A. A
solution of 3 (2 mg) in 200 μL of phosphate buffer (pH 7.4)
containing 1 drop of acetone was warmed at 37 °C for 1 h. The
reaction mixture was acidified with 1 N HCl and poured into a SepPak
C18 cartridge. Inorganic solutes were washed out from the
cartridge with H2O, while adsorbed tannin was recovered (1.9 mg)
with MeOH. Conversion of 3 into remurin A was monitored by cochromatographic
analyses with standard samples isolated from the
plant on normal-phase (tR 6.48 min, remurin A and 3) and reversedphase
HPLC (tR 7.02 min for remurin A and tR 9.70 min for 3) and
was confirmed by the 1
H NMR data comparison.
Chemical Conversion of Nilotinin T1 (5) into Hirtellin T2 (6). A
solution of 5 (2 mg) in 200 μL of phosphate buffer (pH 7.4)
containing 1 drop of acetone was incubated at 37 °C for 2 h. The
experiment was completed as mentioned above. A conversion of 5 into
6 was detected by co-chromatographic analyses with standard samples
isolated from the plant on normal-phase (tR 15.56 min, 5 and 6) and
reversed-phase HPLC (tR 5.76 min for 1 and tR 5.28 min for 6) and
the 1
H NMR data comparison.