Studies on the monoterpene glucosides: V. The x-ray investigation of monotropein molecule

Homosecoiridoids from the flower buds of Lonicera japonica

Homosecoiridoids (1-15) were isolated from the flower buds of Lonicera japonica. Compounds 1-4, designated as loniphenyruviridosides A-D, possess unprecedented skeletons featuring phenylpyruvic acid derived moieties coupled with an iridoid or a secoiridoid nucleus. Compounds 5-15 (lonijaposides D-N) are additional examples of the unusual pyridinium alkaloid-coupled secoiridoids (lonijaposides A-C). The validity of the CD data to determine the configuration of the secoiridoid derivatives is discussed on the basis of detailed CD data analysis and semisynthesis of 2 and 3 with the co-occurring secologanic acid. The configuration of secologanic acid was determined by a single-crystal X-ray crystallographic analysis using anomalous scattering of Cu Kα radiation. Biosynthetic pathways of the homosecoiridoids were postulated. Compounds 1-4 inhibited STAT-3 activity of HELF cells, and lonijaposides F (7), H (9), I (10), and K (12) showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor.

Pyridinium alkaloid-coupled secoiridoids from the flower buds of Lonicera japonica

Three pyridinium inner salt alkaloids, lonijaposides A-C (1-3), based on an unprecedented skeleton of an N-substituted nicotinic acid nucleus coupled through C-5 with C-7 of a secoiridoid, together with seven known iridoids, have been isolated from the flower buds of Lonicera japonica. Their structures were elucidated by spectroscopic and chemical analyses. Lonijaposide C (3) showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by the platelet-activating factor.