Tolyporphins A–R, unusual tetrapyrrole macrocycles in a cyanobacterium from Micronesia, assessed quantitatively from the culture HT-58-2

O’Donnell, Timothy J.; Gurr, Joshua R.; Dai, Jingqiu; Taniguchi, Masahiko; Williams, Philip G.; Lindsey, Jonathan S.

doi:10.1039/d1nj02108g

Cited by 17 publications

(42 citation statements)

References 46 publications

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“…The appearance of dioxobacteriochlorin CuBC-3 was observed by absorption spectroscopy when the reaction time was extended to as little as 90 s. The unexpected oxidation of the methylene group flanking the gem-dimethyl group highlights the sensitivity of this site, which has been referred to as the Achilles' heel of the hydroporphyrins [49]. Dioxobacteriochlorins have been prepared previously [50] and are of fundamental interest including as the core chromophore of the naturally occurring macrocycles known as tolyporphins, which are found in a cyanobacterium [51]. The nature of the oxidant underlying the formation of dioxobacteriochlorin in this small-scale reaction (1.0-2.0 mg) is not known.…”

Section: Resultsmentioning

confidence: 99%

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

et al. 2022

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Site-specific introduction of isotopes in tetrapyrrole macrocycles provides the foundation for probing physicochemical features germane to photosynthetic energy-transduction processes, but has chiefly been done with porphyrins rather than the more biologically relevant hydroporphyrin analogues of native photosynthetic pigments. A prior study incorporated pairwise 13C or 15N atoms in the skeleton of a bacteriochlorin containing a gem-dimethyl group in each pyrroline ring. Here, a complementary effort is reported that installs deuterium atoms in substituents at the perimeter of a bacteriochlorin. Thus, perdeuteriated 3-methyl-2,4-pentanedione was converted in an 8-step synthesis via the intermediacy of tert-butyl 5-formyl-3,4-bis(trideuteriomethyl)pyrrole-2-carboxylate to the 2,3,12,13-tetrakis(trideuteriomethyl)-8,8,18,18-tetramethylbacteriochlorin (BC-2). The fidelity of isotope substitution was maintained throughout the synthesis. Resonance Raman spectroscopy of the copper chelate (CuBC-2) revealed that addition of the four β-pyrrolic substituents alone is not sufficient to account for the vibronic complexity observed for the copper chelate of bacteriochlorophyll a (CuBChl a). The increased vibronic activity exhibited by the natural pigments and CuBChl a must arise from the increased structural complexity of the macrocycle.

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Section: Resultsmentioning

confidence: 99%

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

et al. 2022

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“…4-Carboethoxy-(E)-2-[(4,4-dimethyl-5-methylenedihydrofuran-2(3H)ylidene)methyl]pyrrole (4). Following a reported procedure 20 with some modification, a solution of TiCp 2 Cl 2 (12.0 g, 48.2 mmol) in toluene (125 mL) under an argon atmosphere was treated dropwise with MeLi (67 mL of 1.6 M solution in Et 2 O, 0.11 mol) over 15 min at 0 1C.…”

Section: Synthetic Proceduresmentioning

confidence: 99%

“…3 The chief bacteriochlorophylls are denoted a , b , and g , 1 whereas the tolyporphins include 14 bacteriochlorin members (A–J, L–O). 4 The structures of bacteriochlorophyll a and tolyporphin A are shown in Chart 1. Total syntheses of bacteriochlorophylls and tolyporphins are not yet available.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of bacteriochlorins bearing diverse β-substituents

et al. 2022

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“…To date, the culture (HT-58-2) from Micronesia is the only known producer of tolyporphins. Examination of the culture (16) has revealed that (i) the cyanobacterium is filamentous, (ii) the culture is non-axenic, (iii) community bacteria are attached to the cyanobacterium sheath (17) and (iv) a high level of production of tolyporphins is only achieved under selected growth conditions (18,19). One of the selected growth conditions entails a restricted supply of nitrate in the medium for periods of 5-8 weeks.…”

Section: Introductionmentioning

confidence: 99%

“…1(c). Most tolyporphins that contain a dioxobacteriochlorin chromophore exhibit a Q y maximum near 667 nm (18,19), to be compared with chlorophyll a at 666 nm in methanol (661 nm in diethyl ether) (22). Data are not available concerning how various growth conditions might alter the ratio of the various tolyporphins, which could impose an additional uncertainty in the analysis.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

Nguyen

Zhang

Taniguchi

et al. 2021

Photochem & Photobiology

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Tolyporphins are distinctive tetrapyrrole natural products found singularly in a filamentous cyanobacterial‐microbial holobiont (termed HT‐58‐2) from Micronesia. The absorption and fluorescence features of tolyporphins resemble those of chlorophyll a, complicating direct analysis of culture samples. Treatment of the crude (unfractionated) organic extract (CH2Cl2/2‐propanol, 1:1) of HT‐58‐2 cultures with NaBH4 in methanol causes reduction of the peripheral ketone auxochromes, whereupon tolyporphins (predominantly 7,17‐dioxobacteriochlorins) exhibit a bathochromic shift (λabs ˜ 676 → ˜ 700 nm) and chlorophyll a (a 131‐oxochlorin) exhibits a hypsochromic shift (λabs 665 → 634 nm). Fluorescence excitation spectroscopy (at 368 and 491 nm with λem 710 nm) enabled detection of reduced tolyporphins amidst abundant reduced chlorophyll a (1:19 ratio), a detection sensitivity >5 times that without reduction. The resulting assay combines simple sample preparation from non‐axenic cultures at microscale quantities (2 mL, 2 μm), absence of any fractionation procedures, and fluorescence detection. Tolyporphins were readily detected in cultures of HT‐58‐2 at reasonable growth periods in the absence of environmental stressors, which was not possible previously.

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Tolyporphins A–R, unusual tetrapyrrole macrocycles in a cyanobacterium from Micronesia, assessed quantitatively from the culture HT-58-2

Abstract: Tolyporphins A–R are the newest additions to the family of native tetrapyrroles. LC-MS-dMRM and absorption spectroscopy have been employed for analysis of mixtures containing the 18 distinctive natural products.

Cited by 17 publications

References 46 publications

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

Synthesis of bacteriochlorins bearing diverse β-substituents

Fluorescence Assay for Tolyporphins Amidst Abundant Chlorophyll in Crude Cyanobacterial Extracts

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