Diterpenes related to grindelic acid and further constituents from Grindelia species

A New Depigmenting‐Antifungal Methylated Grindelane from Grindelia chiloensis

“…The acid fractions were subsequently methylated and subjected to preparative RP‐HPLC to furnish the new grindelane diterpenoid methyl 7 β ‐hydroxy‐8(17)‐dehydrogrindelate ( 1b ) as a methylated derivative of natural product 1a . The known compounds methyl 7 α ‐hydroxy‐8(17)‐dehydrogrindelate ( 2b ), 6‐oxogrindelic acid ( 3a ), methyl 4 β ‐hydroxy‐6‐oxo‐19‐norgrindelate ( 4b ), methyl 19‐hydroxygrindelate ( 5b ), methyl 18‐hydroxygrindelate ( 6b ), methyl 4 α ‐carboxygrindelate ( 7b ), methyl 17‐hydroxygrindelate ( 8b ), methyl 6 α ‐hydroxygrindelate ( 9b ), methyl 8,17‐bisnor‐8‐oxagrindelate ( 10b ), 7 α ,8 α ‐epoxygrindelic acid ( 11a ), and methyl strictanoate ( 12b ) were also obtained here. Nevertheless, 1b , 3b – 5b , 7b , 9b – 12b are reported for the first time like derivatives of G. chiloensis natural products ( Fig.…”

“…Diterpene acids were isolated from the acid fraction; while methyl esters of grindelic acids from the non‐acidic fraction; the remainder of neutrals is a mixture of flavonoids and unidentified waxes . Grindelane acids are often isolated as methyl ester derivatives . Antifungal activity of G. chiloensis compounds has not previously been reported.…”

Labdanes of Natural Origin-Biological Activities (1981-2004)

“…Several hemisynthetic derivatives of these compounds as well as derivatives received after biotransformation of grindelic acid by Cunninghamella echinulata, have also been exhibited similar activities [202][203][204][205][206][207]. As part of search for natural insecticides, some labdanes from Isocoma tenuisecta (Asteraceae) have also showed activities [208].…”

“…camporum, G. discoidea, G. havardii Aphid-deterrent activity [203] G. humilis, G. paludosa, G. stricta Aphid-deterrent activity [202][203][204][205][206][207] Haplopappus chrysanthemifolius Antimicrobial activity [100,101] Helichrysum rupestre Antimicrobial activity [99] Isocoma coronopifolia, I. tenuisecta Natural insecticides [208] Metasequoia glyptostroboides Antifungal activity [83,84] …”

Conformational analysis of 14‐hydroxymodhephene by NMR, x‐ray diffraction and molecular modeling studies

“…14-Hydroxymodhephene (1), isolated from Pluchea sericea, 1 is a member of a very small class of naturally occurring tricyclopentenoid sesquiterpenes, the [3.3.3]propellanes, which also includes 13-hydroxymodhephene, 13-, 14-and 15-acetoxymodhephenes, 1 -3 modhephenepoxide, 4 pulicaral, 5 pulicaric acid 5 and modhephenic glycosides, 5 in addition to the parent compound, modhephene (2). 6 These [3.3.3]propellanes have been isolated from a variety of natural sources.…”