9-Deoxy-delta 9, delta 12-13,14-dihydroprostaglandin D2, a metabolite of prostaglandin D2 formed in human plasma.

Abstract

Incubation of prostaglandin D2 (PGD2) with human plasma yielded a product that has been identified as 9-deoxy-9,10-didehydro-12,13-cdidehydro-13,14-dihydro-PGD2(9-deoxy-_9,9'2-13,14-dihydro-PGD2). The identification was based on mass spectrometry, UV spectrometry, mobilities and retention time on TLC and HPLC, and NMR. The conversion of PGD2 to this product was dependent on the incubation time and the amount of plasma added to a reaction mixture and was abolished by prior boiling. The conversion rate of PGD2 to this metabolite was 0.03 nmol/min per mg of protein of whole plasma at pH 8.0 at 37°C. Similar conversion was also found by incubating PGD2 with human serum albumin added at the concentration found in plasma. These results suggest that the conversion of PGD2 to this product is catalyzed by the enzymatic action of a plasma protein, probably serum albumin. The biological activities of this compound were examined in several systems. It showed negligible activity in inhibition of human platelet aggregation and relaxation of rabbit stomach strip. On the other hand, it exhibited a three times stronger inhibitory activity (IC50, 1.8 ,M) than PGD2 (IC50, 5 ,uM) on the growth of L-1210 cultured cells.Prostaglandin (PG) D2 is formed in a variety of tissues and cells and modulates their functions under various physiological and pathological conditions. For example, it is produced during platelet aggregation and works as a negative feedback modulator of the aggregation process (1-3). It is produced by mast cells during IgE stimulation and modifies the anaphylaxis process (4, 5). It is also produced in the central nervous system of mammals and is involved in brain functions such as hypothermia, sleep, and luteinizing hormone secretion (6-10). A potential antineoplastic effect of PGD2 has been reported (11) and it has been found that 9-deoxy-A9-PGD2, a dehydration product of PGD2, has about three times stronger growth inhibitory effect than PGD2 on L-1210 leukemia cultured cells (12). The present study was undertaken to explore the possible formation of this PGD2 dehydration product in mammals. We report here the conversion in human plasma of PGD2 to a compound that has been identified as 9-deoxy-A9,A12-13,14-dihydro-PGD2 and describe some properties of this metabolite.$ MATERIALS AND METHODS Materials. [5,6,8,9,12,14,15-3H]PGD2 (100 Ci/mmol; 1 Ci = 37 GBq) was purchased from New England Nuclear. PGB2, PGD2, and 9-deoxy-A9-PGD2 were synthetic products from Ono Pharmaceutical (Osaka, Japan All other chemicals were of reagent grade.Pregaration of 9-Deoxy-A9,Al2-13,14-dihydro-PGD2. 9-Deoxy-A -GD2 was synthesized as described (12), and conversion of 9-deoxy-A9-PGD2 to 9-deoxy-A9,A&12-13,14-dihydro-PGD2 was carried out as described by Bundy et al. (13) for the conversion of PGD2 to A12-13,14-dihydro-PGD2. 9-Deoxy-A9-PGD2 (48 mg) was dissolved in 3 ml of tetrahydrofuran and the solution was stirred at 4°C. 1,5-Diazabicyclo(4.3.0)non-5-ene (17.8 mg) in 0.18 ml of tetrahydrofuran was added to the solution and the mixtu...

UVB light upregulates prostaglandin synthases and prostaglandin receptors in mouse keratinocytes

“…Decreased production of PGD 2 is consistent with an earlier report demonstrating that UVB suppressed production of this arachidonic acid metabolite in hairless mouse skin (Ruzicka et al, 1983). PGD 2 is relatively unstable and degrades by spontaneous dehydration and isomerization reactions to PGJ 2 which is metabolized to a variety of biological active metabolites (Kikawa et al, 1984). Increased levels of PGJ 2 in keratinocytes after UVB may be due to increased PGD 2 biosynthesis (see Figure 1).…”

Δ12-Prostaglandin J2, a Plasma Metabolite of Prostaglandin D2, Causes Eosinophil Mobilization from the Bone Marrow and Primes Eosinophils for Chemotaxis

“…PGD 2 is a major mast cell mediator released during the allergic response (5), and recently, PGD 2 and some of its metabolites have been characterized as potent chemoattractants of eosinophils, basophils, and subsets of Th2 lymphocytes through a novel receptor, CRTH2 (6,7). In the present study we show that the PGD 2 metabolite ⌬ 12 -PGJ 2 , which is present in human plasma (12,13), not only induces chemotaxis and respiratory burst of eosinophils, but also mobilizes eosinophils from the bone marrow and effectively facilitates their migration toward other chemoattractants, thus suggesting two novel roles of PGD 2 metabolites in the regulation of eosinophil function in allergic disease.…”

“…These degradation products of PGD 2 are, however, also present in plasma (12,13) and might therefore have important systemic effects on the allergic response. We found that ⌬ 12 -PGJ 2 caused eosinophil mobilization from the bone marrow with similar magnitude as reported for eotaxin and IL-5 (26).…”

“…The apparent half-life of PGD 2 in the blood has been reported to be 1.5 min (11), and PGD 2 is rapidly metabolized in plasma to ⌬ 12 -PGJ 2 , which arises from catalytic conversion of PGJ 2 by albumin (12,13). The importance of ⌬ 12 -PGJ 2 as a systemic PGD 2 metabolite is also underlined by the fact that it can be detected in human urine in relevant amounts, which are increased after i.v.…”

An improved LC–MS/MS method for the quantification of prostaglandins E2 and D2 production in biological fluids

“…In RAW cells stimulated by LPS, COX-2 protein expression reached its peak after 24 h while PGD 2 production reached a maximum concentration at 6 h and declined thereafter. The difference in these time courses might be the result of the chemical instability of PGD 2 which can spontaneously dehydrate to form PGJ 2 [31,38] and then Δ 12 -PGJ 2 through albumin catalysis [31,39]. PGD 2 levels reflect the sum of the rates of de-novo synthesis and decomposition.…”