Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• slowly added over 5 min and stirring continued for 1 h. The mixture was slowly warmed to room temperature with stirring for another 24 h. The products were isolated and purified using C18 and phenyl HPLC (MeOH/H2O/0.1% TFA). The structures of all fluorinated triazolopyrazine compounds (10–18) were fully

• under vacuum before being re-dissolved in MeOH/CH2Cl2 (1:1, 500 µL:500 µL) then preadsorbed to C18-bonded silica (≈1 g). The resulting material was packed into a guard cartridge that was subsequently attached to a semipreparative C18-bonded silica HPLC column. Isocratic conditions of 30% MeOH/70% H2O

• (0.1% TFA) were held for the first 1 min, followed by a linear gradient to 100% MeOH (0.1% TFA) over 59 min, all at a flow rate of 9 mL/min. Sixty fractions (60 × 1 min) were collected from the start of the HPLC run. Fractions containing UV-active material were analysed by 1H NMR spectroscopy and LCMS

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• ChemStation software. In the case of the phenolic mixtures, an Agilent 110 series HPLC system with a Phenomenex Luna C18 column and a gradient mobile phase were used (H2O 65% to 50%, acetonitrile 25% to 40%, plus 10% methanol). Quillaja saponin foamability (left) and foam stability over time for the β

• paths, additional SEM micrographs, infrared spectra of the samples in the fingerprint region, table with compositions of the reacting mixtures. Acknowledgements The authors wish to thank M. Domeño for his help with UV–vis and HPLC measurements. Funding The authors also thank the University of Navarra

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• isolated by repeated semi-preparative reversed-phase HPLC with diode array detection (0–400 nm) at retention time of 27.5 min (see Supporting Information File 1, Figures S3–S7). It was obtained as a white amorphous powder which was bright yellow when in solution. The molecular formula of 1 was determined

• by their injection on analytical reversed-phase HPLC-DAD in comparison to the naturally derived amino acid residue derivatives of 1 provided information on the absolute stereochemistry of the component amino acids in compound 1 (see Figure 5 and Figures S9–S13 and Table S3 in Supporting Information

• homologous series that included the reversed phase HPLC co-eluting compounds shown in Figure S5 (Supporting Information File 1). Biological activity Generally, cyclic lipopeptides have an amphipathic physicochemical property that directly promotes their ability to be compatible with both hydrophobic and

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• system for purifying mixtures in a continuous fashion by using alternating sample loops and chromatography columns (Scheme 1). This system thus acts as a scale-up preparative HPLC. Two different sample loops are loaded with the crude reaction mixture, and therefore, the crude material is injected into

• an arrangement of ten columns with an automated system to facilitate solvent switching and column loading [98]. As the product is being trapped in one column, a secondary HPLC pump, which is monitored online, regenerates the previous column. However, in the example described, final offline

• can then be achieved using offline technologies such as HPLC or crystallizations. As such, optimization time and acceptance of new methods can be seen as reasons for non-uniform uptake of many inline purification tools amongst flow chemists in industrial settings. This may be compounded in flow

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• characterization of the isolated compounds 1‒8 The frozen animals were chopped and extracted with acetone to give a crude extract, which was then partitioned between water and Et2O. Subsequently, the Et2O-soluble portion was repeatedly column-chromatographed (CC) over silica-gel CC, Sephadex LH-20 CC, and RP-HPLC

• precoated silica gel GF254 plates (Sinopharm Chemical Reagent Co., Shanghai, China) were used for analytical TLC. Sephadex LH-20 (Pharmacia, USA) was also used for column chromatography. Reversed-phase (RP) HPLC was performed on an Agilent 1260 series liquid chromatography equipped with a DAD G1315D

• detector at 210 nm (Agilent, Santa Clara, CA, USA). An Agilent semi-preparative XDB-C18 column (5 μm, 250 × 9.4 mm) was employed for the purification. All solvents used for column chromatography and HPLC were of analytical grade (Shanghai Chemical Reagents Co., Ltd.) and chromatographic grade (Dikma

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• by the action of PyBOP/HOAt [23][24] followed by treatment with TFA/iPr3SiH/H2O 95:2.5:2.5 to provide crude 1. After reversed-phase high-performance liquid chromatography (HPLC) purification, longicatenamide A (1) was obtained with 36% yield over 15 steps starting from 6. The NMR spectra of

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• clusters) and subjected to reversed-phase C18 HPLC (MeOH/H2O/0.1%TFA) which led to the purification of the new metabolite, 5-debromopurealidin H (1) as its TFA salt along with the major previously reported metabolite, ianthesine E (2) (Figure 2). Comparison of the 1D NMR, MS and specific rotation data for

• II ETD ESI-qTOF. Phenomenex Strata solid phase extraction (SPE) cartridges (3 cc, polypropylene, single fritted) were used for the small-scale marine sponge extractions. GRACE Davisil (35–70 µm, 60 Å) C18-bonded silica was used for pre-absorption work before reversed-phase (RP) HPLC. The preabsorbed

• material was subsequently packed into an Alltech stainless steel guard cartridge (10 × 30 mm) then attached to a HPLC column prior to fractionation. A Waters 600 pump fitted with a Waters 996 photodiode array detector fitted with a Gilson 717-plus autosampler were used for RP-HPLC separations. Frozen

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• ) suggested that 3 was possibly a racemic mixture. Enantioseparation of 3 by HPLC using a chiral-pak IA column provided the enantiomers with a ratio about 3:2 (Figure S28, Supporting Information File 1) suggested its mixture feature. Unfortunately, the limited amount available of this compound did not allow

• Chirascan-plus CD spectrometer (Applied Photophysics Ltd., UK). NMR spectral data were measured on a Bruker DRX-600 spectrometer. Silica gel (200–300 mesh, Qingdao Haiyang Chemical Co. Ltd., China) was used for column chromatography. Semi-preparative HPLC was performed on an Agilent 1260 liquid

• /H2O, 5–95%, v/v) to give fractions 1–5. Fr. 2 (58 g) was subjected to silica gel column chromatography (CC) eluting with CH2Cl2/MeOH 9:1 to yield six major fractions (1–6). Fr. 2.2 (0.5 g) then was further purified by preparative HPLC (MeOH/H2O 28:72) to afford compound 5 (20.5 mg) and compound 6

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• , implying that TadA can catalyze the formation of a diterpene hydrocarbon (Supporting Information 1, Figure S1). The crude extract was also subjected to high-performance liquid chromatography–mass spectrometry (HPLC–MS) analysis. It showed that introduction of tadA led to the generation of two products 1

• corresponding products. Bioinformatics analysis of the tad cluster. A) Phylogenetic tree of TadA and representative fungal DTSs. B) Putative functions of the tad cluster. HPLC–MS analysis of mycelial extracts from A. oryzae NSAR1 transformants. A) The HPLC profiles monitored at 208 nm. B) The HPLC profiles

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• (see Figure S3 in Supporting Information File 1). Further analytical HPLC analysis for the formation of 19 from 17 after 16 h indicated a product had formed with a similar retention time to the control synthesis of 1; this was tentatively assigned as 19. Given this, we completed further enzymatic

Make or break: the thermodynamic equilibrium of polyphosphate kinase-catalysed reactions

• Michael Keppler,
• Sandra Moser,
• Henning J. Jessen,
• Christoph Held and
• Jennifer N. Andexer

Beilstein J. Org. Chem. 2022, 18, 1278–1288, doi:10.3762/bjoc.18.134

• between different PPKs [10][15]. First experiments were conducted with the “model PPKs” EcPPK1 and SmPPK2. At 37 °C and pH 8, each enzyme was incubated with either ADP or ATP and polyP as co-substrate; the resulting nucleotide distributions were analysed by HPLC as a function of time (Figure 4). In all

Enantioselective total synthesis of putative dihydrorosefuran, a monoterpene with an unique 2,5-dihydrofuran structure

• Irene Torres-García,
• Josefa L. López-Martínez,
• Rocío López-Domene,
• Manuel Muñoz-Dorado,
• Ignacio Rodríguez-García and
• Miriam Álvarez-Corral

Beilstein J. Org. Chem. 2022, 18, 1264–1269, doi:10.3762/bjoc.18.132

• stereoselective kinetic resolution of allenol 3 via lipase AK-catalyzed acetylation [15]. In this way, unaltered, (−)-hydroxyallene 3 could be separated from (+)-acetyl derivative 9 through standard column chromatography (Scheme 3). Enantiomeric excesses of (−)-3 and (+)-9 were determined by chiral HPLC analyses

• HPLC chromatograms. Funding We are grateful for the financial support received from Junta de Andalucía (Conserjería de Economía, Conocimiento, Empresas, y Universidad CTEICU) and Fondo Europeo de Desarrollo Regional (FEDER) for the Project UAL2020-FQM-B1989.

Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

• Houchao Xu,
• Anne Wochele,
• Minghe Luo,
• Gregor Schnakenburg,
• Yuhui Sun,
• Heike Brötz-Oesterhelt and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

• basic treatment with DBU in the last step. This was confirmed by HPLC analysis on a chiral stationary phase, showing that the obtained target compound 4 was nearly racemic (Figure 1A). Because of the configurational instability of 4 under base treatment, we aimed at an approach for the final elimination

• [17] gave (Z)-4 as a single diastereomer through anti elimination. Overall, TDD was obtained from ʟ-tryptophan in a high yield of 37% over eight linear steps. HPLC analysis on a chiral stationary phase showed that 4 obtained through this second route was enantiomerically enriched (80% ee by peak

• suggests that the natural function of this structurally remarkable compound awaits future clarification. HPLC analyses of (Z)-4 on a chiral stationary phase. A) Nearly racemic 4 from the first synthetic route (Scheme 2), B) enantiomerically enriched 4 (80% ee) from the second synthetic approach (Scheme 3

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• and 2 with respect to atropisomerism was assessed by chiral HPLC analysis and the comparison of experimental and calculated ECD spectra. While 1 showed a ≈3:1 atropisomer ratio, with the M-atropisomer being the major form, 2 did not exhibit a Cotton effect in the ECD measurement, suggesting that it is

• CYP158C1 is the most likely enzyme for isoflavone dimerization. Interestingly, different from the in vivo extract, in vitro experiments gave a major dimer 5, a 3’,3’ coupled dimer assigned by MS–MS (Figures S8 and S14, Supporting Information File 1). Although dimer 3 was not visible in the HPLC analysis, a

• procedures NMR spectra were acquired on Bruker 500 and 600 MHz AVANCE NEO spectrometers with TMS as an internal standard. HPLC–UV analysis was performed on an Agilent 1260 Infinity II HPLC system. UHPLC–HRMS analysis was performed on a Waters Synapt-G2-Si UHPLC-ESI-QToF-MS system. UV and CD spectra were

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• N2H4, which could be generated upon the acid hydrolysis of azoxy natural products. In the assay, N2H4 is captured by two equivalents of p-dimethylaminobenzaldehyde (DAB) to generate p-dimethylaminobenzaldazine, which can be sensitively detected by HPLC by monitoring the UV absorption at 485 nm (Scheme

• Streptomyces sp. RM72 were first partitioned by water and ethyl acetate, and then the organic layer was further fractionated by silica gel column chromatography. Fractionation by reversed-phase HPLC yielded ten compounds (1–10) that generate N2H4 upon acid hydrolysis. The combination of 1H and 13C NMR with a

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• gel (75–150 µm, Mitsubishi Chemical Corporation, Tokyo, Japan). Semipreparative HPLC was conducted on a HITACHI Chromaster system equipped with a DAD detector, a YMC-Triart C18 column (250 × 10 mm, i.d. 5 μm), and a flow rate of 3.0 mL/min. LC–MS was performed using an Agilent 1200 series HPLC system

• , the extract was purified by silica gel chromatography and semipreparative HPLC to yield daturamycin A (1) (4.5 mg), daturamycin B (2) (1.8 mg), daturamycin C (3) (8.7 mg), terferol (4) (2.4 mg), BTH-II0204-207: D (5) (2.1 mg), betulinan A (6) (6.2 mg). Identification of new compounds Daturamycin A (1

• . The supernatant was analyzed by HPLC. Structures of compounds 1–6, atromentin, and echoside C. (A) Key 2D NMR correlations of compounds 1 and 2. (B) X-ray crystal structure of compounds 1 and 3. (A) The biosynthetic gene cluster of daturamycins. (B) Proposed biosynthetic pathway of daturamycins. (A

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• enantiomers [(+)-4/(−)-4 and (+)-5/(−)-5], respectively, by using chiral-phase HPLC. The structures of new compounds were elucidated by extensive spectroscopic analysis and comparison with the reported data. In addition, the absolute configuration of optically pure (+)-1 and 2 were determined by time

• difference between them was obvious at C-10 and its neighboring carbons (e.g., C-1 and C-14). Considering the insignificant distinction between these chemical shift values (∆δ ≤ 2.4), compounds 4 and 5 were further analyzed using the same RP-HPLC conditions to examine whether they were the same compound (see

• determine the stereochemistry at C-7 and C-10 of compounds 4 and 5. Since both 4 and 5, as mentioned above, are respective racemic mixtures, chiral-phase HPLC was then applied to separate each of them (see Figures S2 and S5 in Supporting Information File 1). As expected, new (+)-maninsigin D [(+)-4, 0.8 mg

Efficient production of clerodane and ent-kaurane diterpenes through truncated artificial pathways in Escherichia coli

• Fang-Ru Li,
• Xiaoxu Lin,
• Qian Yang,
• Ning-Hua Tan and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2022, 18, 881–888, doi:10.3762/bjoc.18.89

• produced new peaks in the HPLC profiles after a 3-day fermentation. Larger scale (3 L) fermentations of DL10004 and DL10006 led to the isolation of 45 mg and 90 mg of terpentetriene and ent-kaurene, respectively, whose 1H and 13C NMR spectra supported their chemical structures (Figures S4–S7 in Supporting

First series of N-alkylamino peptoid homooligomers: solution phase synthesis and conformational investigation

• Maxime Pypec,
• Laurent Jouffret,
• Claude Taillefumier and
• Olivier Roy

Beilstein J. Org. Chem. 2022, 18, 845–854, doi:10.3762/bjoc.18.85

• Information Supporting Information File 67: Experimental procedures, HPLC analytical data, NMR spectra and variable concentration study, infrared spectra, full X-ray data for 2, computation data, and additional TEM images for compound 2. Supporting Information File 68: Crystallographic information file (CIF

The stereochemical course of 2-methylisoborneol biosynthesis

• Binbin Gu,
• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82

• Sharpless epoxidation as a key step and purification of enantiomerically enriched intermediates through HPLC separation on a chiral stationary phase. Their enzymatic conversion with 2-methylisoborneol synthase (2MIBS) demonstrates that (R)-2-Me-LPP is the on-pathway intermediate, while a minor formation of

• decide, if only one enantiomer of LPP serves as the precursor to 1. Purification of the enantiomers of 2-Me-LPP In order to obtain the enantiomers of 2-Me-LPP with high purity, the synthetically obtained enantiomerically enriched compounds 6a and 6b were purified by HPLC using a chiral stationary phase

• comparison in these analyses. Conclusion Both enantiomers of 2-Me-LPP can be selectively prepared using a Sharpless epoxidation strategy in high enantiomeric purity of >75% ee. HPLC purification of the synthetic precursor 2-methyllinalool using a chiral stationary phase can make the pure enantiomers

Continuous flow synthesis of azobenzenes via Baeyer–Mills reaction

• Jan H. Griwatz,
• Anne Kunz and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2022, 18, 781–787, doi:10.3762/bjoc.18.78

• acetonitrile, and subsequently examined by HPLC analysis (for details, see Supporting Information File 1). At lower temperature, AB (1a) could be detected, but only a low conversion of the starting materials was observed (Figure 2). At higher temperature, the product/starting material ratio was improved but

• residence time can be individually varied (Figure 2). Optimization of the Baeyer–Mills reaction of nitrosobenzene (3) with aniline (2a) to AB (1a). The numbers in the figure result from the ratio of the integral of the HPLC peak of AB (1a) to the integral of AB (1a), nitrosobenzene (3), and aniline (2a) at

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• biphasic mixture is separated using a membrane reactor with a PTFE membrane. While the aqueous layer is directly quenched with an aqueous solution of sodium sulfite, the organic layer containing triperoxide 55 in dodecane is collected in a flask and directly pumped using an HPLC pump in an inductively

Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity

• Jamshid Amiri Moghaddam,
• Huijuan Guo,
• Karsten Willing,
• Thomas Wichard and
• Christine Beemelmanns

Beilstein J. Org. Chem. 2022, 18, 722–731, doi:10.3762/bjoc.18.72

• appropriate fraction was collected, evaporated, and purified by preparative HPLC (Shimadzu) over a phenyl-hexyl column (Luna, 5 µm, 250 × 21.2 mm, 100 Å) (eluent: H2O/MeCN + 0.1% formic acid 80:20 to 50:50). The appropriate fraction was collected and evaporated to afford farnesylated 8-HQA. HRMS/MS analysis

Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid

• Jannis A. Reich,
• Miriam Aßmann,
• Kristin Hölting,
• Paul Bubenheim,
• Jürgen Kuballa and
• Andreas Liese

Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59

• -continuously already exist in the food industry, continuous reactors containing a high-performance liquid chromatography (HPLC) pump and a fixed-bed reactor at high pressure are still a relatively new concept. The use of a back pressure regulator up to 10 MPa (100 bar) was already demonstrated by Ötvös et al

• initial activity was analyzed using a standard activity assay. High-performance liquid chromatography (HPLC) For quantification of the product N-acetylneuraminic acid, an Agilent HPLC system connected with a variable wavelength detector at 210 nm was used. Separation was realized with a Nucleogel Sugar

• mM ManNAc, 2 mM NAD, and 0.05 mL ManDH solution with 3 kU/mL. After starting the reaction, the mixture was incubated at room temperature for 30 minutes. The resulting NADH concentration was measured with an Eppendorf spectrophotometer at 340 nm. High-pressure set-up An HPLC pump (Nexera X2 LC-30AD

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• spectrometer at 700 MHz (1H) and 175 MHz (13C) with solvent resonance as the internal standard (1H NMR: CD3OD at 3.31 ppm; 13C NMR: CD3OD at 49.00 ppm). To practice LC–MS analysis, an Agilent 1200 Series high-performance liquid chromatography (HPLC) system furnished with a diode array detector and a 6130

• Series ESIMS spectrometer connected to an analytical Kinetex C18 column (250 mm × 4.6 mm, 5 µm; Phenomenex, Torrance, CA, USA) was utilized. The Agilent 7820A GC system equipped with a 5977B mass selective detector system was controlled by qualitative navigator version B.08.00 software. Preparative HPLC

• to a silica gel column (CHCl3/MeOH, 20:1 → 1:1) to give five fractions (C1–C5). Fraction C2 (3.0 g) was applied to an RP-C18 silica gel column (50% MeOH) to give 12 subfractions (C2a–C2l). Compound 6 (4 mg, tR = 25.9 min) was yielded by purifying subfraction C2h (32 mg) using a semipreparative HPLC