[A new dihydrostilbene from aerial part of Cannabis sativa].

The present study investigated the chemical constituents in the aerial part of Cannabis sativa. The chemical constituents were isolated and purified by silica gel column chromatography and HPLC and identified according to their spectral data and physicochemical properties. Thirteen compounds were isolated from the acetic ether extract of C. sativa and identified as 3',5',4″,2-tetrahydroxy-4'-methoxy-3-methyl-3″-butenyl p-disubstituted benzene ethane(1), 16R-hydroxyoctadeca-9Z,12Z,14E-trienoic acid methyl ester(2),(1'R,2'R)-2'-(2-hydroxypropan-2-yl)-5'-methyl-4-pentyl-1',2',3',4'-tetrahydro-(1,1'-biphenyl)-2,6-diol(3), ß-sitosteryl-3-O-ß-D-glucopyranosyl-6'-O-palmitate(4), 9S,12S,13S-trihydroxy-10-octadecenoate methyl ester(5), benzyloxy-1-O-ß-D-glucopyranoside(6), phenylethyl-O-ß-D-glucopyranoside(7), 3Z-enol glucoside(8), α-cannabispiranol-4'-O-ß-D-glucopyranose(9), 9S,12S,13S-trihydroxyoctadeca-10E,15Z-dienoic acid(10), uracil(11), o-hydroxybenzoic acid(12), and 2'-O-methyladenosine(13). Compound 1 is a new compound, compound 3 is a new natural product, and compounds 2, 4-8, 10, and 13 were isolated from Cannabis plant for the first time.

Approaching the quantum limit in two-dimensional semiconductor contacts.

The development of next-generation electronics requires scaling of channel material thickness down to the two-dimensional limit while maintaining ultralow contact resistance1,2. Transition-metal dichalcogenides can sustain transistor scaling to the end of roadmap, but despite a myriad of efforts, the device performance remains contact-limited3-12. In particular, the contact resistance has not surpassed that of covalently bonded metal-semiconductor junctions owing to the intrinsic van der Waals gap, and the best contact technologies are facing stability issues3,7. Here we push the electrical contact of monolayer molybdenum disulfide close to the quantum limit by hybridization of energy bands with semi-metallic antimony ([Formula: see text]) through strong van der Waals interactions. The contacts exhibit a low contact resistance of 42 ohm micrometres and excellent stability at 125 degrees Celsius. Owing to improved contacts, short-channel molybdenum disulfide transistors show current saturation under one-volt drain bias with an on-state current of 1.23 milliamperes per micrometre, an on/off ratio over 108 and an intrinsic delay of 74 femtoseconds. These performances outperformed equivalent silicon complementary metal-oxide-semiconductor technologies and satisfied the 2028 roadmap target. We further fabricate large-area device arrays and demonstrate low variability in contact resistance, threshold voltage, subthreshold swing, on/off ratio, on-state current and transconductance13. The excellent electrical performance, stability and variability make antimony ([Formula: see text]) a promising contact technology for transition-metal-dichalcogenide-based electronics beyond silicon.

Photocatalytic conversion of CO to fuels with water by B-doped graphene/g-C3N4 heterostructure.

Photocatalytic reduction of carbon monoxide (CO) is a promising route to the production of high-value chemicals and fuels, as a supplement to high energy-input Fischer-Tropsch synthesis (FTS) and a key step in direct photo/electro-reduction CO2 to multi-carbon products. However, many current research efforts for high-efficiency FTS/CO2 reduction mainly focus on the metal-based catalysts, while metal-free and solar-driven photocatalysts are rarely explored. Here, by means of Lewis acid sites, a metal-free composite photocatalyst for CO reduction, namely boron (B) doped-graphene/g-C3N4 heterostructure, is proposed. First-principles calculations show that the dopants (B) as catalytic sites can effectively capture and activate CO molecules and reduce CO to CH3OH and CH4 in different doping content. It is worth noting that C2 products, i.e., C2H5OH, can be produced with low free energy barriers on para-doped graphene/g-C3N4. Meanwhile, the competitive hydrogen evolution reaction (HER) can be greatly suppressed, leading to the high selectivity of CO reduction. Moreover, the formation of a built-in electric field in heterostructure enhances the separation of photogenerated electrons and holes, which further accelerates the transmission of photogenerated electrons to the catalytic sites and improves the reaction efficiency. Overall, this work not only proposes a new strategy from a new perspective to solve problems of high energy consumption and low selectivity of FTS, but also provides a tandem strategy to solve problems of CO2 to multi-carbon products.

Exploitation of the Large-Area Basal Plane of MoS2 and Preparation of Bifunctional Catalysts through On-Surface Self-Assembly.

The development of nonprecious electrochemical catalysts for water splitting is a key step to achieve a sustainable energy supply for the future. Molybdenum disulfide (MoS2) has been extensively studied as a promising low-cost catalyst for hydrogen evolution reaction (HER), whereas HER is only catalyzed at the edge for pristine MoS2, leaving a large area of basal plane useless. Herein, on-surface self-assembly is demonstrated to be an effective, facile, and damage-free method to take full advantage of the large ratio surface of MoS2 for HER by using multiscale simulations. It is found that as supplement of edge sites of MoS2, on-MoS2 M(abt)2 (M = Ni, Co; abt = 2-aminobenzenethiolate) owns high HER activity, and the self-assembled M(abt)2 monolayers on MoS2 can be obtained through a simple liquid-deposition method. More importantly, on-surface self-assembly provides potential application for overall water splitting once the self-assembled systems prove to be of both HER and oxygen evolution reaction activities, for example, on-MoS2 Co(abt)2. This work opens up a new and promising avenue (on-surface self-assembly) toward the full exploitation of the basal plane of MoS2 for HER and the preparation of bifunctional catalysts for overall water splitting.

[Chemical constituents from roots of Ixeris chinensis].

Silica gel column chromatography and preparative HPLC were applied to isolate the chemical constituents from the roots of Ixeris chinensis. Fifteen compounds were isolated and their structures were elucidated by the physicochemical properties and spectral analysis as chinensioide G(1), chinensioide B(2), 10α-hydroxy-guaia-12,6-lactone-3-keton(3), chinensioide C(4), 10α-hydroxy-11ßH-guaia-4(5) -ene-12,6-lactone (5), 3ß, 10α-dihydroxy-11ßH-guaia-11 (13)-ene-12,6-lactone (6), 3ß, 10α-dihydroxy-4ßH, 11ßH-guaia-12,6-lactone(7), 3ß, 10α-dihydroxy-guaia-4 (15), 11 (13) -diene-12, 6-lactone (8), caffeic acid (9), p-hydorxyphenylacetic acid(10), methyl p-hydroxyphenylacetate (11), ethyl p-hydroxyphenylacetate (12), sitosterol (13), daucosterol (14), and ixerin D(15). Compound 1 was new, and 6 and 7 were isolated from I. chinensis for the first time.

[Chemical constituents from Euphorbia lunulata].

The chemical constituents from Euphorbia lunulata was investigated in this paper. Fourteen compounds were isolated and purified by column chromatographies on silica gel and preparative HPLC. Their structures were identified by physiochemical properties and NMR data analysis as lupeol (1), euphol (2), cassipourol(3) , 24-methylenecycloartan-3beta-ol (4), 24-hydroperoxycycloart-25-en-3beta-ol (5), 25-hydroperoxycycloart-23-en-3beta-ol (6), betulin (7), uvaol (8), (23E) -25-methoxycycloart-23-en-3beta-ol (9), (23E) -cycloart-23,25-dien-3beta-ol (10), 24-methylenecycloartan-3beta, 28-diol (11), salicinolide (12), 2alpha, 3beta, 5alpha, 9alpha, 15beta-pentaacetoxy-11,12-epoxy-7beta, 8alpha-diisobutyryloxyjatropha-6 (17) -en-14-one (13) and 3beta, 5alpha, 15beta-triacetoxy-7beta-isobutyryloxy-9alpha-nicotinoyloxyjatropha-6 (17), 11(E)-dien-14-one (14). Among them, compounds 1-11 were isolated from E. lunulata for the first time.

[Study on chemical constituents of Scutelliaria regeliana].

OBJECTIVE: To study the chemical constituents in ethyl acetate fraction from the root of Scutelliaria regeliana. METHOD: The compounds were isolated by silica gel column chromatography and HPLC, and their structures were elucidated by means of spectral analyses. RESULT: 23 compounds were isolated and identified. CONCLUSION: Compound 1 is new, named as scutellariae flavonol, and the others were isolated from S. regeliana for the first time.

[Study on chemical constituents of the Ixeris chinensis].

OBJECTIVE: To study the chemical constituents of the Ixeris chinensis . METHODS: The constituents were isolated by silica gel column chromatography, HPLC and recrystallization and their structures were elucidated on the basis of spectral analysis. RESULTS: Fifteen compounds were isolated and identified as Methyl-4-hydroxyphenylacetate (1), Daucosterol (2), Sitosterol (3), Luteolin-7-O-beta-D-glucoside (4), 15-hydroxy-2-oxoguaia-1 (10), 3,11 (13)-triene-12,6-lactone (5), Chinensiolide B (6), Chinensiolide E (7), Ixerochinoside (8), Chinensiolide C (9), 10alpha-hydroxy-guaia-4(15)-ene-12,6-lactone (10), 10alpha-hydroxy-guaia-4 (15), 11 (13)-diene-12,6-lactone-3beta-O-beta-D-(6'-p-hydroxyphenylacetyl) glucopyranoside (11), Epiloliolide (12), Apigenin-O-beta-D-glucopyranoside (13), Luteolin (14), Lutein (15). CONCLUSION: Compounds 1,10,11,12 and 15 are isolated from this plant for the first time.

[Studies on the chemical constituents of Pharbitis purpurea].

OBJECTIVE: To study the chemical constituents of Pharbitis purpurea. METHODS: The constituents were isolated by silica gel column chromatography, HPLC and recrystallization and their structures were elucidated on the basis of spectral analysis. RESULTS: Fourteen compounds were isolated and identified as daucosterol (1), umbelliferone (2), ursolic acid (3), N-p-hydroxy-cis-coumaroyltyramine (4), N-p-hydroxy-trans-coumaroyltyramine (5), N-cis-feruloyltyramine (6), N-trans-feruloyltyramine (7), (3R, 5R, 6S, 7E, 9S)-megastigman-5,6-epoxy-7-ene-3,9-diol (8), (6S,9R)-vomifoliol (9), (+)-syringaresinol (10), isovitexin (11), syringopicroside( 12), uricil (13), (6S,9R)-roseoside (14). CONCLUSION: Compounds 3, 8-2,14 are isolated from the genus for the first time.

[Study on the chemical constituents from fresh roots of Euphorbia fischeriana].

OBJECTIVE: To study the chemical constituents in ethyl acetate fraction from the Euphorbia fischeriana. METHODS: The compounds were isolated by silica gel column chromatography and HPLC, and their structures were elucidated by means of spectral analyses. RESULTS: Fourteen compounds were identified as 2,4-dihydroxy-6-methoxy-3-methylacetophenone (1), 12-deoxyphorbol-13-hexadecanoate (2), ethylgallate (3), esculetin (4), 2,4-dihydroxy-6-methoxy-acetophenone (5), 12-deoxyphorbol-13-acetate (6), 12-deoxyphorbol-13,20-diacetete (7), jolkinolide B (8), 17-hydroxyjolkinolide B (9), 17-hydroxy-jolkinolide A (10), langduin C (11), 3-methylp-hydroxybenzoic acid (12), methyl gallate (13), 3, 3'-diacetyl-pyridine-4,4'-dimethoxy-2, 2', 6, 6'-tetrahydroxydiphenylmethane (14). CONCLUSION: Compounds 3, 5, 12, 13 are isolated from this plant for the first time.

[Studies on chemical constituents of Astragalus dahuricus].

OBJECTIVE: To study the chemical constituents in Astragalus dahuricus. METHOD: The compounds were isolated and purified by column chromatography on silica gel and HPLC, and their structures were elucidated by their spectroscopic evidences. RESULT: Six compounds were identified as: 7, 2'-dihydroxy-3', 4'-dimethoxyisoflavan (1), 2'-hydroxy-3', 4'-dimethoxyisoflavan-7-O-beta-D-glucopyranoside (2), 8, 2'-dihydroxy-7, 4'-dimethoxyisoflavan (3), 7-hydroxy-4'-methoxyisoflavone (4), 7, 3'-dihydroxy-4'-metho-xyisoflavone (5), 9, 10-dimethoxypterocarpan-3-O-beta-D-glucopyranoside (6). CONCLUSION: Compounds 1-6 were obtained from this plant for the first time.

Bioactive guaianolides from siyekucai (Ixeris chinensis).

Two new guaianolides, named chinensiolides D (5) and E (6), were isolated from Ixeris chinensis Nakai, and their structures were determined to be 10alpha-hydroxy-3-oxoguaia-11(13)-eno-12,6alpha-lactone (5) and 10alpha-hydroxy-3beta-O-[2,6-di(p-hydroxyphenylacetyl)-beta-glucopylanosyl]guaia-4(15),11(13)-dieno-12,6alpha-lactone (6). The first isolation of (11S)-10alpha-hydroxy-3-oxoguaia-4-eno-12,6alpha-lactone (4) from natural sources and its characterization are also reported. Chinenciolide E (6) showed significant growth inhibitory activity toward VA-13 malignant lung tumor cells (IC50 = 0.72 microM).

Three new triterpenes from Nerium oleander and biological activity of the isolated compounds.

New ursane-type triterpene 1, oleanane-type triterpene 2, and dammarane-type triterpene 15 were isolated from the leaves of Nerium oleander together with 12 known triterpenes, 3beta-hydroxy-12-ursen-28-oic acid (ursolic acid, 3), 3beta,27-dihydroxy-12-ursen-28-oic acid (4), 3beta,13beta-dihydroxyurs-11-en-28-oic acid (5), 3beta-hydroxyurs-12-en-28-aldehyde (6), 28-norurs-12-en-3beta-ol (7), urs-12-en-3beta-ol (8), urs-12-ene-3beta,28-diol (9), 3beta-hydroxy-12-oleanen-28-oic acid (oleanolic acid, 10), 3beta,27-dihydroxy-12-oleanen-28-oic acid (11), 3beta-hydroxy-20(29)-lupen-28-oic acid (betulinic acid, 12), 20(29)-lupene-3beta,28-diol (betulin, 13), and (20S,24R)-epoxydammarane-3beta,25-diol (14). On the basis of their spectroscopic data, the structures of the new compounds 1, 2, and 15 were established as 3beta,20alpha-dihydroxyurs-21-en-28-oic acid, 3beta,12alpha-dihydroxyoleanan-28,13beta-olide, and (20S,24S)-epoxydammarane-3beta,25-diol, respectively. The anti-inflammatory activity of the seven isolated compounds and methyl esters of ursolic acid and oleanoic acid in vitro was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). The anticancer activity of the 14 isolated compounds, including 1, 2, 15, and methyl esters of ursolic acid and oleanolic acid in vitro was examined on the basis of the cell growth inhibitory activities toward three kinds of human cell lines.