Exceptional contact elasticity of human enamel in nanoindentation test.

OBJECTIVE: Tooth enamel has unsurpassed hardness and stiffness among mammalian tissue structures. Such stiff materials are usually brittle, yet mature enamel can survive for a lifetime. Understanding the nanoscale origin of enamel durability is important for developing advanced load-bearing biomaterials. Here, nanoscale exceptional contact elasticity of the human tooth enamel, based on nanoindentation tests, is reported. METHODS: Spherical indenter tips with radii of 243 and 1041nm were used to determine stress-strain curves of enamel. Force-displacement curves were recorded using quasi-static loading strain rates of 0.031, 0.041, and 0.061s-1. The storage moduli from a superimposed signal amplitude (dynamic strain at 220Hz) embedded during primary quasi-static loading and from quasi-static elastic theory were simultaneously measured. Modulus mapping was considered to be an extremely low quasi-static loading strain rate indentation test. RESULTS: The elastic limits were 7-9GPa and 5-6GPa for the small and large indenters, respectively. The elastic-plastic transition point and elastic modulus value increased with substantially increased quasi-static loading strain rate. The results suggested that the increase of the elastic limit during high-loading strain was associated with exceptional contact elasticity at the nanoscale of the enamel structure and the consequent extension of the contact area (i.e., a temporary pile-up response, dependent on the enamel nanocrystals and protein glue). SIGNIFICANCE: Structural modification at this scale effectively prevents the initiation of cracking from localized strain, thus reinforcing the bulk structure. These results may provide valuable insight for conceptualizing bio-inspired nanocomposites.

Six New Lanostane Triterpenoids from the Fruiting Body of Tyromyces sambuceus and Antiproliferative Activity.

During the search for secondary metabolites with antiproliferative activity, six new lanostane triterpenoids, tyrosamic acids A-F (1-6) together with ten known compounds (7-16), were isolated from the fruiting body of Tyromyces sambuceus. Their structures were elucidated using MS analyses, extensive 2D-heteronuclear NMR data interpretation and the structure of 3 was further confirmed by single-crystal X-ray data analyses. All lanostane triterpenoids (1-16) possesses a carboxy group at C-20 position and their strength of antiproliferative activity was affected by the presence or absence of a hydroxy group at C-15 position and at the side chain. Four of the compounds (1, 6, 10, 14) showed antiproliferative activities against human cancer cell lines with IC50 values of 16.8-48.3 µM (HL-60).

Phenanthrene and phenylpropanoid constituents from the roots of Cymbidium Great Flower 'Marylaurencin' and their antimicrobial activity.

Two new phenanthrenes, and one new phenylpropanoid, named ephemeranthoquinone C (1), and marylaurencinols C (2) and D (3), were isolated from the roots of Cymbidium Great Flower 'Marylaurencin', respectively. These structures were determined on the basis of 2D NMR experiments. The compounds were tested for antimicrobial activity against Bacillus subtilis, Klebsiella pneumoniae, and Trichophyton rubrum.

Two novel aromatic glucosides, marylaurencinosides D and E, from the fresh flowers of Cymbidium Great Flower 'Marylaurencin'.

Two novel aromatic glucosides, named marylaurencinosides D (1) and E (2), were isolated from the fresh flowers of Cymbidium Great Flower 'Marylaurencin'. In addition, eight known aromatic compounds (3-10) were isolated. These structures were determined on the basis of NMR experiments as well as chemical evidence.

Constituents of Caryopteris incana and their antibacterial activity.

Two new compounds named caryocanolide (1), and caryocanoside A (2), together with nine known compounds (3-11) were isolated from the whole plant of Caryopteris incana. These structures were determined mainly on the basis of 2D nuclear magnetic resonance and high resolution fast atom bombardment mass spectroscopy data. Furthermore, the isolated compounds (1, 2, 4-11) were tested for their antibacterial activity. Compound 1 exhibited moderate antimicrobial activity against Bacillus subtilis with a minimum inhibitory concentration value of 35.7 µM.

Phenylpropanoid, sapnol A, lignan and neolignan sophorosides, saposides A and B, isolated from Canadian sugar maple sap.

One new phenolic compound, sapnol A (1), and two new aromatic sophorosides, named saposides A (2) and B (3) were isolated from sugar maple sap. In addition, seven known phenolic compounds 4-10 were isolated. These structures were determined on the basis of NMR experiments as well as chemical evidence. Furthermore, all the isolated compounds 1-10 were tested for antioxidative activity by the superoxide dismutase (SOD)-like assay.

Yellow pigments, fomitellanols A and B, and drimane sesquiterpenoids, cryptoporic acids P and Q, from Fomitella fraxinea and their inhibitory activity against COX and 5-LO.

Yellow pigments, fomitellanols A (1a) and B (2a), and drimane-type sesquiterpenoid ethers of isocitric acid, cryptoporic acids P (3) and Q (4), have been isolated from the fruiting bodies of Fomitella fraxinea (Polyporaceae). Their structures were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analyses, and their biological activity against COX-1, COX-2, and 5-LO was investigated.

Aromatic constituents of Cymbidium Great Flower Marie Laurencin and their antioxidative activity.

Two novel aromatic glucosides, named marylaurecinosides B (1) and C (2), were isolated from Cymbidium Great Flower Marie Laurencin, together with six known aromatic compounds (3-8). These structures were determined on the basis of NMR experiments as well as chemical evidence. All of the isolated compounds (1-8) were tested for antioxidative activity using a superoxide dismutase-like assay.

Phenanthrene derivatives from Cymbidium Great Flower Marie Laurencin and their biological activities.

A new phenanthrendione, ephemeranthoquinone B (1), two phenanthrenes, marylaurencinols A (2) and B (3), and a phenanthrene glucoside, marylaurencinoside A (4), were isolated from the roots of Cymbidium Great Flower Marie Laurencin, along with six known phenanthrenes, 5-10. The structures of these compounds were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analysis and chemical degradation. The compounds were tested for antibacterial activities against Bacillus subtilis and Klebsiella pneumoniae and for cytotoxic activity against the human promyelocytic leukemia (HL-60) cell line. Compounds 1, 3, and 6 showed antibacterial activities with minimum inhibitory concentration (MIC) values in the range of 4.88 to 65.10 µM. Notably, ephemeranthoquinone B (1) had a strong antibacterial effect on B. subtilis. Furthermore, 1 exhibited moderate cytotoxic activity (IC(50) 2.8 µM) against HL-60 cells. Compounds 4-9 also showed weak cytotoxic activity against the HL-60 cell line with IC(50) values of 19.3-52.4 µM.

Aromatic compounds and their antioxidant activity of Acer saccharum.

A new lignan glycoside, 5-(3″,4″-dimethoxy-phenyl)-3-hydroxy-3-(4'-hydroxy-3'-methoxybenzyl)-4-hydroxymethyl-dihydrofuran-2-one 4'-O-α-L: -rhamnopyranoside (1), with seven known compounds, compound 2, koaburside, icariside E(4), cleomiscosin C, cleomiscosin D, scopoletin, and 5'-demethylaquillochin, were isolated from the EtOH extract of the wood of Acer saccharum (Aceraceae). Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) and mass spectroscopy analysis. All of the isolated compounds, 1-8, were tested for their antioxidant activity in superoxide dismutase (SOD)-like assay.

Ipomotaosides A-D, resin glycosides from the aerial parts of Ipomoea batatas and their inhibitory activity against COX-1 and COX-2.

Four new resin glycosides, namely, ipomotaosides A-D (1-4), were isolated from the dried aerial parts of Ipomoea batatas. The structures of 1-4 were elucidated by analysis of their spectroscopic data and by chemical derivatization and were tested for their anti-inflammatory activity against cyclooxygenase (COX)-1 and -2.

Novel phthalide compounds from Sparassis crispa (Hanabiratake), Hanabiratakelide A-C, exhibiting anti-cancer related activity.

Sparassis crispa (SC), known as Hanabiratake in Japanese, is an edible mushroom with various medicinal properties. We isolated 3 novel phthalides, designated hanabiratakelide A (1), B (2), and C (3), from the SC fruit body. In this investigation, 3 known phthalides (4-6), ubiquinone-9, and 2 known unsaturated fatty acids were also isolated. Their structures were elucidated primarily through extensive NMR experiments. The isolated compounds 1-6 were tested for their anti-oxidant activity. The in vitro superoxide dismutase-like activity of the 3 hanabiratakelides was stronger than that of vitamin C. The compounds also exerted inhibitory effects on lipopolysaccharide-stimulated nitric oxide and prostaglandin E2 production by a murine macrophage cell line, RAW264. In addition, the growth of the colon cancer cell lines Caco-2 and colon-26 was significantly inhibited by treatment with the 3 hanabiratakelides. In vivo, the frequency of azoxymethane-induced aberrant crypt foci was reduced in SC-fed F344/N rats compared to rats fed a standard diet. In conclusion, 3 novel phthalides, hanabiratakelides, derived from SC were shown to possess anti-oxidant, anti-inflammatory, and anti-tumor activity.

Constituents of the lichen Peltigera dolichorrhiza.

A new aromatic derivative, 5-(3,4-dihydroxyphenyl)-3-methylcyclohex-2-enone (1), and three known compounds, peltigerine, solorinine, and phenyl butanoid, were isolated from the MeOH extract of the lichen Peltigera dolichorrhiza (Peltigeraceae). Their structures were determined by 1D and 2D nuclear magnetic resonance and mass spectroscopy analysis.

Russujaponols G-L, illudoid sesquiterpenes, and their neurite outgrowth promoting activity from the fruit body of Russula japonica.

Six new illudoid sesquiterpene, russujaponols G-L (1-6) were isolated from the fruit bodies of Russula japonica. Their structures were established primarily by 2D NMR experiments. Furthermore, russujaponols I-K showed neurite outgrowth promoting activity in the primary cultured rat cortical neurons.

Novel abietane diterpenoids and aromatic compounds from Cladonia rangiferina and their antimicrobial activity against antibiotics resistant bacteria.

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3-6), four known labdane diterpenoids (7-10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having gamma-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1-17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).

Flavonoids from Acacia pennata and their cyclooxygenase (COX-1 and COX-2) inhibitory activities.

Two new flavonoids quercetin 4'-O-alpha-L-rhamnopyranosyl-3-O-beta-D-allopyranoside (1) and apigenin 6-C-[2''-O-(E)-feruloyl- beta-D-glucopyranosyl]-8-C-beta-glucopyranoside (2), along with the known isorhamnetin 3-O-alpha-L-rhamnopyranoside (3), kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (4), and isovitexin (5) were isolated from the leaves of Acacia pennata Willd. (Mimosaceae) and tested for their anti-inflammatory activity. Their structures were determined by 1D and 2D NMR and mass spectrometry. They were tested for an inhibitory effect on COX-1 and COX-2, showing 60-90% inhibition at 10(-4) g/mL and 5-14% inhibition at 10(-4) g/mL, respectively.

Russujaponols A-F, illudoid sesquiterpenes from the fruiting body of Russula japonica.

Six new illudoid sesquiterpenes, russujaponols A-F (1-6), were isolated from the fruiting bodies of Russula japonica Hongo. Their structures were established primarily by 2D NMR experiments, and the structure of the main compound, russujaponol A (1), was confirmed by X-ray crystallographic analysis of its benzoate (1a). Russujaponol A (1) suppressed invasion of human fibrosarcoma (HT1080) cells into Matrigel in a concentration-dependent manner and caused 63% inhibition at 3.73 microM.

Abietane diterpenoids from the barks of Cryptomeria japonica.

From the bark of Cryptomeria japonica were isolated sugikurojins I (1) and J (2), and an abietane derivative (3) was obtained for the first time as a natural product. These structures were elucidated primarily through extensive NMR experiments. Sugikurojin I (1) has a unique skeleton incorporating an abietane diterpene and a 1,10-secocadinane sesquiterpene. Sugikurojin J (2) is a peroxyester of hydroxyabietane diterpene and isopimarane acid diterpene. Compound 3 was p-quinone acid, which occurred by cleavage between C-7 and C-8 of sugiol; it was deduced to [4'-isopropyl-1(S),3,3-trimethyl-3',6'-dioxo-bicyclohexyl-1',4'-dien-2(R)-yl]-acetic acid. Also obtained in this investigation were three known diterpenes (4-6).

Three abietane diterpenes and two diterpenes incorporated sesquiterpenes from the bark of Cryptomeria japonica.

Three new abietane diterpenes, sugikurojins D (1), E (2), and F (3), and two new abietanes which incorporate cadinane, sugikurojins G (4) and H (5) were isolated from the bark of Cryptomeria japonica. These structures were elucidated primarily by extensive NMR experiments. The structure of sugikurojin D (1) was deduced to be 6alpha-acetoxy-7beta,11-dihydroxy-12-methoxy-8,11,13-abietatriene. Sugikurojin E (2) was deduced to be 6alpha-acetoxy-7beta,12-dihydroxy-8,11,13-abietatriene. Sugikurojin F (3) was 7alpha-methoxy-8,13-abietadien-11,12-dione. Sugikurojins G (4) and H (5) had a unique skeleton incorporating an alpha-cadinol or a 1alpha-hydroxy-T-cadinol in ferruginol, respectively. Also obtained in this investigation were the known diterpenes (6-14). An antibacterial activity of ten among these against Staphylococcus aureus and Escherichia coli was inactive at the (MIC: 125 microg/ml) level. Meanwhile, in the cytotoxic activity against HL-60, compounds 4, 8, and 11 showed moderate (IC50: 4, 35.4; 8, 28.0; 11, 52.4 microM) though weak (IC50: 4, 100; 8, 80.8; 11, 100 microM) activity against HCT-15.

Cytotoxic constituents of the fruit body of Daedalea dickisii.

Three new lanostane triterpenoids (1, 7, 8) and five new lanostane triterpene glucosides (2-6) have been isolated from the fruit bodies of Daedalea dickinsii. Their structures were established primarily by NMR experiments, and their biological activity against HL-60 and HCT-15 cell lines was investigated. Compounds 3-6 induced internucleosomal DNA fragmentation characteristic of apoptotic cell death in the HL-60 cell line.