Lacinilene C,A revised structure,and lacinilene C 7-methyl ether from Gossypium bracts

Two sesquiterpenes, which exhibit brilliant yellow fluorescence in the ultraviolet, have been isolated from frost-killed cotton bracts. They have been identified as lacinilene C and its 7-methyl ether. A revised structure related to the cadinane ring system is proposed for lacinilene C.     

Variations in flavonoid patterns within the genus Chondropetalum (restionaceae)

HPLC and chemical analyses of the flavonoids in culms of 11 Chondropetalum species divide the genus into two groups: seven, with glycosides of myricetin larycitin and syringetin; and four, with glycosides of kaempferol, quercetin, gossypetin, gossypetin 7-methyl ether and herbacetin 4′-methyl ether. This chemical dichotomy is correlated with anatomical differences and confirms the view that the genus requires taxonomic revision. HPLC measurements on those species with myricetin derivatives show that taxa with a qualitatively similar pattern of glycosides can be readily separated on quantitative grounds. Syringetin 3-arabinoside and a glycoside of herbacetin 4′-methyl ether are reported for the first time from the genus.     

Isoflavones from Dipteryx odorata

Five isoflavones have been isolated from the heartwood of Dipteryx odorata: retusin, retusin 8-methyl ether, 3′-hydroxyretusin 8-methyl ether, odoratin (7,3′-dihydroxy-6,4′-dimethoxyisoflavone) and dipteryxin (7,8-dihydroxy-6,4′-dimethoxyisoflavone).     

2-Hydroxy-7-methoxycadalene. The precursor of lacinilene C 7-methyl ether in Gossypium

Two sesquiterpenoid naphthols, 2,7-dihydroxycadalene and 2-hydroxy-7-methoxycadalene, have been isolated from green and field-dried cotton bracts. These naphthols rapidly autoxidize on silica gel to lacinilene C and lacinilene C 7-methyl ether, respectively. The latter compound has been implicated as a causative of byssinosis. Lacinilene C and its methyl ether derivative isolated from field-dried cotton leaves and bracts were optically active, indicating that the lacinilenes are produced enzymatically from the naphthols. Therefore, bioassays for byssinotic activity using racemic synthetic lacinilene C 7-methyl ether, rather than the naturally occurring optically active compound, must be scrutinized carefully.     

5,6,4′-trihydroxy-7,8-dimethoxyflavone from Thymus membranaceus

From the extracts of Thymus membranaceus subsp. membranaceus, the new naturally occurring 5,6,4′-trihydroxy-7,8-dimethoxyflavone (thymusin), has been isolated and identified. Its structure was elucidated by comparison with its isomeric flavone obtained on acid treatment (isothymusin); thymusin is demethylated at the 8-position during this treatment.     

3-Hydroxyisoflavanones from the stem bark of Dalbergia melanoxylon: Isolation,antimycobacterial evaluation and molecular docking studies

Two new 3-hydroxyisoflavanones, (S)-3,4′,5-trihydroxy-2′,7-dimethoxy-3′-prenylisoflavanone (trivial name kenusanone F 7-methyl ether) and (S)-3,5-dihydroxy-2′,7-dimethoxy-2″,2″-dimethylpyrano[5″,6″:3′,4′]isoflavanone (trivial name sophoronol-7-methyl ether) along with two known compounds (dalbergin and formononetin) were isolated from the stem bark of Dalbergia melanoxylon. The structures were elucidated using spectroscopic techniques. Kenusanone F 7-methyl ether showed activity against Mycobacterium tuberculosis, whereas both of the new compounds were inactive against the malaria parasite Plasmodium falciparum at 10 μg/ml. Docking studies showed that the new compounds kenusanone F 7-methyl ether and sophoronol-7-methyl ether have high affinity for the M. tuberculosis drug target INHA.     

A flavanone glycoside from Prunus cerasoides

During a phytochemical investigation of the seeds of Prunus cerasoides, a new flavanone glycoside, naringenin 4′-methyl ether 7-xyloside, was cha     

On the natural occurrence of gossypetin 7- and 8-monomethyl ethers

The 7-methyl ether of gossypetin occurs, as a mixture of 4 glycosides, in the yellow inflorescence of Eriogonum nudum. In contrast to previous reports, however, it does not occur in Lotus corniculatus flowers, nor is it present in leaves of Medicago sativa. The 8-methyl ether, which is present in Lotus flowers, has been found for the first time in the Compositae, in flowers of Geraea canescens.     

Brickellin,a novel flavone from brickellia veronicaefolia and b. chlorolepis

A new highly oxygenated flavone methyl ether has been isolated from Brickellia veronicaefolia and B. chlorolepis. It has been identified as 5,6′-dihydroxy-6,7,2′,3′,4′-pentamethoxyflavone and given the name brickellin.     

An approach to the chemosystematics of the zygophyllaceae

The Zygophyllaceae occur in arid zones and have been reported to contain, among other compounds, flavonoids and alkaloids. The flavonoids in representatives of three of the seven subfamilies have been studied and their distribution is discussed with respect to their chemosystematic significance. The aglycones identified were kaempferol, quercetin, isorhamnetin, herbacetin and herbacetin-8-O-methyl ether. Glycosidic patterns elucidated range from mono- to tri-glycosides, five of which are novel in plants. Alkaloids were also shown to be present, and the importance of those cited in the literature has been surveyed in relation to the chemosystematics of the Zygophyllaceae.     

Monuron metabolism in excised gossypium hirsutum leaves: Aryl hydroxylation and conjugation of 4-chlorophenylurea*

A new glycoside was isolated as a minor metabolite in excised cotton leaves treated with either [carbonyl-¹⁴C] or [ring-¹⁴C] 3-(4-chlorophenyl)-1-methylurea and 4-chlorophenylurea. The aglycone from β-glucosidase or hesperidinase hydrolysis was identified as 4-chloro-2-hydroxyphenylurea by TLC, radioisotope dilution and MS.     

Flavonoids from the leaf resin of Adenostoma sparsifolium

Four flavonoids were identified from the external leaf extract of Adenostoma sparsifolium: the two new flavones 3, 7-dihydroxy-5, 6-dimethoxyflavone and 3, 5, 7-trihydroxy-8-methoxyflavone and the known compounds galangin and pinocembrin.     

Sesquiterpenoid aldehyde quinones and derivatives in pigment glands of Gossypium

The resistance of Gossypium species to insects is enhanced by compounds in their lysigenous pigment glands. In cultivated cottons, glands in achlorophyllous plant parts contained predominately the terpenoid aldehyde gossypol in G. hirsutum, and gossypol and its methyl and dimethyl ethers in G. barbadense. Glands in young green tissues, however, contained hemigossypolone as the predominant terpenoid aldehyde in G. hirsutum, and a new quinone, hemigossypolone-7-methyl ether, in G. barbadense. As glands aged in green tissues, the sesquiterpenoid quinones were replaced by several C₂₅-terpenoids formed by the Diels-Alder reaction of the quinones with myrcene or trans-β-ocimene. Two C₂₅-terpenoids isolated from G. barbadense, but not G. hirsutum, were the methyl ethers of heliocides H₁ and H₄ and were designated heliocides B₁ and B₄, respectively. A dark red pigment, gossyrubilone, from glands of young leaves of both species is the isopentylimine of hemigossypolone. Similar red imines, formed from sesquiterpenoid quinones and amino acids, resembled the red coloration of the envelope cells surrounding the gland sac. The terpenoid quinones of Gossypium had physical characteristics different from quinones in Bombax which apparently were incorrectly identified as being the same. A survey of the terpenoid quinones and their heliocide derivates in wild Gossypium species and related genera in the Gossypieae showed considerable diversity which may be used for establishing biochemical and phylogenetic relationships.     

Flavonoids from the stem bark of Millettia hemsleyana

The stem bark of Millettia hemsleyana has yielded six simple flavonoids of which three are novel. Dihydromilletenone methyl ether and dihydroisomilletenone methyl ether represent the two keto—enol tautomers of the known β-hydroxychalcone milletenone, trapped by methylation and reduction, and the third new compound, 3′,4′-methylenedioxy-7-methoxyflavone, is the cyclized form of a demethylated milletenone. All compounds were identified on the basis of detailed spectral analysis.     

Polyphenols from Achyrocline satureioides

Galangin, galangin 3-methyl ether, querectin, querectin 3-methyl ether, caffeic acid and two esters of calleryanin (3,4-dihydroxybenzylalcohol 4-glucoside), with caffeic acid and protocatechuic acid, have been isolated from aerial parts of Achyrocline satureioides.     

Two flavonols from Euodia glabra

Two flavonols in Euodia glabra have been characterized as 3,7,3′-trimethylquercetin (I) and 7-isopentenyl-3,3′-dimethylquercetin (II).