Date of Award

4-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Rabah Iratni

Second Advisor

Dr. Yusra Al Dhaheri

Third Advisor

Fayez Safadi

Abstract

Plants have been shown to be an excellent source of new drugs, including anticancer agents. Origanum majorana commonly known as marjoram is a plant that is known to possess different therapeutic values including antioxidant and antimicrobial activities.

Our research team has previously tested the ethanoic extract of O. majorana on triple negative breast cancer and published the findings. The ethanoic extract promoted mitotic arrest at G2/M phase, induced apoptosis as well as inhibition of migration and metastasis. The promising potential of the ethanoic extract encouraged us to test the effects of O. majorana essential oil on human colon cancer cell lines.

We demonstrated that O. majorana essential oil inhibited the proliferation of HT- 29 and Caco-2 colon cancer cell lines in a time- and dose- dependent manner. Colony forming assay illustrated that O. majorana essential oil reduced the ability of HT-29 to form colonies, and when established colonies were treated with the essential oil, it showed that the treatment was able to reduce colonies’ size at low concentrations while at higher concentrations, the oil was able to completely eliminate the already formed colonies. Moreover, the essential oil, induced cell death and minimal cell cycle arrest at G1 phase. Annexin V staining revealed induction of apoptosis in HT-29 cells treated with the essential oil. Western blot assessment further confirmed apoptosis for being the main programmed cell death mechanism triggered by the plant’s essential oil. Blotting for surviving, which is a protein that belongs to the inhibitor of apoptosis protein (IAP) family, levels indicate that O. majorana essential oil exerts its cytotoxic anti-cancer effect at least partially through the down-regulation of surviving. These preliminary results make O. majorana oil a promising alternative candidate against colon cancer.

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