Advances in the biosynthesis of cyclodipeptide type natural products derived from actinomycetes / 生物工程学报

Cyclodipeptide (CDP) composed of two amino acids is the simplest cyclic peptide. These two amino acids form a typical diketopiperazine (DKP) ring by linking each other with peptide bonds. This characteristic stable ring skeleton is the foundation of CDP to display extensive and excellent bioactivities, which is beneficial for CDPs' pharmaceutical research and development. The natural CDP products are well isolated from actinomycetes. These bacteria can synthesize DKP backbones with nonribosomal peptide synthetase (NRPS) or cyclodipeptide synthase (CDPS). Moreover, actinomycetes could produce a variety of CDPs through different enzymatic modification. The presence of these abundant and diversified catalysis indicates that actinomycetes are promising microbial resource for exploring CDPs. This review summarized the pathways for DKP backbones biosynthesis and their post-modification mechanism in actinomycetes. The aim of this review was to accelerate the genome mining of CDPs and their isolation, purification and structure identification, and to facilitate revealing the biosynthesis mechanism of novel CDPs as well as their synthetic biology design.

Antibacterial sorbicillin and diketopiperazines from the endogenous fungus Penicillium sp. GD6 associated Chinese mangrove Bruguiera gymnorrhiza / 中国天然药物

One new sorbicillin derivative, 2-deoxy-sohirnone C (1), one new diketopiperazine alkaloid, 5S-hydroxynorvaline-S-Ile (2), and two naturally occurring diketopiperazines, 3S-hydroxylcyclo(S-Pro-S-Phe) (3) and cyclo(S-Phe-S-Gln) (4), together with three known compounds were isolated from the Chinese mangrove endophytic fungus Penicillium sp. GD6. Their structures were determined on the basis of extensive spectroscopic analyses and by comparison with literature data. The absolute configuration of 3-hydroxyl moiety in 3 was determined by Mosher's method, while the absolute stereochemistry of 2 and 4 was established by comparison with the CD spectra of natural and synthesized diketopiperazines. Compound 1 showed moderate antibacterial activity against Methicillin-resistant Staphylococcus aureus with a MIC value of 80 μg·mL.

Antibacterial sorbicillin and diketopiperazines from the endogenous fungus Penicillium sp. GD6 associated Chinese mangrove Bruguiera gymnorrhiza / 中国天然药物

One new sorbicillin derivative, 2-deoxy-sohirnone C (1), one new diketopiperazine alkaloid, 5S-hydroxynorvaline-S-Ile (2), and two naturally occurring diketopiperazines, 3S-hydroxylcyclo(S-Pro-S-Phe) (3) and cyclo(S-Phe-S-Gln) (4), together with three known compounds were isolated from the Chinese mangrove endophytic fungus Penicillium sp. GD6. Their structures were determined on the basis of extensive spectroscopic analyses and by comparison with literature data. The absolute configuration of 3-hydroxyl moiety in 3 was determined by Mosher's method, while the absolute stereochemistry of 2 and 4 was established by comparison with the CD spectra of natural and synthesized diketopiperazines. Compound 1 showed moderate antibacterial activity against Methicillin-resistant Staphylococcus aureus with a MIC value of 80 μg·mL.

Escherichia coli GutM4 produces 2, 5-diketopiperazines and inhibits human pathogens in vitro

Background: It has been a very common practice to use probiotics or their metabolites as alternative antimicrobial strategies for the treatment and prevention of infections as rampant and indiscriminate use of antibiotics causes the development of antibiotic-resistant pathogens. The objective of this study was to select a potential antimicrobial probiotic strain of Escherichia coli from the human gastrointestinal tract and investigate the production of diketopiperazines that contribute to the antimicrobial activity. Results: E. coli GutM4 was isolated from the feces of a healthy adult. E. coli GutM4 showed significant antagonistic activity against 10 indicator pathogens, and this activity was no less than that of the reference strain E. coli Nissle 1917 against eight of the indicator pathogens. Moreover, E. coli GutM4 produced antagonistic substances containing trypsin-targeted peptide bonds because the inhibitory effects of E. coli GutM4 supernatant significantly decreased upon treatment with trypsin. Consistent with the antagonistic activity and peptide compounds of E. coli GutM4, 14 2,5-diketopiperazines were isolated from the fermented broth of E. coli GutM4, including 12 cyclo(Pro-Phe), 3 cyclo(Pro-Tyr), and 5 cyclo(4-hydroxyl-Pro-Leu), which are reported to have antipathogenic activity. Conclusion: E. coli GutM4 produces 2,5-diketopiperazines that are partly involved in antagonistic action against human pathogens in vitro.

Effect of Ursolic Acid on Breast Cancer Resistance Protein-mediated Transport of Rosuvastatin In Vivo and Vitro / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate whether ursolic acid can inhibit breast cancer resistance protein (BCRP)-mediated transport of rosuvastatin in vivo and in vitro.</p><p><b>METHODS</b>Firstly, we explored the pharmacokinetics of 5-fluorouracil (5-FU, a substrate of BCRP) in rats in the presence or absence of ursolic acid. Secondly, we studied the pharmacokinetics of rosuvastatin in rats in the presence or absence of ursolic acid or Ko143 (inhibitor of BCRP). Finially, the concentration-dependent transport of rosuvastatin and the inhibitory effects of ursolic acid and Ko143 were examined in Madin-Darby Canine Kidney (MDCK) 2-BCRP421CC (wild type) cells and MDCK2-BCRP421AA (mutant type) cells.</p><p><b>RESULTS</b>As a result, significant changes in pharmacokinetics parameters of 5-FU were observed in rats following pretreatment with ursolic acid. Both ursolic acid and Ko143 could significantly affect the pharmacokinetics of rosuvastatin. The rosuvastatin transport in the BCRP overexpressing system was increased in a concentration-dependent manner. However, there was no statistical difference in BCRP-mediated transport of rosuvastatin betweent the wild type cells and mutant cells. The same as Ko143, ursolic acid inhibited BCRP-mediated transport of rosuvastatin in vitro.</p><p><b>CONCLUSION</b>Ursolic acid appears to be a potent modulator of BCRP that affects the pharmacokinetic of rosuvastatin in vivo and inhibits the transport of rosuvastatin in vitro.</p>

Metabolites of Aspergillus fumigatus / 中国中药杂志

Aspergillus fumigatus, a type of endophytic fungi from Erthrophleum fordii, was fermented with GPY culture medium. Fermented liquid and mycelium were extracted from fermented products after freezing and thawing treatment. After alcohol extraction, mycelium was extracted with ethyl acetate and n-butyl alcohol, respectively. According to the results of cytotoxity of tumor cells, ethyl acetate extracts were studied for their chemical constituents. Five diketopiperazine compounds were separated and purified with silica gel, MCI and Sephadex LH-20 column chromatography, reversed-phase chromatographic column and preparative HPLC, their structures were identified as cyclo- (R-Pro-R-Phe) (1), cyclo- (trans-4-OH-D-Pro-D-Phe) (2), cyclo- (R-Tyr-S-Ile) (3), cyclo-(R-Phe-S-Ile) (4), and cyclo-(R-Val-S-Tyr) (5) by using spectral methods.

ABCG2-overexpressing S1-M1-80 cell xenografts in nude mice keep original biochemistry and cell biological properties / 癌症

S1-M1-80 cells, derived from human colon carcinoma S1 cells, are mitoxantrone-selected ABCG2-overexpressing cells and are widely used in in vitro studies of multidrug resistance(MDR). In this study, S1-M1-80 cell xenografts were established to investigate whether the MDR phenotype and cell biological properties were maintained in vivo. Our results showed that the proliferation, cell cycle, and ABCG2 expression level in S1-M1-80 cells were similar to those in cells isolated from S1-M1-80 cell xenografts (named xS1-M1-80 cells). Consistently, xS1-M1-80 cells exhibited high levels of resistance to ABCG2 substrates such as mitoxantrone and topotecan, but remained sensitive to the non-ABCG2 substrate cisplatin. Furthermore, the specific ABCG2 inhibitor Ko143 potently sensitized xS1-M1-80 cells to mitoxantrone and topotecan. These results suggest that S1-M1-80 cell xenografts in nude mice retain their original cytological characteristics at 9 weeks. Thus, this model could serve as a good system for further investigation of ABCG2-mediated MDR.

Chemical constituents from the mycelia of Alternaria sp. YD-01 / 药学学报

To study the chemical constituents of the mycelia of the Endophytes YD-01, 2, 3-dihydroxy-quinoline-4-O-beta-D-glucopyranoside (1), 3-methyl-pyrrol opiperazine-2, 5-dione (2) and naringenin (3) were isolated from its acetone extracts by using silica gel column chromatography and Sephadex LH-20. Their structures were elucidated on the basis of spectroscopic analysis. Compound 1 is a new compound.