3730-56-1Relevant articles and documents
Molecular basis of pimarane compounds as novel activators of large-conductance Ca2+-activated K+ channel α-subunit
Imaizumi, Yuji,Sakamoto, Kazuho,Yamada, Aki,Hotta, Aya,Ohya, Susumu,Muraki, Katsuhiko,Uchiyama, Masanobu,Ohwada, Tomohiko
, p. 836 - 846 (2002)
Effects of pimaric acid (PiMA) and eight closely related compounds on large-conductance K+ (BK) channels were examined using human embryonic kidney (HEK) 293 cells, in which either the α subunit of BK channel (HEKBKα) or both α and β1 (HEKBKαβ1) subunits were heterologously expressed. Effects of these compounds (10 μM) on the membrane potential of HEKBKαβ1 were monitored by use of DiBAC4(3), a voltage-sensitive dye. PiMA, isopimaric acid, sandaracoisopimaric acid, dihydropimaric acid, dihydroisopimaric acid, and dihydroisopimarinol induced substantial membrane hyperpolarization. The direct measurement of BKαβ1 opening under whole-cell voltage clamp showed that these six compounds activated BKαβ1 in a very similar concentration range (1-10 μM); in contrast, abietic acid, sclareol, and methyl pimarate had no effect. PiMA did not affect the charybdotoxin-induced block of macroscopic BKαβ1 current. Single channel recordings of BKαβ1 in inside-out patches showed that 10 μM PiMA did not change channel conductance but significantly increased its open probability as a result of increase in sensitivity to Ca2+ and voltage. Because coexpression of the β1 subunit did not affect PiMA-induced potentiation, the site of action for PiMA is suggested to be BKα subunit. PiMA was selective to BK over cloned small and intermediate Ca2+ activated K+ channels. In conclusion, PiMA (gt;1 μM) increases Ca2+ and voltage-sensitivity of BKα when applied from either side of the cell membrane. The marked difference in potency as BK channel openers between PiMA and abietic acid, despite only very small differences in their chemical structures, may provide insight into the fundamental structure-activity relationship governing BKα activation.
Directed Functionalization of the Pimarane Skeleton, II. - Formation of the D-Ring for the Synthesis of Higher Terpenes
John, Michael,Haslinger, Ernst
, p. 1019 - 1028 (2007/10/02)
The conversion of the pimarane skeleton 1 into the tetracyclic compound 3 is described.The synthetic route includes the formation of the D-ring and the stereoselective introduction of an angular methyl group at C-14.D-ring construction has been achieved by selective oxidation of the double bond systems of 2 which lead via 14 to compound 18.This was alkylated to 19 and subsequently converted into 20.Further oxidation gave 21 and the ester 24 which upon treatment with potassium tert-butoxide formed 25.The angular methyl group was introduced using an organocopper reagent: 26.After decarboxylation and hydrogenation 3 was obtained.It can be used as building unit for the construction of higher terpenes (e.g., tirucallanes 4). Key Words: Terpenes / Pimaric acid
METABOLITES OF THE HONEY MUSHROOM, Armillaria mellea
Ayer, William A.,Macaulay, John B.
, p. 7 - 14 (2007/10/02)
The fungus Armillaria mellea (Vahl ex.Fr.) Kummer is responsible for severe losses in timber and fruit production.The metabolites isolated when certain strains of this fungus are grown in liquid culture have been identified as diterpenoid acids posessing the abietane (1) and pimarane (2) skeletons.These compounds, known collectively as resin acids, have not been reported previously from fungal source.In addition to the resin acids dehydroabietic acid (3), pimaric acid (4), isopimaric acid (5), and sandaracopimaric acid (6), three additional acids, levopimaric acid endo-peroxide (7), 7-oxodehydroabietic acid (9), and 7-oxo-15-hydroxydehydroabietic acid (10) were obtained.On one accasion three orange pigments, austocystin F (11), averufin (12), and averufanin (13), all previously known fungal metabolites, were isolated.
