A facile enzyme assisted route to enantiomerically pure δ - lactones

Discovery of nontriterpenoids from the rot roots of Panax notoginseng with cytotoxicity and their molecular docking study and experimental validation

“…The 1 H– 1 H COSY correlations of H 2 -5/H-6/H 2 -7/H 2 -8/H 2 -9/H 2 -10/H 3 -11 and HMBC correlations of H-6 with C-2/C-4/C-5/C-7/C-8, H 2 -5 with C-3/C-4/C-6/C-7, H-3 with C-2/C-4/C-6, and methoxyl protons ( δ H 3.66) with C-4, established the plane structure of 7. Moreover, the optical rotation of 7 ([ a ] −97.4) was consistent with a synthesized analogue ( R )-6-hexyl-4-methoxy-6-hydroxy-2 H -pyran-2-one ([ a ] −103.5, >99% ee) 9 and opposite to the corresponding isomer ([ a ] +80.1, 83% ee) with the identical skeletal structure to 7 but surplus S -isomer, 10 indicating R -configuration for 7. Therefore, compound 7 was identified ( R )-6-(1-hydroxyhextyl)-4-methoxy-2(5 H )-pyranone.…”

“…Panaxytriol (PXT), widely existing in Panax species, was also found in the infected PN roots in the present study, and its absolute conguration was identied as 3R,9R,10R by circular dichroism (CD) analysis 11 and synthetic method. 12 Based on the structure of natural PXT and the obtained intermediates (8,9), a plausible transformation pathway from PXT to four lactones (3-6) is proposed in Scheme 1. Under the high degree of oxidization in the infected plant, the olenic bond, C-8, C-11, and terminal fatty chain of natural PXT were selectively oxidized to intermediate products (8,9).…”

“…12 Based on the structure of natural PXT and the obtained intermediates (8,9), a plausible transformation pathway from PXT to four lactones (3-6) is proposed in Scheme 1. Under the high degree of oxidization in the infected plant, the olenic bond, C-8, C-11, and terminal fatty chain of natural PXT were selectively oxidized to intermediate products (8,9). Their second alkynyl (C-6, C-7) was then oxidatively cracked into the carboxyl group, which was further esteried with one of the hydroxyl groups randomly to form a veor six-member lactone ring.…”

“…5 Continuing study showed that the remaining fractions displayed signicant cytotoxicity against lung cancer A-549 and hepatocellular carcinoma cancer SMMC7721 cells (inhibition rates > 96%) at a concentration of 100 mg mL −1 via MTS assay. Further bioassayguided isolation yielded nine new nontriterpenoids, including two novel alkaloids (1, 2), ve a,b-unsaturated furanones or pyranones (3-7), and two polyacetylenic alcohols (8,9) (Fig. 1).…”

“…The alkaloids (1, 2) contained a unique N-methylacetamido substituent on their unreported 1-oxotetrahydropyrimidine skeleton, representing the rst rare non-amino acid alkaloid from ginseng plants. were biogenetically considered to be transformed from panaxatriol (PXT), a polyacetylene naturally occurring in the genus Panax, through their intermediate products (8,9) by a series of reactions. Herein, the structural elucidation of nine new nontriterpenoids (1-9), the plausible bio-transformed pathway for lactones, as well as their antiproliferative activity against ve human cancer cell lines, were deduced in detail.…”