The structural elucidation of a novel iridoid derivative fromTachiadenus longiflorus (Gentianaceae) using the LSD programme and quantum chemical computations

Abstract

Oleanolic acid, scoparone, scopoletin and a novel iridoid derivative, angelone, were isolated from Tachiadenus longiflorus (Gentianaceae). The structure of angelone was determined from NMR data, given as input to the Logic for Structure Determination Programme, and was finally confirmed by comparison of experimental 13C-NMR chemical shifts with those obtained by quantum mechanical calculations.

Logic Structure Determination (LSD) as a Computer Assisted Structure Elucidation (Case) for Molecular Structure Determination of Cytotoxic Cembranoids from Soft Coral

“…An important limitation of NMR-based structure elucidation, with manual elucidation or computer assist, is VLCR. VLCR may exists in COSY and HMBC through more than 3 (HMBC) or 4 (COSY) chemical bonds (Mulholland et al, 2006). This study shows that VLCR significantly affects the LSD calculation to generate the possible structures.…”

“…There are solutions to avoid VLCR effects. First, user can decide manually whether each correlation is a VLRC or not based on the qualitative estimation of their intensity (Mulholland et al, 2006). However, as shown in Table 1, the use of HMQC, COSY, and HMBC with the estimation of small intense correlation as VLCR results in a numerous possible structures.…”

“…One among these is Logic Structure Determination (LSD) software. So far, previous studies have shown that LSD successfully elucidates flavonoid, alkaloid, and steroid compounds (Mulholland et al, 2006;Elyashberg et al, 2010;Hubert et al, 2015). However, none of those studies had been applied to cembranoid class.…”

Minor secoiridoid aglycones from the low-polarity part of the traditional Chinese herb: Swertia mileensis

“…Secoiridoids without glycosylation should be present in the low-polarity part of S. mileensis, however this part was ignored in the previous investigation, for its lowcontent and less-activity. Therefore, further investigation was focused on secoiridoid aglycones and was performed on the low-polarity part of S. mileensis, resulting in eleven new (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), as well as six pre-existing compounds (12)(13)(14)(15)(16)(17). This paper will discuss their isolation, structural elucidation, and anti-HBV properties on HepG 2.2.15 cell line in vitro.…”

“…Presently, quite a few cases of secoiridoids other than C 10 skeleton have been reported. [5][6][7] Subsequently, the discovery of more secoiridoid aglycones with dissimilar skeletons will help to formulate a greater understanding of these compounds.…”