Neo-clerodane diterpenoids and other constituents from Baccharis species

A new neo-clerodane dilactone, desoxyarticulin, and dihydrotucumanoic acid, together with other known compounds, were isolated from Baccharis pedicellata and Baccharis marginalis. The structures of the new compounds were elucidated by spectroscopic methods.     

Diterpene resin acids from the needle oleoresin of pinus strobus

The resin acid components of P. strobus needles were isolated, and the major constituents identified as labdenoic diterpenes. In addition to anticopalic and strobic acids previously reported in the needles, 3-oxoanticopalic, 3β-acetoxyanticopalic, 3β-hydroxyanticopalic acids and the 8α-hydroxy derivative of anticopalic acid were found along with two new compounds. The structures of the two new compounds, a cycloanticopalic acid and an abcoanticopalic acid, were determined by NMR. The composition of the diterpene resin acids was obtained for several samples of P. strobus needles from provenance tests.     

Substrate-like water soluble lipase inhibitors from Filipendula kamtschatica

Filipendula kamtschatica is a plant utilized as a traditional medicine by Ainu people in Japan, but its chemical constituents are not much studied. Pancreatic lipase inhibitors are a promising tool for the treatment of obesity. We searched for natural lipase inhibitors from F. kamtschatica and two new compounds were isolated along with the known flavonoid glycoside. The structure elucidation of new compounds revealed these two to be 2-O-caffeoyl-4-O-galloyl-l-threonic acid and 3-O-caffeoyl-4-O-galloyl-l-threonic acid, which can be recognized as a pancreatic lipase’s substrate-like structure. The isolated compounds all showed an inhibitory activity against porcine pancreatic lipase and one of the isomer, 3-O-caffeoyl-4-O-galloyl-l-threonic acid, possessed the most potent activity with IC₅₀ value showing an order lower value compared to others. The substrate-like structure of the new compounds seemed to be important for their activity.     

9-octadecen-6-ynoic acid from Riccia fluitans

A new acetylenic fatty acid, 9-octadecen-6-ynoic acid, and the known compounds 9,12-octadecadien-6-ynoic acid and 9,12,15-octadecatrien-6-ynoic acid were isolated from the thalli of Riccia fluitans. The structure of the new compound was established by spectroscopic methods.     

Neo-clerodane diterpenoids from Baccharis macraei

Two new neo-clerodane diterpenes, hautriwaic acid acetate and 4β-hydroxyisobacchasmacranone, were isolated from the aerial parts of Baccharis macraei. The structures of the new compounds were elucidated by spectroscopic methods. The structure of hautriwaic acid acetate was confirmed by correlation with its known deacetyl derivative, hautriwaic acid.     

Production of new tricarboxylic acid anhydrides from stearic acid by Pseudomonas cepacia A-1419

Screening for microorganisms converting stearic acid to form new compounds was conducted, Pseudomonas cepacia A-1419 isolated from soil effectively produced two compounds showing strong ultraviolet absorption when the resting cells were incubated with stearic acid. The products were isolated, and identified as (Z)-dec-3-ene-1,3,4-tricarboxylic acid 3,4-anhydride (Product 1) and (Z)-dodec-3-ene-1,3,4-tricarboxylic acid 3,4-anhydride (Product 2) by infrared, mass, and nuclear magnetic resonance spectroscopies, and elemental analysis. Products 1 and 2 were produced from stearic acid at conversion rates of about 18 and 32%, respectively.     

Synthesis of novel azo compounds containing 5(4H)-oxazolone ring as potent tyrosinase inhibitors

Six new azo dyes containing of 5(4H)-oxazolone ring were prepared by diazotization of 4-aminohippuric acid and coupling with N,N-dimethylaniline, 1-naphthol and 2-naphthol and condensation with 4-fluoro benzaldehyde or 4-trifluoromethoxy benzaldehyde. The new compounds were fully characterized by spectroscopic techniques. All synthesized compounds exhibited high tyrosinase inhibitory behavior. The results of mushroom tyrosinase inhibition assays indicate that the 4-trifluoromethoxy derivatives have high degrees of inhibition and N,N-dimethylaniline derivatives are better for tyrosinase inhibition than 1-naphthol and 2-naphthol derivatives. All synthesized azo compounds (4a–4f) showed the most potent mushroom tyrosinase inhibition, comparable to that of Kojic acid and l-mimosine, as reference standard inhibitors.     

Chemical constituents from Sarcopyramis nepalensis Wall

One new megastigmane glycoside 1 and two new terpenic glycosides 2 and 3, along with three known compounds, roseoside, pumilaside A, and terminolic acid were isolated from Sarcopyramis nepalensis Wall. The structures of these new compounds were elucidated on the basis of 1D, 2D NMR, MS spectroscopic analysis, and chemical methods.     

Myrianthic acid: a triterpene acid from the rootwood of Myrianthus arboreus

Arjunolic acid and a new triterpene acid, myrianthic acid, were isolated from the rootwood of Myrianthus arboreus. The structures of the two compounds were elucidated by IR, ¹H NMR and mass spectroscopy.     

Guaiane sesquiterpenes from Decachaeta scabrella

From the dichloromethane extract of leaves of Decachaeta scabrella, in addition to three known guaianolides and two flavonoids, a new guaianolide, 11α, 13-dihydroxerantholide, and two new guaiane acids, pechueloic acid and 11,13-dihydropechueloic acid, were characterized. The structures of the new compounds were determined by spectral and chemical methods.     

New unsaturated fatty acid and other chemical constituents from the roots of Cola rostrata K. Schum. (Malvaceae)

Phytochemical investigation of the roots of Cola rostrata K. Schum. led to the isolation of a new unsaturated fatty acid, named rostratanic acid (1), together with fourteen known compounds, lignoceric acid, friedelan (7), friedelanone (8), bauerenol (3), lupeol (4), herranone (9), acotatarone A (11), betulinic acid (6), betulin (5), nonanedioc acid (2), arjunolic acid (10) stigmasterol, β−sitosterol, and β−sitosterol-3-O-β-D-glucopyranoside. The structure of the new compound as well as those of the known compounds were established by means of spectroscopic methods: NMR analysis (¹H and ¹³C NMR, ¹H–¹H–COSY, HSQC and HMBC) and high-resolution mass spectrometry (HR-ESI-MS), and by comparison with previously reported data. Two of those known compounds were modified chemically to afford three new derivatives. All those compounds were tested for their cytotoxic activity against the human cervix carcinoma KB-3-1 cells and their antibacterial activity against Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa and Staphylococcus aureus. Although the crude extract gave weak antibacterial activity, none of the isolated compounds showed antibacterial activity, and, only the prenylated derivative showed weak cytotoxicity. In addition, the chemotaxonomic significance of the species Cola rostrata is discussed.     

Screening oxime libraries by means of mass spectrometry (MS) binding assays: Identification of new highly potent inhibitors to optimized inhibitors γ-aminobutyric acid transporter 1

Generation and screening of oxime libraries by competitive MS Binding Assays represents a powerful tool for the identification of new compounds, with affinity to mGAT1, the most abundant plasma membrane bound GABA transporter in the CNS. By screening a guvacine derived oxime library, new potent inhibitors of mGAT1 had been revealed. In the present study, oxime libraries generated by reaction of a large excess of a rac-nipecotic acid derivative displaying a hydroxylamine functionality in which various aldehydes under suitable conditions, were examined for new potent inhibitors of mGAT1. The pK_i values obtained of the best hits were compared with those of related compounds displaying a guvacine instead of a nipecotic acid subunit as hydrophilic moiety. Amongst the new compounds one of the most affine ligands of mGAT1 known so far (pK_i?=?8.55?±?0.04) was found.     

Caffeic acid derivatives isolated from the aerial parts of Galinsoga parviflora and their effect on inhibiting oxidative burst in human neutrophils

Four new caffeoyl -glucaric and -altraric acid derivatives along with eleven known compounds were isolated from aerial parts of Galinsonga parviflora. Their structures were elucidated by high-resolution spectroscopic studies. The four new compounds were determined as being 2,3,4,5-tetracaffeoylglucaric acid (1), 2,4,5-tricaffeoylglucaric acid (2), 2,3,4- or 3,4,5-tricaffeoylaltraric acid (3) and 2,3(4,5)-dicaffeoylaltraric acid (4). A reliable criterion for the determination of the linkage position of caffeic acids moieties in glucaric acid derivatives has been proposed, on the basis of detailed analysis of the respective J-couplings, including substitution and solvent influence on the observed values. All hexaric acids derivatives appeared as inhibitors of reactive oxygen species production by stimulated neutrophils.     

Eudesmanolides and diterpenes from Wedelia trilobata and an ent-kaurenic acid derivative from Aspilia parvifolia

The reinvestigation of the aerial parts of Wedelia trilobata afforded, in addition to known compounds, six new eudesmanolides, two ent-kaurenic acid derivatives as well as a degraded one. A corresponding hydroxy compound was present in Gnaphalium undulatum. From Aspilia parvifolia new ent-kaurenic acid epoxides were isolated. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Gutierrezial and further diterpenes from Gutierrezia sarothrae

The aerial parts of Gutierrezia sarothrae afforded in addition to polyalthic acid, daniellic acid and nivenolide, 14 new diterpenes, most of them closely related to polyalthic acid. One of these compounds has a new carbon skeleton. The structures were elucidated by spectroscopic methods and by some chemical transformations.     

Malyngamide 4, a new lipopeptide from the Red Sea marine cyanobacterium Moorea producens (formerly Lyngbya majuscula)

In our continuing effort to discover new drug leads from Red Sea marine organisms, a sample of the marine cyanobacterium Moorea producens (previously Lyngbya majuscula) was investigated. Bioassay-directed purification of a tumor cell-growth inhibitory fraction of the organic extract of the Red Sea cyanobacterium afforded a new compound, malyngamide 4 (1), together with five previously reported compounds, malyngamide A (2) and B (3), (S)-7-methoxytetradec-4(E)-enoic acid (lyngbic acid, 4), aplysiatoxin (5) and debromoaplysiatoxin (6). Assignment of the planar structures of these compounds was based on extensive analysis of one- and two-dimensional NMR spectra and high-resolution mass spectrometric data. The isolated compounds were evaluated for their inhibitory activity against three cancer cell lines. In addition, the antibacterial activity of the compounds against Mycobacterium tuberculosis H₃₇Rv ATCC 27294 (H₃₇Rv) was evaluated. Lyngbic acid (4) was the most active against M. tuberculosis, while malyngamides 4 (1) and B (3) moderately inhibited the cancer cell lines. The other compounds were deemed inactive at the test concentrations.     

A new ent-kaur-16-en-19-oic acid from the aerial parts of Inula bifrons

The phytochemical study of the chloroform extract of the aerial parts of Inula bifrons (L.) L. led to the isolation of one new ent-kaurane diterpenes acid along with twelve known compounds (two ent-kaurane diterpenoids, an eudesmane acid, five sesquiterpene lactones, three triterpenoids and β-sitosterol). All known compounds are found for the first time in I. bifrons. Their structures were elucidated by using spectral methods (NMR, HRESIMS and IR). The distribution of these compounds in the genus Inula and their chemotaxonomic significance is discussed.     

Quinic acid derivatives and coumarin glycoside from the roots and stems of Erycibe obtusifolia

A new quinic acid derivative (1) and a new coumarin glycoside (8), together with six known compounds (2–7) were isolated from the roots and stems of Erycibe obtusifolia. The structures of the new compounds were elucidated by spectroscopic and chemical analyses. The in vitro antiviral activity against the respiratory syncytial virus (RSV) of seven quinic acid derivatives was evaluated by cytopathic effect (CPE) reduction assay. Among them, the dicaffeoylquinic acids (6 and 7) displayed potent in vitro anti-RSV activity.     

Bioactive chemical constituents of Caesalpinia bonduc (Fabaceae)

Phytochemical studies on the ethanolic extracts of Caesalpinia bonduc (Fabaceae) yielded two new homoisoflavonoids, caesalpinianone, and 6-O-methylcaesalpinianone along with five known natural products, namely, hematoxylol, stereochenol A, 6′-O-acetylloganic acid, 4′-O-acetylloganic acid, and 2-O-β-d-glucosyloxy-4-methoxybenzenepropanoic acid. Structures of these compounds were elucidated with the aid of extensive NMR spectral studies. All of these compounds exhibited different levels of glutathione S-transferase (GST) inhibitory and antifungal activities.     

Phytochemicals from the aerial parts of Ligularia thomsonii and their radical scavenging activity

Phytochemical investigation of the aerial parts of Ligularia thomsonii has led to the isolation of three new phenylpropanoid glucosides ligularoside I (1), ligularoside II (2) and ligularoside III (3) along with nine known compounds; cinnamic acid (4), 3-phenylpropanoic acid (5), 3,4,5-trihydroxybenzoic acid (6), 4-hydroxybenzoic acid (7), p-coumaric acid (8), caffeic acid (9), 3,4-dihydroxybenzoic acid (10), kaempferol 3-O-β-d-glucopyranoside (11) and 3,5-di-O-caffeoylquinic acid (12), hitherto unreported from L. thomsonii. Their chemical structures were elucidated by spectroscopic analysis and chemical transformation. All these compounds were tested for antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Among them, compounds 9, 10 and 12 showed significant antioxidant activity against DPPH radicals with IC₅₀ of 19.6, 23.3 and 8.9 μm, respectively.