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U okviru ovog diplomskog rada po prvi puta je provedeno usporedno istraživanje fitokemijskog sastava i antioksidacijskog učinak cvjetova i listova odabranih vrsta roda Inula hrvatske flore (I. crithmoides L., I. ensifolia L., I. oculus-christi L. i I. verbascifolia (Willd.) Hausskn.). Primjenom tankoslojne kromatografije visoke djelotvornosti dokazana je prisutnost fenolnih kiselina i flavonoida. Spektrofotometrijskim metodama je određen sadržaj ukupnih hidroksicimetnih derivata (0,75-8,43 %), flavonoida (0,11-1,52 %) i trjeslovina (0,48-2,15 %) u cvjetovima i listovima istraživanih biljnih vrsta. Ispitan je antioksidacijski potencijal etanolnih ekstrakata odabranih vrsta roda Inula primijenom tri različite spektrofotometrijske metode. Utvrđeno je da svi testirani ekstrakti cvjetova i listova imaju sposobnost hvatanja slobodnih DPPH radikala (IC50: 2,9-33,2 μg/mL), redukcije iona željeza(III) (IC50: 10,1-95,2 μg/mL) i keliranja iona željeza(II) (IC50: 157,3-320,4 μg/mL). Rezultati ovog rada su pokazali da je među istraživanim Inula vrstama, uskolisni oman (I. ensifolia) najbogatiji izvor polifenolnih sastavnica te da različitim mehanizmima djelovanja ostvaruje najsnažniji antioksidacijski učinak. In this diploma thesis, a comparative study of the phytochemical composition and antioxidant activity of flowers and leaves of selected Inula species (I. crithmoides L., I. ensifolia L., I. oculuschristi L. and I. verbascifolia (Willd.) Hausskn.) from Croatian flora was conducted for the first time. The presence of phenolic acids and flavonoids was detected by high-performance thin-layer chromatography. The contents of total hydroxycinnamic derivatives (0.75-8.43 %), flavonoids (0.11-1.52 %), and tannins (0.48-2.15 %) in flowers and leaves of investigated plant species were determined spectrophotometrically. The antioxidant potential of ethanolic extracts of selected Inula species was determined using tree different spectrophotometric assays. All tested ethanolic extracts of flowers and leaves possessed DPPH free-radical scavenging activity (IC50: 2.9-33.2 μg/mL), ferric reducing ability (IC50: 10.1-95.2 μg/mL) and iron-chelating ability (IC50: 157.3- 320.4 μg/mL). The results of this study showed that among the studied Inula species, I. ensifolia is the richest source of polyphenolic constituents, and that acting by different mechanisms, displays the most potent antioxidative activity.

The chemical composition of the volatile oil of Inula aschersoniana was studied by GC and GC-MS. Fortyfive constituents representing 92.9% of the total oil were detected. The oil contained fatty acids (55.2%) and alkanes (14.1%), followed by oxygenated monoterpenes (9.6%), sesquiterpenoids (7.1%) and aromatic compounds (4.5%). It is characterized by relatively low content of terpenoids in total 16.7% only of which linalool (2.1%) and t-cadinol (2.2%) were the dominant components in this class of compounds. Cluster analysis (CA) was used for determination of the relationship between the species in Inula verbascifolia aggregate.

The aerial parts of Inula verbascifolia afforded two new guaianolide-type sesquiterpene lactones. Their structures were determined by spectroscopic methods (IR, MS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMQC, and HMBC).

A clonal propagation method has been developed for Inula verbascifolia (Willd.) Hausskn. subsp. verbascifolia, a species of horticultural as well as potential medicinal interest. Shoots originating from aseptically germinated seeds were used for culture initiation. The highest multiplication rate of 6.5 shoots per explant was achieved in an 8-week culture period on Murashige and Skoog medium supplemented with 2.2 μM 6-benzylaminopurine and 2.9 μM gibberellic acid. During the first three subcultures of the multiplication phase, two-thirds of explants spontaneously rooted on all tested media. Rooting of excised shoots on MS medium supplemented with 3 μM IAA or 3 μM IBA was 100%. Aside from the fact that all the explants were rooted on this root-inducing media, explants developed a surprisingly high mean number of shoots, 4.6 and 2.9 after 4 weeks, on medium supplemented with IAA or IBA, respectively. Rooted plantlets were transferred to potting soil and acclimatized to outdoor conditions.

The aerial parts of Inula verbascifolia afforded two new xanthanes and a new germacranolide derivative, together with the known compounds inusoniolide, 4-O-dihydroinusoniolide and 9β-hydroxyparthenolide. The structures were determined by spectral methods (IR, HRMS,1H NMR, 13C NMR, DEPT, 1H–1H COSY, HMQC and HMBC).

Inula crithmoides L. grows along the Mediterranean coasts and is used as an edible vegetable as the young leaves or shoots are eaten raw, cooked or pickled. Inula verbascifolia (Willd.) Hausskn. is a quite localised species growing mainly along the Adriatic Sea coasts. In this study the volatile components of the aerial part of both species are described. Gas chromatography and gas chromatography mass spectrometry analysis showed the presence of 41 components in I. crithmoides and 75 compounds in I. verbascifolia, respectively, and a very different profile in the composition of the two species. The chemotaxonomy of I. crithmoides, by comparison with other data reported in the literature, is discussed.

Croatia flora is rich with plant species from Asteraceae familiy. Some of these species are well known medicinal plants, widely used in ethnomedicine. Since the substances used in treatment of some diseases are potentially harmful for human health, it is challenge to find active substances of natural origin like medicinal plants. Alzheimer disease (AD) is an incurable form of dementia which causes severe cognitive dysfunctions. AD is manifested as reduction of neurotransmitter acetylcholine inside the cholinergic system, hence the inhibition of acetylcholinesterase (AChE), enzyme that hydrolyses acetylcholine, has an important role in AD treatment. It is also considered that oxidative stress could be a trigger for AD development ; hence the research of AChE inhibitors is accompanied by assessment of their antioxidative activity. The aim of this work was to test AChE inhibitory activity as well as antioxidative activity of extracts from selected Asteraceae species: Centaurea ragusina L., Inula verbascifolia (Willd.) Hausskn and Pallenis spinosa (Cass.) Cass.

Alzheimerova bolest je bolest koja uzrokuje poremećaje koje nazivamo demencijama. Očituje se u poremećaju aktivnosti acetilkolina te se smatra da inhibicija enzima koja uzrokuje njegovu hidrolizu ima važnu ulogu u tretmanu ove teške bolesti. Smatra se također da su brojna oksidativna oštećenja u organizmu povezana s poremećajem metabolizma acetilkolina. Budući su supstance koje se koriste u liječenju ove teške bolesti potencijalno opasne po zdravlje ljudi (takrin, donepezil rivastigmin, galantamin i mamantin) nastoje se pronaći supstance prirodna podrijetla koje će ih uspješno zamijeniti. U ovom radu ispitana je sposobnost inhibicije enzima acetilkolinesteraze ekstraktima biljaka porodice Asteraceae: Centaurea ragusina L., Inula verbascifolia (Willd.) Hausskn i Pallenis spinosa (Cass.) Cass. Ispitivanje sposobnosti inhibicije enzima acetilkolinesteraze pokazalo je da jedino ekstrakti biljke C. ragusina pokazuju slabu inhibiciju ovog enzima, dok ekstrakti druge dvije biljke nemaju učinka na inhibiciju navedenog enzima. Testiranje pak antioksidacijske aktivnosti odabranih ekstrakata pokazalo je da ekstrakti biljaka pokazuju dobru sposobnost hvatanja DPPH radikala, te dobar redukcijski potencijal. Dobra antioksidacijska aktivnost odabranih ekstrakata biljaka u svezi je s sadržajem ukupnih fenola testiranih ekstrakata.