Flavonoids and the taxonomy of Camarea (Malpighiaceae)

Camarea is a South-American endemic genus comprising eight species. In the present work leaf flavonoids of seven species of Camarea were identified, aiming to evaluate the usefulness of their distribution as a taxonomic aid. A total of 12 flavonoids were isolated and identified. Free aglycones, such as apigenin, chrysoeriol, kaempferol and quercetin, as well as 7-O-glycosides of apigenin and luteolin, 3-O-glycosides of kaempferol and quercetin were identified. Flavonoid distribution in Camarea species, taking into account aglycones and aglycone moieties of glycosides, was used to obtain a phenogram of chemical affinities. Apigenin, chrysoeriol and kaempferol were the main discriminating characters for links establishment. The resultant tree suggests the links: 1) Camarea hirsuta, Camarea affinis and C. affinis × C. hirsuta; 2) Camarea elongata and Camarea axillaris; 3) Camarea sericea and Camarea humifusa. The results are in agreement with morphological similarities and disagree with several points of n-alkane evidence. The results support the recognition of Camarea triphylla as synonymy of C. axillaris.     

Composition of epicuticular wax layer of two species of Mandevilla (Apocynoideae,Apocynaceae) from Rio de Janeiro,Brazil

The chemical composition of epicuticular waxes of Mandevilla guanabarica and Mandevilla moricandiana was comparatively analyzed by extraction in n-hexane and chloroform. The mean wax content per unit of leaf area in the n-hexane extract was about 13–30 μg cm⁻² for M. guanabarica, containing 20–28% n-alkanes and 55–63% triterpenes; for M. mori-candiana, the mean content was 19 μg cm⁻², containing 73% n-alkanes and 14% triterpenes. In the chloroform extract, the wax yield was 40–80 μg cm⁻² for M. guanabarica, with about 9–11% n-alkanes and 75–82% triterpenes; while for M. moricandiana, the wax yield was 110 μg cm⁻², with 52% n-alkanes and 14% triterpenes. The major compounds identified were lupeol, pentacyclic triterpenes of the α- and β-amyrin class, and n-alkanes such as nonacosane, hentriacontane and tritriacontane. These results indicate that the quantitative chemical profiles of epicuticular waxes of M. guanabarica and M. moricandiana are distinct and could be used as an additional feature in taxonomic identification.     

Chemotaxonomy of Hypericum genus from Portugal: Geographical distribution and essential oils composition of Hypericum perfoliatum, Hypericum humifusum, Hypericum linarifolium and Hypericum pulchrum

The geographical distribution and analysis of the essential oils of species from three sections of Hypericum L. (Guttiferae/Clusiaceae/Hypericaceae) from Portugal are presented. Hypericum perfoliatum (section Drosocarpium) grows wild in the centre and south of Portugal; Hypericum humifusum and Hypericum linarifolium are both from section Oligostema, the former occurring throughout the country, while the second is distributed mainly in the north and centre; Hypericum pulchrum (section Taeniocarpium) is confined to the littoral north of Portugal. The essential oils were obtained by distillation–extraction, hydrodistillation and distillation in a modified Marcusson apparatus from the dried aerial parts of the different populations and were analysed by GC and GC–MS. Monoterpene hydrocarbons constituted the main fraction in all oils (43–69%, 53–85%, 28–45% and 48–65% for H. perfoliatum, H. humifusum, H. linarifolium and H. pulchrum, respectively). Sesquiterpene hydrocarbons (2–13%, 6–18%, 21–27% and 16–18%, respectively) and a third fraction of non-terpenic compounds (20–29%, 3–16%, 2–14% and 5–11%, respectively) from the four species attained relatively high amounts in all oils. Within each species, no major differences were detected in the essential oil composition, despite the fact that different locations, phenological phases and extraction methodologies were used. Notwithstanding the dominance of α-pinene in all four species' oils, cluster and principal components analysis on the identified components showed that the range of α-pinene, β-pinene and n-nonane supported a separation of the four species. The essential oil composition of the four species showed some qualitative resemblances, which correlate well with the taxonomical classification based on morphological characters.     

Homologous very-long-chain 1,3-alkanediols and 3-hydroxyaldehydes in leaf cuticular waxes of Ricinus communis L

Surface extracts from primary leaves of Castor bean were found to contain 1.8 microg cm(-2) of cuticular waxes. The mixture comprised alkanes (C(26)-C(29)), primary alcohols (C(22)-C(38)), aldehydes (C(26) and C(28)), fatty acids (C(20)-C(34)) and triterpenoids (lupeol, beta- and alpha-amyrin). Besides, a series of n-alkane-1,3-diols was detected, with chain lengths ranging from C(22) to C(28), a strong predominance of even-numbered homologs, and a maximum for hexacosane-1,3-diol. Seven other compounds were assigned to a novel class of wax constituents and identified as homologous unbranched 3-hydroxyaldehydes ranging from C(22) to C(28). As the chain length distribution of this series closely paralleled the homolog pattern of 1,3-diols, it seems likely that both compound classes are biosynthetically related.     

Chemical constituents from the fruits of Sonneratia caseolaris and Sonneratia ovata (Sonneratiaceae)

Nine (1–9) and seven (1–6, 10) compounds were isolated from the fruits of Sonneratia caseolaris and Sonneratia ovata, respectively. Their structures were identified by comparing their MS and NMR data as well as the physical properties with the literature. All the isolated compounds were screened against a rat glioma C-6 cell line using the MTT assay method; only compounds (-)-(R)-nyasol (1), (-)-(R)-4′-O-methylnyasol (2) and maslinic acid (6) were found to show moderate cytotoxic activity. Our findings from these two kinds of fruits can be used as a foundation for further chemotaxonomic studies on Sonneratia species. The nor-lignans (1, 2) and 6H-benzo[b,d]pyran-6-one derivatives (3, 4) were isolated from this genus for the first time, indicating that these two classes of compounds may tentatively be considered as taxonomic markers for Sonneratia genus.     

Phytoconstituents from the root of Streptocaulon tomentosum and their chemotaxonomical relevance for separation from S. juventas

A new cardenolide, 17β-H-periplogenin-3-O-β-d-digitoxoside (1), and a new pregnane glycoside, Δ⁵-pregnene-3β,16α-diol-d-O-[2,4-O-diacetyl-β-digitalopyranosyl-(1 → 4)-β-d-cymaropyranoside]-16-O-[β-d-glucopyranoside] (2) were isolated from the roots of Streptocaulon tomentosum (Asclepiadaceae) together with a series of known compounds. Their chemotaxonomic significance for the separation of S. tomentosum from Streptocaulon juventas is discussed, suggesting a rather clear distinction of these species.     

Flavonoids in the species of Cyrtomium (Dryopteridaceae) and related genera

Flavonoids in 19 Cyrtomium, three Cyrtogonellum and two Phanerophlebia taxa were surveyed. Major flavonoids were flavonol O-glycosides based on kaempferol, quercetin, and sometimes myricetin, and C-glycosylflavones, such as isovitexin, vitexin, isoorientin, orientin and their O-glycosides. The C-methylflavanones, farrerol and cyrtominetin, and their 7-O-glucosides were isolated from Cyrtomium devexiscapulae and Cyrtomium laetevirens. Flavanones have been reported from Cyrtomium falcatum sensu lato. Though C. falcatum sensu lato is divided into four taxa, i.e. C. falcatum subsp. falcatum, C. falcatum subsp. australe, C. falcatum subsp. littorale, and C. devexiscapulae, the occurrence of the flavanones was restricted to C. devexiscapulae, and they did not occur in C. falcatum sensu stricto.     

Chemical constituents of the seeds of Ammopiptanthus (Leguminosae) and their systematic and ecological significance

Eleven flavonoids including a new flavone glycoside, 7,3′-dihydroxy-4′-methoxyflavone-7-O-β-glucopyranoside, and a quinolizidine alkaloid, lupanine, were isolated from the seeds of two Ammopiptanthus (Leguminosae) species, Ammopiptanthus mongolicus and Ammopiptanthus nanus. 7,3′-Dihydroxy-4′-methoxyflavone and lupanine were the major constituents in the seeds of both species. The patterns of seed flavonoids presented a clear systematic relationship between the two species. The simple seed alkaloid composition was presumed to be responsible for the weak defense capability of the seeds to insect pests in both species.