## 3 Active Ingredients of Turmeric
### Biological Activity of Other Turmeric Constituents  
Even though the scientific interest focuses mainly on curcumin, there are reports indicating that other components of turmeric also reveal interesting properties. For example, it was found that the components of turmeric oil enhanced pharmacological activity of curcuminoids [78; 79]. The active ingredients of oil act as absorption enhancers, increasing bioavailability of curcuminoids in humans [80]. On the other hand, the analyses focusing on curcuminoids-free turmeric extracts indicate that their pharmacological activity profiles were similar to curcuminoids, and in some cases, they revealed even stronger properties than curcumin. The described effect was observed by [PERSON] et al. [81] who investigated the anti-inflammatory activity of various turmeric extracts. It was observed that the combination of fractions containing the turmeric oils components revealed the highest ability to inhibit the activity of cyclooxygenase 2 (COX-2) in vitro. Quite surprisingly, the obtained results were better than those obtained for isolated curcuminoids. It was also shown that in terms of decreasing the production of prostaglandin E2, turmeric oil revealed similar ability to indomethacin, a well-known and widely applied non-steroidal anti-inflammatory drug. The main components of the oil, i.e. turmerones, also revealed some positive anti-proliferative and immunomodulatory results in in vitro tests, also enhancing the activity of curcuminoids [82]. Ar-tumerone reduced skin inflammation in a psoriatic mice model by suppressing cell proliferation and reducing inflammatory cytokine expression [83; 84], and it also displayed some neuroprotective properties [85; 86]. Moreover, turmerones were also tested positive for antifungal [87] activities, as well as antidiabetic potential related to the activation of peroxisome proliferator-activated receptors \(\gamma\) (PPAR-\(\gamma\)) [88]. Among the other terpenoid constituents, \(\beta\)-elemene, a sesquiterpene revealing anticancer properties, should be mentioned. The activity of the compound against various cancer cell lines was shown in numerous in vitro studies [89]. It was also observed that elemene enhanced the activity of widely applied antitumor drugs, like cisplatin, etoposide and tamoxifen [78]. It is noteworthy that the compound also has the ability to cross the blood-brain barrier [90] which can be advantageous in the treatment of brain tumors.  
Turmeric is also a source of turmerin, a water-soluble protein revealing some interesting pharmacological properties. It was found that turmerin can decrease the activity of \(\alpha\)-amylase and \(\alpha\)-glucosidase, contributing in this way to the antidiabetic profile of turmeric. The compound also has the ability to scavenge reactive oxygen species and bind iron cations which also indicates its antioxidant potential [91].  
Apart from the most important constituents of turmeric rhizome described above, the plant also contains numerous other compounds potentially useful in the pharmacotherapy of various medical conditions. Among the biologically active ingredients of turmeric, other sesquiterpenes like funanodiene, curdione, bisacurone, calebin A, germacrone and several monoterenes, including carvone, geraniol and limonene, are mentioned in the scientific literature [78]. The chemical structures of most important constituents of turmeric other than curcumin are depicted in Figure 4. Taking into consideration the general activity profile of the mentioned compounds, the most important biological properties are similar to those displayed by curcuminoids. It is also noteworthy that the turmeric ingredients can act synergistically which indicates the potentially higher activity of plant extracts compared to pure compounds [79].