Two new highly oxygenated xanthones, named muchimangins E (1) and F (2), have been isolated from the root of Securidaca longepedunculata (Polygalaceae). Their structures were elucidated by the analyses of spectral data to be a novel xanthone with a diphenylmethyl substituent at C-2. Moreover, the structures of muchimangins B (4) and C (5) were revised by careful analysis of the spectral data and by comparing their NMR data with those of 1 and 2, to be xanthones with the diphenylmethyl substituent at C-2, not at C-4 reported previously.

In order to develop new drugs for Alzheimer’s disease, we prepared 17 fatty acid derivatives with different chain lengths and different numbers and positions of double bonds by using Wittig reaction and stereospecific hydrogenation of triple bonds as key reactions. Among them, (4Z,15Z)-octadecadienoic acid (10) and (23Z,34Z)-heptatriacontadienoic acid (16) showed the most potent neurite outgrowth activities on Aβ(25–35)-treated rat cortical neurons, which activities were comparable to that of a positive control, NGF. Both fatty acids 10 and 16 possess two (Z)-double bonds at the n-3 and n-14 positions, which might be important for the neurite outgrowth activity.

Four new germacranes [heyneanones A–D (1–4)], three new guaianes [4,10-epizedoarondiol (5), 15-hydroxyprocurcumenol (6), 12-hydroxycurcumenol (7)], and two new spirolactones [curcumanolides C (8) and D (9)] were isolated from the rhizomes of Curcuma heyneana together with 13 known sesquiterpenes and two known labdane-type diterpenes. Among the isolated compounds, heyneanone A (1), heyneanone C (3), 4,10-epizedoarondiol (5), procurcumenol (16), aerugidiol (17), zerumin A (23), and (E)-15,16-bisnorlabda-8(17),11-dien-13-one (24) inhibited protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 42.5, 35.2, 35.1, 45.6, 35.7, 10.4, and 14.7 μM, respectively.

In a course of our search for anticancer agent based on a novel anti-austerity strategy, we found that the CHCl3 extract of the roots of Securidaca longepedunculata (Polygalaceae), collected at Democratic Republic of Congo, killed PANC-1 human pancreatic cancer cells preferentially in nutrient-deprived medium (NDM). Phytochemical investigation on the CHCl3 extract led to the isolation of 28 compounds including five new polymethoxylated xanthones [1,6,8-trihydroxy-2,3,4,5-tetramethoxyxanthone (1), 1,6-dihydroxy-2,3,4,5,8-pentamethoxyxanthone (2), 8-hydroxy-1,4,5,6-tetramethoxy-2,3-methylenedioxyxanthone (3), 4,6,8-trihydroxy-1,2,3,5-tetramethoxyxanthone (4), 4,8-dihydroxy-1,2,3,5,6-pentamethoxyxanthone (5)] and a new benzyl benzoate [benzyl 3-hydroxy-2-methoxybenzoate (6)]. Among them, 1,6,8-trihydroxy-2,3,4,5-tetramethoxyxanthone (1) and 1,6-dihydroxy-2,3,4,5,8-pentamethoxyxanthone (2) displayed the potent preferential cytotoxicity with PC50 of 22.8 and 17.4 μM, respectively. They triggered apoptosis-like PANC-1 cell death in NDM with a glucose-sensitive mode.

We screened water and methanol extracts of 28 Indonesian medicinal plants for their protein tyrosine phosphatase 1B (PTP1B) inhibitory activities. Nine water extracts, i.e., Alstonia scholaris leaf, Blumea balsamifera, Cinnamomum burmannii, Cymbopogon nardus, Melaleuca leucadendra, Phyllanthus niruri, Piper nigrum, Syzygium aromaticum, and Sy. polyanthum, exhibited ≥70 % inhibition at 25 μg/mL, whereas 11 methanol extracts, i.e., Als. scholaris, Andrographis paniculata, B. balsamifera, Ci. burmannii, Curcuma heyneana, Glycyrrhiza glabra, M. leucadendra, Punica granatum, Rheum palmatum, Sy. polyanthum, and Z. aromaticum, exhibited ≥70 % inhibition at 25 μg/mL. Water extracts of B. balsamifera (IC50, 2.26 μg/mL) and M. leucadendra (IC50, 2.05 μg/mL), and methanol extracts of Ci. burmannii (IC50, 2.47 μg/mL), Pu. granatum (IC50, 2.40 μg/mL), and Sy. polyanthum (IC50, 1.03 μg/mL) exhibited strong inhibitory activity, which was comparable with that of the positive control, RK-682 (IC50, 2.05 μg/mL). The PTP1B inhibitory activity of the constituents of Ci. burmannii and Z. aromaticum was then evaluated. 5′-Hydroxy-5-hydroxymethyl-4″,5″-methylenedioxy-1,2,3,4-dibenzo-1,3,5-cycloheptatriene (2; IC50, 29.7 μM) and trans-cinnamaldehyde (5; IC50, 57.6 μM) were the active constituents of Ci. burmannii, while humulatrien-5-ol-8-one (21; IC50, 27.7 μM), kaempferol-3,4′-di-O-methyl ether (32; IC50, 17.5 μM), and (S)-6-gingerol (33; IC50, 28.1 μM) were those of Z. aromaticum. These results suggest that these medicinal plants may contribute to the treatment and/or prevention of type II diabetes and/or obesity through PTP1B inhibition.

Four new highly oxygenated xanthones, named muchimangins A–D (1–4), with a diphenylmethyl substituent have been isolated as extremely minor constituents from the root of Securidaca longepedunculata (Polygalaceae). Among them, muchimangin B (2) induced an apoptotic-like cell death of human pancreatic cancer PANC-1 cell line preferentially in nutrient deprived condition with PC50 of 38.9 μM.

From the aqueous extract of the wood of Taxus yunnanensis, which showed cytochrome P450 3A4 (CYP3A4) inhibition, a new isoflavan [(3S,4R)-4′-hydroxy-6,3′-dimethoxyisoflavan-4-ol (1)], a new degraded lignan [2,3-bis(hydroxymethyl)-7-hydroxy-6-methoxy-1-tetralone (2)], and a new lignan [(7R)-7-hydroxytaxiresinol (3)] were isolated, together with nine known lignans. Among the isolates obtained, α-conidendrin (12) showed strong CYP3A4 inhibition with an IC50 value of 0.2 μM.

From a MeOH extract of Lunasia amara, which showed the cytochrome P450 2D6 (CYP2D6) inhibition, 14 acridone alkaloids including two new alkaloids [5-hydoroxygraveoline (1) and 8-methoxyifflaiamine (2)] were identified. Among the 14 acridone alkaloids, 5-hydoroxygraveoline (1) and lunamarine (3) showed moderate inhibition selective for CYP2D6, with IC50 values of 4.7 μM and 1.8 μM, respectively.Graphical abstractFrom Indonesian medicinal plant Lunasia amara, two new acridone alkaloids, 5-hydroxygraveroline (1) and 8-methoxyifflaiamine (2), were isolated together with 12 known ones. Among the 14 compounds isolated, 5-hydoroxygraveoline (1) and lunamarine (3) showed moderate inhibition selective to CYP2D6 with IC50 values of 4.7 and 1.8 μM, respectively.Research highlights► From Indonesian medicinal plant Lunasia amara, two new acridone alkaloids, 5-hydroxygraveroline (1) and 8-methoxyifflaiamine (2), were isolated together with 12 known ones. Among the 14 compounds isolated, 5-hydoroxygraveoline (1) and lunamarine (3) showed moderate inhibition selective to CYP2D6 with IC50 values of 4.7 and 1.8 μM, respectively.

Fennel, a seed of Foeniculum vulgare, is used as a culinary spice and traditional medicine. The methanolic extract of fennel showed a characteristic of mechanism-based inactivation on erythromycin N-demethylation mediated by human liver microsomal cytochrome P450 3A4 (CYP3A4). The present study was conducted to identify the fennel constituent having the inhibition. Thirteen compounds have been isolated from a methanol extract of fennel and tested for their inhibition on CYP3A4. Among them, 5-methoxypsoralen (5-MOP) showed the strongest inhibition with an IC50 value of 18.3 µM and a mixed type of inhibition. In addition, with the preincubation time of 20 min only 5-MOP showed preincubation time dependency; the IC50 value decreased from 18.3 µM with a preincubation time of 0 min to 4.6 µM with a preincubation time of 20 min. Further investigation on 5-MOP showed the characteristics of time-dependent inhibition, requirement of NADPH, lack of protecting effect of nucleophiles, and recovery of CYP3A4 activity by the competitive inhibitor. This result suggests that the inhibitory activity of CYP3A4 by 5-MOP was a mechanism-based inactivation. The kinetic parameter for mechanism-based inactivation was characterized by a KI value of 15.0 µM and a kinact value of 0.098 min−1.