Biocontrol Science, 2006, Vol.11, No.2, 49-54

Minireview

The Excellence of Aomori Hiba (Hinokiasunaro) in ItsUse as Building Materials of Buddhist Temples

and Shinto Shrines

YOSHIHIKO INAMORI1*, YASUHIRO MORITA2, YOSHIKAZU SAKAGAMI3,

TOSHIHORO OKABE4, AND NAKAO ISHIDA5

1Osaka University of Pharmaceutical Sciences,2Osaka Organic Chemical Industry Ltd,18-8 Katayama-cho, Kashiwara-shi, Osaka 582-0020,

3Kinki University , Faculty of Agriculture, 3327-204 Nakamachi, Nara-shi, Nara 631-8505, Japan,4Aomori Industrial Research Center, 4-11-6 Daini-tonyamachi, Aomori 030-0113, Japan, and

5 The Sendai Institute of Microbiology , ICR Building 2F, Minamiyoshinari6-6-3 Aoba-ku, Sendai 989-3204, Japan

Received 18 October 2005/Accepted 30 December 2005

Five hinokitiol-related compounds [hinokitiol (ƒÀ-thujaplicin), ƒÀ-dolabrin, ƒÁ-thujaplicin, 4-

acetyltropolone and ƒ¿-thujaplicin] isolated from the acid oil of Aomori Hiba (Thujopsis

dolabrata Sieb. et Zucc. var hondai MAKINO) showed clear antifungal activity against wood-

rotting fungi. These compounds have obvious insecticidal effects on termites. They also ex-

hibited potent acaricidal activity against mites. The above-mentioned features suggest that

Konjiki-do, a well known national treasure, one of the buildings in Chuson-ji Temple of Iwate

Prefecture, Japan, which was built of wood from the tree containing these five compounds,

was kept from harm against noxious insects and wood-rotting fungi for a long time of about

840 years, until it was extensively repaired in 1962. In addition to Konjiki-do, there are some

old famous Buddhist temples and Shinto shrines using Aomori Hiba. From the results, it was

found that Aomori Hiba (Hinokiasunaro) is excellent for use as building materials.

Key words: Aomori Hiba/Hinokitiol-related compound/Building material/Long durability/Konjiki-do.

Aomori Hiba (Thujopsis dolabrata Sieb. et Zucc.var hondai MAKINO, Fig.1) is a needle-leaved treewhich belongs to the genus Thujopsis (Asunaro) ofthe Hinoki Family. Aomori Hiba is a precious tree. Theforest of Aomori Hiba is often called one of the threefinest forests in Japan, together with those of theJapanese cypress (Cryptomeria japonica) in Kiso,Nagano Prefecture and Japanese cedar (Chamacy-

paris obtusa) in Akita Prefecture.Aomori Hiba is specified as the symbol tree of

Aomori Prefecture. Eighty-two percent of all Aomori

FIG. 1. The forest-zone of Aomori Hiba (AomoriPrefecture).

*Corresponding author. Tel&Fax: +81-6-6489-0520.

The address of YOSHIHIKO INAMORI's house: 12-58-708

Nishidaimotsu-cho , Amagasaki-shi , Hyogo 660-0827,

Japan

50 Y. INAMORI ET AL.

Hiba in Japan, as the name implies, is found inAomori Prefecture with forty-two percent found in theShimokita Peninsula and forty percent in the TsugaruPeninsula. Both peninsulas are covered with the

green trees of Aomori Hiba. In the ShimokitaPeninsula, Yagen Valley along the Yagen Riverabounds in scenic and natural wonders. The river re-flects beautifully the wood of Aomori Hiba on bothsides. Yagen and Okuyagen spas are on the YagenRiver. Osorezan, an dormant volcano, is the focal

point of the Shimokita Peninsula. It consists of sevenpeaks, of which Mt Kamabuse (879m) is the highest.At the crater, surrounded by a primeval forest ofAomori Hiba, lies a lake called Usori.

Aomori Hiba is a well-known tree. Yasushi Inouewrote about hinokiasunaro in his well-known novelAsunaro Monogatari (1953). Regarding Aomori Hiba,another famous writer Osamu Dazai emphasized thefollowing point in his work Tsugaru (1944): the tradi-tional product of the Tsugaru district is not apples butAomori Hiba. People in both Kanto and Kansai areaof Japan tend to associate applies with Tsugaru dis-trict, but they do not know much about the excellenceof Aomori Hiba.

Judging from the fact that the ranges of mountainsin Tsugaru are covered with the green trees ofAomori Hiba, the origin of the name of AomoriPrefecture is considered to be due to this tree.Aomori literally means "green wood". The form ofAomori Hiba which grows straight even in severe mid-winter cold seems to show the spirit of the people inTsugaru. In The Reverse Ideas from Hiba House(1996), another favorite book of one of the authors,Yasuo Tsurumaki also tells us about the excellenceof Aomori Hiba.

In this short review, we would like to demonstratethe excellence of Aomori Hiba wood as building ma-terials of Shinto shrines and Buddhist temples. As anold building made of Aomori Hiba, the national treas-ure Konjiki-do (1124, Fig.2), one of the buildings inChuson-ji Temple, Iwate Prefecture, is well-known. Inaddition, there are some other famous old buildingsmade of Aomori Hiba such as the house of HukujiOkamoto(1520) in Aomori, Intaku-ji Temple (1570)in Ishikawa Prefecture, Fushimi-jo Castle (1594) inKyoto, Kamenoko Gate of Hirosaki-jo Castle (1603)in Aomori, the Gate of lwakiyama Shrine (1628) inAomori, and the Main Hall of Seigan-ji Temple (1629)in Aomori.

Furthermore, public institutions such as AomoriPrefecture Forest Museum (1908), Asunaro Hall(1988) in Aomori, and Wood Culture Hall (1987) inMiyagi Prefecture were built of this wood. Becausethe excellence of Aomori Hiba wood as building

FIG. 2. The Inside of the National Treasure, Konjiki-do,one of the buildings of Chusonji Temple and threeBuddhist images built of Aomori Hiba.The photograph was published by the permission of thebook, "Hiraizumi" (the date of publication: July 25, 1986,Chusonji-Temple).

materials has been widely known, many Shintoshrines and Buddhist temples have been built of thiswood (Table 1). Aomori Hiba has recently been usedin the restoration of Heijyo-kyo (1998) in Nara,Kakegawa-jo Castle (1999) in Shizuoka, and in re-construction of Takada-jo Castle (1614) in JoetsuCity in Niigata.

The main building and cultural assets, which havealready been built of Aomori Hiba, are summarized inTable 1. As shown in Table 1, these buildings areseen in every area of our country. This testifies to theexcellence of Aomori Hiba wood as building materi-als.

Of the above-mentioned buildings, Konjiki-do, asstated earlier, is known to have been kept from harmagainst noxious insects and wood-rotting fungi forabout 840 years. However, no work has been done toexplain the long-term durability of this building.

Therefore, in this short review, we would like statethe reasons for the durability of the building built ofAomori Hiba by introducing of our recent reports andprevious papers of Dr.Okabe, one of our collabora-tors. We found that at least one of the reasons forlong-term durability of Aomori Hiba is due to its

LONG DURABILITY OF AOMORI HIBA 51

TABLE 1. Main buildings and cultural assets built of Aomori Hiba.

52 Y. INAMORI ET AL.

FIG. 3. Chemical structure of five hinokitiol-related com-

pounds isolated from the acid oil of Aomori Hiba.

antifungal activity against wood-rotting fungi (Inamori

et al., 2000; Morita et al., 2002) and insecticidal ef-

fects on mites and termites (Inamori et al., 2000;

Morita et al., 2004) by hinokitiol-related compounds

(Fig.3) isolated from the acid oil content obtained

during the distillation of this wood (Okabe et al.,

1990). Namely, four compounds, other than a -thuja-

plicin, showed antifungal activity against five kinds of

wood-rotting fungi. In particular, the antifungal activi-

ties of these four compounds against Daedalea

disckinsii (Japanese name: Hourokutake) . were

strong. Their minimal inhibitory concentration values

(MIC ,ƒÊg/mI)) were 0.2 ,ƒÊg/ml. The antifungal ac-

tivities of these four compounds were almost equal to

that of amphotericin B, which had been used as a

positive control. The MIC values of these four com-

pounds against other wood-rotting fungi were in the

range of 6.25-50.0 ,ƒÊg/ml. Four compounds other

than 4-acetyltropolone exhibited strong insecticidal

activity against termites and the insecticidal activities

(50%-lethal concentration (LC50) values) were in the

range of 0.02-0.07g/m2. Although the insecticidal

effects of these four compounds on termites were

much lower than that of commercial chloropyrifos

(LC50:0.00016 ,ƒÊg/m2), which had been used as a

positive control, their insecticidal effects as natural

products were considerably strong. Except for ƒ¿-

thujaplicin, these compounds also showed potent

acaricidal effect on mites, with their LC50 values being

0.02-0.24g/m2. The acaricidal activities were higher

than that of N,N-diethyl-m-toluamide (DEET, LC50:

0.79g/m2), which is used as a standard agent.

Yoshimura (1966) has already reported that the

mechanism of the decomposition action by termites

on wood is due to the cellulase produced by the sym-

biotic protozoa in the posterior parts of the hindgut of

this insect. Yoshimura et al (1995) also found that

the mechanism of insecticidal effects of hinokitiol on

termites was caused by its action against this symbi-

otic protozoa. The results are supported by our re-

ports (Inamori et al., 2000; Morita et al., 2004a) that

hinokitiol-related compounds inhibited the growth of

wood-rotting fungi with cellulase production activity.

However, no work has yet been done on the inhibition

of the cellulase production of wood-rotting fungi by

five hinokitiol-related compounds.

Okabe et al.(1990) also reported that strong

insecticidal activity on mites and termites was ob-

served with Hiba oil. It was further reported by Okabe

et al.(1990) that Aomori Hiba showed the strongest

antifeedant activity on termites when compared with

other building materials such as Japanese black pine,

Larch of the Northern Sea, artificial Japanese cedar,

Japanese cypress and Japanese cedar. Among the

five hinokitiol-related compounds, hinokitiol has al-

ready been isolated from Chamacyparis taiwanensis

(Nozoe, 1936). After that, hinokitiol-related com-

pounds such as hinokitiol ƒÀ-thujaplicin), ƒ¿-

thujaplicin, ƒÀ-dolabrin, ƒÁ-thujaplicin and 4-

acetyltropolone were isolated from Thujopsis

dolabrata Sieb. et Zucc. by Nozoe et al. (1951;

1957). Hinokitiol (1%) and ƒÀ-dolabrin (1%) were

also found to be contained in Aomori Hiba. In addition

to Aomori Hiba and Taiwan Hinoki, Ezo Hiba, Kurobe

(Thuja standishii, Japanese name: Nezuko) and

Western Red Cedar (Thuja plicata Don) are known

for containing hinokitiol. These belong to the Hinoki

Family. Among them, the hinokitiol content was found

to be greatest in the case of Aomori Hiba. As Aomori

Hiba is the same genus as Ezo Hiba botanically, the

hinokitiol content of the former was almost equal to

that of the latter. The hinokitiol content of Taiwan

Hinoki was found to be one half that of Aomori Hiba.

The hinokitiol content of Nezuko and Western Red

Cedar is one twentieth of Aomori Hiba. On the other

hand, Japanese Hinoki contains little hinokitiol.

Hinokitiol was found to be effective as a preserva-

tive which works against the putrefaction of vegeta-

bles (Fukuzawa et al., 1986), flowers (Fukuzawa et

al., 1988) and mushrooms (Kamiyokote et al., 1990)

with its strong antibacterial activity. It is also used as

a plant growth stimulator (Kafuku, 1976). In addition,

it is used as a preservative in toothpaste, hair tonic

and cosmetics (lwama,1959). As hinokitiol also

shows clear antibacterial activity in vitro against

Staphylococcus aureus (Inamori et al., 1999), it is

clinically being tested in the medical treatment of

atopic dermatitis (Akiyama et al., 1994; Baba et al.,

1988; Sakai et al., 1989).

Aomori Hiba has a sweet fragrance. In the first part

of the scientific name of Aomori Hiba, Thujopsis,

thujo means thuja and the word comes from "thuiia" in

LONG DURABILITY OF AOMORI HIBA 53

Greek. "Thuiia" is indicative of fragrance. Although

there are slight differences, the five kinds of

hinokitiol-related compounds isolated from Aomori

Hiba have a sweet fragrance. In addition to these five

compounds, it is known that there are other com-

pounds with a sweet fragrance such as ƒÀ-

thujopsene, cedrol and elenal in Aomori Hiba (Nozoe

et al., 1951; 1957). Although these compounds are

all volatile, they characteristically keep their sweet

fragrance for a long period because of their oiliness.

We are deeply inspired with long durability of the

sweet fragrances of the old Oi-do, which was built of

Aomori Hiba about 800 years ago (in the Kamakura

period). From these results, it was found that termites

and noxious insects were kept away by the sweet fra-

grance of Aomori Hiba. This is also supported by our

reports which show that these five hinokitiol-related

compounds showed strong insecticidal activity on

mites and termites (Inamori et al., 2000; Morita et al.,

2004b).

The above-mentioned results are coincident with

the fact that Konjiki-do was kept from harm against

noxious insects and wood-rotting fungi for long time,

about 840 years, until it was extensively repaired in

1962. Konjiki-do was built in 1124 by Kiyohira

Fujiwara, the clan's first lord of the Tohoku area.

Three Buddhist images enshrined in this temple are

made of Aomori Hiba. Three gold coffins (Fig.4) con-

taining mummies of Kiyohira, Motohira (son of

Kiyohira) and Hidehira (grandson) are also made of

Aomori Hiba. A tub, containing the head of Yasuhira

(great-grandchild), is buried in the coffin of his father,

Hidehira. These coffins were stored under the tables,

namely, so-called "Shumidan" onto which the three

Buddhist images were placed.

Attention has also been focused on the use of

Aomori Hiba for use building materials in the periodic

moving and rebuilding of Ise Shrine, Mie Prefecture.

Namely, in the upcoming sixty-second rebuilding

FIG. 4. The gold coffin containing the mummy of KiyohiraFujiwara.The photograph was published by the permission of thebook, "Hiraizumi" (the date of publication: July 25, 1986,Chusonji-Temple).

(Apr. 25, 2013) of the Ise Shrine, it was decided that

Aomori Hiba would be partly used due to the lack of

Hinoki (Cryptomeria japonica) (Nikkei Sangyou

Shinbun, 2004).

In addition, an inhibitory activity on metalloprotease

(Inamori et al., 1999; Morita et al., 2001; Matsumura

et al., 2001), cytotoxic effect on mammalian tumor

cell lines (Morita et al., 2001; Matsumura et al., 2001;

Morita et al., 2004), and phytogrowth-inhibitory activ-

ity (Inamori et al., 1991; Sakagami et al., 2000) were

also found in these five hinokitiol-related compounds.

From ancient times, Hinoki has been said to be the

most excellent wood as building materials. This has

been supported from the fact that world's oldest

wooden building, Horyu-ji Temple, Nara Prefecture,

which was built of Hinoki, has been known to be kept

from harm against noxious insects and wood-rotting

fungi for a long time, about 1300 years. On the other

hand, although Aomori Hiba is not as well-known as

Hinoki, as stated above, the former has also been

found to be the excellent wood which is not all inferior

to the latter for use as building materials.

So far we have chemically explained the excel-

lence of Aomori Hiba as building materials, but we

must not forget to pay reverence to natural wonder

embodied in Aomori Hiba.

ACKNOWLEDGEMENTS

The authors wish to express their deep gratitude to the

Rev. Hosei SASAKI, Ex-Secretary General of Chuson-ji

Temple, Iwate Prefecture, for his valuable advice during this

project. They also thank the Rev. Yuken KONISHI, the

Priest of Saishou-ji Temple, Osaka, for his genial support

and guidance during this work.

REFERENCES

Akiyama, H., Torigoe, R., Kanzaki, H., and Arata, J.(1994)

Topical use of Hinokitiol ointment in dermatitis patients-

with special reference to colony count of Staphylococcus

aureus on the surface of atopic dermatitics-

Chemotherapy (Tokyo), 42, 1202-1211.

Baba, T., Nakano, H., Tamai, K., Sawamura, D., Haneda, K.,

Hashimoto, L., and Arima, Y. (1988) Inhibitory Effect of

ƒÀ-Thujaplicin on Ultraviolet B-Induced Apoptosis in

Mouse Karatinocytes. J. Invest. Dermatol., 110, 24-28."Chuson -ji Ogon Hiho Ten" Chuson-ji Ogon Hiho Ten JIKKO

IINKAI (1993).

Fukazawa, R., and Sato, M., Japan Kokai Tokkyo Koho Jp

61117289 (Chem. Abstr., 105, 170928n (1986))

Fukazawa, R., and Sato, M., Japan Kokai Tokkyo Koho Jp

62236440 (Chem. Abstr., 108, 130284e (1988))

Inamori, Y., Nishiguchi, K., Matsuo, N., Tsujibo, H., Baba, K.,

and Ishida, N. (1991) Phytogrowth-Inhibitory Activities of

Tropolone and Hinokitiol. Chem. Pharm. Bull., 39, 2378-

2381.

54 Y. INAMORI ET AL.

Inamori, Y., Shinohara, S., Tsujibo, H., Okabe, T., Morita, Y.,

Sakagami, Y., Kumeda, Y., and Ishida, N.(1999)

Antimicrobial Activity and Metalloprotease Inhibition of

Hinokitiol-Related Compounds, the Constituents of

Thujopsis dolabrata S. and Z. hondai Mak. Biol. Pharm.

Bull., 22, 990-993.

Inamori, Y., Sakagami, Y., Morita, Y., Shibata, M., Sugiura,

Y., Kumeda, Y., Okabe, T., Tsujibo H., and Ishida N.

(2000) Antifungal Activity of Hinokitiol-Related

Compounds on the Wood-Rotting Fungi and their

Insecticidal Activities. Biol. Pharm. Bull., 23, 995-997.

Iwama, H. (1959) Study on Experimental Pathology of

Hinokitiol Volume I. Study on the Growth of Hair. Nihon

Taishitsugaku Zasshi, 23, 481.

Kafuku, A. Japan Kokai Tokkyo Koho Jp 7622819 [Chem.

Abstr., 85, 153492 (1976))

Kamiyokote, S., Izumi, K., and Hirota, N. Japan Kokai

Tokkyo Koho Jp 0215729 (Chem. Abstr., 113, 128087c

(1990))

Matsumura, E, Morita Y., Date, T., Tsujibo, H., Yasuda, M.,

Okabe, T., Ishida, N., and Inamori, Y. (2001) Cytotoxicity

of the Hinokitiol-Related compounds, ƒÁ-Thujaplicin and

ƒÀ-Dolabrin . Biol. Pharm. Bull., 24, 299-302.

Morita, Y., Matsumura, E., Okabe, T., Fukui, T., Shibata, M.,

Sugiura, M., Ohe, T., Tsujibo, H., Ishida, N. and Inamori,

Y. (2004a) Biological Activity of ƒ¿-Thujaplicin, the

Isomer of Hinokitiol. Biol. Pharm. Bull., 27, 899-902.

Morita, Y., Matsumura, E., Okabe, T., Fukui, T., Ohe, T.,

Ishida, N., and Inamori,Y. (2004b) Biological Activity of

ƒÀ-Dolabrin, ƒÁ-Thujaplicin, and 4-Acetyltropolone,

Hinokitiol-Related Compounds. Biol. Pharm. Bull., 27,

1666-1669.

Morita, Y., Matsumura, E., Tsujibo, H., Yasuda, M.,

Sakagami, Y., Okabe, T., Ishida, N., and Inamori, Y.

(2001) Biological Activity of ƒ¿-Thujaplicin, the Minor

Component of Thujopsis dolabrata Sieb. et Zucc. var

hondai MAKINO. Biol. Pharm. Bull., 24, 607-611.

Morita, Y., Matsumura, E., Tsujibo, H., Yasuda, M., Okabe,

T., Sakagami, Y., Kumeda, Y., Ishida, N., and Inamori, Y.

(2002) Biological Activity of 4-Acetyltropolone, the Minor

Component of Thujopsis dolabrata Sieb. et Zucc. hondai

MAKINO. Biol. Pharm. Bull., 25, 981-985.

Nikkei Sangyou Shinbun, Chokan, May,11 (2004).

Nozoe, T. (1936) Uber die Farbastoffe in Holtzteile des"Hinoki" baumes

. I . Bull. Chem. Soc. Jpn., 11, 295-298.

Nozoe, T., Yasue, A., and Yamane, K. (1951) On the Acidic

Constituents of Essential Oil of Thujopsis dolabrata.

Occurrence of ƒ¿-Thujaplicin. Proc. Japan Acad., 27, 15-

17.

Nozoe, T., Takase, K., and Ogata, M. (1957) ƒÀ-DOLAB-

RIN: A NEW NATURAL TROPOLONE. Chem. Ind.

(London), 1957, 1070.

Okabe, T., Saito, K., Otomo, Y. and Kudo, Y. (1990)"AOMORI HIBA NO FUSHIGI" AOMORI HIBA

KENKYUKAI SHUPPAN.

Sakagami, Y., Inamori, Y., Isoyama, N., Tsujibo, H., Okabe,

T., Morita, Y., and Ishida, N. (2000) Phytogrowth-

Inhibitory Activities of ƒÀ-Dolabrin and ƒÁ-Thujaplicin,

Hinokitiol-Related Compounds and Constituents of

Thujopsis dolabrata Sieb. et Zucc. var hondai MAKINO.

Biol. Pharm. Bull., 23, 645-648.

Sakai, I., and Tamura, U., Japan Kokai Tokkyo Koho Jp

6318869 (Chem. Abstr., 111, 102562n (1989))

Yoshimura, T. (1966) Studies on the Parasitic Organisms

of the Termite, Coptotermes formosanus Shibata. Jpn. J.

Environ. Entomol. Zool., 1, 48-59.

Yoshimura, T., Takahashi, M., Yoshida, Y., lnukai, T., Chiba,

T., and Kato, N. (1995) Termiticidal Performance of

Hinokitiol and Its Derivatives in Laboratory Test. Jpn. J.

Environ. Entomol. Zool., 7, 72-78.