Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Sağlık Bilimleri Enstitüsü, AĞIZ, DİŞ VE ÇENE CERRAHİSİ ANABİLİM DALI, Turkey
Approval Date: 2019
Thesis Language: Turkish
Student: DİLARA NUR ÖZTÜRK
Supervisor: İnci Rana Karaca
Abstract:
Oral cancers may emerge from anywhere in the oral cavity and unless diagnosed at an early stage
and treatment is initiated immediately they demonstrate high mortality rates. Nearly 90% of all oral
cancers are oral squamous cell carcinomas. Today, there are many ongoing studies in order to find
alterative curative agents against cancer. There are many studies investigating the chemopreventive
properties of various plants, plant extracts and plant-deried chemicals, especially in developing
countries. H. perforatum is known to have many beneficial properties for the organism and has
been used for traditional medicine in various cultures. The purpose of this study was to investigate
the chemopreventive properties of H. perforatum on 7,12-dimethylbenz(a)anthracene-induced rat
oral squamous cell carcinoma model and the plant’s effects on the antioxidant defence
mechanisms. In the study, the in vitro antioxidant efficacy, radical scavenging activity and phenolic
compound content of H. perforatum was determined and an extract was prepared to be used in the
in vivo part of the study. In the in vivo study protocol, 30 Wistar male rats were divided randamly
into 4 groups as 6 in the control and 8 in each of the other groups (Group 1: control, Group 2:
DMBA group, Group 3: HP+DMBA group, Group 4: HP group). The antioxidant defence
mechanisms in tissue and blood samples were evaluated biochemcally and
immunohistochemically, the cancerous changes in connective tissue were investigated
immunohistochemically and epithelial changes in the tissue samples were evaluated
histopathologically. The extract revealed an inhibitory effect on some antioxidant enzymes
especially when it is applied together with the carcinogen. Immunohistochemical evaluations
revealed no invasive changes in the connective tissue. According to the histopathological resuts, H.
perforatum showed chemoprevetive effects although it did not prevent carcinomatous changes in
the epithelium to 100%. The results of this study shows that H. perforatum is a promising
chemopreventive agent and furthes studies without the limitations of this one and dose
determination studies may be able to evaluate the full potential of this plant.
Key Words : H y p ericum perforatum, antioxidant, oral cancer, oral squamous cell
carcinoma