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Rosa rugosa, Sesquiterpene, Bisabolanoid, ExoperoxideFive novel bisabolane sesquiterpenes possessing a tetrahydrofuran ring or a hydroperoxy group were isolated from Rosa rugosa leaves and their structures elucidated by chemical and spectroscopic methods. These highly oxidized sesquiterpenes were structurally related to bisaborosaol A which is the major bisabolanoid o f the plant. IntroductionSesquiterpenes have rarely been found as co n stituents o f R osaceae plants [1]. H ow ever, Rosa ru gosa T hunb. uniquely contains bisab o lan o id s and carotano id s in the leaves as its m ajo r com p o n en ts [2 -4 ], B isaborosaol A (6), the p red o m in an t bis abolanoid o f R. rugosa [4], has an unm odified isoprene unit on the side chain w hich is possibly oxi dized to yield various m etabolites as F lask am p e t al. (1981) have reported referring to a-bisabolol whose derivatives possessed an oxygenated side chain [5,6], A fu rth er survey o f m ore p o lar sesqui terpenes revealed the presence o f two tetrah y d rofurano (1 and 2) an d three exoperoxy (3 -5) deriv atives o f bisaborosaol A (6) (Fig. 1). In this paper, we describe the isolation and stru ctu ral elucidation o f these new and highly oxygenated b isabolanoids from R. rugosa. T he biological im plication o f these com pounds in the tissues is briefly discussed. Results and DiscussionIn a fu rth er survey o f the co n stitu en ts o f leaf ex tractives, o u r interest was a t first focused upon two substances 1 an d 2 w hich gave a yellow pig m ent on thin layer plates w ith v a n illin -H 2S 0 4 test (R { 0.38 and 0.30 in h e x a n e -E tO A c 3:1, respec tively). By colum n c h ro m ato g rap h y over S i 0 2 gel [4], 1 and 2 were eluted w ith 25% EtO A c/hexane. W ith the guidance o f the co lo ratio n w ith v a n illin -H 2S 0 4 reagent, each co m p o u n d was isolated and fu rth er purified by PT L C successively in h e x a n eEtO Ac 3:1 and C H C l3-M e O H 50:2 to give a colReprint requests to Y. Hashidoko.Verlag der Zeitschrift für N aturforschung, D-7400 Tübingen 0939-5075/91/0500-0357 $01.30/0 orless syrup ( 1 ; 160 mg, and 2 ; 120 mg from 6 kg o f R. rugosa leaves). Both show ed M + 282 in FI-M S and sim ilar 'H N M R spectra to th a t o f 6, suggest ing th at the isolates are diastereoisom ers closely related to 6. Two 3 H singlets in 1 at 8H 1.221 and 1.074 were assignable to C -l3 and C -l4 m ethyl groups, not on an olefinic b ut on an oxygenated aliphatic carbon. F urtherm ore, the detection o f m ethine protons (öH 3.415 in 1 and 3.553 in 2) a t tributable to the oxygenated C -l2 suggested the structural m odification from 6 into a cyclic ether on the side chain.W hen 6 was treated with m -CPBA , two p ro d ucts identical with 1 and 2 were afforded in alm ost equivalent am ount. The l3C N M R spectra dis counted the corresponding epoxy structures be cause o f the chemical shift values o f the oxygenat ed carbon at 8C 86.4 (CH -12), 84.6 (C -8) and 70.1 ( C -l3), for exam ple in 1, whose values were too low to be assigned to epoxy carb...

Quantitative levels of three major carotane sesquiterpenes, rugosal A (1), rugosic acid A (2) and carota-1, 4-dienaldehyde (3) were determined in leaves of Rosa rugosa THUNB. Carota-1, 4-dienaldehyde (3) increased during the budding and flowering stages, but drastically decreased after flowering.Compound 1 followed after 3 increased and was at a high level over flowering and ripening stages, and their concentrations were sufficient to suppress many fungi. Compound 2 accumulated through leaf maturation, and diminished in colored or falling leaves. Furthermore, leaf detaching or injury caused a rapid oxidation of 3 into 2 via 1. Compound 1 which is actively released from the tissues when the leaves were mechanically damaged and soaked in water seemed to originate mostly from compound 3 in tissues.

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