海绵Polymastia Sobustia的化学成分研究

首次报道从中国南海海绵Polymas tia sobustia中分离得到5个纯化合物,经过MS,IR,1H NMR,13C NMR (DEPT),HMQC和HMBC等波谱技术鉴定为：豆甾-5-烯-7-羰基-3β-甾醇(1 ),N-(1-羟甲基-2,6-二羟基)十七烷基-5-羟基二十四脂肪酰胺([ ST5”HZ 2),胸腺嘧啶(3),尿嘧啶(4[ ST5”BZ ),对羟基苯甲酸(5);其中化合物1和化合 物2为新化合物。     

Xanthine oxidase inhibiting flavonol glycoside from Amberboa ramosa

A new flavonol glycoside (1) has been isolated from the ethyl acetate soluble fraction of Amberboa ramosa and assigned the structure 5,7,4'-trihydroxy-3,8-dimethoxylflavone 5-O-beta-D-gluco-pyranoside (1). In addition, 6,4'-dihydroxy-3,5,7-trimethoxyflavone (2), 5,7-dihydroxy-4'-methoxyflavone (3) and (23R)-5alpha-cycloart-24-ene-3beta,21,23-triol (4) have also been reported for the first time from this species. The structures were deduced on the basis of 1D and 2D NMR techniques. The compounds 1-3 displayed weak to moderate inhibition against the xanthine oxidase enzyme.     

Tyrosinase inhibitors from Rhododendron collettianum and their structure-activity relationship (SAR) studies

A new coumarinolignoid 8'-epi-cleomiscosin A (1) together with the new glycoside 8-O-beta-D-glucopyranosyl-6-hydroxy-2-methyl-4H-1-benzopyrane-4-one (2) have been isolated from the aerial parts of Rhododendron collettianum and their structures determined on the basis of spectroscopic evidences. Tyrosinase inhibition study of these compounds and their structure-activity relationship (SAR) were also investigated. The compounds exhibited potent to mild inhibition activity against the enzyme. Especially, the compound 1 showed strong inhibition (IC50=1.33 microM) against the enzyme tyrosinase, as compared to the standard tyrosinase inhibitors kojic acid (IC50=16.67 microM) and L-mimosine (IC50=3.68 microM), indicating its potential used for the treatment of hyperpigmentation associated with the high production of melanocytes.     

海绵Polymastia Sobustia的化学成份研究

首次报道从中国南海海绵Polymastiasobustia中分离得到5个纯化合物,经过MS,IR,1^HNMR,13^CNMR(DEPT),HMQC和HMBC等波谱技术鉴定为：豆甾-5-烯-7-羰基-3β-甾醇(1),N-(1-羟甲基-2,6-二羟基)十七烷基-5-羟基二十四脂肪酰胺(2),胸腺嘧啶(3),尿嘧啶(4),对羟基苯甲酸(5);其中化合物1和化合物2为新化合物。     

A new type of stilbene-related secondary metabolite, idenburgene, from Cryptocarya idenburgensis

A new type of natural product, idenburgene (1), was isolated from Crytocarya idenburgensis, and its unique structure was elucidated. Four known compounds, 3-hydroxy-5-methoxystilbene (2), 2',6'-dihydroxy-4'-methoxydihydrochalcone (3), stigmast-4-ene-3-one, and beta-sitosterol were also isolated and identified.     

Chemical constituents and biological studies of the leaves of Grevillea robusta

Three new compounds: Graviquinone (1), cis-3-hydroxy-5-pentadecylcyclohexanone (2), and methyl 5-ethoxy-2-hydroxycinnamate (3), and thirty-eight known compounds were isolated and identified from the leaves of Grevillea robusta. The structures of these compounds were determined by spectroscopic and chemical transformation methods. Graviquinone (1) showed the strongest cytotoxicity against MCF-7, NCI-H460, and SF-268 cell lines. Methyl 2,5-dihydroxycinnamate (4), graviphane (13), and dehydrograviphane (14) exhibited very potent DPPH scavenging activity compared with α-tocopherol. Methyl 2,5-dihydroxycinnamate (4) and bis-norstriatol (17) demonstrated strong inhibition of L-DOPA oxidation by mushroom tyrosinase compared with kojic acid.     

Tyrosinase inhibitory potential of natural products isolated from various medicinal plants

Seven secondary metabolites, p-hydroxybenzoic acid (1), 3,4-dihydroxybenzoic acid (2), ferulic acid (3), 2,6-dimethoxy-4-hydroxy acetophenone (4), lupeol (5), 2'-O-ethylmurrangatin (6) and hibiscetin heptamethyl ether (7) were the natural products isolated from various medicinal plants. Their structures were identified by spectral comparison with previously reported data. The compounds 1-7 were screened for their tyrosinase-inhibitory activity. The compound p-hydroxybenzoic acid (1) was found to have potent activity against tyrosinase enzyme, whereas lupeol (5) showed significant activity.     

Antimutagenic constituents from the thorns of Gleditsia sinensis

Antimutagenic activity-guided fractionation of an extract prepared from the thorns of Gleditsia sinensis LAM. led to the isolation of one triterpenoid and four steroids, which were identified as D:C-friedours-7-en-3-one (1), stigmast-4-ene-3,6-dione (2), stigmastane-3,6-dione (3), stigmasterol (4), and beta-sitosterol (5). Triterpenoid 1 was found for the first time in a natural source and the steroids 2-5 were first isolated from this plant. Stigmasterol was the most active antimutagen, showing 51.2% and 64.2% reduction of the induction factor against the mutagens MNNG and NQO, respectively, in the SOS chromotest. Some NMR data of the steroids 2 and 3 obtained have to be revised.     

Complete 1H and 13C NMR assignments of two phytosterols from roots of Piper nigrum

Using modern NMR techniques, including DQF-COSY, NOESY, HETCOR and HMBC, the full assignments of all 1H and 13C chemical shifts were made for stigmastane-3,6-dione and stigmast-4-ene-3,6-dione, isolated from the roots of Piper nigrum (Piperaceae). Their stereochemistry was resolved by a combination of 2D NOESY data and analysis of coupling constants. The two compounds were isolated from the genus Piper for the first time.     

Constituents of the Heartwood of Diospyros Eriantha

The isolation and identification of fifteen compounds from the heartwood of Diospyros eriantha are described. Their structures were determined on the basis of spectral evidence and/or comparison with authentic samples. These compounds include three steroids (stigmast-4-en-3-one, stigmast-4-ene-3,6-dione, and 3β-hydroxystigmast-5-en-7-one), seven triterpenoids (friedelin, lupeol, betulinaldehyde, 3β-acetoxyurs-11-en-13,28-olide, 3β-acetoxyoleanolic acid, betulin, and betulinic acid), three quinones (2-ethoxy-7-methyljuglone, 3-ethoxy-7-methyljuglone, and 2,6-dimethoxy-1,4-benzoquinone), and two phenols (3,4,5-trimethoxyphenol, and syringic acid).     

Discovery of a series of pyridopyrimidine derivatives as potential topoisomerase Ⅰ inhibitors

A series of new 3-benzoheterocyclic substituted pyridopyrimidines were designed and synthesized.Structures of the compounds were determined by IR,1H NMR, and elemental analyses. The antiproliferation activity of 13 novel compounds was evaluated in A549, HL-60, BGC-823 and SMMC-7721cell lines. Compounds 3, 5, 7, 8, 9, 10 showed potent inhibitory activity against the four tested cancer cell lines. These six compounds were examined for Top I inhibition at 100 mmol/L by measuring the relaxation of supercoiled DNA in plasmid pBR322. Most of the tested compounds inhibited the enzyme at this concentration. The most potent compound 9 was as potent as camptothecin.     

Biotransformation of (+)-androst-4-ene-3,17-dione

Fermentation of (+)-androst-4-ene-3,17-dione (1) with Curvularia lunata for 10 days yielded five oxidative and reductive metabolites, androsta-1,4-diene-3,17-dione (2), 17beta-hydroxyandrosta-1,4-dien-3-one (3), 11alpha-hydroxyandrost-4-ene-3,17-dione (4), 11alpha,17beta-dihydroxyandrost-4-en-3-one (5) and 15alpha-hydroxyandrosta-1,4-dien-17-one (6). The structures of these metabolites were elucidated on the basis of spectroscopic techniques. These microbially transformed products were assayed against the clinically important enzymes, tyrosinase and prolyl endopeptidase.     

Microwave-assisted synthesis and biological evaluation of new thiazolylhydrazone derivatives as tyrosinase inhibitors and antioxidants

In this work, we have synthesized a series of 2-thiazolylhydrazone derivatives ( 1–27 ) and investigated their biological activities as tyrosinase inhibitors and antioxidants. Some compounds showed potent tyrosinase inhibitory activities and 4-(2-(2-(1-(4-Aminophenyl)ethylidene)-hydrazinyl)thiazol-4-yl) phenol ( 26 ) showed more potent inhibitory effect than the standard tyrosinase inhibitor kojic acid (IC₅₀: 9.8 μM vs. 23.6 μM). Compounds 2 , 14 , and 26 exhibited high antioxidant activities in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The structure–activity relationship (SAR) indicated that the substitutions of bromine, hydroxyl group, and amino groups cause great effect to the inhibition effect against tyrosinase. The mechanism and kinetic studies demonstrated that the inhibitory effect of compound 26 on the tyrosinase by acting as the reversible and uncompetitive inhibitor. Docking studies suggests that compound 26 interacts strongly with mushroom tyrosinase via hydrogen bonding.     

Neuroprotective Activities of Boophone haemanthoides (Amaryllidaceae) Extract and Its Chemical Constituents

Parkinson’s disease (PD) is a neurodegenerative condition that progresses as age increases, and some of its major symptoms include tremor and postural and movement-related difficulties. To date, the treatment of PD remains a challenge because available drugs only treat the symptoms of the disease or possess serious side effects. In light of this, new treatment options are needed; hence, this study investigates the neuroprotective effects of an organic Boophone haemanthoides extract (BHE) and its bioactive compounds using an in vitro model of PD involving the toxin 1-methyl-4-phenylpyridinium (MPP⁺) and SH-SY5Y neuroblastoma cells. A total of seven compounds were isolated from BHE, viz distichamine (1), 1α,3α-diacetylnerbowdine (2), hippadine (3), stigmast-4-ene-3,6-dione (4), cholest-4-en-3-one (5), tyrosol (6), and 3-hydroxy-1-(4′-hydroxyphenyl)-1-propanone (7). Six compounds (1, 2, 4, 5, 6 and 7) were investigated, and five showed neuroprotection alongside the BHE. This study gives insight into the bioactivity of the non-alkaloidal constituents of Amaryllidaceae, since the isolated compounds and the BHE showed improved cell viability, increased ATP generation in the cells as well as inhibition of MPP⁺-induced apoptosis. Together, these findings support the claim that the Amaryllidaceae plant family could be a potential reserve of bioactive compounds for the discovery of neuroprotective agents.     

匐枝马尾藻的化学成分研究

首次报道从中国北海匐枝马尾藻Sargassum polycystcum分离得到3个纯化合物 ，经过MS，IR，~1H NMR，~(13)C NMR（DEPT），HMQC和HMBC等波谱技术鉴定为： 豆甾-3β-羟基-5，23，25-三烯(1)，3-二下五烷氧基-1，2-丙二醇(2)，24ξ-甲 基胆甾-3β，5α，6β，25-四醇-25-乙酸酯(3)，其中化合物1为新化合物。     

Novel Anti-Melanogenic Compounds, (Z)-5-(Substituted Benzylidene)-4-thioxothiazolidin-2-one Derivatives: In Vitro and In Silico Insights

To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC₅₀ = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors.     

Synthesis and Preliminary In Vitro Biological Evaluation of 5-Chloro-2-(Substituted Phenyl)Benzo[d]Thiazole Derivatives Designed As Novel Antimelanogenesis Agents

We describe the design, synthesis, and biological activities of 5-chloro-2-(substituted phenyl)benzo[d]thiazole derivatives as novel tyrosinase inhibitors. Among them, 4-(5-chloro-2,3-dihydrobenzo[d]thiazol-2-yl)-2,6-dimethoxyphenol (MHY884) and 2-bromo-4-(5-chloro-benzo[d]thiazol-2-yl)phenol (MHY966) showed inhibitory activity higher than or similar to kojic acid, against mushroom tyrosinase. Therefore, we carried out kinetic studies on the two compounds with potent tyrosinase inhibitory effects. Kinetic analysis of tyrosinase inhibition revealed that all of these compounds are competitive inhibitors. MHY884 and MHY966 effectively inhibited tyrosinase activity and reduced melanin levels in B16 cells treated with ??-melanocyte stimulating hormone (??-MSH). These data strongly suggest that the newly synthesized compounds MHY884 and MHY966 could suppress production of melanin via inhibition of tyrosinase activity.     

α-Glucosidase inhibitory constituents from Acanthopanax senticosus harm leaves

A new triterpene glycoside, 3-O-[(α-L-rhamnopyranosyl)(1→2)]-[β-D-glucuronopyranosyl-6-O-methyl ester]-olean-12-ene-28-olic acid (1) and a new indole alkaloid, 5-methoxy-2-oxoindolin-3-acetic acid methyl ester (5) were isolated from the leaves of Acanthopanax senticosus Harms along with six known compounds. The structures of the new compounds were determined by means of 2D-NMR experiments and chemical methods. All the isolated compounds were evaluated for their glycosidase inhibition activities and compound 6 showed significant α-glucosidase inhibition activity.     

Three New Isoprenylated Flavones from Artocarpus chama Stem and Their Bioactivities

Phytochemical investigation of Artocarpus chama stem was performed by chromatographic techniques, resulting from the isolation and structure elucidation of three new compounds, namely 3′-farnesyl-apigenin (1), 3-(hydroxyprenyl) isoetin (2), and 3-prenyl-5,7,2′,5′-tetrahydroxy-4′-methoxyflavone (3), and five known compounds, namely homoeriodictyol (4), isocycloartobilo-xanthone (5), artocarpanone (6), naringenin (7), and artocarpin (8). From the screening result, A. chama extract showed a potent tyrosinase inhibitory effect. Ihe isolated compounds 1, 4 and 6 also exhibited tyrosinase inhibition with IC₅₀ of 135.70, 52.18, and 38.78 µg/mL, respectively. Moreover, compounds 3, 4, 5, 6, and 8 showed strong activity against Staphylococcus epidermidis, S. aureus, methicillin-resistant S. aureus, and Cutibacterium acnes. This study is the first report on phytochemical investigation with new compounds and biological activities of A. chama. Skin infection can cause dark spots or hyperpigmentation. The isolated compounds that showed both anityrosinase and antimicrobial activities will be further studied in in vivo and clinical trials in order to develop treatment for hyperpigmentation, which is caused by infectious diseases by microorganisms.     

New labdane diterpenes from Solidago canadensis

The ethanol extract of roots of Solidago canadensis yielded eight labdane-type diterpenes. Five of those were new natural compounds (9,13,15,16-bisepoxy-labdane-7-ene-6,15-dione (3a), 13-epi-9,13,15,16-bisepoxy-labdane-7-ene-6,15-dione (3b), 15,16-epoxy-labdane-7,13-diene-6,16-dione (5), 15-ethoxy-9,13,15,16-bisepoxy-labdane-7-ene-6-one (6a) and 13-epi-15-ethoxy-9,13,15,16-bisepoxy-labdane-7-ene-6-one (6b). The known labdane diterpenes deoxysolidagenone (1), solidagenone (2) and 15,16-epoxy-labdane-7,13-diene-6,15-dione (4) were also isolated. Chemical structures were determined using 1D and 2D NMR techniques and MS analysis.