra (data not shown). From the time course data of the five peaks (Figure S2a), peak 2 increased from the initial reaction time to the intermediate time in this reaction but then disappeared in the later reaction time. Peaks 1, 3 and 4 also increased from the initial to intermediate reaction stages, and these three peaks then decreased in the late reaction stage. However, peak 5 increased gradually during the final stages of the reaction. The reaction with a high concentration of methyl linoleate OH
H L
OH
Ferruginol
LOO
LH LOOH O O
H OH
Sugiol L
H
L
LH LOOH
LOO
LH LOOH
LOO
H
O
O
Dehydroferruginol H2O
H 2O
H Ferruginol quinone methide
H
OH
OH
OH
L LOO
H2O H
OH H
7α-Hydroxyferruginol
H
H OH
LH LOOH
7β-Hydroxyferruginol
Figure 2. Proposed mechanism of ferruginol antioxidant activity against methyl linoleate oxidation. Note: [] is the postulated chemical structure.
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H. Saijo et al.
(Figure S2b) proceeded more rapidly and showed the same tendency. Peaks 1, 4 and 5 were identified as dehydroferruginol, 7b-hydroxyferruginol and sugiol, respectively. Peak 3 had a very similar spectrum pattern to peak 4 (Figure S3). Thus, peak 3 was considered likely to be a diastereomer, 7a-hydroxyferruginol, of the peak 4 component. We considered peak 2 to be the first product derived from ferruginol in the above reaction. We explored the isolation of the compound from this reaction solution; however, this compound was very unstable and could not be isolated. The compound showed m/z ¼ 284.2203 (Mþ) (284.2140 calculated for C20H28O) by HR-MS analysis. Peaks 1, 3, 4 and 5 were all compounds oxidised at the 7-position of ferruginol. Therefore, it was estimated that peak 2 had the quinone methide structure derived from ferruginol. Otani and Sumimoto (1983) also indicated the quinone methide as an intermediate in the formation of dehydroferruginol by the chlorine treatment of ferruginol. Thus, this result matches our hypothesis of quinone methide formation in the reaction of ferruginol with oxygen radicals. The antioxidant mechanism (Figure 2) was analysed based on the above results. In the first reaction, ferruginol lost two hydrogen atoms by radical species produced from unsaturated oil to give the ferruginol quinone methide as an intermediate. Dehydroferruginol could be formed from the ferruginol quinone methide by isomerisation. As dehydroferruginol is more stable than the quinone methide, the formation of dehydroferruginol might be predominant in the isomerisation. In an alternative pathway, the ferruginol quinone methide was attacked by H2O produced from oil oxidation to form 7-hydroxygerruginols. 7-Hydroxyferruginols could also be produced by the addition of H2O to dehydroferruginol, and 7-hydroxyferruginols were dehydrated to produce dehydroferruginol. Finally, the radicals of the oxidative oil abstracted two hydrogen atoms from 7-hydroxyferruginols to give sugiol as the final product. From the above mechanism, it can be concluded that ferruginol inhibited oxidation of the oil by trapping free radicals and preventing propagation. Sugiol has weaker antioxidant properties than ferruginol (Wang et al. 2002). Thus, the key step in the antioxidant mechanism of ferruginol is the formation of quinone methide as the initial step. Supplementary material Experimental details relating to this paper are available online, alongside Table S1 and Figures S1 –S3. Funding This study was supported by the 2013 UGAS-IU Student Research Project and Grant-in-Aid for JSPS Fellows.
References Ashitani T, Ujike M, Nagahama S, Ueno T, Sakai K. 2001. Characterization of Sugi (Cryptomeria japonica) bark extracts. Mokuzai Gakkaishi. 47:276–281. Brewer MS. 2011. Natural antioxidants: sources, compounds, mechanisms of action, and potential applications. Compr Rev Food Sci Food Saf. 10:221–247. Chang ST, Cheng SS, Wang SY. 2001. Antitermitic activity of essential oils and components from Taiwania (Taiwania cryptomerioides). J Chem Ecol. 27:717–724. Cheng SS, Chang ST. 2014. Bioactivity and characterization of exudates from Cryptomeria japonica bark. Wood Sci Technol. 48:831–840. Kofujita H, Fujino Y, Ota M, Takahashi K. 2006. Antifungal diterpenes from the bark of Cryptomeria japonica D. Don. Holzforschung. 60:20–23. Kolak U, Kabouche A, Ozturk M, Kabouche Z, Topcu G, Ulubelen A. 2009. Antioxidant diterpenoids from the roots of Salvia barrelieri. Phytochem Anal. 20:320–327. Kusumoto N, Ashitani T, Hayasaka Y, Murayama T, Kawai Y, Ogiyama K, Takahashi K. 2009. Antitermitic activities of abietane-type diterpenes from Taxodium distichum cones. J Chem Ecol. 35:635–642.
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
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Kusumoto N, Ashitani T, Murayama T, Ogiyama K, Takahashi K. 2010. Antifungal abietane-type diterpenes from the cones of Taxodium distichum Rich. J. Chem. Ecol. 36:1381–1386. Masuda T, Inaba Y, Maekawa T, Takeda Y, Tamura H, Yamaguchi H. 2002. Recovery mechanism of the antioxidant activity from carnosic acid quinone, an oxidized sage and rosemary antioxidant. J Agric Food Chem. 50:5863–5869. Masuda T, Inaba Y, Takeda Y. 2001. Antioxidant mechanism of carnosic acid: structure identification of two oxidation products. J Agric Food Chem. 49:5560– 5565. Otani Y, Sumimoto M. 1983. Extractive from the temperate wood species in pulping and paper making. III on brightness of Sugi BKP and chlorination of ferruginol. Jpn TAPPI J. 37:921–931. Rodrıguez JA, Theoduloz C, Yanez T, Becerra J, Schmeda-Hirschmann G. 2006. Gastroprotective and ulcer healing effect of ferruginol in mice and rats: assessment of its mechanism of action using in vitro models. Life Sci. 78:2503–2509. Saijo H, Tsuruta K, Kusumoto N, Ashitani T, Takahashi K. 2013. Growth inhibition activities of Sugi bark components against Heterosigma akashiwo. J Wood Sci. 59:238–242. Shibutani S, Takata K, Doi S. 2007. Quantitative comparisons of antitermite extractives in heartwood from the same clones of Cryptomeria japonica planted at two different sites. J Wood Sci. 53:285– 290. Tena MT, Valcarcel M, Hidalgo RJ, Ubera JL. 1997. Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication. Anal Chem. 69:521–526. Wang SY, Wu JH, Shyur LF, Kuo YH, Chang ST. 2002. Antioxidant activity of abietane-type diterpenes from heart wood of Taiwania cryptomerioides Hyata. Holzforschung. 56:487–492.
Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20
Antioxidant activity and mechanism of the abietane-type diterpene ferruginol a
a
H. Saijo , H. Kofujita , K. Takahashi
ab
ab
& T. Ashitani
a
The United Graduate School of Agricultural Sciences, Iwate University, 18-8, Ueda-3 chome, Morioka 020-8550, Japan b
Faculty of Agriculture, Yamagata University, 1-23, Wakabamachi, Tsuruoka 997-8555, Japan Published online: 14 Jan 2015.
Click for updates To cite this article: H. Saijo, H. Kofujita, K. Takahashi & T. Ashitani (2015): Antioxidant activity and mechanism of the abietane-type diterpene ferruginol, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2014.997233 To link to this article: http://dx.doi.org/10.1080/14786419.2014.997233
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2014.997233
SHORT COMMUNICATION Antioxidant activity and mechanism of the abietane-type diterpene ferruginol H. Saijoa*, H. Kofujitaa, K. Takahashiab and T. Ashitaniab
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
a
The United Graduate School of Agricultural Sciences, Iwate University, 18-8, Ueda-3 chome, Morioka 020-8550, Japan; bFaculty of Agriculture, Yamagata University, 1-23, Wakaba-machi, Tsuruoka 9978555, Japan (Received 6 October 2014; final version received 6 December 2014) OH
OH Free radical OH
L LOO H Dehydroferruginol
OH
Quinone methide
H
O Sugiol
H Ferruginol
LH LOOH
OH H 7-Hydroxyferruginol Antioxidation step of ferruginol
The antioxidant activity of the abietane-type diterpene ferruginol was evaluated by comparison with that of carnosic acid, (^ )-a-tocopherol and dibutylhydroxytoluene using 2,2-diphenyl-1-picrylhydrazyl, b-carotene bleaching and linoleic acid assays. Ferruginol had the lowest antioxidant activity of this group using the 2,2-diphenyl-1picrylhydrazyl and b-carotene methods in polar solvent buffer. However, ferruginol exhibited stronger activity than carnosic acid and a-tocopherol for linoleic acid oxidation under non-solvent conditions. Five peaks corresponding to ferruginol derivatives were detected through GC-MS analysis of the reaction between ferruginol and methyl linoleate. The three reaction products were identified as dehydroferruginol, 7b-hydroxyferruginol and sugiol, and the other two peaks were assumed to be 7ahydroxyferruginol and the quinone methide derivative of ferruginol. The time course of the reaction suggests that the quinone methide was produced early in the reaction and reacted further to produce dehydroferruginol, 7-hydroxyferruginol and sugiol. Thus, we inferred that quinone methide formation was a key step in the antioxidant reaction of ferruginol. Keywords: word; ferruginol; abietane-type diterpene; antioxidant mechanism; quinone methide
1. Introduction The abietane-type diterpene ferruginol is a component of herbaceous and woody plants and is considered a useful natural product because of its various biological effects, including antioxidant (Wang et al. 2002; Cheng & Chang 2014), anti-fungal (Kofujita et al. 2006; Kusumoto et al. 2010), anti-termite (Chang et al. 2001; Kusumoto et al. 2009) and anti-ulcerogenic
*Corresponding author. Email: [email protected] q 2015 Taylor & Francis
H. Saijo et al.
activities (Rodrıguez et al. 2006) and algal growth inhibition properties (Saijo et al. 2013). Several plantation trees are known to produce ferruginol. Japanese cedar (Japanese name ‘Sugi’; Cryptomeria japonica) is one of the primary forested trees in the Japanese wood industry. Sugi contains ferruginol in its heartwood (Shibutani et al. 2007) and bark (Ashitani et al. 2001; Kofujita et al. 2006); its bark contains a substantial amount of ferruginol. Sugi bark is discarded in large quantities during the production of woody material; thus, a large amount of a potential ferruginol source is wasted. Various natural resources derived from plants are used as antioxidants (Brewer 2011), particularly sage (Salvia officinalis) and rosemary (Rosmarinus officinalis), which are used as antioxidants in the food industry worldwide (Tena et al. 1997). Masuda et al. (2001, 2002) reported the antioxidant activity of sage extracts and demonstrated the antioxidant mechanism of the primary active component, carnosic acid, and its derivatives. Carnosic acid is a commercially available antioxidant and, similar to ferruginol, is an abietane-type diterpene. However, the antioxidant mechanisms of ferruginol have not yet been examined. To efficiently utilise this resource, the detailed characterisation and examination of the antioxidant activity of ferruginol from plantation trees are needed. 2. Results and discussion 2.1. Assays for antioxidant activity a-Tocopherol and carnosic acid exhibited the highest activities in the DPPH and b-carotene methods, respectively. Ferruginol, as reported by Kolak et al. (2009), showed the lowest activity than any commercial reagent (Table S1). However, Wang et al. (2002) and Cheng and Chang (2014) reported that ferruginol had comparatively high antioxidant activity in diterpene components. Although the reference compounds dissolved completely in the buffer solution at every concentration, an emulsion was observed at high concentrations (greater than 200 mM) of ferruginol. Thus, the solubility of ferruginol in the buffer solution for both methods was less than the solubility of the other three compounds. Figure 1 shows the antioxidant activities from the linoleic acid method. This experiment was performed to directly estimate the ability of the
120 100 Linoleic acid (%)
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
2
80 60 40 20 0 0
5
10 15 Time (h)
20
Linolic acid
BHT+Linolic acid
α-Tocopherol+Linolic acid
Carnosic acid+Linolic acid
Ferruginol+Linolic acid
Figure 1. Antioxidant activities of ferruginol and reference compounds by the linoleic acid method. Note: The antioxidant activity was evaluated based on the amount of residual linoleic acid.
Natural Product Research
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Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
samples to suppress the oxidation of unsaturated oil. The sample was added directly into the oil. Suppression of oil oxidation was evaluated over a short time period of 1 day at 858C. The activity of ferruginol was weaker than dibutylhydroxytoluene (BHT) but stronger than carnosic acid and a-tocopherol in this method. Thus, the hydrophobic compound ferruginol was able to protect linoleic acid under non-solvent conditions. This result suggests that ferruginol possesses antioxidant activity against the oxidation of linoleic acid.
2.2. Analysis of ferruginol derivatives in methyl linoleate by GC-MS The mixture of ferruginol and methyl linoleate was analysed by GC-MS. Peaks 1 –5 were detected in the MS spectra and were presumed to be ferruginol derivatives (Figure S1). Other peaks were regarded as fragments formed from methyl linoleate by its MS spectra (data not shown). From the time course data of the five peaks (Figure S2a), peak 2 increased from the initial reaction time to the intermediate time in this reaction but then disappeared in the later reaction time. Peaks 1, 3 and 4 also increased from the initial to intermediate reaction stages, and these three peaks then decreased in the late reaction stage. However, peak 5 increased gradually during the final stages of the reaction. The reaction with a high concentration of methyl linoleate OH
H L
OH
Ferruginol
LOO
LH LOOH O O
H OH
Sugiol L
H
L
LH LOOH
LOO
LH LOOH
LOO
H
O
O
Dehydroferruginol H2O
H 2O
H Ferruginol quinone methide
H
OH
OH
OH
L LOO
H2O H
OH H
7α-Hydroxyferruginol
H
H OH
LH LOOH
7β-Hydroxyferruginol
Figure 2. Proposed mechanism of ferruginol antioxidant activity against methyl linoleate oxidation. Note: [] is the postulated chemical structure.
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H. Saijo et al.
(Figure S2b) proceeded more rapidly and showed the same tendency. Peaks 1, 4 and 5 were identified as dehydroferruginol, 7b-hydroxyferruginol and sugiol, respectively. Peak 3 had a very similar spectrum pattern to peak 4 (Figure S3). Thus, peak 3 was considered likely to be a diastereomer, 7a-hydroxyferruginol, of the peak 4 component. We considered peak 2 to be the first product derived from ferruginol in the above reaction. We explored the isolation of the compound from this reaction solution; however, this compound was very unstable and could not be isolated. The compound showed m/z ¼ 284.2203 (Mþ) (284.2140 calculated for C20H28O) by HR-MS analysis. Peaks 1, 3, 4 and 5 were all compounds oxidised at the 7-position of ferruginol. Therefore, it was estimated that peak 2 had the quinone methide structure derived from ferruginol. Otani and Sumimoto (1983) also indicated the quinone methide as an intermediate in the formation of dehydroferruginol by the chlorine treatment of ferruginol. Thus, this result matches our hypothesis of quinone methide formation in the reaction of ferruginol with oxygen radicals. The antioxidant mechanism (Figure 2) was analysed based on the above results. In the first reaction, ferruginol lost two hydrogen atoms by radical species produced from unsaturated oil to give the ferruginol quinone methide as an intermediate. Dehydroferruginol could be formed from the ferruginol quinone methide by isomerisation. As dehydroferruginol is more stable than the quinone methide, the formation of dehydroferruginol might be predominant in the isomerisation. In an alternative pathway, the ferruginol quinone methide was attacked by H2O produced from oil oxidation to form 7-hydroxygerruginols. 7-Hydroxyferruginols could also be produced by the addition of H2O to dehydroferruginol, and 7-hydroxyferruginols were dehydrated to produce dehydroferruginol. Finally, the radicals of the oxidative oil abstracted two hydrogen atoms from 7-hydroxyferruginols to give sugiol as the final product. From the above mechanism, it can be concluded that ferruginol inhibited oxidation of the oil by trapping free radicals and preventing propagation. Sugiol has weaker antioxidant properties than ferruginol (Wang et al. 2002). Thus, the key step in the antioxidant mechanism of ferruginol is the formation of quinone methide as the initial step. Supplementary material Experimental details relating to this paper are available online, alongside Table S1 and Figures S1 –S3. Funding This study was supported by the 2013 UGAS-IU Student Research Project and Grant-in-Aid for JSPS Fellows.
References Ashitani T, Ujike M, Nagahama S, Ueno T, Sakai K. 2001. Characterization of Sugi (Cryptomeria japonica) bark extracts. Mokuzai Gakkaishi. 47:276–281. Brewer MS. 2011. Natural antioxidants: sources, compounds, mechanisms of action, and potential applications. Compr Rev Food Sci Food Saf. 10:221–247. Chang ST, Cheng SS, Wang SY. 2001. Antitermitic activity of essential oils and components from Taiwania (Taiwania cryptomerioides). J Chem Ecol. 27:717–724. Cheng SS, Chang ST. 2014. Bioactivity and characterization of exudates from Cryptomeria japonica bark. Wood Sci Technol. 48:831–840. Kofujita H, Fujino Y, Ota M, Takahashi K. 2006. Antifungal diterpenes from the bark of Cryptomeria japonica D. Don. Holzforschung. 60:20–23. Kolak U, Kabouche A, Ozturk M, Kabouche Z, Topcu G, Ulubelen A. 2009. Antioxidant diterpenoids from the roots of Salvia barrelieri. Phytochem Anal. 20:320–327. Kusumoto N, Ashitani T, Hayasaka Y, Murayama T, Kawai Y, Ogiyama K, Takahashi K. 2009. Antitermitic activities of abietane-type diterpenes from Taxodium distichum cones. J Chem Ecol. 35:635–642.
Downloaded by [Memorial University of Newfoundland] at 08:34 23 January 2015
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Kusumoto N, Ashitani T, Murayama T, Ogiyama K, Takahashi K. 2010. Antifungal abietane-type diterpenes from the cones of Taxodium distichum Rich. J. Chem. Ecol. 36:1381–1386. Masuda T, Inaba Y, Maekawa T, Takeda Y, Tamura H, Yamaguchi H. 2002. Recovery mechanism of the antioxidant activity from carnosic acid quinone, an oxidized sage and rosemary antioxidant. J Agric Food Chem. 50:5863–5869. Masuda T, Inaba Y, Takeda Y. 2001. Antioxidant mechanism of carnosic acid: structure identification of two oxidation products. J Agric Food Chem. 49:5560– 5565. Otani Y, Sumimoto M. 1983. Extractive from the temperate wood species in pulping and paper making. III on brightness of Sugi BKP and chlorination of ferruginol. Jpn TAPPI J. 37:921–931. Rodrıguez JA, Theoduloz C, Yanez T, Becerra J, Schmeda-Hirschmann G. 2006. Gastroprotective and ulcer healing effect of ferruginol in mice and rats: assessment of its mechanism of action using in vitro models. Life Sci. 78:2503–2509. Saijo H, Tsuruta K, Kusumoto N, Ashitani T, Takahashi K. 2013. Growth inhibition activities of Sugi bark components against Heterosigma akashiwo. J Wood Sci. 59:238–242. Shibutani S, Takata K, Doi S. 2007. Quantitative comparisons of antitermite extractives in heartwood from the same clones of Cryptomeria japonica planted at two different sites. J Wood Sci. 53:285– 290. Tena MT, Valcarcel M, Hidalgo RJ, Ubera JL. 1997. Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication. Anal Chem. 69:521–526. Wang SY, Wu JH, Shyur LF, Kuo YH, Chang ST. 2002. Antioxidant activity of abietane-type diterpenes from heart wood of Taiwania cryptomerioides Hyata. Holzforschung. 56:487–492.
