Phenolic bisabolane sesquiterpenoids from a Thai mangrove endophytic fungus, Aspergillus sp. xy02.

Seven new phenolic bisabolane sesquiterpenoids, (7R,10S)-7,10-epoxysydonic acid (1), (7S,10S)-7,10-epoxysydonic acid (2), (7R,11S)-7,12-epoxysydonic acid (3), (7S,11S)-7,12-epoxysydonic acid (4), 7-deoxy-7,14-didehydro-12-hydroxysydonic acid (5), (Z)-7-deoxy-7,8-didehydro-12-hydroxysydonic acid (6), and (E)-7-deoxy-7,8-didehydro-12-hydroxysydonic acid (7), along with five known analogues (8-12), were obtained from the culture of an endophytic fungus Aspergillus sp. xy02 isolated from the leaves of a Thai mangrove Xylocarpus moluccensis. All structures were assigned on the basis of detailed spectroscopic analyses. The absolute configurations of 1-4, being two pairs of epimers, were established by TDDFT-ECD calculations. Compound 12 showed mild antioxidative activity to scavenge DPPH radical with an IC50 of 72.1 µM, whereas 2, 3, 5, 7, 9, 11, and 12 displayed moderate inhibitory activities against Staphylococcus aureus ATCC 25923 with IC50 values ranging from 31.5 to 41.9 µM.

Bysspectin A, an unusual octaketide dimer and the precursor derivatives from the endophytic fungus Byssochlamys spectabilis IMM0002 and their biological activities.

Bysspectin A (1), a polyketide-derived octaketide dimer with a novel carbon skeleton, and two new precursor derivatives, bysspectins B and C (2 and 3), were obtained from an organic extract of the endophytic fungus Byssochlamys spectabilis that had been isolated from a leaf tissue of the traditional Chinese medicinal plant Edgeworthia chrysantha, together with a known octaketide, paecilocin A (4). Their structures were determined by HRMS, 1D and 2D NMR spectroscopic analysis. A plausible route for their biosynthetic pathway is proposed. Compounds 1-3 were tested for their antimicrobial activities. Only compound 3 was weakly active against Escherichia coli and Staphyloccocus aureus with MIC values of 32 and 64 µg/mL, respectively. Further, the inhibitory effects on human carboxylesterases (hCE1, hCE2) of compounds 1 and 4 were evaluated. The results demonstrated that bysspectin A (1) was a novel and highly selective inhibitor against hCE2 with the IC50 value of 2.01 µM. Docking simulation also demonstrated that active compound 1 created interaction with the Ser-288 (the catalytic amino-acid in the catalytic cavity) of hCE2 via hydrogen bonding, revealing its highly selective inhibition toward hCE2.

[Enzymatic glycosylation of 4'-demethylepipodophyllotoxin].

The glycosides of 4'-demethylepipodophyllotoxin (DMEP) possess various pharmacological activities; however, the chemical synthesis of these glycosides faces challenges in regioselectivity, stereoselectivity, and the protection and de-protection of functional groups. In this work, a novel glycosyltransferase (GT) gene AbGT5 from Aloe barbadensis was successfully cloned, heterogeneously expressed and purified. Recombinant AbGT5 was able to catalyze the glycosylation of DMEP and the glycosylated product, which was separated from the preparative scale reaction, was characterized as DMEP 4'-O-ß-D-glucoside via MS, 1H-NMR, 13C-NMR, HSQC and HMBC. According to the investigations of enzyme properties, AbGT5 show the highest activity around 20 ℃ in the buffer of pH 9.0, and it was independent of divalent metal ions. Under the optimum conditions, the conversion rate of DMEP can reach 80%. Above all, in this work the enzymatic glycosylation of DMEP was achieved with high efficiency by the novel GT AbGT5.

[Cloning,expression and functional identification of secoisolariciresinol dehydrogenase gene from Dysosma versipellis callus].

Secoisolariciresinol dehydrogenase (SDH) is a key enzyme involved in the biosynthetic pathway of podophyllotoxin.In this study, two SDH candidate genes,SO282 and SO1223, were cloned from callus of Dysosma versipellis by homology-based PCR and rapid amplification of cDNA end (RACE).The SDH candidate genes were expressed in Escherichia coli and the subsequent enzyme assay in vitro showed that recombinant SO282 had the SDH activity. These results pave the way to the follow-up investigation of the biosynthetic of podophyllotoxin.

[Flavonoid glycosides from callus cultures of Dysosma versipellis].

Various chromatographic techniques, including silica gel column chromatography, Sephadex LH-20, preparative thin-layer chromatography, and preparative HPLC, were employed to isolate the chemical constituents from callus cultures of Dysosma versipellis. Structures of the compounds were elucidated based on UV, IR, MS and NMR spectroscopic data analysis. Totally, seven flavonoid glycosides were isolated from the 95% ethanol extract of the callus cultures and identified as kaempferol-3-O-[6″-(3″'-methoxy)-malonyl]-ß-D-glucopyranoside(1), kaempferol-3-O-(6″-O-acetyl)-ß-D-glucopyranoside(2), kaempferide-3-O-ß-D-glucopyranoside(3), kaempferol-3-O-ß-D-glucopyranoside(4), isoquercitrin(5), quercetin-4'-O-ß-D-glucopyranoside(6) and kaempferol-3-(6″-malonyl)-ß-D-glucopyranoside(7), respectively.All these compounds were isolated from callus cultures of D. versipellis for the first time.Compounds 1, 2, 3, 6 and 7 were firstly obtained from plant materials of D. versipellis, and compound 1 was a new compound.

[A new lactone derivative from plant endophytic fungus Periconia sp. F-31].

To investigate the secondary metabolites of endophytic fungi Pericinia sp. F-31. Column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC were used to separate and purify the compounds. Two compounds were isolated from the fermentation broth of Periconia sp. Their structures were identified as 5-(1-hydroxyhexyl) -6-methyl-2H-pyran-2-one (1) and 2-(3-hydroxy-4-methylphenyl) -propanoic acid (2). Compound 1 was a new lactone compound, compound 2 was new natural product, and the NMR data of compound 2 was reported for the first time.

New 2-arylbenzofuran metabolite from cell cultures of Morus alba.

A new 2-arylbenzofuran compound, 5-dehydroxy-moracin U (1), along with 10 known compounds (2-11), were isolated from cell cultures of Morus alba. Their structures were elucidated on the basis of extensive spectroscopic analyses. The anti-inflammatory activity assay of 1-8 showed that 2 and 8 exhibited significant inhibitory effect on LPS-induced NO production with the values of 76.4% and 98.7% at 10(- 5) M, respectively.

[Microbial transformation of glycyrrhetinic acid by Cunninghamella blakesleeana].

A study on the microbial transformation of glycyrrhetinic acid (GA) was conducted by a fungus, Cunninghamella blakesleeana CGMCC 3.970 systematically. After incubation with the cell cultures of C. blakesleeana CGMCC 3.970 at 25 degrees C for 7 days on a rotary shaker operating at 135 r x min(-1), GA was converted into one major product and five minor products. The products were extracted and purified by solvent extraction, macroporous adsorbent resin, silica gel column chromatography, and semi-preparative RP-HPLC chromatography. Their structures were identified as 3-oxo-15α-hydroxy-18ß-glycyrrhetinic acid(1), 3-oxo-15ß-hydroxy-18ß-glycyrrhetinic acid (2), 7ß,15α-dihydroxy-18ß-glycyrrhetinic acid (3), 3-oxo-7ß, 15α-dihydroxy-18ß-glycyrrhetinic acid (4), 7ß-hydroxy-18ß-glycyrrhetinic acid(5) and 15α-hydroxy-18ß-glycyrrhetinic acid(6) by the analyses of MS, 1H-NMR and 13C-NMR spectroscopic data respectively. Among them, 2 was a new compound. These results suggest that C. blakesleeana CGMCC 3.970 has the capability of selective ketonization and hydroxylation for GA. [Key words] glycyrrhetinic acid; Cunninghamella blakesleeana CGMCC 3. 970; microbial transformation

[Sulfation of naringenin by Mucor sp].

Naringenin (1) was transformed to three metabolites (2-4) by Mucor sp. Based on LCMS(n)-IT-TOF and NMR spectroscopic data, 2-4 were identified as naringenin-7-O-sulphate, naringenin-4'-O-sulphate, and naringenin-5-O-sulphate, respectively. These results might provide hints to the mammalian/human metabolism of naringenin.

[Regulation of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid biosynthesis in cell suspension cultures of Saussurea involucrata].

Syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid are three main bioactive ingredients in herbs of Saussurea involucrata with various pharmacological properties, while their contents are very low. In this study, the biosynthesis of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid in the cell suspension cultures of S. involucrata were regulated by feeding carbon sources and precursors, which resulted in a great increase of the contents and yields of the above three bioactive ingredients. After 16 days of fermentation, the yields of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid reached 339.0, 225.3, 512.7 mg x L(-1), respectively. Meanwhile, their contents increased up to 67.9, 1.9, 10.6 times of wild medicinal material, respectively. The results provided a solid basis for further studies on application of cell suspension cultures of S. involucrata for large-scale production of bioactive compounds syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid.

[Diversity and in vitro antitumnor activity of endophytic fungi from mangrove plants Xylocarpus].

A total of 24 biologically pure entophytic fungal strains were isolated from stems, leaves, and seed coats of Xylocarpus plants by repeated purification, and identified with Internal Transcribed Spacer (ITS) rDNA molecular method, which belonging to 14 genera, 11 families, 9 orders and 3 classes. There were differences in genus and species levels among three plant materials from different habitats and species, and it was found that the strains of Phomopsis and Colletotrichum existed in all three plant materials. In vitro assay of antitumor activity by MTT method revealed that the EtOAc extracts of 15 strains exhibited potent antitumor activity. These results suggest that it is of value for further investigation on the above fungal strains.

Two new sesquiterpene derivatives from Chinese eaglewood.

Two new sesquiterpene derivatives, (+)-8ß-hydroxy-longicamphenylone (1) and 11ß-hydroxy-13-isopropyl-dihydrodehydrocostus lactone (2), were isolated from Chinese eaglewood. Their structures were elucidated on the basis of spectroscopic analyses including HR-ESI-MS, (1)H and (13)C NMR, DEPT, (1)H-(1)H COSY, HSQC, HMBC, and NOE. The two compounds exhibited potent anti-depressant activity in vitro by inhibiting [(3)H]-5-HT reuptake in rat brain synaptosomes by 54.8% and 51.9%, respectively, at 10 µM.

[Chemical constituents from cell suspension cultures of Cudrania tricuspidata].

Ten compounds were isolated and purified from cell suspension cultures of Cudrania tricuspidata with silica-gel column chromatography, semi-preparative HPLC and Sephadex LH-20. On the base of their physicochemical properties and spectral data, their structures were identified as 1, 3, 5-trihydroxy4-(3, 3-dimethylallyl) xanthone (1), wighteone (2), 6-prenylapigenin (3), licoflavone C(4), cudraflavanone C(5), erythrivarone A (6), derrone (7), carthamidin (8), genistein (9) and aromadendrin (10). Among them, compounds 2-10 were flavonoids, and compound 1 was a xanthone which was isolated from the plant for the first time.

[Chemical constituents from cell cultures of Morus alba].

The column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC were used to separate and purify the compounds from the EtOAc extract of medium and MeOH extract of cell cultures of Morus alba. Eight compounds were isolated. Based on physico-chemical properties and spectroscopic data, their structures were identified as isobavachalcone (1), genistein (2), norartocarpetin (3), albanin A (4), guangsangon E (5), mulberrofuran F (6), chalcomoracin (7), kuwanon J (8). Compounds 3-6 were isolated from the cell cultures of M. alba for the first time.

Microbial transformation of asiatic acid by Alternaria longipes.

Asiatic acid is a major pentacyclic triterpene isolated from Centella asiatica. It shows a variety of bioactivities. In order to obtain its derivatives, potentially useful for detailed pharmacological studies, the substrate was subjected to incubations with selected micro-organisms. In this work, asiatic acid was converted into three new compounds: 2α,3ß,23,30-tetrahydroxyurs-12-ene-28-oic acid (1), 2α,3ß,22ß,23-tetrahydroxyurs-12-ene-28-oic acid (2), and 2α,3ß,22ß,23,30-pentahydroxyurs-12-ene-28-oic acid (3) by the fungus Alternaria longipes AS 3.2875. The structures of the three metabolites were determined by 1D and 2D NMR spectral data.

[Isolation and analysis of syringin in cell suspension cultures of Saussurea involucrata].

Syringin is one of the main bioactive ingredients in Saussurea involucrata. In this study, various chromatographic techniques were employed to isolate and purify syringin in the polar extraction of cell suspension cultures of S. involucrata. The structure of syringin was characterized by the analysis of spectroscopic data. A quantitative analytical method for the content of syringin in cultures of S. involucrata was established with RP-HPLC. The method is convenient, accurate and reliable. All this results provided a basis for further studies on application of cell suspension cultures of S. involucrata for large-scale production of bioactive compound syringin.

Biotransformation of 6beta-santonin by Phytolacca acinosa cell suspension cultures.

AIM: To obtain more valuable derivatives for the further structural modification of 6beta-santonin (1) via biotransformation by using cell suspension cultures of Phytolacca acinosa. METHODS: The substrate 1 was incubated with cell suspension cultures of P. acinosa, the products were obtained by chromatography, and identified on the basis of their physical and spectral data (HRMS, 1D NMR, 2D NMR, NOE and IR). RESULTS: After incubation with cell suspension cultures of P. acinosa, 1 was converted into five products. Among them, 3 is a new compound. CONCLUSION: 6beta-santonin could be selectively reduced and hydroxylated by the cell suspension cultures of P. acinosa, which would provide valuable intermediates for its further structural modification.

[Microbial transformation of sinenxan A, a rich constituent in callus cultures of Taxus].

AIM: To study the microbial transformation of sinenxan A. METHODS: Choose two strains of Fungi (Mucor spinosus AS 3.3450 and Cunninghamella echinulata AS 3.3400) and a strain of bacterium (Proteus vulgaris AS 1.1208) to transform the substrate. RESULTS: Three products were obtained and identified as 10-deacetylsinenxan A1, 6 alpha-hydroxy-10-deacetylsinenxan A2 and 9 alpha-hydroxy-10-deacetylsinenxan A3 respectively. CONCLUSION: Sinenxan A is facile to be transformed by microorganisms, the 10-acetyl group of which is an active group.

Biotransformation of 4(20),11-taxadienes by cell suspension cultures of Platycodon grandiflorum.

Platycodon grandiflorum cell suspension cultures were employed to biotransform the taxane diterpenoids 2alpha,5alpha,10beta,14beta-tetraacetoxy-4(20),11-taxadiene (1) and 9alpha-hydroxy-2alpha,5alpha,10beta,14beta-tetraacetoxy-4(20),11-taxadiene (2). One product, 10beta-hydroxy-2alpha,5alpha,14beta-triacetoxy-4(20),11-taxadiene (3) was obtained from 1 and two products, 9alpha,10beta-dihydroxy-2alpha,5alpha,14beta-triacetoxy-4(20),11-taxadiene (4) and 10beta-hydroxy-2alpha,5alpha,9alpha,14beta-tetraacetoxy-4(20),11-taxadiene (5) were obtained from 2 incubated with Platycodon cultured cells respectively, among which 5 is characterized as a new taxoid compound. The effects of the addition stage for 1 and 2 on the biotransformation were investigated and the results revealed that: (1) the optimal addition stage for 1 was in the early logarithmic phase (6th day) of the cell growth period, in which 78% of 1 was converted and the yield for 3 reached 75%; (2) the optimal addition stage for 2 was on the mid-logarithmic phase (12th day) of the cell growth period, in which 25.3% of 2 was converted and the yields for 4 and 5 reached 18.9 and 14.5%, respectively.