Promocijas darbs

Darbā ir izveidota analītiskā pieeja polifenolu savienojumu kvalitatīvai un kvantitatīvai analīzei alkšņu mizās un kviešu salmos. Izmantojot hromatogrāfiskās un spektrofotometriskās metodes veikta diarilheptanoīdu un flavonoīdu-lignīna kompleksu identifikācija un puskvantitatīva noteikšana, dominējošo savienojumu (oregonīna, tricīna-lignīna oligomēru) kvantificēšana. Orientējoties uz bioloģisko aktivitāti veikta attīrīšana, iegūstot tos ar augstu hromatogrāfisko tīrību (≥ 90%, LC-MS). Tie raksturoti kā laboratorijas references materiāli. Kviešu salmu ekstraktu bioloģiskā aktivitāte raksturota ar antioksidanto aktivitāti, bet oregonīnam pierādīta inovatīva labvēlīga ietekme uz reproduktīvo sistēmu. POLIFENOLI, DIARILHEPTANOĪDI, TRICĪNA-LIGNĪNI, IDENTIFIKĀCIJA, KVANTIFICĒŠANA, BIOLOĢISKĀ AKTIVITĀTE, MIZAS, SALMI.An analytical approach for the qualitative and quantitative analysis of polyphenols in alder bark and wheat straw was developed. The chromatographic and spectrophotometric methods were applied for identification and semi quantification of diarylheptanoids and flavonoid-lignins and for quantification of dominant compounds (oregonin, tricin-lignin oligomers). Biological activity guided purification of them was performed, they were obtained with high chromatographic purity (≥ 90%, LC-MS). They were characterized as laboratory reference materials. The biological activity of wheat straw extracts was characterized by antioxidant activity and an innovative beneficial effect of purified oregonin on the reproductive system was demonstrated. POLYPHENOLS, DIARYLHEPTANOIDS, TRICIN-LIGNINS, IDENTIFICATION, QUANTIFICATION BIOLOGICAL ACTIVITY, BARK, STRAW

Flavonoids in the Spotlight : Bridging the Gap between Physicochemical Properties and Formulation Strategies

Flavonoids are hydroxylated polyphenols that are widely distributed in plants with diverse health benefits. Despite their popularity, the bioavailability of flavonoids is often overlooked, impacting their efficacy and the comparison of products. The study discusses the bioavailability-related physicochemical properties of flavonoids, with a focus on the poorly soluble compounds commonly found in dietary supplements and herbal products. This review sums up the values of pKa, log P, solubility, permeability, and melting temperature of flavonoids. Experimental and calculated data were compiled for various flavonoid subclasses, revealing variations in their physicochemical properties. The investigation highlights the challenges posed by poorly soluble flavonoids and underscores the need for enabling formulation approaches to enhance their bioavailability and therapeutic potential. Compared to aglycones, flavonoid glycosides (with sugar moieties) tend to be more hydrophilic. Most of the reviewed aglycones and glycosides exhibit relatively low log P and high melting points, making them “brick dust” candidates. To improve solubility and absorption, strategies like size reduction, the potential use of solid dispersions and carriers, as well as lipid-based formulations have been discussed.Peer reviewe

Antibacterial Activity of Tanacetum vulgare L. Extracts against Clinical Isolates of Bovine Mastitis

Funding Information: This research was funded by the European Union’s Horizon 2020 research and innovation program under the grant agreement No 857287 and this research is supported by the Ministry of Agriculture and Rural Support Service Republic of Latvia with the European Agricultural Fund for Rural Development—Development of herbal plant containing medical extracts with anti-parasitic effect No 18-00-A01620-000028. Publisher Copyright: © 2023 by the authors.A bovine mastitis is an infectious disease, which is usually treated with antibiotics. Alternatively, herbal medicine has been proposed due to bacterial resistance. The aim of this study was to determine the antibacterial activity of the acetonic and ethanolic extracts of dried flowers and leaves of Tanacetum vulgare L. against bovine mastitis-inducing clinical isolates such as Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, and reference cultures of S. aureus and E. coli. The extracts of T. vulgare showed partial antibacterial activity against tested strains of S. aureus. The MIC and MBC values of a 70% ethanol extract of flowers (MIC = 3.4 mg/mL, MBC = 3.4–6.8 mg/mL) were lower than for the 70% ethanol extract of leaves (MIC = 15.7–31.4 mg/mL, MBC = 62.9–125.9 mg/mL). The flower extracts showed low activity against E. coli (MIC = 53.9 mg/mL, MBC = 53.9–107.8 mg/mL) and S. agalactiae (MIC, MBC = 53.9 mg/mL). T. vulgare leaf extracts had minimal antibacterial effects against Streptococcus strains (MIC = 31.4–62.9 mg/mL, MBC = 53.9–125.9 mg/mL) and Serratia liquefaciens (MIC, MBC = 125.9 mg/mL). However, flower extracts had a higher phenolic content that did not correlate with antibacterial effects. T. vulgare flower and leaf extracts could be combined to obtain broader antibacterial effects.publishersversionPeer reviewe

Determination and separation of low-molecular compounds from alder growing in Latvia

Zemmolekulāru savienojumu noteikšana un izdalīšana no Latvijā augošiem alkšņiem. Roze L., zinātniskie vadītāji Dr.h.ķīm., prof. Teliševa G., Dr.ķīm., doc. Osīte A. konsultants: PhD., pētnieks Bikovens O. Maģistra darbs, 87 lappuses, 44 attēli, 12 tabulas, 70 literatūras avoti, 5 pielikumi. Latviešu valodā. Darbā ir analizēti zemmolekulārie savienojumi baltalkšņa un melnalkšņa mizās, baltalkšņa čiekuros un atzarojumu vietu koksnē. Izmantojot gāzes - šķidruma hromatogrāfiju un gāzes - šķidruma hromatogrāfiju masspektometriju ir identificēti un kvantitatīvi noteikti lipofīlie savienojumi (taukskābes, triterpēni, sterilesteri, di- un triglicerīdi) Latvijā augošajos alkšņos. Izmantojot AEŠH-UV-MS precizēts alkšņa hidrofīlo ekstraktu dialiheptanoīdu sastāvs. Pirmo reiz melnalkšņa mizā ir identificēti diarilheptanoīdi: hidroksi oregonīns (1,7-bis(3,4-dihidroksifenil)-heptān-3-ols-5-O-ksilopiranozīds) un platofilozīds (5-hidroksi-1,7-bis (4-hidroksifenil)-3-heptanon-5-O-glikopiranozīds). Hidroksi oregonīna laboratorijas standarts tika iegūts reducējot no baltalkšņa mizas izdalīto oregonīnu ar NaBH4. Reakcijas rezultātā iegūstot hidroksi oregonīna epimēru maisījumu. Platifilozīda laboratorijas standarts tika izdalīts no āra bērza mizas, izmantojot preparatīvo hromatogrāfiju. Iegūtie savienojumi tika identificēti izmantojot UV, IS, MS un KMR spektroskopijas metodes. BALTALKSNIS, MELNALKSNIS, MIZA, ČIEKURI, ATZAROJUMU VIETU KOKSNE, LIPOFĪLĀS EKSTRAKTVIELAS, DIARILHEPTANOĪDI.Determination and separation of low-molecular compounds from alder growing in Latvia. Roze L., supervisors Dr. habil. chem., prof. Galina Telysheva, Dr. chem., Agnese Osīte, consultant: PhD., researcher Bikovens O. Master thesis, 87 pages, 44 figures, 12 tables, 70 literature references, 5 appendices. In Latvian. This paper deals with analyzing low-molecular compounds in the bark, cones and in the knotwood of grey and black alders. Lipophilic compounds (fatty acids, triterpenes, sterylester, di- and triglycerides) in alder growing in Latvia are identified and quantitatively determined by gas-liquid chromatography and gas chromatography–mass spectrometry. The content of the hydrophilic alder extracts is specified by HPLC-UV-MS. For the first time the diarylheptanoids are identified in the bark of black alder: hydroxyl oregonin (1,7-bis-(3,4-dihydroxyphenyl)-3-hydroxyheptane-5-O-β-D-xylopyranoside) and platyphylloside (5-hydroxy-1,7-bis-(4- hydroxyphenyl)-3-heptanone-5-O –glucopyranoside). The standard of hydroxy-oreginin is determined reducing the oregonin extracted from bark of grey alder with NaBH4. The result of this reaction is the determination of mixture of hydroxyl-oregonin-epimere. The standard of platyphylloside is determined from the bark of outdoor birch by preparative chromatography. The determined compounds are identified using such spectroscopic methods like UV, IS, MS and NMR. GREY ALDER, BLACK ALDER, BARK, CONES, KNOTWOOD, LIPOPHILIC EXTRACTIVES, DIARYLHEPTANOIDS