Antioxidant Extracts from Greek and Spanish Olive Leaves: Antimicrobial, Anticancer and Antiangiogenic Effects

Olea europaea L. is the most valuable species of the Olea type, and its products offer a wide range of therapeutical uses. The olive tree has been extensively studied for its nourishing qualities, and the "Mediterranean diet", which includes virgin olive oil as a key dietary component, is strongly associated with a reduced risk of cardiovascular disease and various malignancies. Olive leaves, a by-product in the olive harvesting process, are valued as a resource for developing novel phytomedicines. For this purpose, two ethanolic extracts obtained from Olivae folium from Spain (OFS) and Greece (OFG) were investigated. Our findings contribute to a wider characterization of olive leaves. Both extracts displayed important amounts of phenolic compounds and pentacyclic triterpenes, OFG having higher concentrations of both polyphenols, such as oleuropein and lutein, as well as triterpenes, such as oleanolic acid and maslinic acid. The antioxidant capacity is similar for the two extracts, albeit slightly higher for OFG, possibly due to metal polyphenol complexes with antioxidant activity. The extracts elicited an antimicrobial effect at higher doses, especially against Gram-positive bacteria, such as Streptococcus pyogenes. The extract with lower inorganic content and higher content of polyphenols and triterpenic acids induced a strong anti-radical capacity, a selective cytotoxic effect, as well as antimigratory potential on A375 melanoma cells and antiangiogenic potential on the CAM. No irritability and a good tolerability were noted after evaluating the extracts on the in vivo Hen's Egg Test-Chorioallantoic Membrane (HET-CAM). Therefore, the present data are suggestive for the possible use of the two types of olive leaf products as high-antioxidant extracts, potentially impacting the healthcare system through their use as antimicrobial agents and as anticancer and anti-invasion treatments for melanoma.

Novel Triterpenic Acid—Benzotriazole Esters Act as Pro-Apoptotic Antimelanoma Agents

Pentacyclic triterpenes, such as betulinic, ursolic, and oleanolic acids are efficient and selective anticancer agents whose underlying mechanisms of action have been widely investigated. The introduction of N-bearing heterocycles (e.g., triazoles) into the structures of natural compounds (particularly pentacyclic triterpenes) has yielded semisynthetic derivatives with increased antiproliferative potential as opposed to unmodified starting compounds. In this work, we report the synthesis and biological assessment of benzotriazole esters of betulinic acid (BA), oleanolic acid (OA), and ursolic acid (UA) (compounds 1–3). The esters were obtained in moderate yields (28–42%). All three compounds showed dose-dependent reductions in cell viability against A375 melanoma cells and no cytotoxic effects against healthy human keratinocytes. The morphology analysis of treated cells showed characteristic apoptotic changes consisting of nuclear shrinkage, condensation, fragmentation, and cellular membrane disruption. rtPCR analysis reinforced the proapoptotic evidence, showing a reduction in anti-apoptotic Bcl-2 expression and upregulation of the pro-apoptotic Bax. High-resolution respirometry studies showed that all three compounds were able to significantly inhibit mitochondrial function. Molecular docking showed that compounds 1–3 showed an increase in binding affinity against Bcl-2 as opposed to BA, OA, and UA and similar binding patterns compared to known Bcl-2 inhibitors.

Olive Trees By-Products as Sources of Bioactive and Other Industrially Useful Compounds: A Systematic Review

The need to produce an ever-increasing quantity of material products and food resulting from the planet globalization process has contributed to the spread of modern agriculture based on a linear production resulting in the generation of tons of waste. This huge amount of waste is generally accumulated in landfills, causing different environmental problems. Hence, researchers moved on to study the processes used to recover agro-industrial by-products within a circular and sustainable bio-economy concept. A systematic quest on Scopus and PubMed databases was performed to identify the data available to date on recycling agro-industrial by-products of Olea europaea L. This systematic review summarizes the knowledge regarding the use of olive trees by-products for producing animal feed, biocomposites, bioethanol, cellulose pulp, activated carbon, and as a fuel source for energy production. Furthermore, the data regarding the potential biological activity of extracts from olive roots, wood, bark, and pruning were analyzed. Olive trees by-products are, indeed, rich in molecules with antioxidant, antimicrobial, cardioprotective, and anticancer activity, representing a promising candidate for treat several human diseases.

Effect of oleanolic acid for prevention of acute lung injury and apoptosis

Background

This study aims to evaluate the efficiency of oleanolic acid on acute lung injury and acute respiratory distress syndrome.

Methods

The study included 70 female Wistar albino rats (weighing 180 to 200 g). We created seven groups, each consisting of 10 rats. Then, we generated acute lung injuries by intra-tracheal peroxynitrite injection in every group except for the control group. We investigated the effect of oleanolic acid. For this purpose, we measured the levels of malondialdehyde, interleukin 1 beta, interleukin 4, interleukin 10 and tumor necrosis factor alpha in the collected blood samples from the rats. In addition, we examined the lung tissue samples histopathologically and assessed the rate of apoptosis.

Results

Peroxynitrite injected groups at 24 and 48 h showed a statistically significant increase in interleukin 1 beta, tumor necrosis factor alpha, interleukin 4, interleukin 10 and malondialdehyde levels, which are accepted as mediators of the inflammatory process, compared to the control group. When peroxynitrite injected groups at 24 and 48 h were compared to the treatment groups of the same hour, a statistically significant decrease was detected. According to histopathological examination, peroxynitrite injected groups at 24 and 48 h showed a significant increase of tissue injury scores compared to the control group. However, the groups that were treated with oleanolic acid showed a significant decrease compared to the peroxynitrite groups (p<0.001 for tumor necrosis factor alpha and apoptosis results at 48 h).

Conclusion

In this study, we confirmed that oleanolic acid can be an effective agent for the prevention of acute lung injury generated via peroxynitrite.

Cytotoxic effect of protic ionic liquids in HepG2 and HaCat human cells: in vitro and in silico studies

Protic ionic liquids (PILs) are innovative chemical compounds, which due to their peculiar nature and amazing physico-chemical properties, have been studied as potential sustainable solvents in many areas of modern science, such as in the industrial fields of textile dyeing, pharmaceuticals, biotechnology, energy and many others. Due to their more than probable large-scale use in a short space of time, a wider analysis in terms of ecotoxicity and biological safety to humans has been attracting significant attention, once many ionic liquids were found to be "a little less than green compounds" towards cells and living organisms. The aim of this study is to investigate the cytotoxicity of 13 recently synthesized PILs, as well as to reinforce knowledge in terms of key thermodynamic magnitudes. All the studied compounds were tested for their in vitro toxic activities on two human cell lines (normal keratinocytes HaCaT and hepatocytes HepG2). In addition, due to the enormous number of possible combinations of anions and cations that can form ionic liquids, a group contribution QSAR model has been tested in order to predict their cytotoxicity. The estimated and experimental values were adequately correlated (correlation coefficient R 2 = 0.9260). The experimental obtained results showed their remarkable low toxicity for the studied in vitro systems.

Effects of Damnacanthal and Nordamnacanthal on Proliferation, Apoptosis, and Migration of Oral Squamous Cell Carcinoma Cells

Cancer is one of the most common causes of death in the developed world, with one-third of people diagnosed with cancer during their lifetime. Oral cancer commonly occurs involving the buccal mucosa (cheeks), tongue, floor of the mouth and lip. It is one of the most devastating and disfiguring of malignancies. Morinda citrifolia L., commonly known as ‘noni’, belongs to the Rubiaceae family. It is native to the Pacific islands, Hawaii, Caribbean, Asia and Australia. The plant displays broad curative effects in pharmacological studies. Damnacanthal (DAM) and Nordamnacanthal (NDAM), anthraquinone compounds isolated from the roots of Morinda citrifolia L., has been used for the treatment of several chronic diseases including cancer. The objectives of this study were to evaluate cytotoxicity, morphological changes, cell death mode (apoptosis/necrosis), and cell migration induced by DAM and NDAM on the most common type of oral cancer, oral squamous cell carcinoma (OSCC)cells. Anti-proliferative effects of these compounds against OSCC cell lines were determined by MTT assay. The mode of cell death was analysed by phase contrast and fluorescent microscopy as well as flow cytometry. In addition, cell migration was assessed. The results showed that DAM and NDAM exerted cytotoxicity against OSCC cells with IC₅₀ values of 1.9 to >30 μg/ml after 72 h treatment. Maximum growth inhibition among the tested cell lines for both compounds was observed in H400 cells, and thus it was selected for further study. The study demonstrated inhibition of H400 OSCC cell proliferation, marked apoptotic morphological changes, induction of early apoptosis, and inhibition of cell migration by DAM and NDAM. Therefore, this information suggests that these compounds from noni have potential for used as anti tumor agents for oral cancer therapy.

Anti-proliferative and antibacterial in vitro evaluation of the polyurethane nanostructures incorporating pentacyclic triterpenes

CONTEXT

Oleanolic and ursolic acids are antitumor and antibacterial agents which are extensively studied. Their major disadvantage is the poor water solubility which limits their applications.

OBJECTIVES

Oleanolic and ursolic acid were encapsulated into polyurethane nanostructures that act as drug carriers. In order to evaluate the effectiveness of the particles, anti-microbial and anti-proliferative activity compared to un-encapsulated active compounds was tested.

MATERIALS AND METHODS

Using an interfacial polycondensation technique, combined with spontaneous emulsification, structures with nanoscale dimensions were obtained. Scanning electron microscopy, differential scanning calorimetry and X-ray assays confirmed the encapsulation process. Concentrations of 10 and 30 μM particles and un-encapsulated compounds were tested by MTT viability assay for several breast cancer lines, with an exposure time of 72 h. For the antibacterial studies, the dilution method with MIC determination was used.

RESULTS

Ursolic acid had an excellent inhibitory effect with IC50 value of 2.47, 1.20, 1.26 and 1.34 μM on MCF7, T47D, MDA-MB-231 and MDA-MB-361, respectively. Oleanolic acid did not show anti-proliferative activity. The pure compounds showed their antibacterial activity only against Bacillus species and Candida albicans, but MIC values were too high to be considered efficient antimicrobial agents (2280 and 4570 μg mL - 1, respectively). Polyurethane nanoparticles which incorporated the agents did not show any biological activity.

DISCUSSION AND CONCLUSION

Although the active compounds did not fully exert their anti-proliferative activity following encapsulation inside polymeric nanoparticles, in vivo evaluation is needed in order to obtain an exhaustive conclusion, as the active compounds could be released as a result of metabolic activity.

Epidermal Differentiation Complex: A Review on Its Epigenetic Regulation and Potential Drug Targets

The primary feature of the mammalian skin includes the hair follicle, inter-follicular epidermis and the sebaceous glands, all of which form pilo-sebaceous units. The epidermal protective layer undergoes an ordered/programmed process of proliferation and differentiation, ultimately culminating in the formation of a cornified envelope consisting of enucleated corneocytes. These terminally differentiated cells slough off in a cyclic manner and this process is regulated via induction or repression of epidermal differentiation complex (EDC) genes. These genes, spanning 2 Mb region of human chromosome 1q21, play a crucial role in epidermal development, through various mechanisms. Each of these mechanisms employs a unique chromatin re-modelling factor or an epigenetic modifier. These factors act to regulate epidermal differentiation singly and/or in combination. Diseases like psoriasis and cancer exhibit aberrations in proliferation and differentiation through, in part, dysregulation in these epigenetic mechanisms. Knowledge of the existing mechanisms in the physiological and the aforesaid pathological contexts may not only facilitate drug development, it also can make refinements to the existing drug delivery systems.

European Viscum album: a potent phytotherapeutic agent with multifarious phytochemicals, pharmacological properties and clinical evidence

Viscum albumL. or European mistletoe (Loranthaceae), a semi-parasitic shrub, has been used as a traditional medicine in Europe for centuries to treat various diseases like cancer, cardiovascular disorder, epilepsy, infertility, hypertension and arthritis.

p38 MAPK signaling mediates mitochondrial apoptosis in cancer cells induced by oleanolic acid

Oleanolic acid (OA) is a nutritional component widely distributed in various vegetables. Although it has been well recognized for decades that OA exerts certain anti-tumor activity by inducing mitochondria-dependent apoptosis, it is still unclear that what molecular signaling is responsible for this effect. In this study, we employed cancer cell lines, A549, BXPC-3, PANC-1 and U2OS to elucidate the molecular mechanisms underlying OA anti- tumor activity. We found that activation of MAPK pathways, including p-38 MAPK, JNK and ERK, was triggered by OA in both a dose and time-dependent fashion in all the tested cancer cells. Activation was accompanied by cleavage of caspases and PARP as well as cytochrome C release. SB203580 (p38 MAPK inhibitor), but not SP600125 (JNK inhibitor) and U0126 (ERK inhibitor), rescued the pro-apoptotic effect of OA on A549 and BXPC- 3 cells. OA induced p38 MAPK activation promoted mitochondrial translocation of Bax and Bim, and inhibited Bcl-2 function by enhancing their phosphorylation. OA can induce reactive oxygen species (ROS)-dependent ASK1 activation, and this event was indispensable for p38 MAPK-dependent apoptosis in cancer cells. In vivo, p38 MAPK knockdown A549 tumors proved resistant to the growth-inhibitory effect of OA. Collectively, we elucidated that activation of ROS/ASK1/p38 MAPK pathways is responsible for the apoptosis stimulated by OA in cancer cells. Our finding can contribute to a better understanding of molecular mechanisms underlying the antitumor activity of nutritional components.

Triterpenes as potentially cytotoxic compounds

Triterpenes are compounds of natural origin, which have numerously biological activities: anti-cancer properties, anti-inflammatory, anti-oxidative, anti-viral, anti-bacterial and anti-fungal. These substances can be isolated from plants, animals or fungi. Nowadays, when neoplasms are main cause of death, triterpenes can become an alternative method for treating cancer because of their cytotoxic properties and chemopreventive activities.

Bioactive properties of the main triterpenes found in olives, virgin olive oil, and leaves of Olea europaea

Oleanolic acid, maslinic acid, uvaol, and erythrodiol are the main triterpenes present in olives, olive tree leaves, and virgin olive oil. Their concentration in virgin olive oil depends on the quality of the olive oil and the variety of the olive tree. These triterpenes are described to present different properties, such as antitumoral activity, cardioprotective activity, anti-inflammatory activity, and antioxidant protection. Olive oil triterpenes are a natural source of antioxidants that could be useful compounds for the prevention of multiple diseases related to cell oxidative damage. However, special attention has to be paid to the concentrations used, because higher concentration may lead to cytotoxic or biphasic effects. This work explores all of the bioactive properties so far described for the main triterpenes present in virgin olive oil.

Ethanol extract of Chaenomeles speciosa Nakai induces apoptosis in cancer cells and suppresses tumor growth in mice

Chaenomeles speciosa Nakai is commonly used in traditional Chinese medicine for a variety of health-promoting effects. The present study aimed to investigate the antitumor effects of Chaenomeles speciosa Nakai. The tumor-inhibitory activity of the ethanol extract of Chaenomeles speciosa Nakai (EEC) was evaluated by in vitro growth assays of tumor cells and in vivo H₂₂ tumor formation assays in mice. Mitochondrial membrane potential and DNA ladder assays were used to detect tumor cell apoptosis in the presence of EEC. To investigate the cellular targets of EEC, the immunomodulatory genes PD-L1, Foxp3 and TGF-β were detected in the tumor tissue using reverse transcription polymerase chain reaction (RT-PCR). Immune responses were determined by hemolysis and lymphocyte proliferation assays. EEC markedly inhibited the proliferation of the H₂₂ cells in a dose-dependent manner. Moreover, it induced DNA fragmentation and decreased the mitochondrial membrane potential. In vivo, EEC inhibited tumor growth and enhanced the immune responses in mice, while the expression of PD-L1, Foxp3 and TGF-β was inhibited in the tumor tissue. These results provide the first evidence that EEC may inhibit tumor growth by directly killing tumor cells and enhancing immune function. Thus, it is a natural source for safe anticancer medicine.