Recent Studies Showing Anti-Cancer Effects of Essential Oils
Study: An essential oil and its major constituent isointermedeol induce apoptosis by increased expression of mitochondrial cytochrome c and apical death receptors in human leukaemia HL-60 cells.
Kumar A, Malik F, Bhushan S, Sethi VK, Shahi AK, Kaur J, Taneja SC, Qazi GN, Singh J.
Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
An essential oil from a lemon grass variety of Cymbopogon flexuosus (CFO - a species of Lemongrass essential oil) and its major chemical constituent sesquiterpene isointermedeol (ISO) were investigated for their ability to induce apoptosis in human leukaemia HL-60 cells because dysregulation of apoptosis is the hallmark of cancer cells. CFO and ISO inhibited cell proliferation with 48h IC50 of approximately 30 and 20mug/ml, respectively. Both induced concentration dependent strong and early apoptosis as measured by various end-points, e.g. annexinV binding, DNA laddering, apoptotic bodies formation and an increase in hypo diploid sub-G0 DNA content during the early 6h period of study. This could be because of early surge in ROS formation with concurrent loss of mitochondrial membrane potential observed. Both CFO and ISO activated apical death receptors TNFR1, DR4 and caspase-8 activity. Simultaneously, both increased the expression of mitochondrial cytochrome c protein with its concomitant release to cytosol leading to caspase-9 activation, suggesting thereby the involvement of both the intrinsic and extrinsic pathways of apoptosis. Further, Bax translocation, and decrease in nuclear NF-kappaB expression predict multi-target effects of the essential oil and ISO while both appeared to follow similar signaling apoptosis pathways.
Conclusion: The easy and abundant availability of the oil combined with its suggested mechanism of cytotoxicity make CFO highly useful in the development of anti-cancer therapeutics.
Study: Cytotoxic effect of essential oil of thyme (Thymus broussonettii) on the IGR-OV1 tumor cells resistant to chemotherapy.
Ait M'barek L, Ait Mouse H, Jaâfari A, Aboufatima R, Benharref A, Kamal M, Bénard J, El Abbadi N, Bensalah M, Gamouh A, Chait A, Dalal A, Zyad A.
Laboratory of Immunology, Biochemistry and Molecular Biology, Natural Substances, Cellular and Molecular Immuno-pharmacology Group, Faculty of Sciences and Technologies, University Cadi-Ayyad, Béni-Mellal, Morocco.
The anti-tumor effect of the Moroccan endemic thyme (Thymus broussonettii) essential oil (EOT) was investigated in vitro using the human ovarian adenocarcinoma IGR-OV1 parental cell line OV1/P and its chemoresistant counterparts OV1/adriamycin (OV1/ADR), OV1/vincristine (OV1/VCR), and OV1/cisplatin (OV1/CDDP). All of these cell lines elicited various degrees of sensitivity to the cytotoxic effect of EOT. The IC50 values (mean +/- SEM, v/v) were 0.40 +/- 0.02, 0.39 +/- 0.02, 0.94 +/- 0.05, and 0.65 +/- 0.03% for OV1/P, OV1/ADR, OV1/VCR, and OV1/CDDP, respectively. Using the DBA-2/P815 (H2d) mouse model, tumors were developed by subcutaneous grafting of tumor fragments of similar size obtained from P815 (murin mastocytoma cell line) injected in donor mouse. Interestingly, intra-tumoral injection of EOT significantly reduced solid tumor development. Indeed, by the 30th day of repeated EOT treatment, the tumor volumes of the animals were 2.00 +/- 0.27, 1.35 +/- 0.20, and 0.85 +/- 0.18 cm(3) after injection with 10, 30, or 50 microL per 72 h (six times), respectively, as opposed to 3.88 +/- 0.50 cm(3) for the control animals. This tumoricidal effect was associated with a marked decrease of mouse mortality. In fact, in these groups of mice, the recorded mortality by the 30th day of treatment was 30 +/- 4, 18 +/- 4, and 8 +/- 3%, respectively, while the control animals showed 75 +/- 10% of mortality. These data indicate that the EOT which contains carvacrol as the major component has an important in vitro cytotoxic activity against tumor cells resistant to chemotherapy as well as a significant antitumor effect in mice. However, our data do not distinguish between carvacrol and the other components of EOT as the active factor.
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