Neuroprotective Effects of Pulicaria incisa Infusion on Human Neuroblastoma Cells and Hippocampal Neurons

Reactive oxygen species (ROS) and oxidative stress increase susceptibility to neurodegeneration and other age-related pathologies. We have previously demonstrated that an infusion prepared from Pulicaria incisa (Pi) has protective, anti-inflammatory, and antioxidative effects in glial cells. However, the neuroprotective activities of Pi infusion in cultured neurons and aging mice have never been studied. In the following study, the effects of Pi infusion were explored in a hydrogen peroxide (H₂O₂)-induced oxidative stress model in SH-SY5Y human neuroblastoma cells. Profiling of the infusion by gas chromatography-mass spectrometry identified chlorogenic acid, quercetin, and aucubin as some of its main constituents. H₂O₂-induced ROS accumulation and caspase 3 activity decreased SH-SY5Y viability and were prevented upon the pretreatment of cells with Pi infusion. Additionally, the Pi infusion upregulated cellular levels and the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) as well as the phosphorylation of cyclic AMP response element-binding protein (CREB). Aging mice treated daily for 18 months with Pi infusion exhibited reduced neuronal cell death in the hippocampus as compared to age-matched controls. We, therefore, propose Pi infusion as a candidate regulator of oxidative stress in the brain.

Evaluation of the hepatoprotective activity of Pulicaria incisa subspecies candolleana and in silico screening of its isolated phenolics

ETHNOPHARMACOLOGICAL RELEVANCE

Pulicaria incisa sub. candolleana E. Gamal-Eldin (Asteraceae) was traditionally used by Bedouins as a refreshing tea and as hypoglycemic, in gastrointestinal ailments, sinusitis and headache. Recently a great correlation has been established between liver cirrhosis and gastrointestinal dysfunction reflected by abdominal bloating, pain, diarrhea, constipation, besides decreased food intake. So far, the hepatoprotective effect of P. incisa sub. candolleana E. Gamal-Eldin was not studied before although other Pulicaria species have previously shown hepatoprotective and antioxidant effects.

AIM OF THE STUDY

In this study, we aimed to identify the phytochemical constituents of the P. incisa sub. candolleana E. Gamal-Eldin hydroethanolic extract (PICE), as well as to evaluate the hepatoprotective, anti-inflammatory and antioxidant activities in methotrexate (MTX)- intoxicated rats. Besides, the molecular interaction between the isolated compounds and cyclooxygenase-2 (COX-2) and phospholipase 2 (PLA-2) were assessed by in-silico screening.

MATERIAL AND METHODS

The main phytoconstituents were characterized using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Vacuum liquid chromatography (VLC) aided by preparative high-performance liquid chromatography (HPLC) were also used to isolate the major phenolics from the hydroethanolic extract. Their structures were elucidated using different spectroscopic analysis methods, including 1D and 2D nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI/MS). The hepatoprotective activity of three doses (100, 250, 500 mg/kg) of PICE in MTX-intoxicated rats was assessed and compared to silymarin as a standard. Additionally, in silico docking study on cyclooxygenase-2 (COX-2) and phospholipase 2 (PLA-2) was performed to justify the anti-inflammatory activity of the isolated compounds.

RESULTS

Thirteen compounds were tentatively identified, including flavonoids and phenolic acids. Four main isolated compounds were identified as, eugenol-1-O-β-glucoside, 5-O-caffeoylquinic acid, 3, 5-di-O-caffeoylquinic acid and quercetin-3-O-β-glucoside. Treatment of MTX-intoxicated rats with the 250 mg/kg extract reversed the altered levels of biochemical markers of liver damage, ameliorated the oxidant status and reduced the inflammatory mediators, similar to treatment with silymarin. Quercetin-3-O-β-glucoside showed the best docking energy score of -19.12 kcal/mol against COX-2, forming four binding interactions with residues Leu 353, Arg 121, Tyr 356 and Ala 528, followed by 3,5-di-O-caffeoylquinic acid (-18.01 kcal/mol).

CONCLUSION

This study reveals P. incisa sub. candolleana as a rich source of phenolics including flavonoids, supporting its anti-inflammatory and hepatoprotective effects and suggesting its usage as a promising candidate in inflammatory conditions.

Essential Oil Analysis and Antimicrobial Evaluation of Three Aromatic Plant Species Growing in Saudi Arabia

Arabian flora is a rich source of bioactive compounds. In this study, we investigated three aromatic plant species with the aim of finding valuable sources of antimicrobial agents against common pathogenic microorganisms. We focused especially on microorganisms, which cause outbreaks of infectious disease during mass gatherings and pilgrimages season in Saudi Arabia. The essential oils of three aromatic plant species were hydrodistilled from flowering aerial parts of Lavandula pubescens Decne. and Pulicaria incisa subsp. candolleana E.Gamal-Eldin, and from leaves, stems, ripe and unripe fruits of Juniperus procera Hochst. Ex Endl. They were subsequently analyzed by gas chromatography-mass spectrometry (GC-MS). The main constituents of L. pubescens were found to be carvacrol (55.7%), methyl carvacrol (13.4%), and β-bisabolene (9.1%). P. incisa subsp. Candolleana essential oil was rich in linalool (33.0%), chrysanthenone (10.3%), eugenol (8.9%), and cis-chrysanthenol (8.0%); the major components of J. procera essential oil were α-pinene (31.3-62.5%) and δ-3-carene (7.3-30.3%). These essential oils were tested against thirteen American Type Culture Collection (ATCC) strains of Gram-positive and Gram-negative bacteria using the agar diffusion assay. The only effective essential oil was that of L. pubescens and the most sensitive strains were Acinetobacter baumannii, Salmonella typhimurium, Shigella sonnei, Enterococcus faecalis and Staphylococcus epidermidis. Carvacrol, the major constituent of L. pubescens, was tested on these strains and was compared with vancomycin, amikacin, and ciprofloxacin. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays of L. pubescens essential oil and carvacrol revealed that Gram-negative strains were more susceptible than the Gram-positive ones.

Plant Growth-Promoting Endophytic Bacterial Community Inhabiting the Leaves of Pulicaria incisa (Lam.) DC Inherent to Arid Regions

In this study, 15 bacterial endophytes linked with the leaves of the native medicinal plant Pulicaria incisa were isolated and identified as Agrobacterium fabrum, Acinetobacter radioresistant, Brevibacillus brevis, Bacillus cereus, Bacillus subtilis, Paenibacillus barengoltzii, and Burkholderia cepacia. These isolates exhibited variant tolerances to salt stress and showed high efficacy in indole-3-acetic acid (IAA) production in the absence/presence of tryptophan. The maximum productivity of IAA was recorded for B. cereus BI-8 and B. subtilis BI-10 with values of 117 ± 6 and 108 ± 4.6 μg mL-1, respectively, in the presence of 5 mg mL-1 tryptophan after 10 days. These two isolates had a high potential in phosphate solubilization and ammonia production, and they showed enzymatic activities for amylase, protease, xylanase, cellulase, chitinase, and catalase. In vitro antagonistic investigation showed their high efficacy against the three phytopathogens Fusarium oxysporum, Alternaria alternata, and Pythium ultimum, with inhibition percentages ranging from 20% ± 0.2% to 52.6% ± 0.2% (p ≤ 0.05). Therefore, these two endophytic bacteria were used as bio-inoculants for maize seeds, and the results showed that bacterial inoculations significantly increased the root length as well as the fresh and dry weights of the roots compared to the control plants. The Zea mays plant inoculated with the two endophytic strains BI-8 and BI-10 significantly improved (p ≤ 0.05) the growth performance as well as the nutrient uptake compared with an un-inoculated plant.

Metabolite profiles of Pulicaria crispa and P. incisa in relation to their in-vitro/ in-vivo antioxidant activity and hepatoprotective effect: A comparative mass spectrometry-based metabolomics

Plants of the genus Pulicaria (family: Asteraceae) are widely used in central Asia and the Middle East for treatment of different human diseases. Ultra performance liquid chromatography coupled to high resolution mass spectrometry (UPLC/MS) was utilized to establish the metabolic profiles of two Pulicaria species: P. crispa and P. incisa. 122 metabolites were identified including flavonoids (37), phenolic acids (22), sesquiterpenes (17), diterpenes (7), and fatty acids (27), with enrichment in methoxylated flavonoids (20), caffeoylquinic acid conjugates (14) xanthane sesquiterpenes (9) and hydroxylated fatty acids (20) in both Pulicaria species. The metabolite profile of P. incisa was characterized by the presence of tri- and tetra-methoxylated flavonoids while xanthane sesquiterpenes were the main chemical markers of P. crispa. Additionally, a novel sesquiterpene acid (dihydropulicaric acid) was annotated in both species based on its MS fragments. Antioxidant activity for P. crispa and P. incisa methanol extracts was assessed in vitro based on DPPH and ABTS assays and further in vivo using chlorpromazine intoxicated rat model. Results revealed that P. incisa extract was more effective in inhibiting both DPPH and ABTS free radicals (IC₅₀ 0.36 and 0.52 mg/mL, respectively) than P. crispa (IC₅₀ 0.51 and 0.73 mg/mL). In the animal model, antioxidant activity of P. incisa (20 mg/kg/day) was also slightly higher causing a 55 % reduction in MDA levels and 65 % increase in GSH activity compared to untreated animals. Furthermore, both extracts showed a hepatoprotective effect as revealed by improvement in levels of serum biomarkers of liver functions: total bilirubin, alanine transaminase (ALT) and aspartate transaminase (AST) comparable to silymarin at 25 mg/kg/day. These findings were also supported by the preserved integrity of the hepatic tissues of animals receiving either extracts at a dose of 20 mg/kg b.wt. The present study reveals for the potential antioxidant and hepatoprotective effects for Pulicaria in relation to its bioactive metabolites.

Growth, hydrolases and ultrastructure of Fusarium oxysporum as affected by phenolic rich extracts from several xerophytic plants

Fusarium oxysporum, the causal agent of rot and wilt diseases, is one of the most detrimental phytopathogens for the productivity of many economic crops. The present study was conducted to evaluate the potentiality of some xerophytic plants as eco-friendly approach for management of F. oxysporum. Phenolic rich extracts from five plants namely: Horwoodia dicksoniae, Citrullus colocynthis, Gypsophila capillaris, Pulicaria incisa and Rhanterium epapposum were examined in vitro. The different extracts showed high variability in their phenolic and flavonoid contents as well as total antioxidant capacity. A strong positive correlation existed between the antifungal activity of the tested extracts and their contents of both total phenolics and flavonoids (r values are 0.91 and 0.82, respectively). Extract of P. incisa was the most effective in reducing the mycelial growth (IC₅₀=0.92mg/ml) and inhibiting the activities of CMCase, pectinase, amylase and protease by 36, 42, 58 and 55%, respectively. The high performance liquid chromatography analysis of P. incisa extract revealed the presence of eight phenolic acids along with five polyphenolic compounds. The flavonol, quercetin and its glycosides rutin and quercetrin were the most abundant followed by the phenolic acids, t-cinnamic, caffeic, ferulic and vanillic. P. incisa extract not only affects the growth and hydrolases of F. oxysporum but also induces ultrastructure changes in the mycelium, as revealed by transmission electron microscopy. To our knowledge, this is the first study to investigate the mechanisms underlying the antifungal activity of P. incisa.

Potency of extracts from selected Egyptian plants as inducers of the Nrf2-dependent chemopreventive enzyme NQO1

Medicinal plants from the Egyptian Sinai Peninsula are widely used in traditional Bedouin medicine to treat a range of conditions including cancer, and as such are a promising resource for novel anti-cancer compounds. To achieve scientific justification of traditional use and/or to recommend the use of those plants as medicinal herbs for cancer chemoprevention, a group of 11 Sinai plants of different species that belong to 3 families (Asteraceae, Lamiaceae, and Euphorbiaceae) were biologically screened for cancer preventive activity using the chemoprevention marker enzyme

NAD(P)H

quinone oxidoreductase 1 (NQO1). Among the fractions assayed, a solvent extract from Pulicaria incisa had potent NQO1 inducing activity. Further analysis of the mechanism of induction revealed the concentration-dependent stabilization of the transcription factor NF-E2 p45-related factor 2 (Nrf2) and a coordinate upregulation of the Nrf2-dependent enzymes NQO1, heme oxygenase 1 and glutathione S-transferase-Pi. These results establish P. incisa as a promising target for future phytochemical characterization for cancer preventive components.