## 1 Introduction  
The twenty-first century is the age of easily-accessible mass-produced synthetic drugs which dominate the pharmaceutical market all over the world. However, recently, an increased interest in non-conventional medicine and phytotherapy is observed. A number of non-conventional therapeutic approaches are considered as controversial and do not fall into the evidence-based medicine category. However, plant-based medicines and plant-derived compounds are subjects of numerous scientific studies, and phytotherapy has sound scientific foundations. The current knowledge on medicinal plants comprises not only the detailed information on their chemical composition but also on the processes and mechanisms underlying their pharmacological activities. It is estimated that 80% of the worldwide population uses herbal medicines, with even higher rates reported for developing countries [1]. It is also noteworthy that a lot of currently marketed active ingredients widely accepted for the treatment of numerous conditions, including cancer and cardiovascular diseases, either originate from plant sources or were synthesized based on phytochemicals [2]. Among the most important examples of plant-derived compounds that have played an enormous role in pharmacotherapy, morphine extracted from _Papaver somniferum_ should be mentioned [3]. Some of the plants used for centuries for medical and non-medical purposes have recently become a subject of numerous studies showing their excellent therapeutic potential in many different areas. It is important to note that the biological activity of plants is often a complex interplay of numerous compounds showing synergistic effects, and the active ingredients isolated from them and applied separately do not reveal the same efficacy as the original herbal source. The described phenomenon makes the recognition of the mechanisms responsible for pharmacological activity of plant-derived medicines more challenging compared to the synthesized drugs. It is also important to note that a number of herbal drugs display multidirectional biological activities which may be particularly useful in the treatment of the conditions with complex etiology and pathogenesis, including cancer [4]. These natural products frequently act as chemopre agents, inhibiting tumor initiation step, and antiproliferative compounds, hampering tumor growth and metastasis. The mechanisms underlying these processes are even more complex and include immunomodulatory and anti-inflammatory effects [5]. One of the most extensively investigated plant materials revealing diverse beneficial health effects is turmeric, a well-known herb cultivated and applied in the India, Southeast Asia and Indonesia regions. The beneficial health effects of turmeric applied as a spice in Indian cuisine have been known for centuries. In traditional Indian and Chinese medicine, the plant was used as a remedy for various medical conditions, including hepatic problems, like jaundice, dermatological conditions, rheumat, asthma, urinary tract infections and diabetic wounds [6]. Nowadays, turmeric constituents, including curcumin and other curcuminoids, have been confirmed as versatile active ingredients revealing numerous interesting properties and potentially useful in numerous conditions, as has been proven in many clinical studies [7]. Among the most important and early recognized advantages of turmeric and turmeric-derived compounds, their anti-inflammatory and anti-microbial activities should be mentioned. Turmeric was traditionally used in India as a hygien agent in dentistry, and current studies indicate its usefulness in relieving the symptoms occurring in the inflammatory conditions localized in the mouth [8]. It is noteworthy that oral inflammatory condition is a general term, and it comprises several different diseases, including periodontal disease, gingivitis, mucositis, lichen planus and many others.