Obilje bilja – zbirke Botaničkoga vrta Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu (3): Zbirka perunika (Iris, Iridaceae)

In this paper, the plant lists of the genus Iris (Iridaceae family) grown in Zagreb Botanical Garden of the Faculty of Science since 1895 are studied. Synonymy, nomenclature and origin of plant material were sorted. Lists of species grown in the last 124 years have been constructed to show that during that period at least 273 taxa of wild and cultivated irises inhabited the Garden’s collections. Today we have 168 species, cultivars and hybrids.U ovom članku sastavljeni su popisi svojta perunika (rod Iris, porodica Iridaceae) uzgajanih u Botaničkom vrtu zagrebačkog Prirodoslovno-matematičkog fakulteta između 1895. i 2019. godine. Uređena je sinonimika i nomenklatura te istraženo podrijetlo biljnog materijala. Rezultati pokazuju da su tijekom 124 godine kroz zbirke Botaničkog vrta prošle najmanje 273 divlje i uzgojne svojte perunika. Danas uzgajamo 168 vrsta, kultivara i križanaca

Extraction and formulation of plant substances

The aim of this thesis was to investigate the extraction of potential valuable neutraceuticals from different rhizomes: Iris germanica L. and Curcuma longa. On the one hand, three different curcuminoids (curcumin, dimethoxy-, and bisdemethoxycurcumin) from Curcuma longa were extracted. On the other hand, extraction and isolation of isoflavones and benzophenones of Iris germanica L. were performed. Most of the isolated compounds from Iris germanica L. were tested for their potential anti-inflammatory and antibacterial abilities. First, curcuminoids were successively extracted from Curcuma longa using a green, sustainable, bio-degradable and food-approved surfactant-free microemulsion (SFME) consisting of water, ethanol (EtOH) and triacetin (TriA) exhibiting high extraction yields (15.28 mg curcuminoids per g Curcuma longa). The best yield was achieved by the usage of a SFME consisting of 40/24/36 H2O/EtOH/TriA (wt%). The maximum of solubility of curcumin was investigated in the binary mixture EtOH/TriA via UV measurements. The binary mixture EtOH/TriA (40/60 in wt%) turned out to be the best one for the solubilisation of curcumin. The structuring of the SFME was previously investigated with DLS and conductivity measurements. It was also found and demonstrated that the addition of water to the binary mixture of EtOH/TriA was responsible for the structuring of the SFME and for the high extraction yield. Indeed, bisdemethoxycurcumin, one of the curcuminoids, is the most “polar” curcuminoid and therefore, the most sensitive to water. Compared to the binary mixture EtOH/TriA (40/60 in wt%), the extraction yield of demethoxycurcumin and especially bisdemethoxycurcumin could be increased by 14 % and 32 % respectively. Recycling and up-concentration of the SFME with curcuminoids was attempted. Therefore, the SFME was re-used to perform several extraction cycles and to concentrate the curcuminoids in the SFME. One of the goals of this study was to solubilise the curcuminoids in an aqueous solution. Therefore, different purification methods (hydro distillation, vacuum distillation and freeze-drying) were used to remove the essential oils of Curcuma longa and to enhance the relative purity of the extract. Purification of the extract was achieved by freeze-drying the rhizome of Curcuma longa, as it leads to high relative purity of the extract (about 94%) through repetitive lyophilisation cycles and did not destroy the curcuminoids before extraction. Using an appropriate composition of the SFME (50/32.5/17.5 H2O/EtOH/TriA in wt%), dilution of the curcuminoids extract solution with water and stabilisation against day light and precipitation were achieved. The extraction efficiencies of the curcuminoids were further enhanced using different additives, which were solubilised in the water phase of the SFME. Meglumine has been found to be the best additive while using pyroglutamic acid (PCA) as pH regulator of the SFME and as hydrotrope for curcumin. Using meglumine with and without PCA, high extraction efficiencies of the curcuminoids were achieved: 17.3 mg curcuminoids per g Curcuma longa using a SFME (15/34/51 H2O/EtOH/TriA in wt%) at pH 9 containing 5 wt% meglumine neutralised with PCA in pure water and 18.3 mg curcuminoids per g Curcuma longa using a SFME (5/38/57 H2O/EtOH/TriA in weight percent) at pH 11.5 containing 15 wt% meglumine without PCA in pure water. A simple water extraction (water containing 15 wt% of meglumine) achieved the best extraction efficiency for bisdemethoxycurcumin (3.46 ± 0.62 mg per g Curcuma longa). Further, another SFME consisting of water, sodium salicylate (NaSal) and ethyl acetate (EtOAc) was investigated concerning its capacity to solubilize, stabilize and separate the three curcuminoids. The extraction efficiency of one curcuminoid could be enhanced using different SFME compositions: H2O/NaSal/EtOAc 17/12/71 and 7/13/80 (in wt%) for respectively bisdemethoxy- and demethoxycurcumin and the pure EtOAc for curcumin. The presence of NaSal in the SFME enhanced the stability of curcumin and the other two curcuminoids in solution, because of its antioxidant and UV absorbing properties. In the second part of this thesis, isoflavones and benzophenones were successively extracted and isolated from the rhizomes and the roots of Iris germanica L. by chromatographic methods (silica gel column followed by high-performance liquid chromatography (HLPC) and semi preparative HPLC). Using NMR and LC-MS data, structures of eleven isolated compounds were revealed. Some of the isolated compounds were tested as potential anti-inflammatory agents but had unexpected pro-inflammatory properties, of which the rhizome extract showed the highest pro-inflammatory activity. The isolates and the extracts were also tested as potential antibacterial agents. None of the extracts nor isolates were active against the bacterium S. aureus. Only the iris butter (the essential oil of orris) showed a potent antibacterial activity, certainly due to the presence of irones. The iris butter showed also an antibacterial activity against the bacterium E. coli