Oxidation Products of Abietic Acid and Its Methyl Ester

Abstract

Abietic acid (1) and its methyl ester (2) were investigated under various storage conditions to provide an indication of their preferred oxidation mechanisms and to investigate the most susceptible positions for modification in the abietane skeleton. Six known compounds, methyl 7alpha,13beta-dihydroxyabiet-8(14)-enoate (4a), methyl 7alpha,13alpha-dihydroxyabiet-8(14)-enoate (4b), methyl 12-oxoabietate (6), methyl 7-oxodehydroabietate (7), methyl 7alpha-hydroxydehydroabietate (8), and 13,14-seco-13,14-dioxoabiet-7(8)-enoic acid (11), were identified. Compounds 7 and 8 are regarded as potent allergens. In addition, six new oxidation products were isolated, methyl 13beta-ethoxy-7alpha-hydroxyabiet-8(14)-enoate (3a), methyl 13alpha-ethoxy-7alpha-hydroxyabiet-8(14)-enoate (3b), methyl 7alpha-hydroperoxy-13alpha-hydroxyabiet-8(14)-enoate or methyl 13alpha-hydroperoxy-7alpha-hydroxyabiet-8(14)-enoate (5), 7alpha,13beta-dihydroxyabiet-8(14)-enoic acid (9a), 7alpha,13alpha-dihydroxyabiet-8(14)-enoic acid (9b), and 7alpha,15-dihydroxydeydroabietic acid (10). Their structures were characterized on the basis of spectroscopic data interpretation. The cytotoxicity of several compounds against KB cells was evaluated, and weak activity was observed for 6, 7, and 8 with IC(50) values of 12.5, 4.5, and 5.8 microg/mL, respectively.

A novel phenolic compound from Pinus yunnanensis

“…Nevertheless, there was an obvious difference: an up-field methylene resonance was absent and replaced by an aromatic ketone carbonyl carbon at d C 187.4 (s) in 1, suggesting that the C-4 methylene was converted into a ketone group. This deduction can be validated by the observable HMBC correlations (Table 1) By comparison with their spectroscopic data with those previously reported, 16 known diterpenoids were identified as daturabietatriene (2) [18], and 7a,15-dihydroxypodocarp-8(14)-en-13-one (17) [19]. The present study showed that abietane diterpenoids were the fat-soluble representative constituents of the cones and seeds, and moreover, compounds 3, 4, 11, 12, 14, 15, and 17 were obtained for the first time from the genus Pinus.…”

Pumilol, a Diterpenoid with a Rare Strobane Skeleton from Pinus pumila (Pinaceae)

“…The crude extract was separated using column chromatography over silica gel to yield a diterpenoid, pumilol (1), possessing the rare strobane diterpenoid skeleton ( Figure 1). In addition to pumilol, 17 known compounds including four labdanes: agatholic acid (2), [3] [4] 18-O-succinylagatholic acid (3), [3] labda-8 (17),13-dien-15-oic acid (4) [4][5][6] and agathic acid (5) [3] [4] ; four abietanes: dehydroabietic acid (6), [4 -6] 15-hydroxydehydroabietic acid (7), [4 -6] 15-hydroxy-7oxodehydroabietic acid (8) [6] and 7a,15-dihydroxydehydroabietic acid (9) [7] ; one abietane: isopimaric acid (10) [4] [5] ; three serratane triterpenoids: 3b-methoxyserrat-14-en-21-one (11), [8] 21b-hydroxy-3b-methoxyserrat-14-ene (12), [8] 21b-acetoxy-3b-methoxyserrat-14-ene (13) [8] ; four borneol ester derivatives: bornyl (E)-4hydroxycinnamate (14), [3] bornyl (E)-ferulate (15), [3] bornyl (Z)-4-hydroxycinnamate (16), [3] bornyl (Z)-ferulate (17) [3] [9] and catechin (18) [10] were also isolated (Figure 1).…”

“…Fractions 1 – 61 that had been eluted with 100% hexane with gradient eleution to hexane/methylene chloride 1:1 gave a mixture of glycerols and fatty acids compounds that were not purified. Fractions 62 – 64 eluted using hexane/methylene chloride 2:3 gave compounds 11 (53 mg, 3 β ‐methoxyserrat‐14‐en‐21‐one) and 13 (5 mg, 21 β ‐acetoxy‐3 β ‐methoxyserrat‐14‐ene) on further purification using hexane/methylene chloride 1:1 on 1 cm diameter SiO 2 column chromatography, fractions 68 – 69 eluted using hexane/methylene chloride 1:4 gave compounds 12 (5 mg, 21 β ‐hydroxy‐3 β ‐methoxyserrat‐14‐ene), 15 (4 mg, bornyl ( E )‐ferulate) and 17 (133 mg, bornyl ( Z )‐ferulate) [ ][ ] on further purification using 100% methylene chloride on 1 cm diameter SiO 2 column chromatography. Fractions 90 – 110 eluted using 100% methylene chloride gave compounds 14 (bornyl ( E )‐4‐hydroxycinnamate) and 16 (20 mg, bornyl ( Z )‐4‐hydroxycinnamate) and fractions 115 – 120 eluted using 1% methanol in methylene chloride gave compound 6 (30 mg, dehydroabietic acid) and 8 (13 mg, 15‐hydroxy‐7‐oxodehydroabietic acid) .…”

Distinct Roles for Two CYP226 Family Cytochromes P450 in Abietane Diterpenoid Catabolism by Burkholderia xenovorans LB400

“…However, the latter route was not supported by the data obtained after disruption of ditQ in BKME-9, which severely limited growth on DhA but had little effect on growth on AbA (39). Other workers previously suggested that biotransformation of AbA can yield 7-hydroxy-AbA (7) or 7,8-epoxyAbA (31). Also, fungal biotransformation of pimaradiene diterpenes, containing a B ring structure with a 7,8 double bond similar to AbA, led mainly to epoxides with the 7,8 double bond plus 7-oxo derivatives (12,13).…”