Table 2.
Amounts of the suberin constituents cis-/trans-1,18-octadec-9-enedioic acid (1/2) and 1,20-eicosanedioic acid (3) detected in the samples.
| Sample | Percentage (w/w) of extractives obtained after Soxhlet extraction, based on weight of untreated material | Percentage (w/w) of dried extract obtained after methanolate-induced cleavage, based on weight a) of untreated material b) after Soxhlet extraction |
Amount of compound a) mg per g of untreated material b) mg per g of residue after methanolysis |
|
|---|---|---|---|---|
| Compounds 1 and 2 | Compound 3 | |||
| Cellulose thimble (Negative control) | 1.6% |
(a) 3.9% (b) 4.1% |
< LOD | < LOD |
|
Quercus suber bark (Positive control) |
6% |
(a) 33.5% (b) 41.9% |
(a) 0.318 (b) 0.764 |
(a) 0.146 (b) 0.353 |
|
Sample I (Outer layer interpreted as fossil bark) |
40% |
(a) 15.7% (b) 26.3% |
(a) 0.148 (b) 0.941 |
(a) 0.0777 (b) 0.493 |
|
Sample II (Inner tissue interpreted as degraded fossil wood) |
73% |
(a) 1.3% (b) 4.9% |
< LOD | < LOD |
| Sample III (Inner tissue of fossil laticifers) | 81% |
(a) 12.8% (b) 66.7% |
< LOD | < LOD |
Amounts of compounds 1/2 and 3 are given as mg of compound per g of untreated material, and per g of residue obtained after methanolysis, respectively. The percentage (w/w) of residue obtained after methanolysis and extraction of fossil samples I–III, of the positive control (recent Quercus suber), and of the negative control (cellulose thimble used for extraction) were calculated and compared to the starting weight before sample preparation, and to the sample weight after Soxhlet extraction. The percentage (w/w) of extractives obtained after Soxhlet extraction in relation to the starting weight of the samples was additionally calculated.