Triterpenes from Gymnosporia emarginata

Triterpene quinone-methides, lupenone, β-amyrin, dulcitol, and sitosterol have been isolated from the timber, root and leaf extracts of Gymnosporia emarginata. Their chemotaxonomic significance is discussed.     

Phenolic derivatives from Garcinia multiflora Champion ex Bentham and their chemotaxonomic significance

A phytochemical investigation of the leaves and twigs of Garcinia multiflora Champion ex Bentham led to the isolation of eleven phenolic derivatives, including a new polycyclic polyprenylated acylphloroglucinol (PPAP, 1), five known PPAPs (2–6), three xanthones (7–9), a benzophenone (10), and a methyl phenyl acetate derivative (11). Their structures were established by extensive spectroscopic analysis, including HR-ESI-MS and NMR. Five compounds (1, 2, 4, 5, and 11) were first found in the genus Garcinia, of which compounds 1 and 11 were reported from the family Guttiferae for the first time. The chemotaxonomic significance of the isolated compounds was discussed. Furthermore, six PPAPs showed good cytotoxicities with IC₅₀ values ranging from 1.79 to 9.40 μM.     

Diterpenoids from the stems of Tripterygium hypoglaucum (Celastraceae) and cytotoxic evaluation

Four new diterpenoids, 2α,16α-hydroxy-ent-kauran-19,20-olide (1), isopimara-8(14),15-diene-11β,19-diol (2), isopimara-8(14),15-diene-12α,19-diol (3), and 3-oxo-14,15-dihydroxyabieta-8,11,13-trien-19-ol (4), along with seven known compounds (5–11) were isolated from Tripterygium hypoglaucum. Their structures were established on the basis of extensive spectroscopic analysis. Triptolide (5) and 2-epitripdiolide (6) showed significant cytotoxicity against A549, DU145, KB, KBvin and MDA-MB-231 cell lines with IC₅₀ values of 0.0012–0.1306 μM in vitro.     

Cytotoxic diterpenes from roots of Crossopetalum gaumeri,a Celastraceae species from Yucatan Peninsula

Four new diterpenes, crossogumerins A–D (1–4) along with six known ones (5–10) were isolated from the root bark of Crossopetalum gaumeri, an endemic medicinal plant from the Yucatan Peninsula. Their structures were elucidated on the basis of 1D and 2D NMR techniques, including HMQC, HMBC, and ROESY experiments. Compounds 1–5, 8–10 were evaluated for cytotoxicity against HeLa (carcinoma of the cervix) and Hep-2 (lung carcinoma) human tumor cells lines and against normal Vero cells (African green monkey kidney) in lag and log phase of growth. Podocarpane diterpenes, crossogumerin B (2) and nimbiol (10), exhibited the highest activity against HeLa cells (IC₅₀ values of 3.1 and 8.1 μM, respectively), but also selectivity on Vero cells (SI 22.6 and 7.5, respectively). The preliminary SAR studies suggest that an epoxy moiety in ring B and a hydrogen bond-donor group strategically positioned in the diterpene core are important requirements for cytotoxicity and selectivity.     

Cytotoxic and anti-oxidant biphenyl derivatives from the leaves and twigs of Garcinia multiflora

Three new biphenyl derivatives (1–3), together with five known compounds, were isolated from the leaves and twigs of Garcinia multiflora. Their structures were determined by extensive spectroscopic techniques including NMR spectroscopy and mass spectrometry. All eight isolates showed weak cytotoxicity on five human tumor cell lines. In addition, the three biphenyl derivatives showed moderate anti-oxidant activity with IC₅₀ values ranging from 7.78 to 8.78 μM.     

Three new oxygenated triterpenoids of the lupane series from Gymnosporia wallichiana

Two new epimeric triterpenoid acids, gymnosporic acid, 3β-hydroxy-(20R)-lupan-29-oic acid, wallichianic acid, 3β-hydroxy-(20S)-lupan-29-oic acid and a new diol wallichianol, (20S)-lupane-3β,29-diol have been isolated from Gymnosporia wallichiana, in addition to β-amyrin, friedelin, 3β-hydroxy-29-norlupan-20-one and dulcitol.     

Flavonoids from the leaves and twigs of Knema elegans

Knema elegans, a tropical evergreen plant, belongs to Myristicaceae family. Phytochemical investigation on the leaves and twigs of K. elegans led to the isolation and identification of two new flavonoids knemavones A and B (1 and 2), along with fifteen known analogues (3–17). These compounds belong to four subtypes of flavonoids, including chalcones, flavanes, flavones, and isoflavones. The structures of 1 and 2 were elucidated by means of spectroscopic techniques, including HRESIMS, 1D, and 2D NMR experiments. Compounds 3–17 are isolated from the title plant for the first time. Moreover, the new chalcones 1 and 2 could serve as chemotaxonomic markers of K. elegans.     

Triterpenes from the leaves of Pleurostylia opposita

Friedelin, friedelan-3β-ol, sitosterol, α-amyrin, 6β,20-dihydroxylupan-3-one, lup-20(29)-en-3β,6β-diol, 6β,28-dihydroxylup-20(29)-en-3-one and dulcitol were isolated from the leaves of Pleurostylia opposita. The distribution of lupanes in the Celastraceae and their chemotaxonomic significance is discussed.     

Alkaloids from the leaves of Isatis indigotica fortune and their chemotaxonomic significance

From the leaves of Isatis indigotica Fortune, one new alkaloid, namely (2E)-N-(2-hydroxyphenyl)-2-(1-hydroxy-3-oxoindolin-2-ylidene) acetamide (1), together with four known ones, such as phaitanthrin D (2), methyl quindoline-11-carboxylate (3), cephalandole B (4) and 2,2-di (3-indolyl)-3-indolone (5) were isolated and identified. The structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS together with 1D and 2D NMR experiments. Compounds 1, 2 and 5 were obtained from this genus for the first time. Chemotaxonomic significance of these compounds is described herein.     

Sesquiterpene lactones from the leaves of Magnolia sirindhorniae

Five sesquiterpene lactones, costunolide (1), santamarine (2), reynosin (3), parthenolide (4), and lipiferolide (5), were isolated from the leaves of Magnolia sirindhorniae. Their structures were identified by analysis of spectroscopic data and comparison with those reported in the literature. Compound 5 was isolated from the Magnolia for the first time, and this is the first report of the isolation of the sesquiterpene lactones from M. sirindhorniae.     

Flavonoids and phenolic acids from the roots of Sophora tonkinensis Gagnep

Phytochemical study on the roots of Sophora tonkinensis Gagnep. led to the isolation of fifteen compounds, including eleven flavonoids (1–11) and four phenolic acids (12–15). The structures of these compounds were elucidated based on NMR and HR-ESIMS analysis, further supported by comparison with previous literatures. Among them, compounds 2, 3, 4, 6, 9, 12 and 13 were firstly discovered from S. tonkinensis, compound 8 was firstly discovered from the genus Sophora. Furthermore, the chemotaxonomic significance of the obtained compounds was discussed in detail.     

Chemotaxonomic consideration of flavonoids from the leaves of Chrysanthemum arcticum subsp. arcticum and yezoense,and related species

We examined the foliar flavonoids of Chrysanthemum arcticum subsp. arcticum and yezoense, and related Chrysanthemum species. Five flavonoid glycosides (luteolin 7-O-glucoside and 7-O-glucuronides of luteolin, apigenin, eriodictyol and naringenin) were isolated from these taxa. Luteolin 7-O-xylosylglucoside, luteolin, apigenin and quercetin 3-methyl ether were found in subsp. yezoense as very minor compounds that were not recognised by high-performance liquid chromatography/photodiode array (HPLC/PDA). The related species C. yezoense contained acacetin 7-O-rutinoside and some methoxylated flavone aglycones as major compounds. Thus, C. arcticum was distinguished from C. yezoense according to their flavonoid profiles.     

Pterosin derivatives from Pteris morii Masamune

The phytochemical investigation of the aerial parts of Pteris morii Masamune led to the isolation of a new pterosin derivative pteririene A (1), together with seven pterosin sesquiterpenes (2–8). Structure elucidation of these compounds were performed on the basis of NMR spectral data and MS. All compounds were isolated from the P. morii for the first time. The chemotaxonomic significance of the isolates was also discussed.     

Design and synthesis of the novel oleanolic acid-cinnamic acid ester derivatives and glycyrrhetinic acid-cinnamic acid ester derivatives with cytotoxic properties

Oleanolic acid (OA) and glycyrrhetinic acid (GA) are natural products with anticancer effects. Cinnamic acid (CA) and its derivatives also exhibited certain anticancer activity. In order to improve the anticancer activity of OA and GA, we designed and synthesized a series of novel OA-CA ester derivatives and GA-CA ester derivatives by using molecular hybridization approach. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to assess their in vitro cytotoxicity on three cell lines (HeLa (cervical cancer), MCF-7 (breast cancer) and L-O2 (a normal hepatic cell)). Among the evaluated compounds, 3o presented the strongest selective cytotoxicity on HeLa cells (IC₅₀ = 1.35 μM) and showed no inhibitory activity against MCF-7 cells (IC₅₀ > 100 μM) and L-O2 cells (IC₅₀ > 100 μM), and 3e presented the strongest selective inhibition of the MCF-7 cells (IC₅₀ = 1.79 μM). What’s more, compound 2d also showed very strong selective inhibitory activity against HeLa cells (IC₅₀ = 1.55 μM). The further research using Hoechst 33342, AO/EB dual-staining, flow cytometric analysis and DCFH-DA fluorescent dye staining assay presented that 2d and 3o could induce HeLa cells apoptosis and autophagy.     

Triterpenoid saponins from Aesculus sylvatica W. Bartram

16 triterpenoid saponins including two new compounds were isolated from the seeds of A esculus sylvatica W. Bartram. The two new saponins were assigned as 3-O-[β-D-glucopyranosyl-(1 → 2)]-α-L-arabinofuranosyl-(1 → 3)-β-D-glucuronopyranosyl-21,22-O-ditigloyl-3β,16α,21β,22α,24,28 hexahydroxyolean-12-ene (aesculioside S1, 1) and 3-O-[β-D-glucopyranosyl-(1 → 2)]-α-L-arabinofuranosyl-(1 → 3)-β-D-glucuronopyranosyl-21-O-tigloyl-22-O-angeloyl 3β,16α,21β,22α,24,28-hexahydroxyolean-12-ene (aesculioside S2, 2). Aesculioside S1 and S2 displayed moderate cytotoxicity against human non-small cell lung cancer cells (A549) and prostate cancer cells (PC3) (GI₅₀ ranged from 8.7 to 18.2 μM). The structural analysis of the saponins isolated from Aesculus supports the taxonomic placement of A. sylvatica under the section Pavia of Aesculus genus.     

Polyhydroxyagarofuran derivatives from Austroplenckia populnea

The larvicidal extract of Austroplenckia populnea leaves gave two new polyesters of 8-oxo-1,2,3,4,9,14-hexahydroxydihydroagarofuran, a compound which is typical of Celastraceae species.     

Isoquinoline alkaloids from the leaves of Annona leptopetala (Annonaceae)

The phytochemical investigation of the leaves of Annona leptopetala (R. E. Fr.) H. Rainer led to the characterization of tetrahydroprotoberberine corypalmine, and four aporphine (laurotetanine, anonaine, norannuradhapurine and nornuciferine) alkaloids. The structures were established after analysis of their NMR spectral data including 2D NMR experiments. This is the first report of laurotetanine and nornuciferine in A. leptopetala as well as norannuradhapurine in the genus Annona. The ¹³C NMR data of the natural alkaloid norannuradhapurine are reported here for the first time, and the NMR data for the compound corypalmine are reviewed.