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).     

8β-hydroxypimar-15-en-19-oic acid from Taxodium mucronatum

A new diterpenoid has been isolated from the leaves and fruits of Taxodium mucronatum. Its structure, 8β-hydroxypimar-15-en- 19-oic acid, was established by chemical and spectroscopic means.     

15-Acetoxycostunolide from Magnolia sieboldii

A new germacranolide isolated from M. sieboldii was shown to be 15-acetoxycostunolide by spectroscopic and chemical methods. ¹H NMR spin decoupling and NOE experiments in the presence of a lanthanide shift reagent were used for structure elucidation.     

A new antiangiogenic C24 oxylipin from the soft coral Sinularia numerosa

A new oxylipin, 15-hydroxy-tetracosa-6,9,12,16,18-pentaenoic acid (15-HTPE; 1) was isolated as an inhibitor of tube-formation from the soft coral Sinularia numerosa. Its structure was elucidated by means of spectral analysis and chemical degradation. 15-HTPE inhibited tube formation of EA.hy926 cells at the concentration of 20–40 μM.     

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 sideritis pusilla subsp. flavovirens

Several new 14-hydroxybeyerene acetates have been isolated from the aerial parts of Sideritis pusilla subsp. flavovirens. In addition, an ent-kaur-15-ene (siderol) and a new ent-7α, 18-dihydroxybeyer-15-ene (flavovirol) have been obtained from the same source. The structures of these new acetates have been established by chemical and spectroscopic means and the structure of flavovirol has been confirmed by ¹³C NMR.     

Toxic lanostane triterpenes from the basidiomycete Ganoderma amboinense

A highly oxygenated new lanostane triterpene, designated as ganodermacetal (1), together with 15 related known compounds, has been isolated from the fruiting bodies of the basidiomycetous fungus Ganoderma amboinense. The structure of the new metabolite was elucidated on the basis of extensive spectroscopic analyses and chemical transformations. Ganodermacetal (1) possesses an uncommon 7,15-acetonide unit. Some of the isolated compounds showed significant toxic activity against brine shrimp larvae.     

α-(15-Hydroxyhexadecyl)itaconic acid from Usnea aliphatica

The structure of a new aliphatic acid from Usnea aliphatica was established by spectroscopic and chemical methods as α- (15-hydroxyhexadecyl)itaconic acid.     

Bisabolene derivatives from Stevia salicifolia

The aerial parts of Stevia salicifolia afforded two new bisabolene type sesquiterpenes. The structures were elucidated by spectroscopic, chemical transformations and correlation with 15-acetoxy bisabol-1-one.     

Diterpenoids from Acacia leucophloea

From the root bark of Acacia leucophloea (Mimosaceae) two new pimar-8(14)-ene diterpenoids have been isolated. Their structures have been established by chemical and spectroscopic means as 1β,15R,16-trihydroxypimar8(14)-ene(leucophleol) and 15R,16-epoxy-1β,11α-dihydroxypimar-8(14)-ene(leucophleoxol).     

Sempervirenic acid,a diterpene acid from Solidago sempervirens

Sempervirenic acid, a new diterpene has been isolated from Solidago sempervirens and its structure determined by spectroscopic methods and chemical conversions to be 3β-acetoxy-labda-7,13-diene-15-oic acid.     

Beyerene derivatives and other constituents from Petunia patagonica

Two new diterpenes of the beyerene type, ent-19-hydroxy-1 7-acetoxybeyer-15-ene and ent-beyer-15-en-17-oic acid, and two previously characterized kauranoids, ent-16β-hydroxy-17-acetoxykaurane and ent-16β,1 7-dihydroxy-kaurane, as well as two known flavonoids, luteolin-7,3′,4′-trimethyl ether and luteolin-7,3′-dimethyl ether, and a triterpenoid, oleanoic acid, were obtained from a chloroform extract of Petunia patagonica. The new structures were elucidated by spectral data and chemical transformations.     

Ent-kaurene diterpenoids and lignan from Leontopodium leontopodioides and their inhibitory activities against cyclooxygenases-1 and 2

Two new ent-kaurene diterpenoids, 13α,15α-dihydroxy-18-carboxy-19-nor-ent-kaur-16-ene-2β-O-(2′-angelate)-β-d-glucopyranoside (leontocin A, 1), 13α,15α-dihydroxy-18-carboxy-19-nor-ent-kaur-16-ene-2β-O-(2′-angelate-6′-acetyl)-β-d-glucopyranoside (leontocin B, 2), and one new lignan, 2,3-bis[(3,4-di-hydroxyphenyl)methylene]-monoethyl ester-butanedioic acid (leontolignan A, 3), together with three known phenolic acids (4-6) were isolated from the aerial parts of Leontopodium leontopodioides (Asteraceae). Their structures were elucidated by chemical and spectroscopic methods. All isolates were evaluated for their anti-inflammatory activities by measuring their inhibitory effects against cyclooxygenase-1 and 2 in vitro.     

Isolation,structure and biological activities of platencin A2–A4 from Streptomyces platensis

Natural products serve as a great reservoir for chemical diversity and are the greatest source for antibacterial agents. Recent discoveries of platensimycin and platencin as inhibitors of bacterial fatty acid biosynthesis enzymes supplied new chemical scaffolds for potential antibacterial agents to overcome resistant pathogens. Discovery of natural congeners augment chemical modification in understanding of structure–activity relationship (SAR). Chemical and biological screening of the extracts led to isolation of three hydroxylated analogs of platencin. The C-12, C-14 and C-15 hydroxylated analogs showed attenuated activities which provided significant understanding of functional tolerance in the diterpenoid portion of the molecule. A truncated and oxidized C-13 natural congener was isolated which suggested direct intermediacy of ent-copalyl diphosphate for the biosynthesis of platensimycins and platencins.     

The structure of leocardin,two epimers of a diterpenoid from Leonurus cardiaca

From the aerial part of Leonurus cardiaca a new labdane diterpenoid, leocardin, has been isolated and its structure was established by spectroscopic and chemical means. It has been shown to be 8β-acetoxy-9α,13α,15,16-bisepoxy-15-hydroxy-7-oxo-labdan-6β,19-olide present as a C-15 epimeric mixture.     

Oxo fatty acid esters from Cryptocoryne spiralis rhizomes

Two new compounds, isolated from the rhizomes of Cryptocoryne spiralis, have been characterized as ethyl 14-oxotetracosanoate and 15-oxoeicosanyl 14-oxoheptadecanoate by spectral data and chemical studies. Hentriacontane and sitosterol have also been isolated and identified.     

New diterpenes from Chamaecyparis pisifera

Three new diterpenes, pisiferin, 15-hydroxyferruginol, and O-methyl pisiferic acid have been isolated and the presence of 12-hydroxyabieta-8,11,13-trien-20-al has been confirmed in studies of the leaves of Chamaecyparis pisifera. The structure of pisiferin, a phenolic diterpene with a new carbon skeleton, has been determined by chemical degradation. The presence of diterpenes of the ferruginol type in the leaves of four varieties of C. pisifera has been examined.     

Neue ent-atisiren- und ent-kaurensäure-derivate aus Helianthus-arten

The investigation of four Helianthus species afforded, in addition to known compounds, four new atisirenic acid derivatives, a new ent-kaurenic acid derivative, three new labdane derivatives and an unknown C₁₅-acetylenic compound. The structures of the diterpenes were elucidated by intensive NMR studies and some chemical transformations. An unusual fragmentation in the mass spectra of the atisirenes is discussed briefly.     

One new flavonoid xyloside and one new natural triterpene rhamnoside from the leaves of Syzygium grande

One new flavonoid glycoside, myricetin 4′-methyl ether 3-O-β-d-xylopyranoside (1) and one new natural triterpene glycoside, grandoside (2) were isolated from a MeOH extract of the leaves of Syzygium grande, together with thirteen known compounds (3–15). The structures of the new compounds were determined through a combination of spectroscopic and chemical analyses. All of the isolated compounds were evaluated for their antifungal, antibacterial, anti-leishmania, DPPH radical-scavenging and cytotoxic activities by means of MTT assay.     

Beesioside III,a cyclolanostanol xyloside from the rhizomes of Beesia calthaefolia and Souliea vaginata

The chemical constituents of Beesia calthaefolia and Souliea vaginata were examined. From the rhizomes of B. calthaefolia, four new 9,19-cyclolanostanol xylosides, named beesiosides I–IV were isolated. Beesiosides 111 and IV were found also in the rhizomes of S. vaginata. On the basis of chemical and spectral evidence the structure of beesioside III was established as 15α-acetoxy-20ξ₁,24ξ₂-epoxy-9,19-cyclolanostane-3β,12β,16β,25-tetraol-3-O-β-D-xylopyranoside.