Two new chlorinated sesquiterpenes from Sigesbeckia orientalis

Two new chlorinated guaianane-type sesquiterpenes (named chlosigesolides A and B) together with eight known compounds were isolated from the leaves and twigs of Sigesbeckia orientalis. Their structures were determined by analysis of HR-ESI-MS, 1D- and 2D-NMR spectral data as well as comparison with the literature. Absolute configurations of new compounds were elucidated by NOESY and ECD methods. Chlosigesolide A inhibited NO production in LPS-stimulated RAW264.7 macrophages with IC50 value of 10.9 ± 0.8 μM. Other compounds exhibited inhibitory activity at IC50 in range of 26.5 to 49.7 μM.

New Guaiane-Type Sesquiterpene and Norsesquiterpene from Alisma plantago-aquatica and Their Xanthine Oxidase Inhibitory Activity

A new sesquiterpene (1) and a new norsesquiterpene (2) belonging guaiane-type skeleton together with six known compounds (3-8) were isolated from the rhizomes of Alisma plantago-aquatica. Their structures were determined by HR-ESI-MS, 1D and 2D NMR spectroscopic methods. Absolute configurations of new compounds were established by experimental and TD-DFT computational ECD spectra. Compounds 1-8 exhibited xanthine oxidase inhibitory activity with their IC50 values in range of 9.4-66.7 μM. The sesquiterpenoids 1-5 displayed the inhibitory activity and hence they could be potential xanthine oxidase inhibitors from A. plantago-aquatica.

Gymsyloside F and Gymsyloside G, Two New Pregnane Glycosides From the Leaves of Gymnema sylvestre and Their α-Glucosidase and α-Amylase Inhibitory Activities

Two new pregnane glycosides were isolated from the leaves of Gymnema sylvestre (Retz.) R.Br. ex Sm. Their chemical structures were determined as (20 S)−12 β-tigloyloxy-5 α-hydroperoxy-3 β,8 β,14 β,17 β,20-pentahydroxypregn-6-ene 3- O-β-D-glucopyranosyl-(1→4)‐6-deoxy-3- O-methyl- β-D-allopyranosyl-(1→4)- β-D-oleandropyranosyl-(1→4)- β-D-cymaropyranosyl-(1→4)- β-D-cymaropyranoside (1) and (20 S)−12 β-benzoyloxy-5 α-hydroperoxy-3 β,8 β,14 β,17 β,20-pentahydroxypregn-6-ene 3- O-β-D-glucopyranosyl-(1→4)‐6-deoxy-3- O-methyl- β-D-allopyranosyl-(1→4)- β-D-oleandropyranosyl-(1→4)- β-D-cymaropyranosyl-(1→4)- β-D-cymaropyranoside (2) on the basis of the extensive spectroscopic methods, including 1D, 2D NMR, HRESIMS, and in comparison with the reported data. At the concentration of 200 µM, compounds 1 and 2 showed moderate anti α-glucosidase and α-amylase activities with inhibitory percentage of 31.1 ± 1.2 and 42.3 ± 1.7% (for α-glucosidase), and 27.8 ± 1.3 and 34.5 ± 1.5% (for α-amylase), respectively.

Oleanane-type triterpene saponins from Aralia armata leaves and their cytotoxic activity

Two new, aramatosides A and B (1 and 2), together with seven known oleanane-type triterpene saponins (3-9) were isolated from the leaves of Aralia armata. Their structures were determined by combination of HR-ESI-MS, 1 D and 2 D NMR spectral data as well as comparison with the previous literature. Compounds 6-9 exhibited cytotoxic effects towards three human cancer cell lines (HT29, A2058, and A549) with IC₅₀ values ranging from 2.01 ± 0.17 to 18.8 ± 1.17 µM. Especially, compound 7 (narcissiflorin) showed significant cytotoxic activity against HT29 and A549 cell lines with IC₅₀ values of 2.02 ± 1.65 and 2.01 ± 0.17 µM, respectively, which are smaller than those of positive control irinotecan hydrochloride (IC₅₀ values of 10.3 ± 1.32 and 9.89 ± 0.19 µM).

New lupane-type and ursane-type triterpene saponins from the leaves of Trevesia palmata

Three new triterpene saponins including two lupane-types and an ursane-type were isolated from the leaves of Trevesia palmata. Their structures were determined as 2α,3β,23-trihydroxylup-20(29)-en-28-oic acid 3-O-α-L-arabinopyranoside (1), 2α,3β,23-trihydroxylup-20(29)-en-28-oic acid 3-O-[α-L-arabinopyranoside]-28-O-[β-D-glucopyranosyl] ester (2), and 2α,3β,23-trihydroxyurs-12-en-28-oic acid 3-O-[α-L-arabinopyranoside]-28-O-[β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl] ester (3) by analysis of their HR-ESI-MS, 1D and 2D NMR spectra. The 2α,3β,23-trioxygenated pentacyclic triterpenes were uncommonly found in the nature. At concentration of 100 µM, compounds 1-3 inhibited NO production in LPS activated BV2 cells with inhibitory rates of 17.4 ± 1.8%, 33.1 ± 1.2%, and 11.7 ± 2.2%, respectively. But, they did not significantly inhibit yeast α-glucosidase activity.

Chemical Constituents of Phoebe poilanei and Their Cytotoxic Activity

Two new flavonol glycosides, rhamnocitrin 3- O-α-L-rhamnopyranosyl-(1→6)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (1) and quercetin 3- O-6- Z- p-coumaroyl-β-D-glucopyranosyl-(1→2)-α-L-rhamnopyranoside (2), along with 3 flavonol glycosides, isoquercitrin (3), rutin (4), and quercetin 3- O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside (5), and two known sesquiterpenes, alismol (6) and spathulenol (7), were isolated from the leaves of Phoebe poilanei Kosterm. Their chemical structures were elucidated by analyses of their high-resolution electrospray ionization mass spectral data and nuclear magnetic resonance spectral data and comparison with those reported in the literature. Two sesquiterpenes 6 and 7 were found to exhibit moderate cytotoxic activity with IC50 values ranging from 21.6 to 29.8 µM.

A New Picrotoxane Sesquiterpene Glucoside from Dendrobium nobile

A new picrotoxane sesquiterpene glucoside, dendrobinoside A (1), and three known secondary metabolites dendronobilin G (2), dendromoniliside D (3), massonside A (4) were isolated from the stems of Dendrobium nobile Lindl.. Their chemical structures were elucidated on the basis of HR-ESI-MS, NMR spectroscopic data and comparison with reported values. Chemical structure of new compound was further investigated via its aglycone by enzymatic hydrolysis.

Steroidal Glucosides from the Rhizomes of Tacca Chantrieri and Their Inhibitory Activities of NO Production in BV2 Cells

Two new steroidal glucosides, chantriolides D and E (1 and 2), along with four known compounds, chantriolide A (3), chantriolide B (4), chantriolide C (5), and (25 S)-spirost-5-en-3-ol 3- O-α-L-rhamnopyranosyl-(1→2)- O-[α-L-rhamnopyranosyl-(1→3)]-β-D-glucopyranoside (6) were isolated from the rhizomes of Tacca chantrieri. Their structures were determined by 1D and 2D NMR spectroscopic and HR-ESI-MS data, as well as by comparison with reported data. Compounds 1 and 2 were found to show strong inhibitory NO effect in BV2 cells, with IC50 values of 12.45 and 59.03 μM, respectively.

Steroidal Glucosides from the Rhizomes of Tacca chantrieri and Their Inhibitory Activities of NO Production in BV2 Cells

Two new steroidal glucosides, chantriolides D and E (1 and 2), along with four known compounds, chantriolide A (3), chantriolide B (4), chantriolide C (5), and (25S)-spirost-5-en-3-ol 3-O-α-L-rhamnopyranosyl-(1-->2)-O-[α-L-rhamnopyranosyl-(1-->3)]-β-D-glucopyranoside (6) were isolated from the rhizomes of Tacca chantrieri. Their structures were determined by 1D and 2D NMR spectroscopic and HR-ESI-MS data, as well as by comparison with reported data. Compounds 1 and 2 were found to show strong inhibitory NO effect in BV2 cells, with IC₅₀ values of 12.45 and 59.03 µM, respectively.

Synthesis of a cofacial chlorin dimer of defined symmetry

Special pair chlorophylls arranged in a cofacial dimeric structure play an important role in the initial step of light induced electron transfer of photosynthetic reaction centers of bacteria and plants. For mimicking the natural photosynthetic reaction center we aimed on synthesis of an artificial special pair 13 constructed from two chlorin subunits 5a, b and a rigid biphenylene spacer moiety 11. Due to the reduced C2h symmetry of the chlorin units compared with so far used D4h porphyrins and due to the rigid spacer a cofacial dimer of defined symmetry and distance was obtained.