Salicylic Acid sans Aspirin in Animals and Man: Persistence in Fasting and Biosynthesis from Benzoic Acid

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Abstract

Salicylic acid (SA), which is central to defense mechanisms in plants and the principal metabolite of aspirin, occurs naturally in man with higher levels of SA and its urinary metabolite salicyluric acid (SU) in vegetarians overlapping with levels in patients on low-dose aspirin regimens. SA is widely distributed in animal blood. Fasting for major colorectal surgery did not cause disappearance of SA from plasma, even in patients following total proctocolectomy. A ¹³C ₆ benzoic acid load ingested by six volunteers led, between 8 and 16 h, to a median 33.9% labeling of urinary salicyluric acid. The overall contribution of benzoic acid (and its salts) to the turnover of circulating SA thus requires further assessment. However, that SA appears to be, at least partially, an endogenous compound should lead to reassessment of its role in human (and animal) pathophysiology.

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Rapid planetesimal formation in turbulent circumstellar discs

Anders Johansen, Jeffrey S. Oishi, Mordecai-Mark Mac Low … (2007)

The initial stages of planet formation in circumstellar gas discs proceed via dust grains that collide and build up larger and larger bodies (Safronov 1969). How this process continues from metre-sized boulders to kilometre-scale planetesimals is a major unsolved problem (Dominik et al. 2007): boulders stick together poorly (Benz 2000), and spiral into the protostar in a few hundred orbits due to a head wind from the slower rotating gas (Weidenschilling 1977). Gravitational collapse of the solid component has been suggested to overcome this barrier (Safronov 1969, Goldreich & Ward 1973, Youdin & Shu 2002). Even low levels of turbulence, however, inhibit sedimentation of solids to a sufficiently dense midplane layer (Weidenschilling & Cuzzi 1993, Dominik et al. 2007), but turbulence must be present to explain observed gas accretion in protostellar discs (Hartmann 1998). Here we report the discovery of efficient gravitational collapse of boulders in locally overdense regions in the midplane. The boulders concentrate initially in transient high pressures in the turbulent gas (Johansen, Klahr, & Henning 2006), and these concentrations are augmented a further order of magnitude by a streaming instability (Youdin & Goodman 2005, Johansen, Henning, & Klahr 2006, Johansen & Youdin 2007) driven by the relative flow of gas and solids. We find that gravitationally bound clusters form with masses comparable to dwarf planets and containing a distribution of boulder sizes. Gravitational collapse happens much faster than radial drift, offering a possible path to planetesimal formation in accreting circumstellar discs.

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The Dicke Quantum Phase Transition with a Superfluid Gas in an Optical Cavity

Ferdinand Brennecke, Tilman Esslinger, Christine Guerlin … (2009)

A phase transition describes the sudden change of state in a physical system, such as the transition between a fluid and a solid. Quantum gases provide the opportunity to establish a direct link between experiment and generic models which capture the underlying physics. A fundamental concept to describe the collective matter-light interaction is the Dicke model which has been predicted to show an intriguing quantum phase transition. Here we realize the Dicke quantum phase transition in an open system formed by a Bose-Einstein condensate coupled to an optical cavity, and observe the emergence of a self-organized supersolid phase. The phase transition is driven by infinitely long-ranged interactions between the condensed atoms. These are induced by two-photon processes involving the cavity mode and a pump field. We show that the phase transition is described by the Dicke Hamiltonian, including counter-rotating coupling terms, and that the supersolid phase is associated with a spontaneously broken spatial symmetry. The boundary of the phase transition is mapped out in quantitative agreement with the Dicke model. The work opens the field of quantum gases with long-ranged interactions, and provides access to novel quantum phases.

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Pathway of Salicylic Acid Biosynthesis in Healthy and Virus-Inoculated Tobacco.

N Yalpani, J. Leon, M Lawton … (1993)

Salicylic acid (SA) is a likely endogenous regulator of localized and systemic disease resistance in plants. During the hypersensitive response of Nicotiana tabacum L. cv Xanthi-nc to tobacco mosaic virus (TMV), SA levels rise dramatically. We studied SA biosynthesis in healthy and TMV-inoculated tobacco by monitoring the levels of SA and its likely precursors in extracts of leaves and cell suspensions. In TMV-inoculated leaves, stimulation of SA accumulation is accompanied by a corresponding increase in the levels of benzoic acid. 14C-Tracer studies with cell suspensions and mock-or TMV-inoculated leaves indicate that the label moves from trans-cinnamic acid to SA via benzoic acid. In healthy and TMV-inoculated tobacco leaves, benzoic acid induced SA accumulation. o-Coumaric acid, which was previously reported as a possible precursor of SA in other species, did not increase SA levels in tobacco. In healthy tobacco tissue, the specific activity of newly formed SA was equal to that of the supplied [14C]benzoic acid, whereas in TMV-inoculated leaves some isotope dilution was observed, presumably because of the increase in the pool of endogenous benzoic acid. We observed accumulation of pathogen-esis-related-1 proteins and increased resistance to TMV in benzoic acid- but not in o-coumaric acid-treated tobacco leaves. This is consistent with benzoic acid being the immediate precursor of SA. We conclude that in healthy and virus-inoculated tobacco, SA is formed from cinnamic acid via benzoic acid.

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Author and article information

Journal

Journal ID (nlm-ta): J Agric Food Chem

Journal ID (publisher-id): jf

Journal ID (coden): jafcau

Title: Journal of Agricultural and Food Chemistry

Publisher: American Chemical Society

ISSN (Print): 0021-8561

ISSN (Electronic): 1520-5118

Publication date (Electronic): 20 November 2008

Publication date (Print): 24 December 2008

Volume: 56

Issue: 24

Pages: 11648-11652

Affiliations

Dumfries and Galloway Royal Infirmary, Bankend Road, Dumfries DG1 4AP, United Kingdom, and Centre for Chemical Sciences, Royal Holloway, Egham TW20 0EX, United Kingdom

Author notes

[* ] Corresponding author (e-mail Gwen.baxter@ 123456nhs.net ).

[†]

Deceased.

[§]

Dumfries and Galloway Royal Infirmary.

[#]

Centre for Chemical Sciences.

Article

DOI: 10.1021/jf800974z

PMC ID: 2800778

PubMed ID: 19053387

SO-VID: 0305f516-87b8-42ad-9b65-0f3d1cfdb8b3

License:

This is an open-access article distributed under the ACS AuthorChoice Terms & Conditions. Any use of this article, must conform to the terms of that license which are available at http://pubs.acs.org.