Isolation of an anti-HIV diprenylated bibenzyl from Glycyrrhiza lepidota

The organic soluble extract from the leaves of Glycyrrhiza lepidota showed moderate activity in the US National Cancer Institute in vitro anti-HIV-1 bioassay. Chromatographic separation of this extract resulted in the identification of a new diprenylated bibenzyl as the compound responsible for the observed anti-viral activity. Extensive spectroscopic experiments provide the complete 1H NMR and 13C NMR spectral assignments to support the proposed structure. Known compounds glepidotin B and glepidotin A were also isolated from the extract and shown to be inactive in the anti-viral assay.     

Three oxanthrones from Aloe littoralis

The leaf exudate of Aloe littoralis yielded, in addition to the known 10-hydroxyaloin B, two new C-glucoside oxanthrones namely 10-hydroxy-15-O-(2R,3S-nilyl)(6′-O-acetyl)aloin B (littoraloin) and 10-hydroxy-15-O-(2R,3S- nilyl)aloin B (deacetyllittoraloin). Their structures were determined by spectroscopic methods as well as by conversion to the known 10-hydroxyaloin B and nilic acid.     

Sesquiterpene lactones from Liatris acidota, L. Aspera and L. Mucronata

Examination of Liatris mucronata gave the known 15-hydroxylated heliangolides liscundin, liscunditrin, punctaliatrin and two new closely related heliangolides. Liatris acidota furnished six new similar but 15-deoxygenated heliangolides as well as euparin and 3β-acetoxytaraxaster-20-en-30-aldehyde. Liatris aspera gave a known glycosidic germacradienolide and a new germacradienolide as well as several known flavones and a known benzofuran. Structures were established by spectroscopic methods and chemical transformations.     

Diterpenoids from halimium viscosum

In addition to three known acids, five new diterpenoid acids with a rearranged ent-labdane skeleton (ent-halimane) have been isolated from the acid fraction of Halimium viscosum as their methyl ester derivatives.     

Furanoheliangolides from two Eremanthus species and from Chresta sphaerocephala

The investigation of Eremanthus crotonoides afforded in addition to known compounds three new furanoheliangolides, while from E. glomerulatus six new furanoheliangolides and eremantholides were isolated. From the aerial parts of Chresta sphaerocephala a new guaianolide was obtained, while the roots contained known furanoheliangolides. The chemotaxonomy of the subtribe Lychnophorinae is discussed briefly.     

SU3, an oxocycloartane diglucoside from Sutherlandia humilis

The structure of a new cycloartane-type triterpene glycoside was determined as 24,25-O-β-d-diglucopyranosyl-6α-hydroxycycloart-3-one (SU3) by spectroscopic methods. This is the first cycloartane diglycoside reported from the genus Sutherlandia (an important South African traditional medicine and general tonic known as cancer bush). It was isolated from a dwarf form of S. frutescens, currently known as Sutherlandia humilis.     

Three triterpenes from Astraeus hygrometricus

Three new triterpenes, as well as two known steroids, were isolated fromAstraeus hygrometricus. The structures of the new triterpenes were established by chemical and spectroscopic means.     

A furostanol glucuronide from Solanum lyratum

A new furostanol glucuronide and three known glycosides, SL-O, aspidistrin and methyl proto-aspidistrin, were isolated from the fresh immature berries of Solanum lyratum. The structure of the new compound was characterized as 26-O-β-D-glucopyranosyl-(22ξ,25R-3β,22,26-trihydroxyfurost-5-ene 3-O-α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 3)]-β-D-glucuronopyranoside.     

Sesquiterpene lactones from Calea septuplinervia

Chemical analysis of Calea septuplinervia afforded two known flavonoids, acacetin and apigenin 7,4′-dimethyl ether, as well as the known eudesmanolide telekin. The new sesquiterpene lactone septuplinolide was shown to be a 7,8β-lactonized eudesmanolide.     

Eudesmanolide from Centaurea granata

Investigation of the aerial parts of Centaurea granata afforded, in addition to two known polymethoxylated flavones, a new eudesmanolide. The structure of the new compound was elucidated by spectroscopic methods as 8α-hydroxy-11β,13-dihydro onopordaldehyde.     

New diterpenes from Sideritis canariensis

Two new diterpenes ribenol [3α-hydroxy-(?)-13-epimanoyl oxide] (I)and 7β-acetoxy-18-hydroxytrachylobane (IX) as well as the known (?)-13-epimanoyl oxide (IV) have been isolated from Sideritis canariensis Ait.     

Dimeric guaianolides from Artemisia sieversiana

The aerial parts of Artemisia sieversiana afforded in addition to known compounds five new guaianolides and four dimeric guaianolides, three of them closely related to absinthin and one derived from estafiatin as a monomer. The structures were elucidated by extensive NMR studies, which allowed the assignment of the 14 chiral centres. Artemisia frigida afforded several known compounds and one new guaianolide, 8-desoxy-cumambrin B, the most likely precursor of many guaianolides.     

Eudesmanolides and diterpenes from Wedelia trilobata and an ent-kaurenic acid derivative from Aspilia parvifolia

The reinvestigation of the aerial parts of Wedelia trilobata afforded, in addition to known compounds, six new eudesmanolides, two ent-kaurenic acid derivatives as well as a degraded one. A corresponding hydroxy compound was present in Gnaphalium undulatum. From Aspilia parvifolia new ent-kaurenic acid epoxides were isolated. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Zanthomamide: An aromatic amide from Zanthoxylum thomense

From the stem bark of Zanthoxylum thomense a new amide, zanthomamide has been isolated and characterized as N-methyl, N-cinnamyl-(3′,4′-methylenedioxy)-phenylethylamine. Other constituents identified are the known benzophenanthridines, decarine, norchelerythrine and angoline.     

Labdane derivatives from hemizonia species

The investigation of three Hemizonia species afforded in addition to known compounds seven new labdane derivatives, all derived from labd-13-en-15-ol. The absolute configuration of these diterpenes was determined by degradation of the triol by periodate cleavage, which afforded a known norditerpene ketone. From H. fitchii two new chromene esters and the cis-isomer of a known coumarate were isolated. H. congesta afforded in addition to labdane derivatives a hydroxycubebol.     

Iridoid glucosides from Satureja Vulgaris

Satureja vulgaris was shown to contain two new iridoid glucosides, 5-deoxylamiol and 4-methylantirrhinoside, as well as the known iridoid glucosides lamiol and 5-deoxylamioside. The structures of the new glucosides were established by spectroscopic studies and chemical evidence.     

Cardenolides and a lignan from asclepias subulata

Four new glycosides (three cardenolides and a lignan), nine previously reported cardenolide glycosides and a known triterpenoid were isolated from the ethyl acetate extract of the aerial parts of Asclepias subulata. The elucidation of the structures and stereochemistry of the new glycosides has been accomplished using mainly ¹H and ¹³C NMR and mass (EI and FAB) spectral data of their acetyl derivatives and comparison of these data with those of known glycosides from the same plant as well as from other plants. The new compounds were identified as 16α-hydroxycalactin, 3β-(β-D-glucopyranosyloxy)-19-car coroglaucigenin 3β-D-glucoside and 4-(β-D-glucopyranosyloxy)-larciresinol.     

Four eudesmanolides from Montanoa frutescens

Chemical analysis of Montanoa frutescens afforded the known sesquiterpene lactones montafrusins A and B, as well as four new eudesmanolides which we have named montafrusins C, D, E and F. The structures of the new compounds were established by spectroscopic methods.     

Further sesquiterpene lactones from Helianthus maximiliani

By using HPLC, a new melampolide, a known heliangolide and three known germacrolides were isolated as minor constituents from a north central Texas population of Helianthus maximiliani. In an earlier report, we identified the germacrolide desacetyleupaserrin as the principal sesquiterpene lactone from this population.     

Oxepane diterpenoids sesquiterpene lactones from ‘zoapatle’ (montanoa tomentosa), a mexican plant with oxytocic activity

Investigation of the ‘tea’ prepared from the leaves of ‘zoapatle’ (Montanoa tomentosa), resulted in the isolation of the known biologically active oxepane diterpenoids zoapatanol and montanol, the known sesquiterpene lactones zoapatanolide A, C and D as well as two new biologically active oxepane diterpenoids and a new sesquiterpene lactone. The structures of the new compounds were established by spectroscopic methods.