Next Article in Journal
Mushroom Quality Related with Various Substrates’ Bioaccumulation and Translocation of Heavy Metals
Next Article in Special Issue
Volatiles Produced by Yeasts Related to Prunus avium and P. cerasus Fruits and Their Potentials to Modulate the Behaviour of the Pest Rhagoletis cerasi Fruit Flies
Previous Article in Journal
Pathogenesis, Immunology and Management of Dermatophytosis
Previous Article in Special Issue
Recent Developments in Metabolomics Studies of Endophytic Fungi
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
JoF
Volume 8
Issue 1
10.3390/jof8010040
jof-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach

by
Zhiyang Fu
1,
Yuanyuan Liu
1,
Meijie Xu
1,
Xiaojun Yao
2,
Hong Wang
1 and
Huawei Zhang
1,3,*
1
School of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
2
Department of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
3
Key Laboratory of Marine Fishery Resources Exploitment & Utilization of Zhejiang Province, Hangzhou 310014, China
*
Author to whom correspondence should be addressed.
J. Fungi 2022, 8(1), 40; https://doi.org/10.3390/jof8010040
Submission received: 8 December 2021 / Revised: 30 December 2021 / Accepted: 30 December 2021 / Published: 31 December 2021
(This article belongs to the Special Issue Fungi and Fungal Metabolites for the Improvement of Human and Animal Life, Nutrition and Health 2.0)
Browse Figures
Versions Notes

Abstract

:
Endophytic fungi are one of prolific sources of bioactive natural products with potential application in biomedicine and agriculture. In our continuous search for antimicrobial secondary metabolites from Fusarium oxysporum R1 associated with traditional Chinese medicinal plant Rumex madaio Makino using one strain many compounds (OSMAC) strategy, two diastereomeric polyketides neovasifuranones A (3) and B (4) were obtained from its solid rice medium together with N-(2-phenylethyl)acetamide (1), 1-(3-hydroxy-2-methoxyphenyl)-ethanone (2) and 1,2-seco-trypacidin (5). Their planar structures were unambiguously determined using 1D NMR and MS spectroscopy techniques as well as comparison with the literature data. By a combination of the modified Mosher’s reactions and chiroptical methods using time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) and optical rotatory dispersion (ORD), the absolute configurations of compounds 3 and 4 are firstly confirmed and, respectively, characterized as (4S,7S,8R), (4S,7S,8S). Bioassay results indicate that these metabolites 1–5 exhibit weak inhibitory effect on Helicobacter pylori 159 with MIC values of ≥16 μg/mL. An in-depth discussion for enhancement of fungal metabolite diversity is also proposed in this work.

1. Introduction

The assignment of absolute configuration (AC) is one of the most challenging tasks in the structure elucidation of chiral natural products. Application of Mosher’s method or quantum mechanical calculation of chiroptical properties had proved to be practical and reliable, including time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) and optical rotatory dispersion (ORD) [1,2,3,4]. However, some difficulties and uncertainties still exist in determining ACs of molecules with high conformational flexibility using single method. Therefore, a combined application of these approaches is necessary and has been shown to be valid in some cases, such as chenopodolans B and D [5,6], sapinofuranones B and C [7] and ent-thailandolide B [8]. A growing number of evidence indicates that the genus Fusarium is one rich source of secondary metabolites with a wide variety of chemical structures and biological properties [9]. In our continuous search for antimicrobial secondary metabolites from the endophytic strain F. oxysporum R1 associated with traditional Chinese medicinal plant Rumex madaio Makino using one strain many compounds (OSMAC) strategy [10,11], chemical study of the ethyl acetate extract of its rice medium resulted in the isolation of five known compounds including N-(2-phenylethyl)acetamide (1), 1-(3-hydroxy-2-methoxyphenyl)-ethanone (2), neovasifuranones A (3) and B (4) and 1,2-seco-trypacidin (5) (Figure 1). Compounds 3 and 4 are diastereomeric polyketides originally isolated from the phytopathogenic strain Neocosmospora vasinfecta NHL2298 [12,13] and later found to be produced by the soil-derived strain Penicillium sp. SYPF7381 [14] and the endophytic fungus Aspergillus japonicus CAM231 from Garcinia preussii [15]. However, their ACs are still unassigned. Herein the present work highlights on assignment of ACs in 3 and 4 by a combined application of Mosher’s method and quantum mechanical calculation of chiroptical (ECD and ORD) properties.

2. Materials and Methods

2.1. General

The NMR spectra were determined on Bruker Avance DRX600 instruments (600 MHz for 1H and 150.92 MHz for 13C NMR) (Bruker, Fällande, Switzerland). ESIMS were obtained with an Agilent 6210 LC/TOF-MS spectrometer (Agilent Technologies, Santa Clara, CA, USA). Optical rotation and CD spectra were performed on JASCO P-2000 polarimeter and JASCO J-1500 spectrometer (JASCO, Fukuoka, Japan). UV and IR spectra were measured through a Hitachi-UV-3000 spectrometer (Hitachi, Tokyo, Japan) and a Nexus 870 spectrometer (Thermo-Nicolet, Madison, WI, USA), respectively. Reverse phase HPLC was carried out on an Essentia LC-16P apparatus (Essentia, San Diego, CA, USA) fitted with a preparative HPLC column (Phenomenex Gemini-NX C18, 50 mm £ 21.2 mm, 5 mm) or a semi-preparative column (Phenomenex Synergi Hydro-RP, 250 × 10 mm, 4 µm). Acetonitrile and H2O used in HPLC system were chromatographic grade, and all other chemicals were analytical.

2.2. Biological Material

The endophytic fungal strain R1 was isolated from the healthy plant R. madaio Makino collected off the coastal region of Putuo Island, China [16], and molecularly identified as F. oxysporum according to its 18S rDNA gene sequence (GenBank accession No. MF376147) and deposited at China General Microbiological Culture Collection Centre (CGMCC no. 17763) [11].

2.3. Fermentation, Extraction and Isolation

The strain R1 grown on potato dextrose agar (PDA) media was inoculated into 500 mL Erlenmeyer flasks containing 200 mL potato dextrose broth (PDB) medium, and shaken for 3 days at 200 rpm and 30 °C. The fermentation was performed in Erlenmeyer flasks (50 × 1 L) with sterilized rice (160 g) and tap water (320 mL). After autoclaving at 121 °C for 20 min, each flask was inoculated with 5% seed cultures and then incubated at room temperature under static conditions for 30 days. The fermented rice of each flask was extracted with 500 mL EtOAc by an ultrasonic instrument for 20 min, 3 times followed by filtration using gauze. All filtrate was combined and evaporated under vacuum to dryness, affording the crude extract (approximate 19 g). Then the extract was quickly separated using HPLC on a preparative column to afford six fractions A-F, and further purified using a semi-preparative column for subdivision [17]. Compound 1 (1.8 mg, tR = 7.2 min) and compound 2 (1.8 mg, tR = 8.2 min) were obtained from fraction A with 30% CH3CN/H2O with a flow rate of 3.0 mL/min at 210 nm. Compound 3 (23.4 mg, tR = 9.0 min) and compound 4 (8.2 mg, tR = 10.5 min) were isolated from fraction C with 40% CH3CN/H2O. Compound 5 (4.6 mg, tR = 10.7 min) was purified from fraction D with 50% CH3CN/H2O.

2.4. Preparation of (R)- and (S)-MTPA Esters of Compounds 3 and 4

Compound 3 (1.2 mg, 4.26 μmol) was transferred into a NMR tube and dried under vacuum. Pyridine-d5 (0.5 mL) and (S)-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride (5 μL, 26.5 μmol) were added under a N2 gas stream, and the NMR tube was shaken carefully to mix the sample and the MTPA chloride. The acylation was achieved at 20 °C for 36 h [18], suggesting that compound 3 was entirely transformed into the desired product (R)-MTPA ester derivative 3a: 1H NMR (600 MHz, pyridine-d5) δH 5.902 (1H, d, H-5), 5.404 (1H, d, H-7), 1.322 (1H, m, H-8), 1.177 (1H, m, H-9a), 1.291 (1H, m, H-9b), 1.541 (3H, s, H-14), 1.847 (3H, s, H-15), 1.167 (3H, d, H-16). In the same way, compound 3 was treated with (R)–MTPA chloride in pyridine-d5 to give the expected (S)-MTPA ester derivative 3b: 1H NMR (600 MHz, pyridine-d5) δH 5.971 (1H, d, H-5), 5.849 (1H, d, H-7), 1.292 (1H, m, H-8), 1.145 (1H, m, H-9a), 1.123 (1H, m, H-9b), 1.571 (3H, s, H-14), 1.875 (3H, s, H-15), 1.092 (3H, d, H-16), shown as Figures S12 and S13 and Table S1.
By the same method described above, compound 4 (0.5 mg, 1.77 μmol) was, respectively, acylated using (S)- and (R)-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride (3 μL, 15.9 μmol), which resulted in products of (R)-MTPA ester 4a and (S)-MTPA ester 4b, respectively. 4a: 1H NMR (600 MHz, pyridine-d5) δH 6.008 (1H, d, H-5), 4.057 (1H, d, H-7), 1.712 (1H, m, H-8), 1.272 (1H, m, H-9a), 1.269 (1H, m, H-9b), 1.988 (3H, s, H-14), 1.590 (3H, s, H-15), 1.206 (3H, d, H-16). 4b: 1H NMR (600 MHz, pyridine-d5) δH 6.009 (1H, d, H-5), 4.058 (1H, d, H-7), 1.171 (1H, m, H-8), 1.271 (1H, m, H-9a), 1.268 (1H, m, H-9b), 1.989 (3H, s, H-14), 1.590 (3H, s, H-15), 1.206 (3H, d, H-16), shown as Figures S14 and S15 and Table S2.

2.5. Computational Section for Compound 3

To determine the absolute configurations of C-4 and C-8 in 3, time-dependent density functional theory (TDDFT) method as a useful tool was applied for theoretical calculations of ECD spectra [19,20]. The conformational searches were carried out using Spartan software with the preliminary Merck Molecular Force Field (MMFF) in a 10.0 kcal mol−1 energy window [21]. All the obtained conformers were reoptimized at the B3LYP/6-31+G (d, p) level with the IEFPCM solvent model for methanol, and eight, twenty, nineteen and twenty conformers for 3-(4R, 8R), 3-(4R, 8S), 3-(4S, 8R) and 3-(4S, 8S) with a Boltzmann population above 1% were obtained, respectively, shown as Figures S16–S19. The vibrational frequencies of these conformers were also calculated in the M06-2X/6-311++g (d, p) level, demonstrating all conformers are true minima. Then, these conformers were subjected to calculate the ECD spectra using the TDDFT method with the PBE0 functional and the def-TZVP basis set in the same solvent model, and the rotatory strength for a total of 60 exited states were considered. The Boltzmann-weighted ECD spectra from the ZPVE-corrected M06-2X/6-311++g (d, p) energies were generated in GaussView 6.0.16 software, and the results were represented in Figures S16–S19. All calculations were implemented in the Gaussian 16 package [22].

2.6. Antimicrobial Assay

Antimicrobial activity was investigated according to the agar dilution method described by Unemo and coworkers [23], ampicillin was used as a positive standard. Clinical strain H. pylori 159 was obtained from biopsy sample of gastritis patient. Isolation and identification of H. pylori 159 were used standard protocols on basis of colony appearance, Gram staining, and positive reactions in the rapid urease test [24]. Additionally, 10% fetal calf serum (FCS) brain heart infusion (BHI, Becton Dickinson, Sparks, NV, USA) broth or 5% FCS Columbia blood agar (Oxoid, Basingstoke, UK), supplemented with Dent selective supplement (Oxoid), were used for routinely culture of H. pylori strains. Incubation of strains were under microaerophilic conditions (10% CO2, 85% N2, and 5% O2 and 90% relative humidity) using a double-gas CO2 incubator (Binder, model CB160, Tuttlingen, Germany) at 37 °C for 48 to 72 h. Three replicates were performed for every antimicrobial assay.
Anti-H. pylori activities were carried out according to broth microdilution assay [25]. H. pylori cultures in the exponential phase of growth were diluted ten times in BHI broth and inoculated into each well containing 100 μL test compounds. The final concentration of H. pylori was 5 × 105 to 1 × 106 CFU/mL. After incubated in a microaerophilic atmos-phere at 37 °C for 3 days, the plates were examined visually. Antimicrobial activity testing of pure compound followed Antimicrobial Susceptibility Testing Standards outlined by the Clinical and Laboratory Standards Institute (CLSI) document M07-A7 (Clinical and Laboratory Standards Institute 2008) against strain H. pylori 159. MIC value indicated the minimum inhibitory concentration for each compound.

3. Results

3.1. Structure Elucidation

By careful comparison of the 1H and 13C NMR and ESI-MS spectral data with literature (Table 1, Figures S1 and S2), the chemical structures of compounds 3 and 4 were, respectively, identified as neovasifuranone A and neovasifuranone B [12,13,14,15], while compounds 1, 2 and 5 were, respectively, characterized as N-(2-phenylethyl)acetamide [26], 1-(3-hydroxy-2-methoxyphenyl)-ethanone [27] and 1,2-seco-trypacidin [28].
The absolute configurations of compounds 3 and 4 were further confirmed by a combination of modified Mosher’s reactions and calculated electronic circular dichroism (ECD) and optical rotatory dispersion (ORD) analysis. Since the more abundant compound 3 possessed two readily acylable hydroxyl groups at C-7 and C-13, its (S)- and (R)-MTPA esters (3a and 3b) were prepared as detailed elsewhere [29,30,31]. The chemical shift deviations (ΔδS–R, Figure 2) calculated from the 1H NMR spectral data of 3a and 3b indicated the presence of a 7S-configuration. Obviously, the calculated ECD spectra for 3-(4S, 8R) and 3-(4S, 8S) are similar to their experimental ECD spectra (Figure 3). Furthermore, computed ORD values for 3-(4S, 8R) and 3-(4S, 8S) under the 589.3 nm are, respectively, −163° and −39°, whereas the experimental ORD value for 3 is −140°, which closely agrees with the calculated ORD value of 3-(4S, 8R) [32,33]. Therefore, the absolute configuration of 3 is unambiguously established as (4S, 7S, 8R).
As far as compound 4 concerned, the Mosher’s reaction result has a similar trend with compound 3. The chemical shift deviations (ΔδS–R, Figure 4) calculated from the 1H NMR spectral data of 4a and 4b indicated the presence of a 7S-configuration in 4. By comparison of ECD spectrum of compounds 3 with that of 4 (Figure 5), they had very similar cotton effects, which one valley at 202 nm and a peak at 306 nm were respectively shown in the first negative and the positive cotton effect regions, and the other elliptical valley was apparent at 267 nm in the negative cotton effect region [34]. Furthermore, the experimental ORD value for 4 is −92°, which is similar to that of its isomer 3-(4S, 8S), suggesting that three chiral centers at C-4, C-7 and C-8 in 4 are S configurations. Accordingly, the absolute configuration of 4 is undoubtedly characterized as (4S, 7S, 8S).

3.2. Antimicrobial Activity

Antimicrobial tests were carried out on one of the most serious pathogenic bacteria Helicobacter pylori 159. The results indicated that none of these compounds 1–5 had remarkable inhibitory effect on H. pylori 159, which MIC values are no less than 16 μg/mL (Table 2).

4. Discussion

To the best of our knowledge, more than 50% of the currently used drugs are chiral compounds. The enantiomers of the same drug have the same physical and chemical properties, but they exhibit differences in pharmacokinetics, pharmacodynamics and toxicity [35]. Owing to inherent structural and stereochemical complexity, fungal secondary metabolites play a significant role in drug discovery and development processes. In this study, the absolute configurations of two flexible molecules neovasifuranones A (3) and B (4) from F. oxysporum R1 were firstly determined by a combination of Mosher’s reactions and quantum mechanical calculation of chiroptical (ECD and ORD) properties. These findings will assist in further analysis of structure-activity relationship of compounds 3 and 4.
Endophytic fungi are one of important sources of bioactive secondary metabolites with potential application in biomedicine and agriculture [36,37]. Fusarium microorganisms are ubiquitous in nature including terrestrial and marine environments and plants. Genome sequencing and analysis indicate that these microbes possess a great number of secondary metabolites biosynthetic gene clusters (BGCs), including polyketide synthetase, non-ribosomal peptide synthetase and terpene synthetase [9]. However, most of these cryptic BGCs are not expressed under conventional culture conditions, which result in an unfavorable trend that the number of novel natural products from the genus Fusarium has been decreasing in the past decade. Therefore, more efforts should be made to awaken their silent BGCs to produce novel functional biomolecules using OSMAC strategy and advanced interdisciplinary technology, such as genome mining, metabonomics, gene heteroexpression and functional characterization [38,39].

Supplementary Materials

The following are available online at https://www.mdpi.com/article/10.3390/jof8010040/s1, Figure S1: (+) ESI-MS spectrum of compound 3; Figure S2: (+) ESI-MS spectrum of 4; Figure S3: IR (KBr) spectrum of 3; Figure S4: IR (KBr) spectrum of 4; Figure S5: 1H NMR (600 MHz, (CD3)2SO) spectrum of 3; Figure S6: 13C NMR (151 MHz, (CD3)2SO) spectrum of 3; Figure S7: 1H NMR (600 MHz, CDCl3) spectrum of 4; Figure S8: 13C NMR (151 MHz, CDCl3) spectrum of 4; Figure S9: DEPT-135 (CDCl3) spectrum of 4; Figure S10: UV spectrum of 3 in MeOH; Figure S11: UV spectrum of 4 in MeOH; Figure S12: 1H NMR (600 MHz, pyridine-d5) spectrum of (R)-MTPA of 3; Figure S13: 1H NMR (600 MHz, pyridine-d5) spectrum of (S)-MTPA of 3; Figure S14: 1H NMR (600 MHz, pyridine-d5) spectrum of (R)-MTPA of 4; Figure S15: 1H NMR (600 MHz, pyridine-d5) spectrum of (S)-MTPA of 4; Table S1: 1H NMR spectral data for 3 and two MTPA esters 3a and 3b (1H, 600 MHz); Table S2: NMR spectral data for 4 and two MTPA esters 4a and 4b (1H, 600 MHz); Figure S16: Optimized conformers (≥1%) of 3-(4R, 8R); Figure S17: Optimized conformers (≥1%) of 3-(4R, 8S); Figure S18: Optimized conformers (≥1%) of 3-(4S, 8S); Figure S19: Optimized conformers (≥1%) of 3-(4S, 8R).

Author Contributions

Conceptualization, project administration and funding acquisition, H.Z.; methodology, Z.F. and Y.L.; software, X.Y.; formal analysis, Z.F. and H.Z.; investigation, Z.F., Y.L. and M.X.; resources, H.Z.; data curation, H.W.; writing—original draft preparation, Z.F.; writing—review and editing, X.Y. and H.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work was co-financially supported by the National Key Research and Development Program of China (2018YFC0311004), the National Natural Science Foundation of China (41776139) and the Fundamental Research Fund for the Provincial Universities of Zhejiang of China (RF-C2019002).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Zhou, Z.F.; Kurtán, T.; Yang, X.H. Penibruguieramine A, a novel pyrrolizidine alkaloid from the endophytic fungus Penicillium sp. GD6 associated with chinese mangrove Bruguiera gymnorrhiza. Org. Lett. 2014, 45, 1390–1393. [Google Scholar] [CrossRef]
  2. Sun, L.L.; Li, W.S.; Li, J. Uncommon diterpenoids from the south china sea soft coral Sinularia humilis and their stereochemistry. J. Org. Chem. 2021, 86, 3367–3376. [Google Scholar] [CrossRef]
  3. Ye, F.; Zhu, Z.D.; Chen, J.S. Xishacorenes A–C, diterpenes with bicyclo[3.3.1]nonane nucleus from the Xisha soft coral Sinularia polydactyla. Org. Lett. 2017, 19, 4183–4186. [Google Scholar] [CrossRef]
  4. Seco, J.M.; QuinOá, E.; Riguera, R. The assignment of absolute configuration by NMR. Chem. Rev. 2004, 104, 17–118. [Google Scholar] [CrossRef]
  5. Evidente, M.; Cimmino, A.; Zonno, M.C.; Masi, M.; Berestetskyi, A.; Santoro, E.; Superchi, S.; Vurro, M.; Evidente, A. Phytotoxins produced by Phoma chenopodiicola, a fungal pathogen of Chenopodium album. Phytochemistry 2015, 117, 482–488. [Google Scholar] [CrossRef] [PubMed]
  6. Evidente, M.; Cimmino, A.; Zonno, M.C.; Masi, M.; Santoro, E.; Vergura, S.; Berestetskiy, A.; Superchi, S.; Vurro, M.; Evidente, A. Chenopodolans E and F, two new furopyrans produced by Phoma chenopodiicola and absolute configuration determination of chenopodolan B. Tetrahedron 2016, 72, 8502–8507. [Google Scholar] [CrossRef]
  7. Mazzeo, G.; Cimmino, A.; Masi, M.; Longhi, G.; Maddau, L.; Memo, M.; Evidente, A.; Abbate, S. Importance and difficulties in the use of chiroptical methods to assign the absolute configuration of natural products: The case of phytotoxic pyrones and furanones produced by Diplodia corticola. J. Nat. Prod. 2017, 80, 2406–2415. [Google Scholar] [CrossRef]
  8. El-Elimat, T.; Figueroa, M.; Raja, H.A.; Alnabulsi, S.; Oberlies, N.H. Coumarins, dihydroisocoumarins, a dibenzo-alpha-pyrone, a meroterpenoid, and a merodrimane from Talaromyces amestolkiae. Tetrahedron Lett. 2021, 72, 153067. [Google Scholar] [CrossRef]
  9. Li, M.Z.; Yu, R.L.; Bai, X.L.; Wang, H.; Zhang, H.W. Fusarium: A treasure trove of bioactive secondary metabolites. Nat. Prod. Rep. 2020, 37, 1568–1588. [Google Scholar] [PubMed]
  10. Yu, R.; Li, M.; Wang, Y. Chemical investigation of a co-culture of Aspergillus fumigatus D and Fusarium oxysporum R1. Rec. Nat. Prod. 2020, 15, 130–135. [Google Scholar] [CrossRef]
  11. Chen, J.; Bai, X.; Hua, Y.; Zhang, H.; Wang, H. Fusariumins C and D, two novel antimicrobial agents from Fusarium oxysporum ZZP-R1 symbiotic on Rumex madaio Makino. Fitoterapia 2019, 134, 1–4. [Google Scholar] [CrossRef]
  12. Furumoto, T.; Fukuyama, K.; Hamasaki, T. Neovasipyrones and neovasifuranones: Four new metabolites related to neovasinin, a phytotoxin of the fungus Neocosmospora vasinfecta. Phytochemistry 1995, 40, 745–751. [Google Scholar] [CrossRef]
  13. Furumoto, T.; Hamasaki, T.; Nakajima, H. Biosynthesis of phytotoxin neovasinin and its related metabolites, neovasipyrones A and B and neovasifuranones A and B, in the phytopathogenic fungus Neocosmospora vasinfecta. Cheminform 1999, 30, 131–136. [Google Scholar]
  14. Feng, Q.M.; Li, X.Y.; Li, B.X. Isolation and identification of two new compounds from the Penicillium sp. SYPF7381. Nat. Prod. Res. 2019, 34, 1–7. [Google Scholar] [CrossRef] [PubMed]
  15. Jouda, J.B.; Fopossi, J.; Kengne, F.M. Secondary metabolites from Aspergillus japonicus CAM231, an endophytic fungus associated with Garcinia preussii. Nat. Prod. Res. 2017, 31, 861–869. [Google Scholar] [CrossRef] [PubMed]
  16. Wei, Y.L.; Wu, J.; Deng, Y.P. Optimization of extraction process of total flavonoids from Rumex madaio Makino. Food Res. Dev. 2015, 14, 20–24. (In Chinese) [Google Scholar]
  17. Zhang, H.; Loveridge, S.T.; Tenney, K.; Crews, P. A new 3-alkylpyridine alkaloid from the marine sponge Haliclona sp. and its cytotoxic activity. Nat. Prod. Res. 2015, 30, 1262–1265. [Google Scholar] [CrossRef] [Green Version]
  18. Zhang, H.W.; Zhang, J.; Hu, S.; Zhang, Z.J.; Zhu, C.J.; Ng, S.W.; Tan, R.X. Ardeemins and cytochalasins from Aspergillus terreus residing in Artemisia annua. Planta Med. 2010, 76, 1616–1621. [Google Scholar] [CrossRef]
  19. Lin, S.; Shi, T.; Chen, K.Y.; Zhang, Z.X.; Shan, L.; Shen, Y.H.; Zhang, W.D. Cyclopenicillone, a unique cyclopentenone from the cultures of Penicillium decumbens. Chem. Commun. 2011, 47, 10413–10415. [Google Scholar] [CrossRef]
  20. Suárez-Ortiz, G.A.; Cerda-García-Rojas, C.M.; Fragoso-Serrano, M.; Pereda-Miranda, R. Complementarity of DFT calculations, NMR anisotropy, and ECD for the configurational analysis of brevipolides K–O from Hyptis brevipes. J. Nat. Prod. 2017, 80, 181–189. [Google Scholar] [CrossRef]
  21. Agarwal, M.; Frank, M.I. SPARTAN: A software tool for parallelization bottleneck analysis. In Proceedings of the 2009 ICSE Workshop on Multicore Software Engineering, Vancouver, BC, Canada, 18 May 2009; pp. 56–63. [Google Scholar]
  22. Frisch, M.J.; Trucks, G.W.; Schlegel, H.B.; Scuseria, G.E.; Robb, M.A.; Cheeseman, J.R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G.A.; et al. Gaussian 2016, Revision, A. 03; Gaussian, Inc.: Wallingford, CT, USA, 2016. [Google Scholar]
  23. Unemo, M.; Fasth, O.; Fredlund, H.; Limnios, A.; Tapsall, J. Phenotypic and genetic characterization of the 2008 WHO Neisseria gonorrhoeae reference strain panel intended for global quality assurance and quality control of gonococcal antimicrobial resistance surveillance for public health purposes. J. Antimicro. Chemother. 2009, 63, 1142–1151. [Google Scholar] [CrossRef] [PubMed]
  24. Castellote, J.; Guardiola, J.; Porta, F.; Falco, A. Rapid urease test: Effect of preimmersion of biopsy forceps in formalin. Gastrointest. Endosc. 2001, 53, 744–746. [Google Scholar] [CrossRef]
  25. Covacci, A.; Censini, S.; Bugnoli, M.; Petracca, R.; Burroni, D.; Macchia, G.; Massone, A.; Papini, E.; Xiang, Z.; Figura, N.; et al. Molecular characterization of the 128-kDa immunodominant antigen of Helicobacter pylori associated with cytotoxicity and duodenal ulcer. Proc. Natl. Acad. Sci. USA 1993, 90, 5791–5795. [Google Scholar] [CrossRef] [Green Version]
  26. Daoud, N.N.; Foster, H.A. Antifungal activity of Myxococcus species 1 production, physiochemical and biological properties of antibiotics from Myxococcus flavus S110 (Myxobacterales). Microbios 1993, 73, 173–184. [Google Scholar]
  27. Giri, A.; Zelinkova, Z.; Wenzl, T. Experimental design-based isotope-dilution SPME-GC/MS method development for the analysis of smoke flavouring products. Food Addit. Contam. 2017, 34, 2069–2084. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  28. Liu, R.; Zhu, W.M.; Zhang, Y.P.; Zhu, T.J.; Liu, H.B.; Fang, Y.C.; Gu, Q.Q. A new diphenyl ether from marine-derived fungus Aspergillus sp. B-F-2. J. Antibiot. 2006, 59, 362–365. [Google Scholar] [CrossRef] [Green Version]
  29. Ohtani, I.; Kusumi, T.; Kashman, Y. High-field FT NMR application of Mosher’s method. The absolute configurations of marine terpenoids. J. Am. Chem. Soc. 1991, 113, 4092–4096. [Google Scholar] [CrossRef]
  30. Kusumi, T.; Fujita, Y.; Ohtani, I. Anomaly in the modified Mosher’s method: Absolute configurations of some marine cembranolides. Tetrahedron Lett. 1991, 32, 2923–2926. [Google Scholar] [CrossRef]
  31. Konno, K.; Fujishima, T.; Liu, Z. Determination of absolute configuration of 1,3-diols by the modified Mosher’s method using their di-MTPA esters. Chirality 2010, 14, 72–80. [Google Scholar] [CrossRef] [PubMed]
  32. Ma, Z.; Hano, Y.; Feng, Q. Determination of the absolute stereochemistry of lupane triterpenoids by fucofuranoside method and ORD spectrum. Tetrahedron Lett. 2004, 45, 3261–3263. [Google Scholar] [CrossRef]
  33. Dreyer, D.L. Citrus bitter principles-III: Application of ORD and CD to stereochemical problems. Tetrahedron 1968, 24, 3273–3283. [Google Scholar] [CrossRef]
  34. Lee, S.; Hoshino, M.; Fujita, M. Cycloelatanene A and B: Absolute configuration determination and structural revision by the crystalline sponge method. Chem. Sci. 2017, 8, 1547–1550. [Google Scholar] [CrossRef] [Green Version]
  35. Sanganyado, E.; Lu, Z.; Fu, Q. Chiral pharmaceuticals: A review on their environmental occurrence and fate processes. Water Res. 2017, 124, 527–542. [Google Scholar] [CrossRef]
  36. Venugopalan, A.; Srivastava, S. Endophytes as in vitro production platforms of high value plant secondary metabolites. Biotechnol. Adv. 2015, 33 Pt 1, 873–887. [Google Scholar] [CrossRef]
  37. Zhang, H.W.; Bai, X.L.; Zhang, M.; Chen, J.W.; Wang, H. Bioactive natural products from endophytic microbes. Nat. Prod. J. 2018, 8, 86–108. [Google Scholar] [CrossRef]
  38. Pan, R.; Bai, X.L.; Chen, J.W.; Zhang, H.W.; Wang, H. Exploring structural diversity of microbe secondary metabolites using OSMAC strategy: A literature review. Front. Microbiol. 2019, 10, 294–313. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  39. Atanasov, A.G.; Zotchev, S.B.; Dirsch, V.M.; The International Natural Product Sciences Taskforce; Supuran, C.T. Natural products in drug discovery: Advances and opportunities. Nat. Rev. Drug Discov. 2021, 20, 200–216. [Google Scholar] [CrossRef] [PubMed]
Jof 08 00040 g001 550
Figure 1. Chemical structures of compounds 1–5 from Fusarium oxysporum R1.
Figure 1. Chemical structures of compounds 1–5 from Fusarium oxysporum R1.
Jof 08 00040 g001
Jof 08 00040 g002 550
Figure 2. ΔδS–R values for MTPA esters of compounds 3a and 3b.
Figure 2. ΔδS–R values for MTPA esters of compounds 3a and 3b.
Jof 08 00040 g002
Jof 08 00040 g003 550
Figure 3. Calculated and experimental ECD spectra of compound 3.
Figure 3. Calculated and experimental ECD spectra of compound 3.
Jof 08 00040 g003
Jof 08 00040 g004 550
Figure 4. ΔδS–R values for MTPA esters of compounds 4a and 4b.
Figure 4. ΔδS–R values for MTPA esters of compounds 4a and 4b.
Jof 08 00040 g004
Jof 08 00040 g005 550
Figure 5. Experimental ECD spectra of compounds 3 and 4.
Figure 5. Experimental ECD spectra of compounds 3 and 4.
Jof 08 00040 g005
Table
Table 1. NMR spectral data for compounds 3 and 4 (1H, 600 MHz and 13C 150 MHz).
Table 1. NMR spectral data for compounds 3 and 4 (1H, 600 MHz and 13C 150 MHz).
PositionCompound 3 (in DMSO-d6)Compound 4 (in CDCl3)
δCδH (in ppm, J in Hz)δCδH (in ppm, J in Hz)
1189.6 190. 9
2112.1 112.4
3203.9 206.6
487.7 89.1
5121.75.37 (1H, m)123.25.42 (1H, s)
6143.5 144.1
778.03.60 (1H, t, J = 4.2)81.43.70 (1H, d, J = 6.9)
7-OH 8.31 (1H, s)
836.91.39 (1H, m)37.51.50 (1H, m)
925.91.06 (1H, m)26.41.05 (1H, m)
1.31 (1H, m) 1.31 (1H, m)
1011.60.84 (3H, t, J = 7.2)11.90.87 (3H, t, J = 7.5)
1121.92.62 (1H, q, J = 7.2)22.92.65 (2H, m)
2.67 (1H, q, J = 7.8)
1210.51.16 (3H, t, J = 7.2)10.91.24 (3H, t, J = 7.5)
1350.54.01 (2H, s)53.14.24 (2H, m)
1424.01.37 (3H, s)24.51.47 (3H, s)
1513.61.60 (3H, d, J = 0.6)13.51.64 (3H, d, J = 1.3)
1613.70.71 (3H, d, J = 6.6)14.30.84 (3H, d, J = 6.7)
Table
Table 2. In vitro anti-Helicobacter pylori effects of compounds 1-5.
Table 2. In vitro anti-Helicobacter pylori effects of compounds 1-5.
CompoundMIC Value (μg/mL)
Helicobacter pylori 159
1>16
2>16
3>16
4>16
516
Ampicillin sodium4
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Fu, Z.; Liu, Y.; Xu, M.; Yao, X.; Wang, H.; Zhang, H. Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach. J. Fungi 2022, 8, 40. https://doi.org/10.3390/jof8010040

AMA Style

Fu Z, Liu Y, Xu M, Yao X, Wang H, Zhang H. Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach. Journal of Fungi. 2022; 8(1):40. https://doi.org/10.3390/jof8010040

Chicago/Turabian Style

Fu, Zhiyang, Yuanyuan Liu, Meijie Xu, Xiaojun Yao, Hong Wang, and Huawei Zhang. 2022. "Absolute Configuration Determination of Two Diastereomeric Neovasifuranones A and B from Fusarium oxysporum R1 by a Combination of Mosher’s Method and Chiroptical Approach" Journal of Fungi 8, no. 1: 40. https://doi.org/10.3390/jof8010040

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop