2025. gadā aizstāvētie promocijas darbi un kopsavilkumi

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Browsing 2025. gadā aizstāvētie promocijas darbi un kopsavilkumi by Author "Koka, Rudīte"

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    Antibacterial activity against bovine mastitis-inducing pathogens and antiradical activity of polyphenolic-compounds-containing plant extracts. Doctoral Thesis
    (Rīga Stradiņš University, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
    Bovine mastitis is an infectious disease of the cow’s udder, which is usually treated with antibiotics. The overuse and misuse of antibiotics has led to the widespread development of bacterial resistance. Restrictions on the use of antibiotics create a need for alternative treatments and prophylactic measures to reduce the incidence and spread of mastitis. Antioxidant properties of plants – ability to scavenge free radicals, help animals recover and heal faster. Herbal medicine has been used traditionally by farmers for centuries to treat infectious and chronic diseases. However, there is little scientific evidence on the veterinary use of plant extracts. The Thesis aims to provide information on the use of plant extracts against bovine mastitis pathogens, their antiradical activity and to characterise their polyphenolic content. The dried plant material was extracted with 30 %, 50 %, 70 % ethanol and acetone and then freeze-dried for further analysis. The total phenolic, flavonoid, and tannin contents were determined by spectroscopic methods. Fourier transform infrared spectroscopy and high-performance liquid chromatography were used to characterise the chemical composition of the extracts. Clinical isolates inducing bovine mastitis (Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus) and reference cultures of S. aureus and E. coli were used for antibacterial tests. All extracts were screened for their antibacterial activity using a disc diffusion test, and the minimum inhibitory concentration and the minimum bactericidal concentration were determined for the most effective extracts. The antiradical activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The type of solvent affected the amount of phenolics extracted and the pharmacological effects of the extracts. The plants contained comparable amounts of tannins, which are not often reported in studies but have pharmacological activities. The acetone extracts had a higher total phenolic content and a higher total flavonoid content. All the plant extracts analysed were effective against S. aureus, but the effect against other bovine mastitis pathogens varied by the type of extract used. The types of phenolic compounds present in these plant extracts have a significant impact on the antioxidant activity. The bark of Q. robur and the herbs of C. vulgaris, and the flower and leaf of T. vulgare had good antioxidant and antibacterial potential. Plant extracts have promising pharmacological effects in vitro for the development of a product for bovine mastitis.
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    Antibacterial activity against bovine mastitis-inducing pathogens and antiradical activity of polyphenolic-compounds-containing plant extracts. Summary of the Doctoral Thesis
    (Rīga Stradiņš University, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
    Bovine mastitis is an infectious disease of the cow’s udder, which is usually treated with antibiotics. The overuse and misuse of antibiotics has led to the widespread development of bacterial resistance. Restrictions on the use of antibiotics create a need for alternative treatments and prophylactic measures to reduce the incidence and spread of mastitis. Antioxidant properties of plants – ability to scavenge free radicals, help animals recover and heal faster. Herbal medicine has been used traditionally by farmers for centuries to treat infectious and chronic diseases. However, there is little scientific evidence on the veterinary use of plant extracts. The Thesis aims to provide information on the use of plant extracts against bovine mastitis pathogens, their antiradical activity and to characterise their polyphenolic content. The dried plant material was extracted with 30 %, 50 %, 70 % ethanol and acetone and then freeze-dried for further analysis. The total phenolic, flavonoid, and tannin contents were determined by spectroscopic methods. Fourier transform infrared spectroscopy and high-performance liquid chromatography were used to characterise the chemical composition of the extracts. Clinical isolates inducing bovine mastitis (Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus) and reference cultures of S. aureus and E. coli were used for antibacterial tests. All extracts were screened for their antibacterial activity using a disc diffusion test, and the minimum inhibitory concentration and the minimum bactericidal concentration were determined for the most effective extracts. The antiradical activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The type of solvent affected the amount of phenolics extracted and the pharmacological effects of the extracts. The plants contained comparable amounts of tannins, which are not often reported in studies but have pharmacological activities. The acetone extracts had a higher total phenolic content and a higher total flavonoid content. All the plant extracts analysed were effective against S. aureus, but the effect against other bovine mastitis pathogens varied by the type of extract used. The types of phenolic compounds present in these plant extracts have a significant impact on the antioxidant activity. The bark of Q. robur and the herbs of C. vulgaris, and the flower and leaf of T. vulgare had good antioxidant and antibacterial potential. Plant extracts have promising pharmacological effects in vitro for the development of a product for bovine mastitis.
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    Polifenolus saturošu augu ekstraktu antioksidatīvā un antibakteriālā iedarbība pret govs mastīta izraisītājiem. Promocijas darba kopsavilkums
    (Rīgas Stradiņa universitāte, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
    Govs mastīts ir bakteriāls tesmeņa iekaisums, ko parasti ārstē ar antibiotikām. Slimības ārstēšana un antibiotiku atliekvielas pienā rada ievērojamus zaudējumus saimniecībām. Antibiotiku nepareiza un pārmērīga lietošana ir radījusi antibiotiku rezistenci baktērijās un rada globālus draudus veselības aprūpē. Līdz ar to tiek meklēti alternatīvi risinājumi mastīta profilaksei un ārstēšanai. Ārstniecības augi ir izmantoti gadsimtiem ilgi tautas medicīnā arī dzīvnieku aprūpē ne tikai to antibakteriālo īpašību dēļ, bet arī antioksidantu īpašību, kas veicina atveseļošanos. Diemžēl trūkst pētījumu par pielietojumu veterinārā medicīnā. Šī pētījuma mērķis bija noteikt augu ekstraktu polifenolu sastāvu un to farmakoloģiskos efektus mastīta ārstēšanā. Pētījumā tika izmantoti žāvētu augu ekstrakti (ozola miza, biškrēsliņa zieds un lapa, virša laksts), kas pagatavoti, macerējot ar 30 %, 50 %, 70 % etalonu vai acetonu. Pēc ekstrakcijas šķīdumi tika ietvaicēti un liofilizēti. Tika noteikts kopējais polifenolu, flavonoīdu un miecvielu daudzums ekstraktos. Izmantojot Furjē transformācijas infrasarkanā starojuma spektrometriju (FTIR) un augstas precizitātes šķīdumu hromatogrāfiju (HPLC), raksturots augu polifenolu sastāvs. Izmantojot mikroatšķaidīšanas metodes, noteikta augu ekstraktu antibakteriālā darbība pret govs mastīta izraisītājiem Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, un divām references kultūrām: S. aureus un E.coli. Visi analizētie ekstrakti saturēja ievērojamu daudzumu polifenolu tipa savienojumu, arī iepriekš mazāk aprakstītās miecvielas, kurām piemīt būtiskas farmakoloģiskas īpašības. Ekstraktu sastāvs un aktivitāte ir saistāma ar izvēlēto šķīdinātāju veidu un koncentrāciju. Visiem ekstraktiem bija nozīmīgs efekts pret S. aureus, bet pret pārējiem mastīta ierosinātājiem rezultāts bija atkarīgs no auga un ekstrakta veida. Augu ekstraktiem piemīt arī antioksidantu īpašības, kas saistāms ar polifenoliem to sastāvā. Ozola mizas, viršu lakstu, biškrēsliņu lapu un ziedu ekstraktiem ir antibakteriālas un antioksidanta īpašības pret mastīta izraistītājiem in vitro, un to var izmantot veterināra produkta izveidē.