Studies on the Constiuents of Viburnum Species. Part XIII. Isolation and Absolute Structures of the Neolignan Glycosides with the Enantiometric Aglycones from the Leaves of Viburnum awabuki K. KOCH.

Caffeic Acid Oligomers with Hyaluronidase Inhibitory Activity from <i>Clinopodium gracile</i>

“…The circular dichroism (CD) spectrum showed a negative Cotton effect at 225 nm, suggesting 7′S. [9][10][11] Based on this data, the structure of clinopodic acid J was elucidated as 1.…”

“…The absolute stereochemistry of the dihydrobenzofuran ring of clinopodic acids K, L, and M was determined as shown from the negative Cotton effect at 223-226 nm in the CD spectrum. 9) Clinopodic acid N (5) was isolated as a colorless amorphous solid. The molecular formula of 5 was established as In the 13 C-NMR spectrum, C-1′ of unit B was observed at δ 129.2, which was shifted upfield by about 4 ppm compared with that of trans-type dihydrobenzofuran compounds such as 1-4, indicating a cis-type dihydrobenzofuran moiety.…”

Anticholinesterase and β-Site Amyloid Precursor Protein Cleaving Enzyme 1 Inhibitory Compounds from the Heartwood of <i>Juniperus chinensis</i>

“…The coupling constants of the methine signals at δ 5.54 (H-7) and δ 3.34 (H-8) were 5.81 Hz, indicating a 7,8-trans configuration. 27) In addition, a negative Cotton effect at 330 nm and a positive Cotton effect at 270 nm in the CD spectrum were similar to those of a known compound (pterolinus C, with a negative Cotton effect at 319 nm and a positive Cotton effect at 255 nm), 28) suggesting that the absolute configurations were 7S and 8S. Consequently, 21 was determined to be (…”

A new megastigmane diglycoside from Litsea glutinosa (Lour.) C. B. Rob.

“…The absolute configuration at C-9 of the aglycon was assigned as R on the basis of a diagnostic chemical shift of the C-9 signal (d 76.8) in the 13 C NMR spectrum. 21 Consequently, the structure of 1 was determined to be (6S, 7E, 9R)-6,9-dihydroxy-4,7-megastigmadien-3-one-9-O-[a-L-arabinofuranosyl-(l"→6')]-b-d-glucopyranoside (Figure 1). Earlier study reported the isolation of (6S, 7E, 9R)-6, 9-dihydroxy-4, 7-megastigmadien-3-one-9-O-[a-L-arabinopyranosyl-(l→6)]-b-d-glucopyranoside from Lonicera gracilipes Var.…”