Inhibition of soluble epoxide hydrolase activity by compounds isolated from the aerial parts of Glycosmis stenocarpa

The aim of this study is to search for soluble epoxide hydrolase (sEH) inhibitors from natural plants, bioassay-guided fractionation of lipophilic n-hexane and chloroform layers of an extract of the aerial parts of Glycosmis stenocarpa led to the isolation of 12 compounds (1–12) including murrayafoline-A (1), isomahanine (2), bisisomahanine (3), saropeptate (4), (24?S)-ergost-4-en-3,6-dione (5), stigmasta-4-en-3,6-dion (6), stigmast-4-en-3-one (7), β-sitosterol (8), 24-methylpollinastanol (9), trans-phytol (10), neosarmentol III (11) and (+)-epiloliolide (12). Their structures were elucidated on the basis of spectroscopic data. Among them, neosarmentol III (11) was isolated from nature for the first time. All the isolated compounds were evaluated for their inhibitory activity against sEH. Among isolated carbazole-type compounds, isomahanine (2) and bisisomahanine (3) were identified as a potent inhibitor of sEH, with IC₅₀ values of 22.5?±?1.7 and 7.7?±?1.2?µM, respectively. Moreover, the inhibitory action of 2 and 3 represented mixed-type enzyme inhibition.     

Immunopotentiating activity of abrin,a lectin from Abrus precatorius Linn

A non-toxic dose of abrin, (1.25 microg/kg body wt) consecutively for five days in normal mice stimulated specific humoral responses. A noticeable increase was observed in total leucocyte count, lymphocytosis, weights of spleen and thymus, circulating antibody titre, antibody forming cells, bone marrow cellularity and alpha-esterase positive bone marrow cells. The results suggest that abrin can potentiate the humoral immune response of the host.     

Triterpenoids isolated from the aerial parts of Salvia chinensis

A new triterpenoid, 2α, 3β, 20β, 23-tetrahydroxy-urs-12, 19 (29)-dien-28-oic acid, together with eight known triterpenoids, was isolated from the aerial parts of Salvia chinensis. Their structures were identified by spectroscopic analyses. The antiproliferative effects and differentiation induction abilities of these compounds were determined in human leukemia HL-60 cells.     

Physical studies on three lectins from the seeds of Abrus precatorius

The physical properties of three lectins from the seeds of the Abrus precatorius plant, abrin C, abrin A and the Abrus agglutinin, were studied. All three exhibited similar circular dichroic (CD) spectra in the near-ultraviolet having negative maxima at 286 and 293 nm. In addition, d-galactose induced similar conformational alterations in the three proteins as observed through changes in the near-ultraviolet CD from 280 to 295 nm. The near-ultraviolet CD spectrum of the toxic subunit of abrin C was very different from that of the parent molecule. The fluorescence emission spectra of the three proteins were also studied. All exhibited fluorescence near 335 nm which is quenched 9% by galactose. Iodide quenching of fluorescence using the Stern-Volmer analysis indicated different tryptophan accessibilities in the presence and absence of d-galactose for the Abrus agglutinin. The result suggest that there is a saccharide-induced conformational change which buries several partially exposed tryptophan residues. A comparable analysis of the closely related Ricinus agglutinin revealed that its tryptophan residues are more buried than those of the Abrus agglutinin and, unlike the Abrus agglutinin, there was no saccharide-induced change in tryptophan accessibility.     

Binding of Saccharides to Abrin-b Isolated from Abrus precatorius Seeds

The nature of the binding of saccharides to arbin-b, a toxic lectin isolated from Abrus precatorius seeds, was studied by equilibrium dialysis and fluorescence spectroscopy. Equilibrium dialysis data indicate that abrin-b has two saccharide-binding sites, a high affinity site (HA-site) and a low affinity site (LA-site), to which both galactopyranosides and N-acetylgalactosamine can bind. With excitation at 290 nm, abrin-b displayed a fluorescence spectrum with an emission maximum at 345 nm. Upon binding with specific saccharides, this spectrum shifted to a wavelength shorter by 5 nm, suggesting that saccharides bind to abrin-b in such a manner as to induce a change in the environment of the tryptophan residue or residues at or near the respective binding sites. From the variation of fluorescence at 320 nm with saccharide concentrations, the association constants for binding of saccharides to the respective sites were measured. The results suggest that the HA-site has a subsite favorable for saccharides having β-1,4 linked galactopyranoside at the non-reducing end like lactose in addition to the galactose-recognition site, while the LA-site may not have such a subsite.     

Eight new glycosides with hepatoprotective activity isolated from the aerial parts of Morinda parvifolia

Eight new glycosides, morindaparvins P–W, were isolated from the butanol extract of the aerial parts of Morinda parvifolia. These new structures were elucidated by comprehensive spectroscopic analysis and by comparing the experimental and calculated electronic circular dichroism spectra. The butanol extract was observed to significantly reduce the levels of alanine aminotransferase, aspartate transaminase, and lactate dehydrogenase in the sera of mice with concanavalin A-induced hepatitis. At a concentration of 10 μM, five compounds (1, and 4–7) isolated from the butanol extract possessed hepatoprotective activities against the damage induced by acetaminophen in human HepG2 liver cancer cells.     

Two new compounds from the aerial parts of Elsholtzia densa

Two new compounds, named edensa acid (1), and edensaoside A (2), as well as twenty-nine known compounds (3–31) were isolated from the aerial parts of Elsholtzia densa Benth. The chemical structures of the new compounds were determined by spectrometric data interpretation using NMR, HRESIMS, IR and UV spectroscopy. In addition, all compounds were evaluated for their anti-influenza virus activities against A/WSN/33(H1N1). Among these, compounds 18 and 19 exhibited moderate anti-influenza virus activities with IC₅₀ values of 18.79 μM and 59.87 μM respectively.     

Immunomodulatory role of native and heat denatured agglutinin from Abrus precatorius

Lectins are known as polyclonal activators of lymphocytes and work through the induction of battery of cytokines, which vary from lectin to lectin. Most widely used biological response modifier Mistletoe lectin (ML-1) in therapy stimulates lymphocytes, macrophages, and natural killer cells and induces both TH1 and TH2 type cytokines. Abrus agglutinin, similar to ML-1 with respect to carbohydrate specificity [gal (beta1-->3) gal/Nac], was studied both in native (NA) and heat denatured (HDA) condition for murine splenocyte proliferation, cytokine secretion, NK-cell activation, and thymocyte proliferation in vitro with a view to assess its potential as an immunomodulator. Both NA and HDA activate splenocytes and induce production of cytokines like IL-2, IFN-gamma and TNF-alphabeta indicating a TH1 type of immune response. Native agglutinin and HDA induced conditioned media of adherent splenocytes could stimulate non-adherent splenocytes and vice versa. Heat denatured agglutinin was able to induce NK-cell activation at much lower concentration than that of NA, but the extent of NK-cell activation was higher for NA. Proliferation of thymocytes by NA and HDA was also observed. This study indicates that Abrus agglutinin could be a potential immunomodulator both in native as well as in heat denatured form.     

Bioactive phenolic compounds from aerial parts of Plinia glomerata

The present work describes the antinociceptive properties and chemical composition of the aerial parts of Plinia glomerata (Myrtaceae). Both of the extracts evaluated, acetonic and methanolic, showed potent antinociceptive action, when analyzed against acetic acid-induced abdominal constrictions in mice, with calculated ID50 (mg/kg, i. p.) values of 24.8 and 3.3, respectively. Through usual chromatographic techniques with an acetonic extract, the following compounds were obtained: 3,4,3'-trimethoxy flavellagic acid (1), 3,4,3'-trimethoxy flavellagic acid 4'-O-glucoside (3) and quercitrin (4), which were identified based on spectroscopic data. Compounds 1 (ID50 = 3.9 mg/kg, i. p., or 10.8 micromol/kg) and 3 (ID50 = 1.3 mg/kg or 2.5 micromol/kg) were notably more active than some well-known analgesic drugs used here for comparison.     

A characterization of abrin a from the seeds of the Abrus precatorius plant

Abrin A was purified from the seeds of the Abrus precatorius plant and its physical and biological properties were studied. The biological properties of abrin A were found to be similar to the better studied Abrus protein, abrin C, in that it is toxic to cell-free protein synthesis and binds d-galactose.Abrin A contains carbohydrate moieties including both neutral and amine sugars but no metals, similar to the other two Abrus proteins (abrin C and the Abrus agglutinin). Amino acid compositions of the subunits of abrin A indicated that it consists of two different subunits of comparable size. Furthermore, one of the subunits showed microheterogeneity suggesting that abrin A is a mixture of isolectins. A comparative study of abrin A and abrin C based on compositions and tryptic maps reveals them to be closely related. The evidence suggests that the two abrins may have the same mechanisms of toxic action.Far-ultraviolet circular dichroic studies of abrin A show it to contain 47% β-pleated sheet and 10% α-helix, again similar to the other two Abrus proteins.     

Anti-inflammatory and enzyme inhibitory activities of a crude extract and a pterocarpan isolated from the aerial parts of Vitex agnus-castus

A new compound, 6a,11a-dihydro-6H-[1] benzofuro [3,2-c][1,3]dioxolo[4,5-g]chromen-9-ol was isolated from the ethyl acetate fraction of Vitex agnus-castus. The structure of this compound was identified with the help of spectroscopic techniques ((13)C NMR, (1)H NMR, HMBC, HMQC, NOESY and COSY). The compound showed low urease- (32.0%) and chymotrypsin- (31.4%) inhibitory activity, and moderate (41.3%) anti-inflammatory activity. The crude extract and various fractions obtained from the aerial parts of the plant were also screened for possible in vitro hemagglutination, antibacterial and phytotoxic activities. No hemagglutination activity against human erythrocytes was observed in crude extracts and fractions of V. agnus-castus. The fractions and crude methanolic extract showed moderate and low antibacterial activity. Exceptions were the CHCl(3) fraction, which showed significant antibacterial activity against Klebsiella pneumonia (81% with MIC(50)=2.19 mg/mL), the n-hexane fraction, which exhibited no activity against Salmonella typhi, and the CHCl(3) and aqueous fractions, which showed no activity against Bacillus pumalis. Moderate phytotoxic activity (62.5%) was observed by n-hexane fraction of V. agnus-castus against Lemna minor L at 1000 μg/mL.     

Antihyperglycemic activity of Teramnus labialis (Fabaceae).

In vivo bioassay-guided fractionation of the aqueous alcohol extract of the aerial parts of Teramnus labialis (Roxb.) Benth. (Fabaceae), using C57BL/Ks-db/db mice as a model for type 2 diabetes, yielded an active fraction containing a mixture of coumarins. The major coumarin present in the active fraction was identified as fraxidin.     

Flavonoids and other compounds from the aerial parts of Viola etrusca

The non-volatile constituents of the rare species Viola etrusca Erben (Violaceae), collected at Mount Amiata, Italy, were phytochemically investigated for the first time. Two new flavonoid glycosides, 4'-methoxyrhamnetin (1) and violetruscoside (2), an isorhamnetin derivative, were isolated from the flowering aerial parts, together with eleven known substances, including eight flavonoids, a phenolic acid, glycerin, and a coumarin derivative. The NMR data of violanthin (10) and isoviolanthin (11) are reported for the first time.     

Phenolic compounds from aerial parts as chemosystematic markers in the Scorzonerinae (Asteraceae)

In continuation of our chemosystematic survey of the Lactuceae tribe of the Asteraceae family and of the Scorzonerinae subtribe in particular, we have studied the profiles of phenolic compounds of aerial parts of Geropogon glaber L., and seven representatives of each of the genera Scorzonera and Tragopogon. Employing HPLC-MS³, 56 phenolics amongst the seven phenolic acids and 49 flavonoids were characterized. All phenolic acids were assigned as caffeoyl quinic acid derivatives and 15 of the flavonoids were identified as aglyca and glycoside of apigenin, luteolin, and quercetin, whilst the remaining flavonoids were only partially characterized. Multivariate data analyses of the HPLC-DAD quantification data revealed no significant differences between the three genera Geropogon, Scorzonera, and Tragopogon. However, some clusters of chemically very similar species amongst them the group of Tragopogon minor Mill., Tragopogon orientalis L., and Tragopogon pratensis L. (also regarded as subspecies of T. pratensis by some authors) were identified. In contrast, the three taxa of Scorzonera hispanica s.l. (Scorzonera crispatula Boiss., S. hispanica L., and Scorzonera trachysperma Guss.) were chemically less similar and partially clustered with other morphologically less closely related species.     

Two flavonoids and other compounds from the aerial parts of Centaurea bracteata from Italy

The flowering aerial parts of Centaurea bracteata Scop. (Asteraceae) have been studied for the first time. Nineteen compounds were isolated and identified, namely a sterol glucoside, two phenolic acids, three quinic acid derivatives, and 13 flavonoids, two of which, are new natural products. Structural elucidation was performed mainly by mean of FABMS, 1D and 2D NMR spectroscopy.