In vitro and in vivo toxicological evaluations of methyl ferulate, methyl p-coumarate, and pulegone 1,2-epoxide

Molecular Interaction Studies and Phytochemical Characterization of Mentha pulegium L. Constituents with Multiple Biological Utilities as Antioxidant, Antimicrobial, Anticancer and Anti-Hemolytic Agents

Multiple biological functions of Mentha pulegium extract were evaluated in the current work. Phytochemical components of the M. pulegium extract were detected by Gas Chromatography-Mass Spectrometry (GC-MS) and High-performance liquid chromatography (HPLC). Moreover, M. pulegium extract was estimated for antioxidant potential by 2,2-Diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging, antimicrobial activity by well diffusion, and anticoagulant activity via prothrombin time (PT) and activated partial thromboplastin time (APTT). GC-MS analysis detected compounds including cholesterol margarate, stigmast-5-en-3-ol, 19-nor-4-androstenediol, androstan-17-one, pulegone-1,2-epoxide, isochiapin B, dotriacontane, hexadecanoic acid and neophytadiene. Chrysoeriol (15.36 µg/mL) was followed by kaempferol (11.14 µg/mL) and 7-OH flavone (10.14 µg/mL), catechin (4.11 µg/mL), hisperdin (3.05 µg/mL), and luteolin (2.36 µg/mL) were detected by HPLC as flavonoids, in addition to ferulic (13.19 µg/mL), cinnamic (12.69 µg/mL), caffeic (11.45 µg/mL), pyrogallol (9.36 µg/mL), p-coumaric (5.06 µg/mL) and salicylic (4.17 µg/mL) as phenolics. Antioxidant activity was detected with IC50 18 µg/mL, hemolysis inhibition was recorded as 79.8% at 1000 μg/mL, and PT and APTT were at 21.5 s and 49.5 s, respectively, at 50 μg/mL of M. pulegium extract. The acute toxicity of M. pulegium extract was recorded against PC3 (IC50 97.99 µg/mL) and MCF7 (IC50 80.21 µg/mL). Antimicrobial activity of M. pulegium extract was documented against Bacillus subtilis, Escherichia coli, Pseudomonasaureus, Candida albicans, Pseudomonas aeruginosa, but not against black fungus Mucor circinelloides. Molecular docking was applied using MOE (Molecular Operating Environment) to explain the biological activity of neophytadiene, luteolin, chrysoeriol and kaempferol. These compounds could be suitable for the development of novel pharmacological agents for treatment of cancer and bacterial infections.

Chitosan Hydrogels with Embedded Thermo- and pH-Responsive Microgels as a Potential Carrier for Controlled Release of Drugs

We report a promising strategy based on chitosan (CS) hydrogels and dual temperature- and pH-responsive poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPAM-co-MAA) microgels to facilitate release of a model drug, moxifloxacin (MFX). In this protocol, first, the microgels were prepared using a free radical copolymerization method, and subsequently, these carboxyl-group-rich soft particles were incorporated inside the hydrogel matrix using an EDC-NHS amidation method. Interestingly, the resulting microgel-embedded hydrogel composites (MG-HG) acting as a double barrier system largely reduced the drug release rate and prolonged the delivery time for up to 68 h, which was significantly longer than that obtained using microgels or hydrogels alone (20 h). On account of the dual-responsive features of the embedded microgels and the variation of water-solubility of drug molecules as a function of pH, MFX could be released in a controllable manner by regulating the temperature and pH of the delivery medium. The release kinetics followed a Korsmeyer-Peppas model, and the drug delivery mechanism was described by Fickian diffusion. Both the gel precursors and the hydrogel composites exhibited low cytotoxicity against mammalian cell lines (HeLa and HEK-293) and no deleterious hemolytic activity up to a certain higher concentration, indicating excellent biocompatibility of the materials. Thus, the unprecedented combination of modularity of physical properties caused by soft particle entrapment, unique macromolecular architecture, biocompatibility, and the general utility of the stimuli-responsive polymers offers a great promise to use these composite materials in drug delivery applications.

Toxicity of Selected Monoterpenes and Essential Oils Rich in These Compounds

Monoterpenes make up the largest group of plant secondary metabolites. They can be found in numerous plants, among others, the Lamiaceae family. The compounds demonstrate antioxidative, antibacterial, sedative and anti-inflammatory activity, hence, they are often employed in medicine and pharmaceuticals. Additionally, their fragrant character is often made use of, notably in the food and cosmetic industries. Nevertheless, long-lasting studies have revealed their toxic properties. This fact has led to a detailed analysis of the compounds towards their side effects on the human organism. Although most are safe for human food and medical applications, there are monoterpene compounds that, in certain amounts or under particular circumstances (e.g., pregnancy), can cause serious disorders. The presented review characterises in vitro and in vivo, the toxic character of selected monoterpenes (α-terpinene, camphor, citral, limonene, pulegone, thujone), as well as that of their original plant sources and their essential oils. The selected monoterpenes reveal various toxic properties among which are embryotoxic, neurotoxic, allergenic and genotoxic. It is also known that the essential oils of popular plants can also reveal toxic characteristics that many people are unaware of.

Development of nanostructured lipid carriers as a promising tool for methotrexate delivery: physicochemical and in vitro evaluation

The aim of the present study is to fabricate the stable nanostructured lipid carriers (NLCs) using biocompatible excipients for the encapsulation of Methotrexate (MTX), a chemotherapeutic agent for breast cancer treatment. MTX has restricted clinical applications owing to its low solubility, non-specific targeting and adverse side effects. Glyceryl Monostearate (GMS) and Miglyol 812 (MI1) were chosen as solid and liquid lipids, respectively, for the fabrication of NLCs, and the influence of variation of solid and liquid composition was investigated. The prepared NLCs exhibited long-term stability and spherical shape morphology as characterized by electron microscopy. The internal structure of fabricated NLCs was arranged into cubic crystalline as confirmed by small-angle X-ray scattering (SAXS) analysis. MTX's encapsulation efficiency of ∼85 ± 0.9%. and sustained in vitro release of MTX ∼ 52% ± 3.0 in 24 h was achieved. Classical molecular dynamics (MD) simulations were performed to study the structural stability of the MTX encapsulated NLCs. Hemolysis carried out on the NLCs showcased the biosafety of the formulation under the tolerance limit (<10%). Further, the MTT assay demonstrates that MTX-loaded NLCs exhibited toxicity against HeLa and MCF-7 cell lines as compared to blank NLCs. The finding demonstrates NLCs as promising vehicles for MTX delivery to address cancer.Communicated by Ramaswamy H. Sarma.

Buchu (Agathosma betulina and A. crenulata): Rightfully Forgotten or Underutilized?

Today, the term buchu refers to the two species in commerce, Agathosma betulina (P.J.Bergius) Pillans and Agathosma crenulata (L.) Pillans (Rutaceae). Its traditional use in urinary tract infections and related ailments made it a popular remedy, specifically in the US, in 19th century, but with the advent of antibiotics it became largely obsolete. Recent focus is on technological use and on the essential oil for use in the perfume and food-flavouring industry. A review of the scarce pharmacological research revealed moderate antimicrobial activity for a leaf extract but not the essential oil of both species in the MIC assay. In the 5-lipoxygenase (5-LO) assay the essential oil of both species revealed IC50 values of 50.37 ± 1.87 μg/ml and 59.15 ± 7.44 μg/ml, respectively. In another study 98% inhibitory activity was determined for 250 μg/ml of an ethanolic extract of A. betulina on cyclooxygenase (COX)-1 and a 25% inhibitory activity on COX-2. Analgesic activity of an ethanolic extract of A. betulina was shown in mice. Moderate antioxidant activity was determined for methanol:dichlormethane extracts of A. betulina and A. crenulata and an aqueous extract of A. betulina showed a Trolox equivalent antioxidant capacity (TEAC) of 11.8 µM Trolox. Recent in vitro studies with a commercial aqueous extract of buchu revealed increased uptake of glucose added to 3T3-L1 cell line, significant inhibition of the respiratory burst of neutrophils and monocytes, reduction in the expression of adhesion molecules and inhibition of the release of IL-6 and TNF-α. In diabetic rats the ingestion of aqueous buchu extract completely normalized the glucose level and in rats receiving a high fat diet the consumption of aqueous buchu extract resulted in less weight gain and less intraperitoneal fat gain as well as reduction of elevated blood pressure to normal associated with cardioprotective effects. Limitations in the hitherto conducted research lie in the undisclosed composition of the buchu extracts used and the difficulty in extrapolating data from animal studies to humans. Health claims for buchu products need to be substantiated by randomized, double-blind and placebo-controlled studies. Only then can they be promoted for their true therapeutic potential.

Structure basis of the caffeic acid O-methyltransferase from Ligusiticum chuanxiong to understand its selective mechanism

Caffeic acid O-methyltransferase from Ligusticum chuanxiong (LcCOMT) showed strict regiospecificity despite a relative degree of preference. Compared with caffeic acid, methyl caffeate was the preferential substrate by its low Km and high Kcat. In this study, we obtained the SAM binary (1.80 Å) and SAH binary (1.95 Å) complex LcCOMT crystal structures, and established the ternary complex structure with methyl caffeate by molecular docking. The active site of LcCOMT included phenolic substrate pocket, SAM/SAH ligand pocket and conserved catalytic residues as well. The regiospecificity of LcCOMT that permitted only 3-hydroxyl group to be methylated arise from the interactions between the active site and the phenyl ring. However, the propanoid tail governed the relative preference of LcCOMT. The ester group in methyl caffeate stabilized the anionic intermediate caused by His268-Asp269 pair, whereas caffeic acid was unable to stabilize the anionic intermediate due to the adjacent carboxylate anion in the propanoid tail. Ser183 residue formed an additional hydrogen bond with SAH and its role was identified by S183A mutation. Ile318 residue might be a potential site for determination of substrate preference, and its mutation led to the change of tertiary conformation. The results supported the selective mechanism of LcCOMT.

Antioxidant and Wound Healing Potential of Essential Oil from Citrus reticulata Peel and Its Chemical Characterization

BACKGROUND

Fruit peels are considered as waste and contribute to a major proportion of the biomass. They can be a good source of various therapeutic benefits. Peels biomass of citrus fruits is usually considered as garbage. Such peels may have many important and valuable medicinal components with pharmacological activities. Citrus reticulata, (Rutaceae family, local name tangerine) is a local seasonal fruit in Pakistan, a very good example of wastage of its peels.

OBJECTIVE

The study is based on the exploration of a citrus fruit peel derived essential oil, its chemical characterization, identification of various bioactive components and the exploration of pharmacological potentials (antibacterial and wound healing activity).

METHODS

Essential oil was recovered by hydro-distillation of freshly collected peels. Chemical constituents of oil were determined by Gas Chromatography-Mass Spectroscopy (GC-MS) analysis. Antioxidant activities were evaluated by total phenolic contents, total flavonoid content, DPPH scavenging activity and reducing power assay. Antibacterial activity was determined using disc diffusion assay. In vivo wound healing potential was determined in rabbits after topical administration of oil. Wound scoring was calculated followed by histological study.

RESULTS

GC-MS analysis showed the presence of various components with the greatest proportion of D-Limonene (89.31%). Total flavonoid and phenolic contents were found to be 14.63 ± 0.95 mg CE/g and 17.03 ± 3.24 mg GAE/g respectively, while DPPH activity was found to be 73.32%. A better antibacterial activity was shown against E. coli. In vivo studies showed significant reduction in wound diameter in essential oil treatment groups. Further, the essential oil was found non-irritant in draize scoring.

CONCLUSION

The study concluded that essential oil of this fruit peel might be used for antibacterial and wound healing purposes.

Facially Amphiphilic Cholic Acid-Lysine Conjugates as Promising Antimicrobials

The emergence of multidrug-resistant microbes is a significant health concern posing a constant need for new antimicrobials. Membrane-targeting antibiotics are promising candidates with reduced ability of microbes to develop resistance. In the present investigation, the principal reason behind choosing cholic acid as the crucial scaffold lies in the fact that it has a facially amphiphilic nature, which provides ample opportunity to refine the amphiphilicity by linking the amino acid lysine. A total of 16 novel amphipathic cholic acid derivatives were synthesized by sequentially linking lysine to C3-β-amino cholic acid methyl ester to maintain the hydrophobic/hydrophilic balance, which could be the essential requirement for the antimicrobial activity. Among the synthesized conjugates, a series with fluorenyl-9-methoxycarbonyl moiety attached to cholic acid via lysine linker showed promising antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. A pronounced effect of increase in lysine residues was noted on the observed activity. The lead compounds were found to be active against drug-resistant bacterial and fungal clinical isolates and also improved the efficacy of antifungal agents amphotericin B and voriconazole. Membrane-permeability studies demonstrated the ability of these compounds to induce membrane damage in the tested microbes. The active conjugates did not show any hemolytic activity and were also found to be nontoxic to the normal cells as well as the examined cancer cell lines. The observed antimicrobial activity was attributed to the facial amphiphilic conformations, hydrophobic/hydrophilic balance, and the overall charge on the molecules.

Characterizing the interaction between methyl ferulate and human serum albumin by saturation transfer difference NMR

Methyl ferulate (MF) is an alkyl ferulate ester that widely exists in edible plants and has application value in the food and medicine industries. Thus, its effect on biological macromolecules should be considered. In this study, we exploit saturation transfer difference NMR (STD-NMR) to characterize the interaction of all protons of MF with human serum albumin (HSA) at the molecular level. STD-NMR and K_a (1.298 × 10³ M⁻¹) revealed that protons H1–6 and H8 bound to HSA with a medium affinity. Binding epitope mapping further showed that the aromatic ring played a key role in the HSA–MF interaction. STD-NMR site-marker-displacement experiments and circular dichroism spectroscopy revealed that MF prefered to bind to site II of HSA without changing the basic skeleton of HSA. Computer simulations confirmed these experimental results. Overall, this work elucidates the molecular level interaction of MF with HSA and provides new insights into the possibility of the potential applications of MF in the food and medicine industries.

STD-NMR technique characterized the recognition mechanism of methyl ferulate and human serum albumin qualitatively and quantitatively.

Defense Responses, Induced by p-Coumaric Acid and Methyl p-Coumarate, of Jujube ( Ziziphus jujuba Mill.) Fruit against Black Spot Rot Caused by Alternaria alternata

The esterified fraction of jujube ( Ziziphus jujuba Mill.) peel extract showed strong antifungal activity on Alternaria alternata. p-Coumaric acid (pCA) was found to be the most predominant individual phenolic acid that was correlated highly with the antifungal activity of the esterified fraction. Thus, effects of postharvest treatments with pCA and its simplest esterified derivative methyl p-coumarate (MeCA) against black spot rot on jujube fruit caused by A. alternata were investigated. pCA and MeCA strongly suppressed in vitro growth of the fungus and significantly reduced postharvest Alternaria rot on fresh jujubes. Biochemical and transcriptional analysis revealed that pCA and MeCA regulated the expression of some genes encoding antioxidant enzymes and their enzymatic activities, enhanced the phenylpropanoid pathway metabolism, and activated the expression of genes encoding pathogenesis-related proteins. These results suggested that, apart from its direct antifungal activity, pCA and MeCA induced defense responses in jujube fruit against postharvest Alternaria rot.

Methylferulate from Tamarix aucheriana inhibits growth and enhances chemosensitivity of human colorectal cancer cells: possible mechanism of action

Background

Natural products are valuable sources for anticancer agents. In the present study, methylferulate (MF) was identified for the first time from Tamarix aucheriana. Spectral data were used for identification of MF. The potential of MF to control cell growth, cell cycle, apoptosis, generation of reactive oxygen species (ROS), cancer cell invasion, nuclear factor kappa B (NFkB) DNA-binding activity and proteasomal activities, as well as the enhancement of chemosensitivity in human colorectal cancer cells, were evaluated. The possible molecular mechanism of MF’s therapeutic efficacy was also assessed.

Methods

Column chromatography and spectral data were used for isolation and identification of MF. MTT, immunofluorescence, flow cytometry, in vitro invasion, fluoremetry, EIA and Real time qPCR were used to measure antiproliferative, chemo-sensitizing effects and other biochemical parameters.

Results

MF showed a dose-dependent anti-proliferative effect on colorectal cancer cells (IC₅₀ = 1.73 – 1.9 mM) with a nonsignificant cytotoxicity toward normal human fibroblast. Colony formation inhibition (P ≤ 0.001, 0.0001) confirmed the growth inhibition by MF. MF arrested cell cycle progression in the S and G2/M phases; induced apoptosis and ROS generation; and inhibited NF-kB DNA-binding activity, proteasomal activities and cell invasion in colorectal cancer cells. MF up-regulated cyclin-dependent kinase inhibitors (p19 ^INK4D, p21^WAF1/CIP1, p27^KIP1), pro-apoptotic gene expression (Bax, Bad, Apaf1, Bid, Bim, Smac) and caspases (caspase 2, 3, 6, 7, 8, 9). Moreover, MF down-regulated cyclin-dependent kinases (Cdk1, Cdk2) and anti-apoptotic gene expression (c-IAP-1, c-IAP-2, Bcl2,FLIP). In addition, MF differentially potentiated the sensitivity of colorectal cancer cells to standard chemotherapeutic drugs.

Conclusion

MF showed a multifaceted anti-proliferative and chemosensitizing effects. These results suggest the chemotherapeutic and co-adjuvant potential of MF.