Antoine M. Saab

Antiproliferative effects of essential oils and their major constituents in human renal adenocarcinoma and amelanotic melanoma cells

Abstract.  Objectives: The purpose of this study was to evaluate cytotoxic activity of Platycladus orientalis, Prangos asperula and Cupressus sempervirens ssp. pyramidalis essential oils and to identify active components involved in inhibition of population growth of human cancer cell lines. Materials and methods: Essential oils were obtained by hydrodistillation and were analysed by gas chromatography and gas chromatography coupled to mass spectrometry. Antiproliferative activity was tested on amelanotic melanoma C32 cells and on renal cell adenocarcinoma cells, using the sulphorhodamine B assay. Results: Cupressus sempervirens ssp. pyramidalis leaf oil exerted the highest cytotoxic activity with an IC50 value of 104.90 µg/mL against C32, followed by activity of P. orientalis and P. asperula on the renal adenocarcinoma cell line (IC50 of 121.93 and 139.17 µg/mL, respectively). P. orientalis essential oil was also active against amelanotic melanoma with an IC50 of 330.04 µg/mL. Three identified terpenes, linalool, β‐caryophyllene and α‐cedrol, were found to be active on both cell lines tested. Conclusions: Our findings provide novel insights into the field of cytotoxic properties of essential oils. This study provided evidence on how cytotoxic activity of the oils is not always related to their major constituents, except for lower activity found in both cell lines for α‐cedrol. Interestingly, β‐caryophyllene and linalool exhibited comparable IC50 values to the commercial drug vinblastine on the ACHN cell line. This opens a new field of investigation to discover mechanisms responsible for the observed activity.

In vitro inhibitory activities of plants used in Lebanon traditional medicine against angiotensin converting enzyme (ACE) and digestive enzymes related to diabetes

AIM OF THE STUDY In recent years the use of medicinal plants has been growing worldwide and this is particularly true in Lebanon. In the present investigation we report the inhibitory activity against digestive enzymes related to diabetes and angiotensin converting enzyme (ACE) of extracts of nine plant species collected in Lebanon, where they have a traditional use against diabetes. MATERIALS AND METHODS In order to evaluate if the extraction procedure could influence the activity we decided to perform different extractions with methanol, n-hexane and chloroform of Calamintha origanifolia, Satureja thymbra, Prangos asperula, Sideritis perfoliata, Asperula glomerata, Hyssopus officinalis, Erythraea centaurium, Marrubium radiatum and Salvia acetabulosa and test each of them. RESULTS AND CONCLUSIONS Marrubium radiatum and Salvia acetabulosa methanol extracts exerted the highest activity against alpha-amylase (IC(50) 61.1 and 91.2 microg/ml, respectively) and alpha-glucosidase (IC(50) 68.8 and 76.9 microg/ml, respectively). The same extracts exhibited a strong inhibitory activity against ACE with IC(50) of 72.7 and 52.7 microg/ml, respectively. The results support the traditional use of some the species examined.

Phytochemical Analysis and in vitro Antiviral Activities of the Essential Oils of Seven Lebanon Species

The chemical composition of the essential oils of Laurus nobilis, Juniperus oxycedrus ssp. oxycedrus, Thuja orientalis, Cupressus sempervirens ssp. pyramidalis, Pistacia palaestina, Salvia officinalis, and Satureja thymbra was determined by GC/MS analysis. Essential oils have been evaluated for their inhibitory activity against SARS‐CoV and HSV‐1 replication in vitro by visually scoring of the virus‐induced cytopathogenic effect post‐infection. L. nobilis oil exerted an interesting activity against SARS‐CoV with an IC50 value of 120 μg/ml and a selectivity index (SI) of 4.16. This oil was characterized by the presence of β‐ocimene, 1,8‐cineole, α‐pinene, and β‐pinene as the main constituents. J. oxycedrus ssp. oxycedrus oil, in which α‐pinene and β‐myrcene were the major constituents, revealed antiviral activity against HSV‐1 with an IC50 value of 200 μg/ml and a SI of 5.

Comparative chemical composition and antiproliferative activity of aerial parts of Salvia leriifolia Benth. and Salvia acetabulosa L. essential oils against human tumor cell in vitro models.

The aim of this work was to examine the chemical composition and antiproliferative activity of Salvia leriifolia Benth. and Salvia acetabulosa L. oils. S. leriifolia oil was characterized by 50 components, whereas 19 components were identified in S. acetabulosa. S. leriifolia oil was characterized by camphor (10.5%), 1,8-cineole (8.6%), camphene (6.2%), and alpha-pinene (4.7%). alpha-Pinene (52.3%), 1,8-cineole (27.7%), and camphor (6.7%) were the major components in S. acetabulosa oil. Both oils exerted a strong antiproliferative activity comparing with vinblastine against COR-L23 with 50% inhibitory concentration (IC(50)) values of 7.5 and 6.5 microg/mL for S. leriifolia and S. acetabulosa, respectively. Salvia oils showed an interesting activity also on C32 (IC(50) = 6.3 and 9.1 microg/mL for S. acetabulosa and S. leriifolia, respectively). S. acetabulosa was also found to possess cytotoxic activity against renal adenocarcinoma (IC(50) = 6.8 microg/mL). The results clearly showed that for both Salvia species the antiproliferative activity could not be related to the major abundant compounds. Consequently, the minor components may be involved in some type of synergism with the other active compounds.

Phytochemical analysis and cytotoxicity towards multidrug-resistant leukemia cells of essential oils derived from Lebanese medicinal plants.

Juniperus excelsa fruit essential oil as well as J. oxycedrus, Cedrus libani, and Pinus pinea wood essential oils have been obtained with yields between 2.2 ± 0.3 % to 3.4 ± 0.5 % and analyzed by gas chromatography. Sesquiterpenes mainly characterized C. libani and J. oxycedrus essential oils, while in P. pinea and J. excelsa, monoterpenes were the most abundant compounds. In J. oxycedrus, cis-calamenene (7.8 %), cuparene (3.8 %), and cis-thujopsenal (2.0 %) have been detected for the first time. The cytotoxic activity of these essential oils against drug-sensitive CCRF-CEM and multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells has been investigated (IC₅₀ values: 29.46 to 61.54 µg/mL). Remarkably, multidrug-resistant CEM/ADR5000 cells did not reveal cross-resistance, indicating that these essential oils might be useful to treat otherwise drug-resistant and refractory tumors.

Berberis aetnensis and B. libanotica: a comparative study on the chemical composition, inhibitory effect on key enzymes linked to Alzheimer's disease and antioxidant activity

This study involves for the first time the evaluation of Berberis aetnensis C. Presl. and Berberis libanotica Ehrenb. ex C.K. Schneid. roots for anticholinesterase and antioxidant properties, with the aim to search compounds possibly useful for the treatment of Alzheimers disease (AD).

Antiproliferative Activities on Renal, Prostate and Melanoma Cancer Cell Lines of Sarcopoterium spinosum Aerial Parts and its Major Constituent Tormentic Acid

The search for improved cytotoxic agents continues to be an important line in the discovery of modern anticancer drugs. Sarcopoterium spinosum (L.) Spach is mentioned in ethnobotanical surveys as a medicinal plant used for the treatment of cancer. The aim of this study is to investigate and to compare the aerial parts of S. spinosum collected in Italy and Lebanon for their chemical composition and their antiproliferative activity against ACHN, C32, A375, MCF-7, LNCaP and HeLa human cancer cell lines using SRB assay. The main constituent tormentic acid was isolated by MPLC and characterized by spectroscopic techniques (NMR, MS). Non polar compounds were analyzed by GC and GC-MS. S. spinosum showed an interesting antiproliferative activity against ACHN and C32 cell lines with IC(50) values of 2.4 and 2.7 μg/ml for S. spinosum from Italy and Lebanon, respectively. Remarkable results were obtained also against A375 and LNCaP cell lines. The cytotoxicity against ACHN cell line could be partially attributed to tormentic acid that demonstrated a higher cytotoxicity than the positive control vinblastine. Close association between the radical scavenging activity (evaluated by DPPH and ABTS assay) and cytotoxicity was also demonstrated. This investigation demonstrated the potential cytotoxic activity of S. spinosum taking into account also that none of the tested extracts, fractions and isolated compound affected the proliferation of normal cell line 142BR. Tormentic acid, the major constituent isolated from S. spinosum, play an important role in the cytotoxicity exhibited by the extract.

Berberis libanotica extract targets NF-κB/COX-2, PI3K/Akt and mitochondrial/caspase signalling to induce human erythroleukemia cell apoptosis

The aim of this study was to describe and understand the relationship between cyclooxygenase-2 (COX-2) expression and apoptosis rate in erythroleukemia cells after apoptosis induction by Berberis libanotica (Bl) extract. To achieve this goal we used erythroleukemia cell lines expressing COX‑2 (HEL cell line) or not (K562 cell line). Moreover, we made use of COX‑2 cDNA to overexpress COX‑2 in K562 cells. In light of the reported chemopreventive and chemosensitive effects of natural products on various tumor cells and animal models, we postulated that our Bl extract may mediate their effects through apoptosis induction with suppression of cell survival pathways. Our study is the first report on the specific examination of intrinsic apoptosis and Akt/NF-κB/COX‑2 pathways in human erythroleukemia cells upon Bl extract exposure. Even if Bl extract induced apoptosis of three human erythroleukemia cell lines, a dominant effect of Bl extract treatment on K562 cells was observed resulting in activation of the late markers of apoptosis with caspase-3 activation, PARP cleavage and DNA fragmentation. Whereas, we showed that Bl extract reduced significantly expression of COX‑2 by a dose-dependent manner in HEL and K562 (COX‑2+) cells. Furthermore, in regard to our results, it is clear that the simultaneous inhibition of Akt and NF-κB signalling can significantly contribute to the anticancer effects of Bl extract in human erythroleukemia cells. We observed that the Bl extract is clearly more active than the berberine alone on the induction of DNA fragmentation in human erythro-leukemia cells.

In vitro evaluation of the anti-proliferative activities of the wood essential oils of three Cedrus species against K562 human chronic myelogenous leukaemia cells

There are four kinds of Cedar: Cedrus libani naturally occurring in Lebanon, Syria and Turkey, Cedrus atlantica in Morocco and Algeria, Cedrus brevefolia in Cyprus Island and Cedrus deodara which is distributed in Himalayan Mountains. Wood essential oils obtained from C. libani, C. atlantica and C. deodara were tested for the inhibition of K562 cell proliferation and for the induction of erythroid differentiation. The wood essential oils of C. libani, C. atlantica and C. deodara inhibited the proliferation of the K562 cell line exhibiting IC50 values 23.38 ± 1.7, 59.37 ± 2.6 and 37.09 ± 1.4 µg mL−1, respectively. Meanwhile, C. libani wood oils induced a percentage of erythroid differentiation of 15 ± 2% at concentration 5 µg mL−1. Cedrus deodara wood oil indicated a percentage of erythroid differentiation of 20 ± 2% at concentration 25 µg mL−1 and C. atlantica wood oils showed a percentage of erythroid differentiation of 12 ± 1.8% at concentration 10 µg mL−1.

Laurus nobilis L. Seed Extract Reveals Collateral Sensitivity in Multidrug-Resistant P-Glycoprotein-Expressing Tumor Cells

The frequent failure of standard cancer chemotherapy requires the development of novel drugs capable of killing otherwise drug-resistant tumors. Here, we have investigated a chloroform extract of Laurus nobilis seeds. Fatty acids and 23 constituents of the volatile fraction were identified by gas chromotography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS), in good agreement with 1H NMR (nuclear magnetic resonance) spectrum. Multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells were hypersensitive (collaterally sensitive) toward this extract compared to drug-sensitive CCRF-CEM cells, whereas CEM/ADR5000 cells were 2586-fold resistant to doxorubicin as control drug. Collateral sensitivity was verified by measurement of apoptotic cells by flow cytometry. The log10IC50 values of 3 compounds in the extract (limonene, eucalyptol, oleic acid) did not correlate with mRNA expression of the P-glycoprotein-coding ABCB1/MDR1 gene and accumulation of the P-glycoprotein substrate rhodamine in the NCI panel of tumor cell lines. A microarray-based profile of 20 genes predicted resistance to doxorubicin and 7 other anticancer drugs involved in the multidrug resistance phenotype but not to limonene, eucalyptol and oleic acid. In conclusion, our results show that Laurus nobilis seed extract is suitable to kill multidrug-resistant P-glycoprotein expressing tumor cells.