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.     

Flavonol triglycosides of leaves from Maytenus robusta with acetylcholinesterase inhibition

Although Maytenus robusta aqueous infusions of leaves are used in Brazilian traditional medicine for stomach disease treatment, only a few chemical studies of this species are found in literature. The phytochemical investigation of methanol extract from M. robusta leaves yielded the known compound kaempferol (3) and two new flavonol glycosides: kaempferol-3-O-β-d-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranoside (1) and quercetin-3-O-β-d-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranoside (2). The chemical structures of 1 and 2 were elucidated by 1D/2D NMR, ESI–MS and ESI–MS² spectral data. It is the first time flavonoids have been reported from M. robusta. Flavonols 1 and 2 showed 66% and 80% acetylcholinesterase (AChE) inhibition, compared to 93% of the standard eserine, by the Ellman’s method. These substances are one of the few active flavonols linked to a trisaccharide chain in the literature presenting this activity, and contribute to the screening for new types of natural AChE inhibitors.     

Bioactive terpenoids from Euonymus verrucosus var. pauciflorus showing NO inhibitory activities

In our continuous search for new nitric oxide (NO) inhibitory compounds as potential anti-inflammatory agents or lead compounds for inflammatory diseases, the chemical constituents of Euonymus verrucosus var. pauciflorus were investigated, leading to the isolation of eleven terpenoids including six new diterpenoids, designated as euonymupenes A–F. The structures were elucidated on the basis of NMR and ECD data analysis. Euonymupenes A, C, and F feature rare labdane-type norditerpenoid skeletons. The NO inhibitory effects were evaluated and all of the isolates were found to inhibit lipopolysaccharide (LPS)-induced NO production in murine microglial BV-2 cells. Western blotting analysis indicated that the most active compound (5) can regulate iNOS (inducible nitric oxide synthase) expression. The further molecular docking studies exhibited the affinities of bioactive compounds with iNOS.     

Potential oilseed crops from the semiarid region of northeastern Brazil

The caatinga semi-arid ecosystem of northeastern Brazil is characterized by a dry, spiny and predominantly deciduous shrub/forest vegetation, and many species there are potential sources of renewable resources for the oleochemical industry. The present research determined the oil content and fatty acid profiles of seeds from eight caatinga species. Seed oils were extracted in a Soxhlet system, and their fatty acid content identified by GC–MS. Oil content varied between 20.2% in Tabebuia impetiginosa (Mart.) Standl. (Bignoniaceae) and 46.4% in Barnebya harleyi (W.R. Anderson & B. Gates) Malpighiaceae. Anemopaegma laeve DC. (Bignoniaceae) had the highest oleic acid content (63.4%), while high levels of linoleic acid were found in Banisteriopsis pubipetala (Juss.) Cuatrec. (42.8%) and B. harleyi (31.9%) (both Malpighiaceae). Palmitic acid was the major fatty acid (50%) in Hippocratea volubilis (L.) (Celastraceae). High levels of linoleic and linolenic acids were found in Croton adamantinus Mull. Arg. (Euphorbiaceae), averaging 44.2% and 45.2% respectively. Gadoleic acid in was the most abundant fatty acid in the oil produced by Serjania lethalis A. St. Hill. (Sapindaceae), averaging 69.6%. B. pubipetala, B. harleyi, C. adamantinus, and H. volubilis were identified as promising species for cultivation.     

Reappraisal of Microtropis macrocarpa C.Y. Cheng & T.C. Kao (Celastraceae), a critically endangered species endemic to Yunnan, China

Microtropis macrocarpa C.Y. Cheng & T.C. Kao has been treated as a synonym of Microtropis macrophylla Merr. & Freeman in most taxonomic reports in China. According to our study, M. macrocarpa is an independent species endemic to Yunnan, China. Microtropis macrophylla and Microtropis pachyphylla Merr. & Freeman should be treated as synonyms of Microtropis longifolia Wall. ex Kurz. M. macrocarpa is also identified as a critically endangered species, CR B 1 ab (i,ii,iii,v), based on the IUCN Red List Categories and Criteria. The foliar surface, anther and pollen structures were also observed with a scanning electron microscope.     

Celastrus paniculatus seed oil and organic extracts attenuate hydrogen peroxide- and glutamate-induced injury in embryonic rat forebrain neuronal cells

Seed oil of Celastrus paniculatus Willd. (CP) has been reported to improve memory and the methanolic extract (ME) of CP was shown to exhibit free-radical-scavenging properties and anti-oxidant effects in human non-immortalized fibroblasts. In the present study, we have investigated the free-radical-scavenging capacity of CP seed oil (CPO) and two extracts, an ethanolic extract (EE) and a ME. CPO and EE showed dose-dependent, free-radical-scavenging capacity, but to a lesser degree than observed for ME. Oxidative stress involves the generation of free radicals and free radical scavenging is one of the mechanisms of neuroprotection. We therefore investigated the effects of CPO, ME, and EE for protection against hydrogen peroxide (H(2)O(2))- and glutamate-induced neurotoxicity in embryonic rat forebrain neuronal cells (FBNC). Pre-treatment of neuronal cells with CPO dose-dependently attenuated H(2)O(2)-induced neuronal death. Pre-treatment with ME and EE partially attenuated H(2)O(2)-induced toxicity, but these extracts were less effective than CPO for neuronal survival. In H(2)O(2)-treated cells, cellular superoxide dismutase (SOD) activity was unaffected, but catalase activity was decreased and levels of malondialdehyde (MDA) were increased. Pre-treatment with CPO, ME, or EE increased catalase activity and decreased MDA levels significantly. Also, CPO pre-treatment attenuated glutamate-induced neuronal death dose-dependently. The activity of cellular acetylcholinesterase (AChE) was not affected by CPO, ME, or EE, suggesting that the neuroprotection offered by CPO was independent of changes in AChE activity. Taken together, the data suggest that CPO, ME, and EE protected neuronal cells against H(2)O(2)-induced toxicity in part by virtue of their antioxidant properties, and their ability to induce antioxidant enzymes. However, CPO, which exhibited the least antioxidant properties, was the most effective in preventing neuronal cells against H(2)O(2)- and glutamate-induced toxicities. Thus, in addition to free-radical scavenging attributes, the mechanism of CP seed component (CP-C) neuroprotection must be elucidated.     

Peptide and tetrahydroisoquinoline alkaloids from Euonymus europaeus

Three p-aryloxy macrocyclic peptide alkaloids frangulanine, franganine and frangufoline together with the 1-benzyltetrahydroisoquinoline alkaloid armepavine have been isolated from Euonymus europaeus native to Poland. These types of alkaloids are new to the Celastraceae and are of chemotaxonomic interest.     

Monoglycerol ester,galloylglucoside and phenolic derivatives from Gymnosporia senegalensis leaves

Phytochemical investigation of the leaves of Gymnosporia senegalensis (Lam.) Loes. led to the isolation and characterization of eighteen compounds: one new polyunsaturated fatty acid-derived monoglyceride, (2S)-1-O-(4′Z,7′Z,10′Z-octadecatrienoyl) glycerol (1); four galloylglucoside derivatives (2–5), including one new named (2R)-methyl [(6′-O-galloyl)-β-D-glucopyranosyloxy]phenylacetate (2), eleven phenolics (6–16), and two sterols (17–18). The structures of the isolates were determined by means of spectroscopic and spectrometric data, as well as by comparison with literature data. Galloylglucosides, especially cyanogenic constituents (3, 4) are described here for the first time in the genus. Antibacterial and cytotoxic activities of isolated compounds were investigated. None of the tested compounds showed growth inhibition against Staphylococcus aureus NBRC 13276, Bacillus subtilis NBRC 3134 and Escherichia coli NBRC 3972 at 50 μM, while 1, 7, 9, 17, and 18 at 50 μM showed relatively weak to moderate decrease of viability against colon (DLD1), breast (MCF7) and gastric (MKN45) cancer cells. Furthermore, the chemotaxonomic significance of the isolated compounds was discussed.