Flavonoids from Gutierrezia grandis

Thirteen flavonoids, including three new compounds, were isolated from Gutierrezia grandis. The structures of the new compounds were 3,5,7,3′,4′-pentahydroxy-6,8-dimethoxyflavone, 5,7,3′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone and 5,7,3′,5′-tetrahydroxy-3,6,8,4′-tetramethoxyflavone 3′-O-glucoside.     

Highly oxygenated flavonoid aglycones from gutierrezia grandis

Twelve known and nine new highly oxygenated flavonoid aglycones, some of which exhibit 2′-oxygenation, were isolated from Gutierrezia grandis.     

Viscidic acid A and B,two ent-labdane derivatives from Chrysothamnus viscidiflorus

The chemical investigation of Chrysothamnus viscidiflorus afforded, in addition to known bisabolene derivatives, elemicin and p-hydroxyacetophenone, two new diterpene acids. Their structures were determined, by spectroscopic methods and some chemical transformations, as ent-labd-8(17),13E-dien-15-ol-18-oic acid (viscidic acid A) and ent-labd-8(17),13E-dien-15-acetoxy-18-oic acid (visidic acid B).     

Clerodanes from solidago virgaurea

The isolation and structure determination of four known and eight new cis-clerodane lactones from the aerial parts of Solidago virgaurea are described.     

Ent-norlabdane triols from Austroeupatorium inulaefolium

Two new ent-norlabdane triols were isolated from the above-ground parts of Austroeupatorium inulaefolium.     

Ent-Labdanes from Baccharis Sternbergiana

The aerial parts of Baccharis sternbergiana afforded six new ent-labdane derivatives, while those of a Baccharis tricuneata subspecies gave 12-acetoxytremetone.     

An unusual m-hydroxyacetophenone and three new chromanone derivatives from Chrysothamnus viscidiflorus

An unusual m-hydroxyacetophenone, named viscidone, and three new chroman-4-one derivatives were isolated from Chrysothamnus viscidiflorus ssp. lanceolatus, which also contained a known p-hydroxyacetophenone derivative. Their structures were determined by spectroscopic (¹H and ¹³C NMR, UV, IR and MS) and chemical means.     

Ent-kauranes and trachylobanes from Helianthus radula

The aerial parts of Helianthus radula afforded a variety of known ent-kauranoic acids as well as two new substances, 11-oxotrachyloban-19-oic a     

New cadinene derivatives from Heterotheca latifolia

Heterotheca latifolia afforded several new acids all derived from cadinane.     

Ent-kauranes and other constituents of three Helianthus species

Aerial parts of Helianthus debilis subsp. cucumerifolius, H. occidentalis and H. simulans afforded a variety of known and some unknown ent-kauranoic acids. H. occidentalis gave, in addition, ciliaric acid and a new biogenetically related atisane derivative occidentalic acid. H. simulans gave the heliangolide leptocarpin and the flavone hymenoxin in addition to ent-kauranes. Several of the diterpenoids from these species inhibited larval growth of the sunflower moth.     

Benzofuran derivatives from enceliopsis argophylla

From the composite Enceliopsis argophylla several new benzofuran derivatives were isolated. The unusual structure of the skeleton comprises an isopropylidene group at C-2 and a keto function at C-3 of the furan ring. An organ specific analysis by HPLC showed the compounds being present in leaves, peduncles, bracts, ray and disc flowers. The absolute amounts, however, differed greatly being highest in leaves and bracts.     

Ent-pimaranes, ent-kauranes,Heliangolides and other Constituents of three Helianthus species

Aerial parts of Helianthus strumosus gave the C-2′ epimer of the heliangolide 2′,3′-dihydrobudlein A as well as the flavones nevadensin, hyme     

Chemistry of toxic range plants. Highly oxygenated flavonol methyl ethers from Gutierrezia microcephala

The perennial American desert shrub, Gutierrezia microcephala, contains 20 flavonol methyl ethers displaying nine different oxygenation patterns. These include 11 new flavonols: 5,7-dihydroxy-3,6,8,3′,4′,5′-hexamethoxyflavone, 5,7,4′-trihydroxy-3,6,8,3′,5′-pentamethoxyflavone, 5,7,3′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone, 5,7,2′,4′-tetrahydroxy-3,6,8,5′-tetramethoxyflavone, 5,7,3′,4′-tetrahydroxy-3,6,8-trimethoxyflavone, 5,7,8,3′,4′-pentahydroxy-3,6-dimethoxyflavone, 3,5,7,3′,4′-pentahydroxy-6,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,6,8-trimethoxyflavone, 5,7,8,4′-tetrahydroxy-3,3′-dimethoxyflavone, 5,7,8,3′,4′-pentahydroxy-3-methoxyflavone and 5,7,8,4′-tetrahydroxy-3-methoxyflavone. In addition, the following known flavonols were isolated: 5,7-dihydroxy-3,8,3′,4′,5′-pentamethoxyflavone, 5,7,4′-trihydroxy-3,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,8,3′-trimethoxyflavone, 5,7,3′,4′-tetrahydroxy-3,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,6,3′-trimethoxyflavone, 5,7,3′,4′-tetrahydroxy-3-methoxyflavone, 5,4′-dihydroxy-3,6,7,8,3′-pentamethoxyflavone, 5,7,4′-trihydroxy-3,6,8,3′-tetramethoxyflavone and 3,5,7,4′-tetrahydroxy-6,8,3′-trimethoxyflavone.     

Oxygenated nerolidol derivatives from Artemisia alba

From the aerial parts of Artemisia alba of Calabrian origin, five oxygenated nerolidol derivatives were isolated, two of them bearing hydroperoxyl groups. Structures were elucidated by spectral data and chemical reactions. Acetylation of the major hydroperoxyl constituent afforded a tris-nor aldehydic derivative as a result of loss of acetone from an unstable intermediate perester. An internally consistent set of ¹³C NMR assignments for the natural products and some derivatives is presented.     

Oxidized kaurene derivatives from leaves of Solidago missouriensis and S. Rigida

Oxidized kaurene derivatives were isolated from the leaves of Solidago missouriensis and S. rigida and identified as kauran-16β-ol, kaur-16-en-19-oic acid and 7β-hydroxykaur-16-en-19-oic acid. The structure of the latter compound was determined by X-ray crystallographic analysis of its methyl ester.     

Pseudoguaianolides carabrone derivatives from Loxothysanus sinuatus

The aerial parts of Loxothysanus sinuatus afforded in addition to known compounds nine new pseudoguaianolides, three guaianolides and five carabrone derivatives. The structures were elucidated by spectroscopic methods. The chemotaxonomy is discussed briefly. The configurations of two guaianolides were corrected.     

Stereochemistry of strictic acid and related furano-diterpenes from conyza japonica and grangea maderaspatana

Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4′-trimethoxyflavone. Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne. The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-cleroclatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and (ent-15,16-epoxy-1,3,13(16),14-clerodatraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid.     

Isoalantolactone derivatives and germacranolides from Blumea densiflora

The germacranolides tagitinin A and tirotundin ethyl ether and a series of new ring A-hydroxylated isoalantolactone derivatives were isolated from Blumea densiflora. Structures were established by spectroscopic methods and chemical transformations.     

Eudesmanolides and costic acid derivatives from Flourensia macrophylla

The aerial parts of Flourensia macrophylla afforded, in addition to compounds similar to those from other Flourensia species, four new eudesman     

Isocedrene derivatives and other sesquiterpenes from moscharia pinnatifida

From the aerial parts of Moscharia pinnatifida nine further α-isocedrene, two guaiane, three cyperene and two nerolidol derivatives were isolated. The structures were elucidated by high field NMR studies. Chemotaxonomic aspects are discussed.