Martin Pošta

Docosahexaenoic acid-derived fatty acid esters of hydroxy fatty acids (FAHFAs) with anti-inflammatory properties

White adipose tissue (WAT) is a complex organ with both metabolic and endocrine functions. Dysregulation of all of these functions of WAT, together with low-grade inflammation of the tissue in obese individuals, contributes to the development of insulin resistance and type 2 diabetes. n-3 polyunsaturated fatty acids (PUFAs) of marine origin play an important role in the resolution of inflammation and exert beneficial metabolic effects. Using experiments in mice and overweight/obese patients with type 2 diabetes, we elucidated the structures of novel members of fatty acid esters of hydroxy fatty acids—lipokines derived from docosahexaenoic acid (DHA) and linoleic acid, which were present in serum and WAT after n-3 PUFA supplementation. These compounds contained DHA esterified to 9- and 13-hydroxyoctadecadienoic acid (HLA) or 14-hydroxydocosahexaenoic acid (HDHA), termed 9-DHAHLA, 13-DHAHLA, and 14-DHAHDHA, and were synthesized by adipocytes at concentrations comparable to those of protectins and resolvins derived from DHA in WAT. 13-DHAHLA exerted anti-inflammatory and proresolving properties while reducing macrophage activation by lipopolysaccharides and enhancing the phagocytosis of zymosan particles. Our results document the existence of novel lipid mediators, which are involved in the beneficial anti-inflammatory effects attributed to n-3 PUFAs, in both mice and humans.

Do fire-related cues, including smoke-water, karrikinolide, glyceronitrile and nitrate, stimulate the germination of 17 Anigozanthos taxa and Blancoa canescens (Haemodoraceae)?

Many species in fire-prone environments germinate after fire including most taxa in the genus Anigozanthos Labill. Following preliminary studies with Anigozanthos manglesii D.Don subsp. manglesii, the response of several Anigozanthos taxa to germination stimulants relating to the post-fire environment including smoke, karrikinolide (KAR1, 3-methyl-2H-furo[2,3-c]pyran-2-one) and nitrate were compared in seed when freshly collected and after a period of burial. Following after-ripening, the response of seed to water, smoke-water, KAR1 and glyceronitrile (2,3-dihydroxypropanenitrile) was examined. Seed of 16 Anigozanthos taxa, and the related monotypic genus Blancoa Lindl., were highly dormant at maturity. Investigations of eight Anigozanthos taxa and B. canescens indicated that these taxa had morphophysiological dormancy. Following a period of either 3- to 4 months or 1 year of burial and exhumation in autumn, many taxa remained dormant. However, dormancy was alleviated and smoke-water stimulated some germination of A. manglesii subsp. manglesii, A. flavidus DC., A. viridis Endl. subsp. viridis, and A. viridis Endl. subsp. Cataby (S.D. Hopper 1786). Nitrate also stimulated germination of A. flavidus in the light. Following 3–3.5 years of laboratory after-ripening, 13 of the 17 Anigozanthos taxa examined were smoke-responsive. When testing individual smoke-derived compounds these taxa germinated in response to glyceronitrile and not KAR1. In contrast, smoke-responsive B. canescens seed responded to KAR1 and not glyceronitrile. These findings suggest a phylogenetic link between responsiveness to different chemicals in smoke in this family that may shed light on the evolutionary development of these smoke responses.

Effect of smoke derivatives on in vitro pollen germination and pollen tube elongation of species from different plant families

Plant-derived smoke stimulates seed germination in numerous plant species. Smoke also has a positive stimulatory effect on pollen germination and pollen tube growth. The range of plant families affected my smoke still needs to be established since the initial study was restricted to only three species from the Amaryllidaceae. The effects of smoke-water (SW) and the smoke-derived compounds, karrikinolide (KAR1 ) and trimethylbutenolide (TMB) on pollen growth characteristics were evaluated in seven different plant families. Smoke-water (1:1000 and 1:2000 v:v) combined with either Brewbaker and Kwacks (BWK) medium or sucrose and boric acid (SB) medium significantly improved pollen germination and pollen tube growth in Aloe maculata All., Kniphofia uvaria Oken, Lachenalia aloides (L.f.) Engl. var. aloides and Tulbaghia simmleri P. Beauv. Karrikinolide (10(-6) and 10(-7) m) treatment significantly improved pollen tube growth in A. maculata, K. uvaria, L. aloides and Nematanthus crassifolius (Schott) Wiehle compared to the controls. BWK or SB medium containing TMB (10(-3) m) produced significantly longer pollen tubes in A. maculata, K. uvaria and N. crassifolius. These results indicate that plant-derived smoke and the smoke-isolated compounds may stimulate pollen growth in a wide range of plant species.

Smoke-Isolated Trimethylbutenolide Inhibits Seed Germination of Different Weed Species by Reducing Amylase Activity

Abstract Weeds pose a great problem to farmers worldwide, and controlling weeds demands a high input cost for herbicides and labor. Because of current environmental regulations, a limited number of herbicides are commercially available (with limited modes of action) to control weeds. Smoke water and the biologically active compounds isolated from smoke affect seed germination in a significant way. Smoke water (SW) and karrikinolide (KAR1, the germination stimulant isolated from smoke) have been tested extensively for their ability to promote seed germination in a vast array of plant species. In addition to KAR1, a germination inhibitor, trimethylbutenolide (TMB), was also isolated from plant-derived smoke. The effects of SW, KAR1, and TMB were tested on five major weed species of South Africa: fleabane, hairy wild lettuce, bugweed, spilanthes, and fameflower. Seeds of these weed species were subjected to 16/8 h light/dark conditions or to constant dark conditions at constant temperatures of 20, 25, 30 C and alternating 30/20 C. SW and KAR1 significantly increased germination, whereas TMB significantly inhibited germination of these weed species. Furthermore, TMB treatment reduced the amylase activity of the tested weed seeds compared with the water control. These results indicate the possibility of manipulating germination of certain weed seeds by SW, KAR1, and TMB. Thus, smoke and smoke-isolated compounds could potentially be used in new weed management strategies. Nomenclature: Karrikinolide, KAR1, 3-methyl-2H-furo[2,3c]pyran-2-one; trimethylbutenolide, TMB, 3,4,5-trimethylfuran-2(5H)-one; bugweed, Solanum mauritianum Scop.; fameflower, Talinum paniculatum (Jacq.) Gaertn.; fleabane, Conyza albida Willd. ex Sprengel; hairy cats ear, Hypochaeris radicata L.; spilanthes, Spilanthes decumbens (Sm.) A.H. Moore.

Genotoxicity testing of 3,4,5-trimethylfuran-2(5H)-one, a compound from plant-derived smoke with germination inhibitory activity

Plant-derived smoke and certain smoke compounds improve seed germination and enhance seedling growth of many species. Thus, smoke-infused water and the active smoke-derived compounds have the potential to be used in different agricultural and horticultural applications. However, despite these interesting and potentially practical properties, it should also be ascertained whether such compounds may pose a health risk, particularly if they are to be used in the production of food or fodder crops. Amongst some of the aspects that would be important to understand are any possible genotoxic properties that the compounds may possess due to potential carry-over effects. Here, we report on a genotoxicity study of 3,4,5-trimethylfuran-2(5H)-one, a compound from plant-derived smoke previously shown to have germination inhibitory activity. Using two in vitro tests, namely the bacterial VITOTOX® test (with/without S9 metabolic activation) and the cytome assay on human C3A cells, no genotoxicity or toxicity was found. Furthermore, these results support a previous study where a related smoke-derived compound with germination promoting properties was investigated.

Synthesis of a 13 C-labelled seed-germination inhibitor (3,4,5-trimethylfuran-2(5 H )-one) for the mode of action elucidation

It has been found that the butenolide 3,4,5-trimethylfuran-2(5H)-one, isolated from plant-derived smoke, efficiently inhibits seed germination and significantly reduces the effect of the highly active germination promotor karrikinolide (KAR1, 3-methyl-2H-furo[2,3-c]pyran-2-one), another smoke-derived compound. This paper reports the synthesis of stable isotope-labelled 3,4,5-trimethylfuran-2(5H)-ones containing one and two 13C atoms for the identification of metabolic degradation products in order to provide insight into the mechanism of action.Graphical abstract