Aphadilactones A-D, four diterpenoid dimers with DGAT inhibitory and antimalarial activities from a Meliaceae plant

Aphadilactones A-D (1-4), four diastereoisomers possessing an unprecedented carbon skeleton, were isolated from the Meliaceae plant Aphanamixis grandifolia. Their challenging structures and absolute configurations were determined by a combination of spectroscopic data, chemical degradation, fragment synthesis, experimental CD spectra, and ECD calculations. Aphadilactone C (3) with the 5S,11S,5'S,11'S configuration showed potent and selective inhibition against the diacylglycerol O-acyltransferase-1 (DGAT-1) enzyme (IC50 = 0.46 ± 0.09 μM, selectivity index > 217) and is the strongest natural DGAT-1 inhibitor discovered to date. In addition, compounds 1-4 showed significant antimalarial activities with IC50 values of 190 ± 60, 1350 ± 150, 170 ± 10, and 120 ± 50 nM, respectively.

Trichinenlides A-T, mexicanolide-type limonoids from Trichilia sinensis

Twenty new mexicanolide-type limonoids, namely, trichinenlides A-T (1-20), and 11 known analogues were isolated from the leaves and twigs of Trichilia sinensis. Trichinenlides B (2) and C (3) and heytrijunolide D exhibited inhibition against lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages with IC50 values of 2.85, 1.88, and 3.33 μM, respectively.

11β-HSD1 inhibitors from Walsura cochinchinensis

A search for inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) from Walsura cochinchinensis yielded 10 new limonoids, cochinchinoids A-J (1-10), and two new triterpenoids, 3-epimesendanin S (11) and cochinchinoid K (12). Their structures were assigned on the basis of spectroscopic data, with the absolute configurations of 1 and 12 being established by X-ray diffraction analysis. Of these compounds, cochinchinoid K (12) displayed inhibitory activity against mouse 11β-HSD1 with an IC50 value of 0.82 μM.

Chemical constituents from Brucea javanica

Fourteen apotirucallane-type triterpenoids, named brujavanones A-N, were isolated from the twigs of Brucea javanica, along with four known quassinoids and seven known lignans from the seeds of B. javanica. Their structures were elucidated on the basis of extensive spectroscopic data analysis. The structure of a previously reported triterpenoid, bruceajavanin C, was revised as its C-21 epimer. The cytotoxic activities of triterpenoids and quassinoids against two human tumor cell lines, HL-60 and A-549, were evaluated, but all the compounds were inactive (IC₅₀>10 μM).

New apotirucallane-type triterpenoids from Chisocheton paniculatus

Two new apotirucallane triterpenoids, namely chisiamols G (1) and H (2), featuring a 21,23-lactone, together with five known triterpenoids, were isolated from the twigs of Chisocheton paniculatus. The structures of the new compounds were elucidated on the basis of spectroscopic and chemical methods.

Ivorenolide A, an unprecedented immunosuppressive macrolide from Khaya ivorensis: structural elucidation and bioinspired total synthesis

Ivorenolide A (1), a novel 18-membered macrolide featuring conjugated acetylenic bonds and five chiral centers, was isolated from Khaya ivorensis. The structure of 1 was fully determined by spectroscopic analysis, single-crystal X-ray diffraction, and bioinspired total synthesis. Both compound 1 and its synthetic enantiomer 2 showed potent and selective immunosuppressive activity.

Potent HGF/c-Met axis inhibitors from Eucalyptus globulus: the coupling of phloroglucinol and sesquiterpenoid is essential for the activity

Eucalyptin A (1), together with two known compounds 2 and 3 exhibiting potent inhibition on HGF/c-Met axis, was discovered from the fruits of Eucalyptus globulus. 1 possessed an unprecedented carbon framework of phloroglucinol-coupled sesquiterpenoid, and its structure was elucidated by spectroscopic method and ECD calculation. A brief structure-activity relationship discussion indicated that the coupling of a phloroglucinol and a sesquiterpenoid is essential for the activity.

Serratustones A and B representing a new dimerization pattern of two types of sesquiterpenoids from Chloranthus serratus

Serratustones A (1) and B (2), featuring a new carbon skeleton and representing a novel dimerization pattern of two different types of sesquiterpenoids, were isolated from Chloranthus serratus. Their structures with absolute configuration were determined on the basis of a detailed explanation of spectroscopic data, X-ray crystallography, and CD analysis in combination with ECD calculation.

Cytotoxic diterpenoids from Sapium insigne

Chemical investigation into the twigs and leaves of Sapium insigne afforded seven new diterpenoids, sapinsignoids A-G (1-7), together with 10 known diterpenoids. The structures of 1-7 were assigned on the basis of detailed spectroscopic analysis and chemical degradation. Compounds 1-4 exhibited significant cytotoxicity against the A-549 tumor cell line (IC(50) 0.2-1.8 μM), while compounds 1-3 showed moderate cytotoxicity against the HL-60 cell line (IC(50) 2.7-6.5 μM).

Sesquiterpenes from Dysoxylum oliganthum and Dysoxylum excelsum

Three new sesquiterpenes (1-3), (6R,7S,11R,10S)-15-hydroxy-sesquisabinene hydrate (1), (6R,7R,11S,10S)-15-hydroxy-sesquisabinene hydrate (2), and (6R,7R,10S)-15-hydroxy-zingiberenol (3), along with three known compounds, were isolated from the stems of Dysoxylum oliganthum; and three new isodaucane (salvionane) sesquiterpenes, namely isodauc-6-ene-10β,14-diol (4), 4-epi-isodauc-6-ene-10β,14-diol (5), and 4-epi-6α,10β-dihydroxy-artabotrol (6) together with 15 known compounds were isolated from the twigs and leaves of D. excelsum. Their structures were established on the basis of extensive spectroscopic analysis and chemical shifts. The absolute configuration of C-10 in compounds 1-3 of a rare class was determined by using Snatzke's method.

Triterpenoids from Aglaia odorata var. microphyllina

Five new apotirucallane-type triterpenoids (1-5), named agladorals A-E, and 28 known compounds (20 triterpenoids and 8 rocaglamides) were isolated from the twigs of Aglaia odorata var. microphyllina. Their structures were elucidated by spectroscopic analysis.

Constituents of Trigonostemon heterophyllus

Six new diterpenoids, 1-6, a new prenylated sesquiterpenoid, 7, and six known compounds were isolated from Trigonostemon heterophyllus. The structures of 1-7 were elucidated on the basis of NMR and MS analysis. The daphnane diterpenoids trigoheterins A (1) and B (2) possess a rare 4,6-oxetane moiety within this compound class, and trigoheteric acid methyl ester (6) is the first example of a 15,16-dinor-3,4-seco-cleistanthane. Trigoheterin E (5) exhibited cytotoxic activity against the HL-60 (IC₅₀) 1.8 μM) and A-549 (IC₅₀ 10.0 μM) human cancer cell lines.

Limonoids from the stems of Toona ciliata var. henryi (Meliaceae)

Ten limonoids, toonacilianins A-J, and two norlimonoids, toonacilianins K and L, together with seven known compounds were isolated from the stems of Toona ciliata var. henryi (Meliaceae). Their structures were elucidated by spectroscopic analysis. Two compounds showed strong cytotoxic activities.