Genetic resources of Tunisian Artemisia arborescens L. (Asteraceae), pattern of volatile metabolites concentration and bioactivity and implication for conservation

Apoptosis induction of essential oils from Artemisia arborescens L. in human prostate cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Prostate cancer originates from cells inside a gland, which begin to grow out of control. In the world, prostate cancer is the most common cancer in the male population. New therapeutic strategies are needed for this tumor which still has a high mortality. A. arborescens leaves and aerial parts have various ethnopharmacological uses such as anti-spasmodic, and their decoctions were used to resolve urticaria, neuralgia and several lung diseases. Often this species has been also used to treat different inflammatory-related diseases such as cancer.

AIM OF THE STUDY

In a continuation of our research on essential oils from medicinal plants, we have selected, two essential oils from Artemisia arborescens L. (Compositae), an aromatic shrub widely used in traditional medicine. We evaluated their pro-apototic effect on androgen-sensitive (LNCaP) and androgen-insensitive (DU-145) human prostate cancer cells. In this study, we also evaluated the anti-Signal transducer and transcription factor 3 (STAT-3) activity of both essential oils in the human prostate cancer cell lines, and the treatment with Tumor necrosis factor (TNF)-Related Apoptosis (TRAIL).

MATERIALS AND METHODS

The cells were exposed to essential oils for 72 h and cell viability and cell membrane integrity were evaluated. Genomic DNA and the activity of caspase-3 was tested to confirm the cell death for apoptosis. Western blot analysis was employed to evaluate the expression of Bcl-2, Bax, cleaved caspase-3, cleaved caspase-9, Hsp70, STAT-3 and SOD proteins. Assays to evaluate reactive oxygen species (ROS) and GSH levels were also performed.

RESULTS

The results showed the capacity of two essential oils to activate an apoptotic process increasing the inhibition of Hsp70 and STAT-3 protein expression. In addition, our natural products sensitize LNCaP cells to Tumor necrosis factor (TNF)-Related Apoptosis (TRAIL)-induced apoptosis.

CONCLUSIONS

In summary, our study provides a further contribution to the hypothesis of the use of essential oils, from traditional medicinal plants, for the treatment of tumors, and suggests that the combination of our samples with other anti-prostate cancer therapies could be used to affect prostate cancer.

New insights into the intraspecific cytoplasmic DNA diversity, maternal lineages classification and conservation issues of Tunisian pearl millet landraces

Tunisian pearl millet (Pennisetum glaucum L.) landraces are still growing in contrasting agro-ecological environments and are considered potentially useful for national and international breeders. Despite its genetic potential, the cropping areas of this species are still limited and scattered which increases the risk of genetic erosion. The chloroplast DNA polymorphism and maternal lineages classification of forty nine pearl millet landraces representing seven populations covering the main distribution area of this crop in Tunisia were undertaken based on informative cpSSR molecular markers. A total of 21 alleles combining to 9 haplotypes were detected with a mean value of 3.5 alleles per locus and a haplotype genetic diversity (Hd) of 0.82. The number of chloroplast haplotypes per population ranged from 1 to 4 with an average of 1.28. The haplotypes median-joining network and UPGMA analyses revealed two probable ancestral maternal lineages with a differential pearl millet seed-exchange rate between the investigated areas. Northern and Central populations presented unique genetic backgrounds while historical farmers' practices in the South-East area resulted in the isolation of their own local landraces. The genetic evidences strongly support at least two introduction origins of pearl millet in Tunisia, one in the North and the other in the South followed by distinct local dispersal histories. Complementary in-situ and ex-situ conservation strategies taking into account the conservation of the maternal lineage cytoplasmic diversity are required. The investigated chloroplast SSRs provide useful molecular markers which could be used in further genetic studies and breeding surveys of pearl millet genetic resources.

Chamazulene-Rich Artemisia arborescens Essential Oils Affect the Cell Growth of Human Melanoma Cells

Artemisia arborescens is an aromatic shrub whose essential oils are considered a potential source of molecules with industrial and pharmaceutical interest. The chemical profile of A. arborescens essential oils (EOs) was shown to be quite variable and various chemotypes have been identified. In this study, we compared the EOs composition of A. arborescens leaves and flowers collected from four different locations in Sicily. The EOs were assayed for their antiproliferative activity against A375 human malignant melanoma cells, also testing cell viability and cell membrane integrity. The evaluation of DNA fragmentation and caspase-3 activity assay was employed for the detection of apoptosis. The expression of Bcl-2, Bax, cleaved caspase-9, PTEN (Phosphatase and tensin homolog), Hsp70 (Heat Shock Protein 70 kilodaltons) and SOD (superoxide dismutase) proteins was evaluated by Western blot analysis. The levels of ROS and GSH were also analyzed. Results show that EOs presented significant differences in their composition, yield, and cytotoxic activity depending on the collection site. The chamazulene/camphor-rich EOs from plants collected in Acqua Calda (Lipari) resulted particularly active on melanoma cancer cells (IC₅₀ values of 6.7 and 4.5 µg/mL), being able to trigger apoptotic death probably interfering with endogenous defense mechanisms. These oils may be considered as a natural resource of chamazulene, containing this compound up to 63%.