Inhibition of hematopoietic prostaglandin D2 Synthase (H-PGDS) by an alkaloid extract from Combretum molle

Abstract

BackgroundHematopoietic prostaglandin D2 synthase (H-PGDS, GST Sigma) is a member of the glutathione S-transferase super family of enzymes that catalyses the conjugation of electrophilic substances with reduced glutathione. The enzyme catalyses the conversion of PGH2 to PGD2 which mediates inflammatory responses. The inhibition of H-PGDS is of importance in alleviating damage to tissues due to unwarranted synthesis of PGD2. Combretum molle has been used in African ethno medicinal practices and has been shown to reduce fever and pain. The effect of C. molle alkaloid extract on H-PGDS was thus, investigated.MethodsH-PGDS was expressed in Escherichia coli XL1-Blue cells and purified using nickel immobilized metal affinity chromatography. The effect of C. molle alkaloid extract on H-PGDS activity was determined with 1-chloro-2, 4-dinitrobenzene (CDNB) as substrate. The effect of C. molle alkaloid extract with time on H-PGDS was determined. The mechanism of inhibition was then investigated using CDNB and glutathione (GSH) as substrates.ResultsA specific activity of 24 μmol/mg/min was obtained after H-PGDS had been purified. The alkaloid extract exhibited a 70% inhibition on H-PGDS with an IC50 of 13.7 μg/ml. C. molle alkaloid extract showed an uncompetitive inhibition of H-PGDS with Ki = 41 μg/ml towards GSH, and non-competitive inhibition towards CDNB with Ki = 7.7 μg/ml and Ki′ = 9.2 μg/ml.ConclusionThe data shows that C. molle alkaloid extract is a potent inhibitor of H-PGDS. This study thus supports the traditional use of the plant for inflammation.

In vivo and in vitro inhibition of rat liver glutathione transferases activity by extracts from Combretum zeyheri (Combretaceae) and Parinari curatellifolia (Chrysobalanaceae)

“…Chemicals with antioxidant properties have the capacity to induce glutathione transferases in vitro and in vivo through the bZIP transcription factor (Nrf2) and the antioxidant response element (ARE) [ 36 , 37 ]. Moyo et al, [ 38 ] showed that another Combretum species, Combretum molle inhibited human recombinant hematopoietic prostaglandin D2 synthase (GST sigma) in vitro, an enzyme that is involved in the synthesis of prostaglandin D2. Combretum leprosum -derived triterpenes have been shown to have anti-inflammatory effects in mice [ 39 ].…”

Suppression of Selective Voltage-Gated Calcium Channels Alleviates Neuronal Degeneration and Dysfunction through Glutathione S-Transferase-Mediated Oxidative Stress Resistance in a Caenorhabditis elegans Model of Alzheimer’s Disease

“…However, genes associated with GST activity ( gstk-1 ) and glutathione peroxidase activity ( pgx-7 ) were significantly downregulated in nimodipine-treated CL2355 worms as compared to untreated controls. HPGDS (GST Sigma) catalyzes glutathione conjugation to molecules and plays a role in prostaglandin D2 biosynthesis, associated with the inflammatory response [ 33 , 34 ]. GST is a large family generally involved in detoxification and removal of oxidative stress.…”

Protocatechuic Acid and Syringin from Saussurea neoserrata Nakai Attenuate Prostaglandin Production in Human Keratinocytes Exposed to Airborne Particulate Matter

“…L-PGDS is a monomeric protein present in several mammalian central nervous system tissues and the male genital organs; in contrary, it is abundant in cerebrospinal fluid [60]. Hematopoietic prostaglandin D synthase (H-PGDS) is a member of the sigma-class of glutathione-S-transferases (GST) [61]. H-PGDS is expressed in various immune and inflammatory cells, such as mast cells in rat model and type 2 T lymphocytes in human cell lines [62,63].…”