7-Isopentenyloxycoumarin: What Is New across the Last Decade

7-Isopentenyloxycoumarin is among the most widespread naturally occurring prenyloxy umbelliferone derivatives. This secondary metabolite of mixed biosynthetic origin has been typically isolated from plants belonging to several genera of the Rutaceae and Apiaceae families, comprising widely used medicinal plants and in general plants with beneficial effects on human welfare, as well as edible fruits and vegetables. Although known for quite a long time (more than 50 years), only in the last two decades has this natural compound been revealed to exert powerful and promising pharmacological properties, such as active cancer chemopreventive, antibacterial, antiprotozoal, antifungal, anti-inflammatory, neuroprotective, and antioxidant properties, among the activities best outlined in the recent literature. The aim of this comprehensive miniature review article is to detail the novel natural sources and the effects described during the last decade for 7-isopentenyloxycoumarin and what has been reported on the mechanisms of action underlying the observed biological activities of this oxyprenylated secondary metabolite. In view of the herein described data, suggestions on how to address future research on the abovementioned natural product and structurally related derivatives in the best ways according to the authors will be also provided.

Citrus auraptene induces drug efflux transporter P-glycoprotein expression in human intestinal cells

P-glycoprotein (encoded by MDR1) is a membrane transport protein expressed in the intestine, liver, kidney, placenta, and blood-brain barrier. It excludes various clinically important drugs from cells, such as verapamil, digoxin, tacrolimus, and vinblastine. Therefore, human P-glycoprotein plays important roles in drug absorption, distribution, and excretion. We reported previously that auraptene, a natural compound occurring widely in citrus fruit (e.g., grapefruit), inhibited P-glycoprotein-mediated drug transport. In this study, we investigated the effects of auraptene and other phenylpropanoids on P-glycoprotein expression using human intestinal epithelial LS174T cells and a reporter plasmid expressing 10.2 kbp of the upstream regulatory region of MDR1. Auraptene (7-geranyloxycoumarin), a prenylated coumarin, and several phenylpropanoids, such as 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans propenoic acid, derricidin [2'-hydroxy-4'-(prenyloxy)chalcone], and 3-(4'-geranyloxyphenyl)-propanoic acid, induced MDR1 promoter activity in LS174T cells. Overexpression of the nuclear receptor human pregnane X receptor gene (NR1I2) enhanced auraptene-induced MDR1 activation. Nuclear factor-kappaB inhibitors, Bay11-7082 and JSH-23, repressed MDR1 activation by auraptene. Western blot analyses showed the induction of P-glycoprotein expression in the auraptene-treated LS174T cells. The citrus phytochemical auraptene can induce the drug efflux transporter P-glycoprotein in human intestinal cells, and thus has the potential to cause food-drug interactions.

Anti-Migratory Effects of 4'-Geranyloxyferulic Acid on LPS-Stimulated U937 and HCT116 Cells via MMP-9 Down-Regulation: Involvement of ROS/ERK Signaling Pathway

Matrix metalloproteinases (MMPs) play a crucial role in tumor angiogenesis, and metastasis. 4'-geranyloxyferulic acid (GOFA) has anti-tumor and anti-inflammatory proprieties. Herein, we aimed to determine whether this compound affects cell survival, invasion, and migration through reactive oxygen species (ROS)-mediated MMPs activation of extracellular signal-regulated kinases (ERKs) and p38 signaling in lymphocytic histiocytoma (U937) and colorectal cancer (HCT116) cells. We observed that lipopolysaccharide (LPS) stimulated U937 and HCT116 cells presented abnormal cell proliferation and increased metalloproteinase (MMP-9) activity and expression. Non-cytotoxic doses of GOFA blunted matrix invasive potential by reducing LPS-induced MMP-9 expression and cell migration via inhibiting ROS/ ERK pathway. GOFA also attenuated apoptosis and cell senescence. Our findings indicate that GOFA, inhibiting cancer cell proliferation and migration, could be therapeutically beneficial to prevent tumor metastasis.

A novel and efficient subcritical butane extraction method and UHPLC analysis of oxyprenylated phenylpropanoids from grapefruits peels

Biologically active prenyoxyphenylpropanoids are well known to be biosynthesized by Citrus species, for which they have been found most abundantly in fruit peels. Although several extraction methodologies have been described, the development of novel and alternative extraction processes is a field of research of current interest. In this preliminary communication, we studied the performance of the subcritical butane promoted extraction of selected oxyprenylated phenylpropanoids from grapefruit peels under a counter-current mode using a handmade extraction apparatus coupled to UHPLC analysis. The application of such a method yielded 7-isopentenyloxycoumarin, auraptene, and boropinic acid in quantities higher than those recorded for other extraction methodologies like the ultrasound- and microwave-assisted macerations (0.234, 1.035, and 0.211 mg/g of dry extract respectively). The use of subcritical butane as the extraction solvent for oxyprenylated phenylpropanoids is reported herein for the first time and can be easily adopted for several other food matrices.

Gercumin synergizes the action of 5-fluorouracil and oxaliplatin against chemoresistant human cancer colon cells

Advanced colon cancer is extremely difficult to cure, underscoring the need to develop novel therapeutic agents. Prenylated curcumins that are semisynthetic curcumin derivatives with significant anti-cancer potential have been studied herein to assess their therapeutic potential for colon cancer and tested to this aim in vitro for their growth inhibitory properties against 5-fluorouracil + oxaliplatin resistant human colon cancer CR-HT29 and HCT-116 cells. The resulting most active product, gercumin (mono-O-geranylcurcumin), has been further tested for its synergistic effects with FOLFOX (a combination of 5-fluorouracil and oxaliplatin) on the same cell lines. Activity of this combination on colonosphere formation was also investigated. Gercumin was able to suppress the growth of cancer cells with a potency similar to that of curcumin. A synergistic effect of this compound and FOLFOX was also observed. doses tested for synergy in the colonosphere assays did not show greater suppression of colonosphere formation than independent treatment with either reagent alone. Only one of the combinations was shown to be more effective at suppressing colonosphere formation [gercumin 5  μM + FOLFOX (2x)]. Thus, the growth inhibitory effects of curcumin against human cancer cells can be modulated and enhanced by the introduction of hydrophobic chains, normally found in several natural compounds, like the geranyl one. Such compounds are also able to synergize with known chemotherapeutics.

P2252Hyperglycemia drives myeloid CD34+ stem cells differentiation towards pro-inflammatory and senescent monocyte subpopulations

Background/Introduction

Diabetes is characterized by a chronic low-grade inflammatory status mediated by cellular senescence and alterations of the circulating cytokine profile and of innate immune system cell components. An abnormal expansion of intermediate (CD14++CD16+) and non-classical (CD14+CD16++) monocyte subpopulations with highly inflammatory and senescent-associated secretory phenotype (SASP) have been observed in T2DM patients with cardiovascular (CV) complications. It is unknown whether CD34+ hematopoietic stem cells (HSCs), players of CV prognosis, are involved in this process.

Purpose

To assess whether hyperglycemia might induce a pro-inflammatory priming of hematopoietic CD34+ HSCs that through senescence and acquisition of SASP skew their myeloid differentiation into more aggressive monocyte populations.

Methods

CD34+ cells were purified from cord blood of healthy donors and expanded in normal-glucose (NG; with 30 mM mannitol for osmotic control) or high-glucose (HG; 30 mM) serum-free medium plus cytokines. The cell were counted after 10, 20 and 30 days. The expression of p27, p21 RELA/p65, IL6, TNFα genes and telomere length was assessed by qPCR and secreted cytokines by ELISA. Apoptosis, ROS and monocyte subpopulations were evaluated by flow cytometry after Annexin V, CellRox and CD14/CD16 staining respectively.

Results

CD34+ HSCs cultured in HG (HG-CD34+) displayed a significant proliferation impairment when compared to their osmotic control (NG-CD34+). This loss of glucose tolerance was associated with a significant increase in mitochondrial ROS production (n=6; p≤0.01) without induction of apoptosis as showed by flow cytometry analysis for Annexin V. Moreover, qPCR assay revealed a significant telomere shortening (n=4; p≤0.05) and up-regulation of cyclin-dependent kinase inhibitors p27 and p21 in HG-CD34+cells (n=13; p≤0.05) along with an enhanced expression and secretion of TNFα (n=9; p≤0.05) and IL6 (n=10; p≤0.05) in HG-CD34+ when compared with NG-CD34+. SASP phenotype in HG-CD34+ was associated to a significant up-regulation of RELA/p65 gene in HG-CD34+ when compared with NG-CD34+ (n=8; p≤0.05). Furthermore, we found that in vitro HG-CD34+ differentiation into myeloid lineage generated higher levels of pro-inflammatory intermediate (n=3; p≤0.05) and non-classical (n=3; p≤0.01) monocyte subsets when compared with the normoglycemic counterpart.

Conclusion(s)

These data suggest that HG exposure primes HSCs myeloid differentiation towards inflammatory and senescent monocyte subpopulations.

Acknowledgement/Funding

This work was supported by Ricerca Finalizzata, Ministero della Salute [PE-2011-02348537]

Modulation of CAT-2B-Mediated l-Arginine Uptake and Nitric Oxide Biosynthesis in HCT116 Cell Line Through Biological Activity of 4'-Geranyloxyferulic Acid Extract from Quinoa Seeds

Chenopodium quinoa Wild is a “pseudocereal” grain which attracts a lot of attention in the scientific community as it has a positive effect on health. Here, we investigate the presence of biologically active O-prenylated phenylpropanoids in the ethanol extract of commercially available quinoa seeds. We claim that 4′-Geranyloxyferulic acid (GOFA) was the only phytochemical product found that belongs to quinoa’s group secondary metabolites. We studied the changes in the oxidative and inflammatory status of the cellular environment in HCT 116 cell line processed with quinoa extract and its component GOFA; the implementation was done through the analysis of the antioxidant enzymes (SOD and CAT), the pro-inflammatory components (iNOS, IL-6 and TNF-α), and the products of intermediary metabolism (ONOO⁻, O₂⁻). Moreover, the l-arginine uptake was proposed as a target of the tested compounds. We demonstrated that the GOFA, through a decrease of the CAT-2B expression, leads to a reduction of the l-arginine uptake, downregulating the harmful iNOS and restoring the altered redox state. These results propose a new molecular target involved in the reduction of the critical inflammatory process responsible for the cancer progression.

UHPLC-UV/Vis Quantitative Analysis of Hydroxylated and O-prenylated Coumarins in Pomegranate Seed Extracts

A simple and rapid analytical UHPLC methodology with spectrophotometric (UV/Vis) detection, coupled with different extraction procedures, has been perfected to investigate the presence of biologically active O-prenylated umbelliferone derivatives, such as auraptene and umbelliprenin, in pomegranate (Punica granatum L.) seed extracts. Absolute ethanol was the most efficient extraction solvent in terms of yields, after a short ultrasound-assisted. The highest concentration values recorded under these experimental conditions were 1.99 μg/g of dry extract and 6.53 μg/g for auraptene and umbelliprenin, respectively. The parent metabolite umbelliferone was also detected (0.67 μg/g). The extraction and UHPLC analytical methodology set up in the present study proved to be an efficient, powerful, and versatile technique for the simultaneous qualitative analysis and quantification of oxyprenylated coumarins in pomegranate seed extracts. The characterization of such secondary metabolites in the mentioned phytopreparation represents, to the best of our knowledge, the first example in the literature.

Lipoxygenase Inhibitory Activity of Boropinic Acid, Active Principle of Boronia Pinnata

Boropinic acid and other natural prenyloxycinnamic and benzoic acids were easily synthesized in high yield by a two-step sequence from the corresponding p-hydroxy aromatic acids and were assayed for radical scavenging activity using the DPPH test and for inhibition of enzymatic lipid peroxidation mediated by soybean 5-lipoxygenase. Compared to other acids and to known antioxidant compounds like BHT, Trolox and ascorbic acid, boropinic acid was far more active in the lipoxygenase test (IC50 = 7.6 ng/mL, p < 0.05). The recorded inhibition value suggested that boropinic acid acted as an enzyme inhibitor rather than a mere radical or peroxide scavenger. This hypothesis was confirmed by studying the interaction between boropinic acid and soybean 5-lipoxygenase by molecular modelling techniques.

A Survey of the Anti-microbial Properties of Naturally Occurring Prenyloxyphenylpropanoids and Related Compounds

O-Prenylphenylpropanoids represent a group of rare natural products. During the last twenty years, such phytochemicals have been revealed to possess a great pharmacological potential. These compounds have been obtained for the most part from plant species of the Rutaceae, Apiaceae, and Fabaceae families, as well as from fungi and bacteria. In this review we wish to detail the state of the art about O-prenylphenylpropanoids having in vitro and in vivo anti-microbial properties from different points of view. The herein cited natural products are effective in inhibiting the virulence of human oral pathogens.

HPLC Analysis and Skin Whitening Effects of Umbelliprenin-containing Extracts of Anethum Graveolens, Pimpinella Anisum, and Ferulago Campestris

Umbelliprenin has recently been shown to have great potential as a skin whitening agent. Wishing to investigate the same effect in plant species known to biosynthesize this coumarin, three plants belonging to the Apiaceae family, namely Anethum graveolens L. (dill), Pimpinella anisum L. (anise), and Ferulago campestris (Besser) Grecescu (field ferula) were screened by HPLC analysis for their respective content of umbelliprenin in extracts obtained with different solvent mixtures and by maceration and ultrasound-assisted processes. EtOH was shown to be the best solvent, providing umbelliprenin yields ranging from 1.7% to 14.4% (with respect to the total amount of extract obtained). Extracts with the highest content of this farnesyloxycoumarin were then assayed as modulators of melanogenesis in cultured murine Melan A cells employing the same umbelliprenin obtained by chemical synthesis as the reference. A parallelism between the content of the coumarin and the recorded depigmenting effect (60% for the EtOH extract of F. campestris as the best value) was revealed for all plants extracts when applied at a dose of 100 μg/mL. Our results demonstrate that the same potential of umbelliprenin can be ascribed also to umbelliprenin-enriched plant extracts which reinforces enforce the widespread use of phyto-preparations for cosmetic purposes (e.g., A. graveolens).

Synthesis and biological evaluation of novel analogues of Gly-l-Pro-l-Glu (GPE) as neuroprotective agents

This study investigated the anti-inflammatory effects of novel pseudotripeptides (GPE 1-3) as potential candidates to counteract neuroinflammation processes in Alzheimer's disease. GPE 1-3 pseudotripeptides are synthetic derivatives of Gly-l-Pro-l-Glu (GPE), the N-terminal tripeptide of IGF-1, obtained through the introduction of isosteres of the amidic bond (aminomethylene unit) to increase the metabolic stability of the native tripeptide. The results showed that all synthetic derivatives possessed higher half-lives (t_1/2 > 4 h) than GPE (t_1/2 = 30 min) in human plasma and had good water solubility. The biological results demonstrated that GPE 1-3 had protective properties in several experimental models of treated THP-1 cells. Notably, the novel pseudotripeptides influenced inflammatory cytokine expression (IL-1β, IL-18, and TNF-α) in Aβ_25-35-, PMA-, and LPS-treated THP-1 cells. In PMA-differentiated THP-1 macrophages, both GPE 1 and GPE 3 reduced the expression levels of all selected cyto-chemokines, even though GPE 3 showed the best neuroprotective properties.

Combined molecular modeling and cholinesterase inhibition studies on some natural and semisynthetic O-alkylcoumarin derivatives

Coumarins of synthetic or natural origins are an important chemical class exerting diverse pharmacological activities. In the present study, 26 novel O-alkylcoumarin derivatives were synthesized and have been tested at 100 µM for their in vitro inhibitory potential against acetylcholinesterase (AChE) and butyrlcholinesterase (BChE) targets which are the key enzymes playing role in the pathogenesis of Alzheimer's disease. Among the tested coumarins, none of them could inhibit AChE, whereas 12 of them exerted a marked and selective inhibition against BChE as compared to the reference (galanthamine, IC₅₀ = 46.58 ± 0.91 µM). In fact, 10 of the active coumarins showed higher inhibition (IC₅₀ = 7.01 ± 0.28 µM - 43.31 ± 3.63 µM) than that of galanthamine. The most active ones were revealed to be 7-styryloxycoumarin (IC₅₀ = 7.01 ± 0.28 µM) and 7-isopentenyloxy-4-methylcoumarin (IC₅₀ = 8.18 ± 0.74 µM). In addition to the in vitro tests, MetaCore/MetaDrug binary QSAR models and docking simulations were applied to evaluate the active compounds by ligand-based and target-driven approaches. The predicted pharmacokinetic profiles of the compounds suggested that the compounds reveal lipophilic character and permeate blood brain barrier (BBB) and the ADME models predict higher human serum protein binding percentages (>50%) for the compounds. The calculated docking scores indicated that the coumarins showing remarkable BChE inhibition possessed favorable free binding energies in interacting with the ligand-binding domain of the target. Therefore, our results disclose that O-alkylcoumarins are promising selective inhibitors of cholinesterase enzymes, particularly BChE in our case, which definitely deserve further studies.

Phytochemistry of the Genus Trichocolea

The genus Trichocolea (Fam. Trichocoleaceae) comprise 31 species of liverworts, most of which are endemic in a wide geographical area of the southern Pacific Ocean including New Zealand, Tasmania, and South Australia. Although few reports have been reported on the phytochemistry and pharmacognosy of these briophytes, data reported so far show a great pharmacological potential for their secondary metabolites. Phytochemicals isolated from Trichocolea spp. include benzoate esters, flavonoids, and diterpenes. The reported biological activities of these natural compounds refer to cancer cells growth inhibitory, antibacterial, anti-fungal, and anti-oxidant effects. The aim of this short review is to examine in detail from a phytochemical and pharmacological point of view what is reported in the current literature about the properties of phytopreparations or individual chemicals obtained from liverworts belonging to the Trichocolea genus.

Selenylated plant polysaccharides: A survey of their chemical and pharmacological properties

Polysaccharides from plants and fungi are considered nowadays as powerful pharmacological tools with a great therapeutic potential. In the meantime, efforts have been addressed to set up effective chemical modifications of naturally occurring polysaccharides to improve their biological effects as well as to positively modify some key parameters like solubility, bioavailability, pharmacokinetic, and similar. To this concern much attention has been focused during the last decade to the selenylation of natural polysaccharides from plants, algae, and fungi, the use of which is already encoded in ethnomedical traditions. The aim of this review article is to provide a detailed survey of the in so far reported literature data and a deeper knowledge about the state of the art on the chemical and pharmacological properties of selenylated polysaccharides of plant, algal, and fungal origin in terms of anti-oxidant, anti-cancer, anti-diabetic, and immunomodulatory activities. In all cases, literature data revealed that selenylation greatly improved such properties respect to the parent polysaccharides, indicating that selenylation is a valid, alternative, and effective chemical modification of naturally occurring carbohydrates.

A New Phytochemical and Anti-oxidant and Anti-inflammatory Activities of Different Lactuca sativa L. var. crispa Extracts

The phytochemical composition of Lactuca sativa L. var. crispa, commonly known as crisphead lettuce, from Morocco has been re-investigated for the presence of oxyprenylated cinnamic acid and coumarin derivatives. In the mean time also the anti-oxidant and anti-inflammatory effects of extracts from leaves obtained by the use of a Soxhlet apparatus have been assessed. The extracts had a high content of polyphenols with remarkable differences ranging from 0.19 to 0.38 mg gallic acid eq/mg, while the content of flavonoids ranged from 3.75 to 9.64 mg catechin eq/g. The hydroalcoholic extract with a polarity index of 5.8 displayed the best anti-oxidant, radical scavenging, and anti-inflammatory activities. The same extracts were screened by reverse-phase HPLC-UV/V analysis for the presence of biologically active oxyprenylated phenylpropanoids. Only 4'-geranyloxyferulic acid was recorded in detectable amounts. Results described herein enforce the nutraceutical value and depict a potential chemopreventive dietary feeding role for crisphead lettuce.

Predictors of treatment response to liraglutide in type 2 diabetes in a real-world setting

AIMS

There is an unmet need among healthcare providers to identify subgroups of patients with type 2 diabetes who are most likely to respond to treatment.

METHODS

Data were taken from electronic medical records of participants of an observational, retrospective study in Italy. We used logistic regression models to assess the odds of achieving glycated haemoglobin (HbA1c) reduction ≥ 1.0% point after 12-month treatment with liraglutide (primary endpoint), according to various patient-related factors. RECursive Partitioning and AMalgamation (RECPAM) analysis was used to identify distinct homogeneous patient subgroups with different odds of achieving the primary endpoint.

RESULTS

Data from 1325 patients were included, of which 577 (43.5%) achieved HbA1c reduction ≥ 1.0% point (10.9 mmol/mol) after 12 months. Logistic regression showed that for each additional 1% HbA1c at baseline, the odds of reaching this endpoint were increased 3.5 times (95% CI: 2.90-4.32). By use of RECPAM analysis, five distinct responder subgroups were identified, with baseline HbA1c and diabetes duration as the two splitting variables. Patients in the most poorly controlled subgroup (RECPAM Class 1, mean baseline HbA1c > 9.1% [76 mmol/mol]) had a 28-fold higher odds of reaching the endpoint versus patients in the best-controlled group (mean baseline HbA1c ≤ 7.5% [58 mmol/mol]). Mean HbA1c reduction from baseline was as large as - 2.2% (24 mol/mol) in the former versus - 0.1% (1.1 mmol/mol) in the latter. Mean weight reduction ranged from 2.5 to 4.3 kg across RECPAM subgroups.

CONCLUSIONS

Glycaemic response to liraglutide is largely driven by baseline HbA1c levels and, to a lesser extent, by diabetes duration.