C-27 Apocarotenoids in the Flowers of Boronia megastigma (Nees)

Abstract

Five C-27 apocarotenoids were detected in acetone extracts of the flowers of Boronia megastigma (Nees) using HPLC with UV-vis photodiode array and MS detection. Comparison of methylated and unmethylated extracts aided identification when considered with the UV-vis and MS data. The five apocarotenoids identified here were hydroxy-apo-10'-carotenoic acid (1), methyl hydroxy-apo-10'-carotenoate (2), apo-10'-carotenoic acid (3), apo-10'-carotenal (4), and methyl apo-10'-carotenoate (5). The data obtained was not sufficient to allow the specific isomeric forms to be unequivocally identified. The results further support speculation that the C-13 norisoprenoids found in boronia are derived from C-40 carotenoids. Possible parent molecules of beta-ionone, an important component of boronia extract, were identified. An understanding of C-13 norisoprenoid biosynthesis may assist in the selection and postharvest processing of boronia flowers for flavor and fragrance applications.

RNA Interference-Mediated Repression of MtCCD1 in Mycorrhizal Roots of Medicago truncatula Causes Accumulation of C27 Apocarotenoids, Shedding Light on the Functional Role of CCD1

“…5). Their UV spectra were similar to those of C 27 apocarotenoid structural variants recently reported with single absorption maxima between 428 and 440 nm (Cooper et al, 2003). In particular, these spectra matched most closely to several C 27 carboxylic acids reported by those authors.…”

“…7). At least three key fragments (m/z 409, 391, and 269) conform precisely to major fragments obtained earlier by atmospheric pressure chemical ionization MS and MS/MS from a nonglycosylated 3-hydroxy-b-apo-10#-carotenoic acid (Cooper et al, 2003), corroborating the proposed structure. While there is still ambiguity on the position of the double bond in the cyclohexene ring (b-or a-ionone type), the a-ionone («-ring) type appears to be more likely.…”

“…Due to the fact that AM-induced cyclohexenone derivatives characterized to date exclusively contain an a-ionone ring (Strack and Fester, 2006), this ionone type is also tentatively proposed for the C 27 apocarotenoic acid identified. The 15-eV collision-induced dissociation (CID) mass spectrum of m/z 733 obtained from triple quadrupole MS shows a consecutive loss of + signal at m/z 409 and a UV light absorption maximum at 431.9 nm in 85% methanol/15% hexane has been reported for a C 27 apocarotenoic acid aglycone (Cooper et al, 2003), which is almost identical with our data under our solvent conditions and provides evidence for the proposed aglycone structure (Fig. 7).…”

“…Their UV spectra exhibited absorption maxima between 418 and 445 nm resembling those of recently described C 27 apocarotenoids, which are known to be yellow-orange ( Fig. 5A; Yokoyama and White, 1966;Cooper et al, 2003). None of these compounds exhibited UV light absorption signatures Figure 3.…”

Diversity of Carotenoid Composition in Flower Petals

“…accumulate crocetin and those of Crocosmia accumulate crocin 38,46 . Various apocarotenoids such as β-ionone, 10'-apocaroten-10'-oic acid, and hydroxy 10'-apocaroten-10'-oic acid are found in the petals of boronia (Boronia megastigma) 5,6 . The red stigma of crocus (Crocus sativus), from which the spice saffron is derived, accumulates a unique mixture of apocarotenoids-crocetin glycosides, picrocrocin, and safranal-which are responsible for the color, taste, and aroma of saffron.…”