Supporting Information Light-Induced Hydrogen Sulfide release from Caged gem-dithiols elmi O. Devarie-Baez, Powell E. Bagdon, Bo Peng, Yu Zhao, Chung-Min Park and Ming Xian* Department of Chemistry, Washington State University, Pullman, WA 99164, USA Contents Materials and Methods 2 Experimental Procedures and Compound Characterization Data 2-8 1 H MR and 13 C MR...9-16 1
MATERIALS AD METHODS Reactions were carried out in dried-round bottom flasks. All solvents were reagent grade. Anhydrous tetrahydrofuran (THF) and methylene chloride (CH 2 Cl 2 or DCM) were obtained by running HPLC grade solvent through a Pure Solv MD-3 Solvent Purification System from Innovative Technology (under an argon atmosphere). Reactions were magnetically stirred and monitored by thin layer chromatography (TLC) with 0.25 mm pre-coated silica gel plates. Flash chromatography was performed with silica gel 60 (particle size 0.040 0.062mm). Yields refer to chromatographically and spectroscopically pure compounds, unless otherwise stated. Proton and carbon-13 MR spectra were recorded on 300 MHz spectrometer. Chemical shifts are reported relative to chloroform (δ 7.26) for 1 H MR and chloroform (δ 77.0) 13 C MR. 1. Experimental Procedures and Compound Characterization Data 1. 1 General procedure for the preparation of compound 4 and 4 3: To a solution of 2-nitrobenzyl bromide (27.8 mmol, 6.0 g) in dry THF (100 ml) was added 1.2 equivalents of thiourea (31.5 mmol, 2.4 g). The resulting heterogeneous mixture was stirred overnight at room temperature. White precipitates were formed, which were filtered and washed thoroughly with ethyl acetate. The white solid was dried under vacuo to provide 2 (7.9 g). Yield: 97%. 1 H MR (300 MHz, CD 3 OD) 8.15 (dd, J= 8.1 Hz, J= 1.5 Hz, 1H), 7.70-7.79 (m, 2H), 7.61-7.66 (m, 1H), 4.89 (br, 2H), 4.78 (s, 2H); 13 C MR (75 MHz, CD 3 OD) δ 170.6, 148.4, 134.2, 132.4, 130.1, 130.0, 125.7, 33.2; FTIR (cm -1 ) 3296, 3266, 3087, 2988, 1639, 1513, 1433, 1350, 1064, 794; mass spectrum (ESI-MS) m/z 211.9; [M] + C 8 H 10 3 O 2 S: calcd for: 212.0. 2
4: To a suspension of 3 (14.7 mmol, 4.29 g) in dichloromethane (80 ml)/water (60 ml) was added 4 equivalents of sodium metabisulfite (a 2 S 2 O 5, 58.8 mmol, 11.2 g). The resulting heterogeneous mixture was refluxed for 4 hr under argon atmosphere. After cooled the solution to room temperature the mixture was partitioned and separated. The aqueous layer was washed once with DCM (20 ml). The combined organic layers were dried over anhydrous a 2 SO 4, filtered and concentrated. Compound 4 was obtained in 2.44 g. Yield: 98%. 1 H MR (300 MHz, CDCl 3 ) 8.00 (dd, J= 8.1 Hz, J= 1.5 Hz, 1H), 7.58 (m, td, J= 7.8 Hz, J= 1.5 Hz, 1H), 7.39-7.49 (m, 2H), 4.00 (d, J= 8.4 Hz, 2H), 2.14 (t, J= 7.8 Hz, 1H); 13 C MR (75 MHz, CDCl 3 ) δ 147.7, 136.9, 133.8, 133.7, 131.5, 128.2, 44.4, 26.4; FTIR (cm -1 ) 3106, 2961, 2852, 2589, 2566, 1608, 1578, 1517, 1350, 1140, 787. 1. 2 General procedure for the preparation of photo-activated donors 1a: To a solution of acetone (1 mmol, 73.4 μl) and o-nitrobenzylmercaptan (2.5 mmol, 433 mg) in CHCl 3 (4 ml) was added 0.20-0.30 equivalents of TiCl 4 at -10 C. Instantly, the solution turned yellowish color with a precipitate formation. The resulting reaction mixture was allowed to warm-up slowly to room temperature and stirred overnight or until the consumption of the corresponding ketone (monitored by TLC). To the resulting heterogeneous mixture was then added brine (5 ml) and DCM (15 ml). The organic layer was separated, dried over anhydrous a 2 SO 4, filtered and concentrated. Purification by flash chromatography (2-4% EtOAc/hexanes) afforded 1a (300 mg). Yield: 79%. 1 H MR (300 MHz, CDCl 3 ) 7.95 (d, J= 7.8 Hz, 2H), 7.53-7.57 (m, 4H), 7.37-7.43 (m, 2H), 3
4.14 (s, 4H), 1.58 (s, 6H); 13 C MR (75 MHz, CDCl 3 ) δ 148.9, 133.5, 133.1, 132.6, 128.1, 125.1, 57.0, 32.2, 30.5; FTIR (cm -1 ) 3070, 2960, 2922, 2865, 1607, 1573, 1519, 1459, 1345, 1110, 720; mass spectrum (ESI-MS) m/z 401.1; [M+a] + C 17 H 18 2 ao 4 S 2 : calcd for: 401.1. 1b was prepared according the procedure outlined for 1a: Yield: 77%. 1 H MR (300 MHz, CDCl 3 ) 7.95 (d, J= 8.1 Hz, 2H), 7.52-7.54 (m, 4H), 7.37-7.43 (m, 2H), 4.15 (s, 4H), 1.83-185 (m, 4H), 1.72-1.75 (m, 4H); 13 C MR (75 MHz, CDCl 3 ) δ 148.9, 133.9, 133.1, 132.7, 128.1, 125.1, 67.2, 41.3, 32.9, 24.1; FTIR (cm -1 ) 3070, 2974, 2858, 1604, 1572, 1516, 1357, 1349, 1165, 953, 786; (mass spectrum (ESI-MS) m/z 427.1; [M+a] + C 19 H 20 2 ao 4 S 2 : calcd for : m/z 427.1. 1c was prepared according the procedure outlined for 1a: Yield: 74%. 1 H MR (300 MHz, CDCl 3 ) 7.94 (d, J= 7.8 Hz, 2H), 7.53-7.55 (m, 4H), 7.37-7.41 (m, 2H), 4.13 (s, 4H), 1.81-1.85 (m, 4H), 1.54-1.60 (m, 4H), 1.39-1.44 (m, 2H); 13 C MR (75 MHz, CDCl 3 ) δ 149.0, 133.7, 133.1, 132.7, 128.1, 125.0, 63.4, 37.6, 30.6, 25.4, 22.2; FTIR (cm - 1 ) 3064, 2940, 2848, 1608, 1572, 1520, 1424, 1346, 1125, 857, 710; mass spectrum (ESI- MS) m/z 441.1; [M+a] + C 20 H 22 2 ao 4 S 2 : calcd for: 441.1. Preparation of 1d: 4
1d was prepared according the procedure outlined for 1a. It was then used to prepare 1d. To a solution of 1d (0.181 mmol, 84 mg) in THF/H 2 O (4 ml/1ml) was added 3 equivalents of lithium hydroxide monohydrate (LiOH. H 2 O, 0.542 mmol, 23 mg) at 0 C. The mixture was warmed up to room temperature and stirred overnight. Then the solution was treated with 1 M HCl (5 ml) and diluted with ethyl acetate (15 ml). The organic layer was separated and washed once with 1 M HCl (5 ml), dried over anhydrous a 2 SO 4, filtered and concentrated. A yellow residue was obtained and subjected to column chromatography (100% DCM to 1% MeOH/DCM). 1d was obtained as a yellowish oil. Yield: 72% over two steps. 1 H MR (300 MHz, CDCl 3 ) 7.97 (d, J= 8.1 Hz, 2H), 7.53-7.59 (m, 4H), 7.39-7.46 (m, 2H), 4.16 (m, 4H), 2.55 (t, J= 7.8 Hz, 2H), 2.09 (t, J= 7.8 Hz, 2H), 1.52 (s, 3H); 13 C MR (75 MHz, CDCl 3 ) δ 178.9, 148.9, 133.2, 133.1, 132.6, 128.3, 125.2, 60.7, 35.1, 31.7, 29.3, 26.8; FTIR (cm -1 ) 3500-2500 (br, carbonyl OH) 3068, 2970, 2925, 1708, 1610, 1524, 1348, 1170, 780; mass spectrum (ESI-MS) m/z 459.1; [M+a] + C 19 H 20 2 ao 6 S 2 : calcd for : 459.1. 1e was prepared according the procedure outlined for 1a: Yield: 24%. 1 H MR (300 MHz, CDCl 3 ) 7.92 (dd, J= 1.5 Hz, 8.1 Hz, 2H), 7.56 (dt, J= 3.3 Hz, 9.0 Hz, 2H), 7.30-7.48 (m, 6H), 6.79 (dt, J= 3.6 Hz, 8.7 Hz, 2H), 3.99-4.13 (m, 4H), 3.80 (s, 3H), 2.05 (s, 3H); 13 C MR (75 MHz, CDCl 3 ) δ 158.8, 148.7, 133.3, 133.0, 132.6, 128.2, 128.0, 125.0, 113.5, 62.3, 55.3, 32.9, 30.5; FTIR (cm -1 ) 3069, 2968, 1606, 1576, 1526, 1344, 5
1251, 1174, 836, 709; mass spectrum (ESI-MS) m/z 492.9; [M+a] + C 23 H 22 2 ao 5 S 2 : calcd for: 493.1. 1f was prepared according the procedure outlined for 1a: Yield: 88%. 1 H MR (300 MHz, CDCl 3 ) 8.06 (dt, J= 3.0 Hz, 9.0 Hz, 2H), 7.93 (dd, J= 1.5 Hz, 7.8 Hz, 2H), 7.78 (dt, J= 2.7 Hz, 9.0 Hz, 2H), 7.30-7.48 (m, 6H), 4.05-4.19 (m, 4H), 2.03 (s, 3H); 13 C MR (75 MHz, CDCl 3 ) δ 150.2, 149.0, 147.0, 133.4, 132.8, 132.7, 128.7, 128.2, 125.5, 123.6, 62.1, 33.2, 30.6; FTIR (cm -1 ) 3072, 2968, 2855, 1606, 1596, 1516, 1436, 1336, 1066, 849, 707; mass spectrum (ESI-MS) m/z 507.9; [M+a] + C 22 H 19 3 ao 6 S 2 : calcd for: 508.1. 2. General procedure for profiling H 2 S release of photo-activated donors 2.1 Calibration curve for the methylene blue method A 5 mm solution of a 2 S in sodium phosphate buffer (20 mm, ph 7.4)/acetonitrile (HPLC grade) (1:1) was prepared (a 2 S. 9H 2 O, 120.20 mg in 100 ml volumetric flask) and used as the stock solution. Aliquots of 50, 100, 200, 400, 600, 800, 1000, 1500 μl of the a 2 S stock solution were added into a 50 ml volumetric flask and dissolved in a mixture of sodium phosphate buffer/acetonitrile to obtain the standard solutions in 5, 10, 20, 40, 60, 80, 100, 150 μm, respectively. 1 ml aliquot of the respective solution was reacted with the methylene blue (MB+) cocktail: 30 mm FeCl 3 (200 μl) in 1.2 M HCl, 20 mm of,-dimethyl-1,4- phenylenediamine sulfate (200 μl) in 7.2 mm HCl, 1% w/v of Zn(OAc) 2 (100 μl) in H 2 O at room temperature for at least 15 min (each reaction was performed in triplicate). The absorbance of methylene blue was measured at λ max = 663 nm in an Evolution 300 UV-Vis spectrophotometer (Thermo Fisher Scientific). To 6
obtain the molar absorptivity of MB+ a absorbance and concentration n. linear regression was plotted with the observed The mechanism of the Methylene Blue Assay 1 H 2-2e - -H + +2e - +H + H H 2 S H SH H H 2 SH H DMPD + DMPD DMPD-SH -2e - -H+ H 2 S H H H 2 S H 2 H S H 2 S - H 3 S S H 2 H 1 Lawrence,. S.; Davis, J. D.; Jones, T. G. J.; Davies, S..; Compton, R. G. Electroanalysis, 2000, 12, 1453 1460. 7
2.2 Determination of H 2 S release of donors H 2 S-release capability of donors was measured using the methylene blue (MB+) method. In this experiment, a 200 μm solution (total volume 20 ml) of the respective substrate was prepared in a 1:1 solution of sodium phosphate buffer (20 mm, ph 7.4)/acetonitrile. This solution was placed in a 24 ml scintillation vial. The resulting reaction vessel was placed in a water bath at room temperature. Photo-irradiation was performed in a Rayonet Photochemical reactor (9 bulbs, RPR-3500). Irradiation was seceded for about 1 min to obtain aliquots (1 ml). The aliquot was mixed immediately with the methylene blue cocktail: 30 mm FeCl 3 (200 μl) in 1.2 M HCl, 20 mm of,-dimethyl-1,4- phenylenediamine sulfate (200 μl) in 7.2 mm HCl, 1% w/v of Zn(OAc) 2 (100 μl) in H 2 O at room temperature for at least 20 min. The absorbance of methylene blue was measured at λ max = 663 nm against a blank: 30 mm FeCl 3 (200 μl) in 1.2 M HCl, 20 mm of,-dimethyl-1,4- phenylenediamine sulfate (200 μl) in 7.2 mm HCl, 1% w/v of Zn(OAc) 2 (100 μl) in H 2 O, AC (500 μl), 20 mm sodium phosphate buffer ph 7.4 (500 μl), in an Evolution 300 UV-Vis spectrophotometer (Thermo Fisher Scientific). Experiments performed in the absence of UV-light were executed in a similar fashion. 2.3 H 2 S release capability measured by WSP-1 In this experiment, a 200 μm solution (total volume 20 ml) of the respective substrate was prepared in a 1:1 solution of sodium phosphate buffer (20 mm, ph 7.4)/acetonitrile. The solution was placed in a 24 ml scintillation vial. The resulting reaction vessel was placed in a water bath at room temperature. Photo-irradiation was performed in a Rayonet Photochemical reactor (9 bulbs, RPR-3500). Irradiation was seceded for about 1 min to obtain aliquots (1 ml). The respective aliquot was mixed immediately with WSP-1 (final concentration= 100 μm) at room temperature and stirred for at least 20 min in the dark. A 900 μl aliquot was taken and diluted in 2 ml of a 1:1 solution of sodium phosphate buffer (20 mm, ph 7.4)/acetonitrile. The fluorescent intensity was recorded at λ em = 516 nm in a Cary Eclipse Fluorescence spectrophotometer (Agilent Technologies). The blank was prepared by mixing 1 ml of a 1:1 sodium phosphate buffer (20 mm, ph 8
7.4)/acetonitrile solution with WSP-1 (final concentration= 100 μm). performed in the absence of UV-light were executed in a similar fashion. Experiments Structure and mechanism of WSP-1. 3. Profiling H 2 S generation of 1d in HeLa cells HeLa cells were cultured in DMEM high glucose medium supplemented with 10% fetal bovine serum (FBS) at 37 C under an atmosphere of 5% CO2 and 95% air. The cells were rinsed with FBS-free medium, and co-incubatedd with 200 μm 1d (stock solution, 20 mm in DMSO) in FBS-free medium at 37 C for 30 min. Then the mixture was irradiated for 15 min with three handheld lamps (entela, UVGL-15, 365 nm, 4-watts each) that were placed ~1.5 inches above the cell dish. After that the mediumm was removed, the cells were washed once with PBS (10 mm) and incubatedd with 50 μmm WSP-1 (stock solution, 2.5 mm in DMSO) and 100 μm CTAB (stock solution, 10 mm in 10% EtOH/water) in PBS (10 mm) for 30 min. The medium was removed, cells were washed twice and suspended in fresh PBS (10 mm). The fluorescence signal was imaged with an Evos microscope using the GFP i channel (Advanced Microscopy Group). For the control, the cells were prepared as stated above and never exposed to UV-light. s fl 4. 1 H and 13 C MR spectrum 9
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