[Rose-scented geranium essential oil from Algeria (Pelargonium graveolens L'Hérit.): Assessment of antioxidant, anti-inflammatory and anticancer properties against different metastatic cancer cell lines]

INTRODUCTION

The study of natural products is one of the strategies implemented for the discovery of new compounds that can be used in cancer therapy. Aromatic herbs and medicinal plants found in Algeria and their anti-angiogenesis and cytotoxic potentials against cancer have not been much explored.

OBJECTIVES

Our work aimed to evaluate the antioxidant, anti-inflammatory and anticancer properties of the essential oil (EO) extracted from rose-scented geranium (Pelargonium graveolens) and its major (citronellol) and characteristic (linalool) constituents.

RESULTS

The chemical composition of EO was determined with chromatographic analysis and revealed the presence of citronellol as the major compound (25.84%). A strong chelating power of terpene alcohols (IC50 = 1.58 ± 0.23 mg/mL for citronellol) was found, with a significant difference (p < 0.05) compared with the standard antioxidants used (L-ascorbic acid and butylated hydroxyanisole). The EO is distinguished by an interesting anti-inflammatory effect with the lowest IC₅₀ (4.63 ± 0.3 mg/mL), and it constitutes a good stabilizer of the erythrocyte membrane. Citronellol also exhibited the best anti-inflammatory effect (IC50 = 0.74 ± 0.09 mg/mL). We also assessed the anticancer effect of EO on two main pathways involved in cancer development, angiogenesis and cell proliferation, using in ovo bioassays with a chorio-allantoic membrane (CAM) of chicken eggs and in vitro assays of its cytotoxicity on different metastatic breast cancer (MDA-MB-231), gastric (AGS) and melanoma (MV3) cell lines. In the CAM model, the density of micro-vessels is 75 ± 10 in the group supplemented with EO compared to 140 ± 9 for the control group (b-FGF). In addition, the EO significantly reduced the number of newly formed vessels. The cytotoxicity was evaluated using the cell proliferation inhibition method and cell viability was measured using the MTT test. Results revealed that the treatment of cancer lines with different concentrations of EO reduces the rate of cell viability in a dose-dependent manner. EO showed the greatest cytotoxicity on the AGS line with an inhibition rate of 92.87 ± 0.13% at the highest dose (4 µL/mL), followed by the MV3 line (88.76 ± 0.96%). Conclusion and Prospects: Data demonstrated that rose-scented geranium EO has an anti-tumor potential on metastatic cancer cell lines. It is distinguished by its anti-proliferative, anti-angiogenic, and anti-inflammatory activities. Medicinal plants might contain new molecules, with new structures, which could become lead candidate among future anticancer drugs.

[Cancer: three eras of personalized medicine]

Since the completion of the first human DNA sequence, genomic approaches have penetrated into cancer research and therapy: first through expression profiling for diagnostic, prognostic and predictive purposes, then by sequencing of tumour DNA in order to define and apply targeted therapies. These overlapping changes occurred quite rapidly and are now overshadowed by immuno-oncology approaches that show much promise. There is however still much left to understand to make this more widely applicable, and the extreme cost of these therapies is a serious concern.

Cyclophosphamide treatment regulates the balance of functional/exhausted tumor-specific CD8+ T cells

An important question is how chemotherapy may (re-)activate tumor-specific immunity. In this study, we provide a phenotypic, functional and genomic analysis of tumor-specific CD8⁺ T cells in tumor (P815)-bearing mice, treated or not with cyclophosphamide. Our data show that chemotherapy favors the development of effector-type lymphocytes in tumor bed, characterized by higher KLRG-1 expression, lower PD-1 expression and increased cytotoxicity. This suggests re-engagement of T lymphocytes into the effector program. IFN-I appears involved in this remodeling. Our findings provide some insight into how cyclophosphamide regulates the amplitude and quality of tumor-specific immune responses.