Seasonal Changes in the Plant Growth-Inhibitory Effects of Rosemary Leaves on Lettuce Seedlings.

Plant biodiversity has been studied to explore allelopathic species for the sustainable management of weeds to reduce the reliance on synthetic herbicides. Rosemary (Rosmarinus officinalis L., syn Salvia rosmarinus Spenn.), was found to have plant growth-inhibitory effects, and carnosic acid was reported as an allelochemical in the plant. In this study, the effects of seasonal variation (2011−2012) on the carnosic acid concentration and phytotoxicity of rosemary leaves from two locations in Tunisia (Fahs and Matmata) were investigated. The carnosic acid concentration in rosemary leaves was determined by HPLC, and lettuce (Lactuca sativa L.) was used as the receptor plant in the phytotoxicity bioassay. The highest carnosic acid concentration was found in rosemary samples collected in June 2011, which also had the highest inhibitory activity. Furthermore, a significant inverse correlation (r = −0.529; p < 0.01) was found between the inhibitory activity on lettuce hypocotyl and the carnosic acid concentration in rosemary leaves. Both temperature and elevation had a significant positive correlation with carnosic acid concentration, while rainfall showed a negative correlation. The results showed that the inhibitory effects of rosemary leaf samples collected in summer was highest due to their high carnosic acid concentration. The phytotoxicity of rosemary needs to be studied over time to determine if it varies by season under field conditions.

Involvement of Carnosic Acid in the Phytotoxicity of Rosmarinus officinalis Leaves.

Weeds are rapidly developing resistance to synthetic herbicides, and this can pose a threat to the ecosystem. Exploring allelopathic species as an alternative weed control measure can help minimize the ecological threat posed by herbicide-resistant weeds. In this study, we aimed to evaluate the contribution of some polyphenols to the allelopathy of rosemary (Rosmarinus officinalis L.). The phytotoxic effects of rosemary (leaves, roots, inflorescences, and stems) crude extracts were tested on lettuce (Lactuca sativa L.). Soils incorporated with dried rosemary leaves were also tested on test plants. Reversed-phase high-performance liquid chromatography (HPLC) analysis was used to determine the content of some polyphenols (caffeic, ferulic, gallic, rosmarinic, carnosic, and chlorogenic acids) in rosemary. The specific activity and total activity of crude extracts and individual compounds were evaluated using lettuce. The crude extract of rosemary leaves showed the highest growth inhibitory effect among the rosemary organs tested. Soil amended with rosemary leaf debris reduced the dry matter and seed emergence of lettuce. Carnosic acid was the main compound detected in rosemary leaves and had a high specific activity when tested on lettuce. During the seed germination period, there was observed filter paper coloration among the test plants treated with carnosic acid (250 µg/mL). The high concentration and strong inhibitory effect of carnosic acid could explain the inhibitory activity of the rosemary leaf extract. Hence, we conclude based on the total activity estimation that carnosic acid among the other tested compounds is the major allelochemical in rosemary leaves.

Agricultural Activities of a Meadow Eliminated Plant Litter from the Periphery of a Farmland in Inner Mongolia, China.

The purpose of our investigation was to clarify the effects of agriculture on the process of loss of litter at the periphery of a farmland. This study revealed the generation process of an ecologically unusual phenomenon that is observed around cropland in semi-arid regions. We hypothesized that the vegetation around a farmland cannot supply plant litter to the ground surface because the ecological structure has been changed by agricultural activities. The study was conducted at Xilingol steppe, Xilingol League, Inner Mongolia Autonomous Region, China. Four study lines were established from the edge of an arable field to the surrounding meadow and parallel to the wind direction during the strong wind season. Key measurement for each line was set at the border between the farmland and steppe. Four study sites were set at intervals along each line. Plant litter, soil particle size distribution, plant species composition, plant volume, and species diversity were investigated. Despite using the same mowing method at the meadows of all study sites, the litter at the only periphery of the farmland completely disappeared. Soil particle size distribution in steppe, which was adjacent to the farmland, was similar to that of the farmland. Plant community structure at the periphery of the farmland was different from that of the far side from the farmland. This implies that soil scattered from the farmland affected the species composition of the steppe. Consequently, the change in plant community structure induced litter loss because of mowing. We concluded that plant litter was lost near the farmland because of the combined effects of farming and mowing. The results support our hypothesis that the vegetation around a farmland cannot supply plant litter because the ecological structure has been changed by agricultural activities.

In Vitro Antiproliferative Effect of Arthrocnemum indicum Extracts on Caco-2 Cancer Cells through Cell Cycle Control and Related Phenol LC-TOF-MS Identification.

This study aimed to determinate phenolic contents and antioxidant activities of the halophyte Arthrocnemum indicum shoot extracts. Moreover, the anticancer effect of this plant on human colon cancer cells and the likely underlying mechanisms were also investigated, and the major phenols were identified by LC-ESI-TOF-MS. Results showed that shoot extracts had an antiproliferative effect of about 55% as compared to the control and were characterised by substantial total polyphenol content (19 mg GAE/g DW) and high antioxidant activity (IC50 = 40 µ g/mL for DPPH test). DAPI staining revealed that these extracts decrease DNA synthesis and reduce the proliferation of Caco-2 cells which were stopped at the G2/M phase. The changes in the cell-cycle-associated proteins (cyclin B1, p38, Erk1/2, Chk1, and Chk2) correlate with the changes in cell cycle distribution. Eight phenolic compounds were also identified. In conclusion, A. indicum showed interesting antioxidant capacities associated with a significant antiproliferative effect explained by a cell cycle blocking at the G2/M phase. Taken together, these data suggest that A. indicum could be a promising candidate species as a source of anticancer molecules.

Identification of 6-octadecynoic acid from a methanol extract of Marrubium vulgare L. as a peroxisome proliferator-activated receptor γ agonist.

6-Octadecynoic acid (6-ODA), a fatty acid with a triple bond, was identified in the methanol extract of Marrubium vulgare L. as an agonist of peroxisome proliferator-activated receptor γ (PPARγ). Fibrogenesis caused by hepatic stellate cells is inhibited by PPARγ whose ligands are clinically used for the treatment of diabetes. Plant extracts of Marrubium vulgare L., were screened for activity to inhibit fibrosis in the hepatic stellate cell line HSC-T6 using Oil Red-O staining, which detects lipids that typically accumulate in quiescent hepatic stellate cells. A methanol extract with activity to stimulate accumulation of lipids was obtained. This extract was found to have PPARγ agonist activity using a luciferase reporter assay. After purification using several chromatographic methods, 6-ODA, a fatty acid with a triple bond, was identified as a candidate of PPARγ agonist. Synthesized 6-ODA and its derivative 9-octadecynoic acid (9-ODA), which both have a triple bond but in different positions, activated PPARγ in a luciferase reporter assay and increased lipid accumulation in 3T3-L1 adipocytes in a PPARγ-dependent manner. There is little information about the biological activity of fatty acids with a triple bond, and to our knowledge, this is the first report that 6-ODA and 9-ODA function as PPARγ agonists.

Anticancer effect of Tamarix gallica extracts on human colon cancer cells involves Erk1/2 and p38 action on G2/M cell cycle arrest.

Taking into account that oxidative stress is among the factors causing cancer-related death; chemoprevention which consists in using antioxidant substances such as phenolics could prevent cancer formation and progression. In the present study, phenolic contents and antioxidant activities of methanolic extracts from the halophyte Tamarix gallica shoots were determined. Moreover, the anticancer effect of this species on human colon cancer cells and the likely underlying mechanisms were also investigated. Shoot extracts showed an appreciable total phenolic content (85 mg GAE/g DW) and a high antioxidant activity (IC50 = 3.3 µg/ml for DPPH test). At 50 and 100 µg/ml, shoot, leaf, and flower extracts significantly inhibited Caco-2 cell growth. For instance, almost all plant part extracts inhibited cell growth by 62 % at the concentration 100 µg/ml. DAPI staining results revealed that these extracts decrease DNA synthesis and confirm their effect on Caco-2 cells proliferation, principally at 100 µg/ml. More importantly, cell mitosis was arrested at G2/M phase. The changes in the cell-cycle-associated proteins (cyclin B1, p38, Erk1/2, Chk1, and Chk2) are correlated with the changes in cell cycle distribution. Taken together, our data suggest that T. gallica is a promising candidate species to be used as a source of anticancer biomolecules.

Metabolomics analysis of Cistus monspeliensis leaf extract on energy metabolism activation in human intestinal cells.

Energy metabolism is a very important process to improve and maintain health from the point of view of physiology. It is well known that the intracellular ATP production is contributed to energy metabolism in cells. Cistus monspeliensis is widely used as tea, spices, and medical herb; however, it has not been focusing on the activation of energy metabolism. In this study, C. monspeliensis was investigated as the food resources by activation of energy metabolism in human intestinal epithelial cells. C. monspeliensis extract showed high antioxidant ability. In addition, the promotion of metabolites of glycolysis and TCA cycle was induced by C. monspeliensis treatment. These results suggest that C. monspeliensis extract has an ability to enhance the energy metabolism in human intestinal cells.

Luteolin enhances cholinergic activities in PC12 cells through ERK1/2 and PI3K/Akt pathways.

Luteolin, a 3', 4', 5, 7-tetrahydroxyflavone, is an active compound in Rosmarinus officinalis (Lamiacea), and has been reported to exert several benefits in neuronal cells. However cholinergic-induced activities of luteolin still remain unknown. Neuronal differentiation encompasses an elaborate developmental program which plays a key role in the development of the nervous system. The advent of several cell lines, like PC12 cells, able to differentiate in culture proved to be the turning point for gaining and understanding of molecular neuroscience. In this work, we investigated the ability of luteolin to induce PC12 cell differentiation and its effect on cholinergic activities. Our findings showed that luteolin treatment significantly induced neurite outgrowth extension, enhanced acetylcholinesterase (AChE) activity, known as neuronal differentiation marker, and increased the level of total choline and acetylcholine in PC12 cells. In addition, luteolin persistently, activated extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt; while the addition of pharmacological MEK/ERK1/2 inhibitor (U0126) and PI3k/Akt inhibitor (LY294002) attenuated luteolin-induced AChE activity and neurite outgrowth in PC12 cells. The above findings suggest that luteolin induces neurite outgrowth and enhanced cholinergic activities, at least in part, through the activation of ERK1/2 and Akt signaling.

Land degradation of abandoned croplands in the Xilingol steppe region, Inner Mongolia, China.

Steppe grasslands are distributed over vast areas in arid and semiarid regions of Eurasia. However, steppe grasslands face desertification or degradation caused by human over-activity. In the last decades, steppe regions have seen increased areas of crop cultivation and subsequent abandonment due to inappropriate agricultural management. Land degradation of abandoned croplands has become a common problem in the Inner Mongolia Autonomous Region, China. A field survey was conducted in the Xilingol steppe, and vegetation was classified into three groups. Based on comparisons of species composition and soil characters, group 1 represents steppe grassland, group 2 represents abandoned croplands and group 3 represents yardangs. The typical indicator species of steppe, abandoned croplands and yardangs are Leymus chinensis, Cleistogenes squarrosa and Elymus dahuricus, respectively. Abandoned croplands are exposed to wind and rain, resulting in soil erosion, which not only increases coarse sand content but also decreases total carbon and total nitrogen in the soil. We found that soil condition is an important factor affecting the early stages of secondary succession in abandoned croplands and that farming in typical steppes might contribute to land degradation. We concluded that abandoned croplands can be converted to yardangs by erosion. The extension of yardangs might then lead to desertification in steppe regions. Land managers should be aware that farming in typical steppes is associated with a risk of desertification. The degree of degradation of steppe can be measured by monitoring these indicator species.

Rosmarinus officinalis polyphenols activate cholinergic activities in PC12 cells through phosphorylation of ERK1/2.

AIM OF THE STUDY: This paper aimed to elucidate the traditional use of Rosmarinus officinalis through the investigation of cholinergic activities and neuronal differentiation in rat pheochromocytoma PC12 cells. These effects were examined in relation to the plant's habitat, the extraction procedure, and the major active compounds of R. officinalis. MATERIALS AND METHODS: Cell viability, cell differentiation, acetylcholinesterase (AChE) activity, total choline, acetylcholine (ACh) and extracellular signal-regulated kinases (ERK1/2) were determined in PC12 cells treated with extracts and HPLC-identified polyphenols of R. officinalis originated from Tunisian semi-arid and subhumid area in comparison with nerve growth factor (NGF). RESULTS: R. officinalis extracts potentiated cell differentiation and significantly enhanced AChE activity in PC12 cells. The highest AChE activity was induced by semi-arid hydro-ethanolic extract (137% of control). Among HPLC-identified and screened polyphenols, carnosic acid (CA) and rosmarinic acid (RA) significantly induced cell differentiation, increased ACh level, and enhanced AChE activity in PC12 cells. U0126, inhibitor of ERK1/2, significantly reduced CA and RA effects on cell differentiation and AChE activity. CONCLUSIONS: R. officinalis' CA and RA exhibited neurotrophic effects in PC12 cells through cell differentiation induction and cholinergic activities enhancement. These effects could be regulated by mitogen-activated protein kinase (MAPK), ERK1/2 signaling pathway.