Survey of natural products reported by Asian research groups in 2020

A new cytotoxic disaccharide glycoside from the tubers of Arisaema franchetianum

A new disaccharide glycoside, franchoside A (1), and 17 known compounds were isolated from the tubers of Arisaema franchetianum Engler. The chemical structure of the previously undescribed compound 1 was elucidated on the basis of detailed spectroscopic analyses. Compounds 1, 2, 6, 10, 14 and 18 showed significant cytotoxic activities at varying IC50 values in the range of 4.0-10.6 μM against five cancer cell lines. Compounds 8, 10, 13 and 17 (10 μM) exhibited moderate anti-inflammatory activities by inhibiting the NF-κB signaling pathway and the release of NO from RAW264.7 macrophages induced by lipopolysaccharide (LPS), while compounds 1, 9, 14, 15 and 16 showed weak anti-inflammatory activities.

Two unusual novel iridoid glycosides from Cornus officinalis fruit and their biological activities

Two unusual novel iridoid glycosides, cornsecoside A (1) and cornsecoside B (2), were isolated from a 40% ethanol elution fraction of a 50% ethanol extract of Cornus officinalis fruit. Their structures were determined by spectroscopic data analysis combined with hydrolysis and ECD spectroscopy. In addition, compounds 1 and 2 exhibited cytotoxic activity against Bel-7402 cells with IC50 values of 8.12 and 9.31 µM, and were neuroprotective against H2O2-induced SH-SY5Y cell injure at a concentration of 10 µM.

Minor terpenoids from the leaves of Craibiodendron yunnanense

One new taraxastane-type triterpenoid, three new grayanane-type diterpenoids (2 - 4), and 12 known compounds (5 - 16) were isolated from the leaves of Craiobiodendron yunnanens W. W. Smith. The structures of these compounds were elucidated on the basis of their spectroscopic data and chemical evidence. Compounds 1 and 8 exhibited partly anti-inflammatory activity based on the inhibition of NF-κB activity in SW480 cells at 10 μM with inhibition ratios of 60.53 and 59.20%, respectively. Compounds 10 and 13 showed excellent cytotoxicity against human leukemia cell (MV4-11) at 10 μM with inhibition ratios of 43.02 and 49.11%, respectively.

Four ionones and ionone glycosides from the whole plant of Rehmannia piasezkii

Four new ionones and ionone glycosides (1-4) were isolated from the whole plant of Rehmannia piasezkii Maxim. Their planar structures as well as absolute configuration were confirmed via spectroscopic analysis, ECD calculation, and X-ray crystallography. Compounds 1-4 were tested for their cytotoxicity against five human tumor cell lines and ability to inhibit LPS-activated NO production in the BV2 cell line.

New stilbenes and phenolic constituents from the rhizomes of Belamcanda chinensis

A pair of stilbenes with γ-lactam unit [(+)-1 and (-)-1], a new phenolic glucoside (2), and a new isoflavone glucoside (3), together with two known compounds (4-5) were isolated from the rhizomes of Belamcanda chinensis. The chemical structures of the undescribed compounds were elucidated on the basis of detailed spectroscopic analyses. Compounds 1, 4, and 5 (10 μM) exhibited anti-inflammatory activities with inhibition rates of 30.46%, 60.34%, and 37.91%, respectively, against the NF-κB signaling pathway.

Three new pyridine alkaloids and one new iridoid analogue from the leaves of Rehmannia glutinosa

As part of an ongoing project on Rehmannia species, three new pyridine alkaloides (glutinosines A - C), and one new iridoid analogue (rehmaglutin E), were isolated from the leaves of Rehmannia glutinosa. The structures of the new compounds were established by extensive spectroscopic analysis and electronic circular dichroism calculations.