Sevgi Gezici a* , Nazim Sekeroglu b a Department of Medical Biology and Genetics, Faculty of Medicine, Gaziantep University, 27310, Gaziantep-Türkiye, E-mail: drsevgigezici@gmail.com ; sevgigezici@gantep.edu.tr b Department of Biology, Faculty of Science and Literature, 27310, Gaziantep University, Gaziantep-Türkiye, E-mail: nsekeroglu@gmail.com , nazimsekeroglu@gantep.edu.tr The use of traditional and complementary medicine practices has become increasingly
important in the world, especially for cancer, diabetes, and neurodegenerative diseases. Dragon
fruit, also called pitaya, is a tropical plant and belongs to the cactus family (Cactaceae). Dragon
fruit usually grows in tropical forests. Mexico, South America, Thailand and Vietnam are the
homeland of this fruit. The fruits of the genus Hylocereus are called sweet pitaya. The skin color
and the fruit’s inside varies depending on the species. The skin can be red or yellow, and the
fruit can be purple, red, or white. The genus Hylocereus generally includes three species: (1)
Hylocereus undatus (white pitaya), (2)
Hylocereus costaricensis (Costa Rican pitaya), (3)
Hylocereus megalanthus (yellow pitaya). These fruits have a nutritional content particularly rich
in active secondary metabolites, giving them pharmacological properties. In this study,
H. undatus fruits were extracted with distilled water (dH
2
O), ethanol (EtOH, 70%) and methanol
(MeOH, 70%). The aim was to determine the cytotoxic and anti-inflammatory activities
mediated by apoptosis and necrosis pathways of the extracts. In this context, 3-(4,5-
dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis was performed to
investigate anti-cancer potential of the extracts against human colon adenocarcinoma (HT29),
colon (HCT-116), and colorectal adenocarcinoma (SW480) cells. The anti-inflammatory
capacities of various extracts of dragon fruit against cyclooxygenase enzymes (COX-1 and
COX-2) were investigated using the COX inhibitor kit. Doxorubicin and ibuprofen were used as
positive controls to determine the anti-cancer and anti-inflammatory activities, respectively. All
conditions and chemicals were the same as described in our previous research. In addition,
apoptotic activity in the cells treated and untreated with the fruit extracts was analyzed in terms
of DNA fragmentation using the ‘Apoptotic DNA-Ladder Kit’. All experiments were performed
at least in triplicate, and linear regression analysis was performed to calculate IC
50
values for
each cell line. The results showed that white pitaya fruits are able to induce growth inhibition
and apoptosis. MTT and COX assays revealed dose- and time-dependent anti-cancer and anti-
inflammatory effects against human colon cancer cells. The EtOH extracts obtained from the
fruit exerted the highest anticancer activity against HT29, closely followed by SW480 colorectal
adenocarcinoma cells. In contrast to the anti-cancer and cytotoxicity results, the dH
2
O extract
also caused the highest apoptosis and DNA fragmentation in a dose- and time- dependently.
Besides increasing extract concentration causing to decrease in the growth rate of the cancer
cells, apoptosis was observed almost in all the human colon cancer cells, which rapidly
exhibited signs of apoptotic cell death as detected by DNA fragmentation. Regarding in vitro
evaluation of COX activity, which gives information about the inflammation, the results found a
similar activity profile as observed in MTT assay. In conclusion, the results revealed that the
extracts of the white dragon fruit
could have remarkable anticancer and anti-inflamatuvar
activities through enhanced apoptosis in colon cancer cells. The data obtained from this research
should be validated using further
in vitro and
in vivo analyses.