Modulation of P450 enzymes by Cuban natural products rich in polyphenolic compounds in rat hepatocytes

Mangiferin ameliorates acetaminophen-induced hepatotoxicity through APAP-Cys and JNK modulation

An overdose of the most popular analgesic, acetaminophen (APAP), is one of the leading causes of acute liver failure. It is well established that glutathione is exhausted by APAP-reactive intermediate N‑acetyl‑p‑benzoquinone-imine (NAPQI). This leads to elevated phosphorylated-c-Jun N-terminal kinase (p-JNK), which further activates reactive oxygen species (ROS), initiates an inflammatory response, and finally leads to severe hepatic injury. The present study was conducted to investigate the protective role of mangiferin (MAN), a naturally occurring xanthone and anti-oxidant, on APAP-induced hepatotoxicity. C57BL/6 mice were pretreated with or without MAN at 1 h prior to APAP challenge. MAN was administered at a dose of 12.5-50 mg/kg along with APAP at a dose of 400 mg/kg. According to the ALT/AST ratio, 25 mg/kg MAN was the most potent dose for further experiments. Serum ALT and AST depletion were observed in APAP + MAN (25 mg/kg)-treated mice at 6, 12, and 24 h. Early (1 h after APAP treatment) GSH depletion by APAP overdose was restored by MAN treatment, which reduced APAP-Cys adduct formation and promoted protection. p-JNK downregulation and AMPK activation were observed in MAN-treated mice, which could mechanistically reduce oxidative stress and inflammation. MAN up-regulated liver GSH and SOD and reduced lipid peroxidation. HO-1 protein and p47 phox mRNA expression indicated that MAN regulated oxidative stress along with JNK deactivation. The expression of inflammatory response genes TNF-α, IL-6, MCP-1, CXCL-1, and CXCL-2 reached the basal levels after MAN treatment. mRNA, protein, and serum levels of IL-1β were reduced, and NF-κB expression was similar to that of the MAN-treated APAP mice. MAN post-treatment (1 h after APAP treatment) also protected the mice from hepatotoxicity. In conclusion, MAN had a protective and therapeutic role in APAP-induced hepatotoxicity by improving the metabolism of acetaminophen and APAP-Cys adduct formation followed by JNK-mediated oxidative stress and inflammation.

Potential inhibition of major human cytochrome P450 isoenzymes by selected tropical medicinal herbs-Implication for herb-drug interactions

BACKGROUND

Increasing use of medicinal herbs as nutritional supplements and traditional medicines for the treatment of diabetes, hypertension, hyperlipidemia, and malaria fever with conventional drugs poses possibilities of herb-drug interactions (HDIs). The potential of nine selected widely used tropical medicinal herbs in inhibiting human cytochrome P450 (CYP) isoenzymes was investigated.

MATERIALS AND METHODS

In vitro inhibition of eight major CYP isoenzymes by aqueous extracts of Allium sativum, Gongronema latifolium, Moringa oleifera, Musa sapientum, Mangifera indica, Tetracarpidium conophorum, Alstonia boonei, Bauhinia monandra, and Picralima nitida was estimated in human liver microsomes by monitoring twelve probe metabolites of nine probe substrates with UPLC/MS-MS using validated N-in-one assay method.

RESULTS

Mangifera indica moderately inhibited CYP2C8, CYP2B6, CYP2D6, CYP1A2, and CYP2C9 with IC 50 values of 37.93, 57.83, 67.39, 54.83, and 107.48 μg/ml, respectively, and Alstonia boonei inhibited CYP2D6 (IC 50 = 77.19 μg/ml). Picralima nitida inhibited CYP3A4 (IC 50 = 45.58 μg/ml) and CYP2C19 (IC 50 = 73.06 μg/ml) moderately but strongly inhibited CYP2D6 (IC 50 = 1.19 μg/ml). Other aqueous extracts of Gongronema latifolium, Bauhinia monandra, and Moringa oleifera showed weak inhibitory activities against CYP1A2. Musa sapientum, Allium sativum, and Tetracarpidium conophorum did not inhibit the CYP isoenzymes investigated.

CONCLUSION

Potential for clinically important CYP-metabolism-mediated HDIs is possible for Alstonia boonei, Mangifera indica, and Picralima nitida with drugs metabolized by CYP 2C8, 2B6, 2D6, 1A2, 2C9, 2C19, and 3A4. Inhibition of CYP2D6 by Picralima nitida is of particular concern and needs immediate in vivo investigations.

In vitro modulation of the cytochrome P450 and ABCB1/P-glycoprotein activities of the aqueous extract of Allophylus cominia (L) Sw. leaves

BACKGROUND

The aqueous extract of the Allophylus cominia (L) Sw (Sapindaceae) leaves has shown anti-diabetic, anti-obesity and anti-inflammatory properties. In the Caribbean region, it is typically used for the treatment of type-2 diabetes.

METHODS

Considering the herb-drug interaction, the aim of this study was to evaluate the potential effects of the A. cominia extract on the cytochrome P450 (CYP) (rat hepatocyte model) and P-glycoprotein (P-gp) (4T1 cell line) systems.

RESULTS

The extract did not decrease the cell viability after being assayed by the MTT test at up to 1500 μg/mL for 72 h. The exposure of the cultured rat hepatocytes to the product (up to 250 μg/mL) for 48 h increased the activities of CYP-1A2, 2C9, and 2E1 by 1.46-, 1.60-, and 1.51-fold, respectively, compared with the controls. The activities of CYP-2B6, 2D6, and 3A4 were not significantly altered, whereas the activity of P-gp decreased by 2- and 4-fold. In addition, the extracts at 100 and 200 μg/mL significantly increased doxorubicin cytotoxicity in these cells 24 h after treatment.

CONCLUSIONS

The findings indicate that the A. cominia extract modulates the CYP and P-gp systems increasing sensitivity to doxorubicin. Further studies are necessary to evaluate the potential herb-drug interaction or chemosensitive properties.

Secondary metabolites of seagrasses (Alismatales and Potamogetonales; Alismatidae): Chemical diversity, bioactivity, and ecological function

Seagrasses are the only higher plants living in fully marine environments; they play a significant role in coastal ecosystems. Seagrasses inhabit the coastal shelves of all continents except Antarctica and can grow in depths of up to 90 m. Because of their eminent ecological importance, innumerous studies have been dedicated to seagrasses and their ecology. However, the phytochemistry has not been equally well investigated yet and many of the existing studies in chemical ecology are only investigating the chemistry at the level of compound classes, e.g. phenolics, and not at the level of chemically defined metabolites. In the present review, the existing literature on secondary metabolites of seagrasses, their known source seagrasses, their bioactivity, and ecological function are compiled and critically assessed. Moreover, research gaps are highlighted and avenues for future research are discussed. Currently, a total of 154 chemically defined natural products have been reported from the about 70 seagrass species known worldwide. Compounds reported include simple phenols derivatives (four compounds), phenylmethane derivatives (14 compounds), phenylethane derivatives (four compounds), phenylpropane derivatives including their esters and dimers (20 compounds), chalkones (four compounds), flavonoids including catechins (57 compounds), phenylheptanoids (four compounds), one monoterpene derivative, one sesquiterpene, diterpenoids (13 compounds), steroids (31 compounds), and one alkaloid. Most of the existing bioactivity studies of seagrass metabolites and extracts have been directed to potential cytotoxic, antimicrobial, or antimacrofouling activity. Antimicrobial studies have been performed towards panels of both human pathogens and ecologically relevant pathogens. In the antimacrofouling studies, investigations of the potential of zosteric acid from the genus Zostera are the most numerous and have yielded so far the most interesting results. Studies on the chemical ecology of seagrasses often have been focused on variation in phenolic compounds and include but are not limited to studies on variation due to abiotic factors, seasonal variation, variation in response to grazing by fish or sea urchins, or following microbial attack.

Natural products-friends or foes?

A trend in the general population has been observed in recent years regarding the orientation toward preventive measures in health; in this context the increased interest from the users and researchers concerning the active effect of food supplements on the health state and on longevity, is noticeable. All over the world, the consumption of natural foods and of vegetal supplements has increased spectacularly over the last 5-10 years. The decreased prevalence of cardio-vascular diseases associated with Mediterranean diet, as well as the French paradox convinced researchers to scientifically document the beneficial outcomes pointed out by traditional use of plants, and to try to develop supplements that would have the same positive effects as these noticed for diet components. The intense research dedicated to this topic revealed the fact that food supplements are linked to some problematic aspects, such as toxicological side effects when associated with classical synthetic drugs. The food supplement-drug interactions are submitted to complex issues regarding pharmacokinetic interactions leading to changes in absorption, distribution, metabolism and excretion processes with direct impact on effect and toxicological potential. The present review based on recent literature aims at discussing the food-drug interactions with direct impact on efficacy and toxicity of drugs.

Modulation of the pharmacokinetics, therapeutic and adverse effects of NSAIDs by Chinese herbal medicines

INTRODUCTION

Concomitant use of NSAIDs and Chinese herbal medicines (CHMs) is frequent, yet summarized information on their interactions is lacking.

AREAS COVERED

A systematic review of literature in four evidence-based English databases was performed. Articles which reported CHMs altering the pharmacokinetics, therapeutic and adverse effects of NSAIDs were identified and summarized. Such interactions may lead to beneficial, detrimental or no change in outcomes. The current review covers four therapeutic effects of NSAIDs, including: i) anti-inflammatory; ii) analgesic; iii) antiplatelet, cardiovascular and cerebrovascular; and iv) anticancer effects and four adverse effects of NSAIDs, including: i) gastrointestinal ulcer; ii) nephrotoxicity; iii) hepatotoxicity; and iv) antiplatelet effects and bleeding.

EXPERT OPINION

While majority of CHMs demonstrated effectiveness in alleviating NSAIDs-induced adverse effects and potentiating the therapeutic effects, this review provides insights for development of CHMs as add-on medications to NSAIDs therapies. However, since limited information was from well-designed clinical trials, the findings are not yet conclusive and more clinical studies are warranted to provide guidance for healthcare professionals. In future, researches on interactions between NSAIDs and CHMs are expected to grow and modern approaches such as pharmacogenomics might enhance the throughput and accuracy of identifying clinically relevant interactions.

Multiparametric evaluation of the cytoprotective effect of the Mangifera indica L. stem bark extract and mangiferin in HepG2 cells

OBJECTIVE

Mango (Mangifera indica L.) stem bark extract (MSBE) is a natural product with biological properties and mangiferin is the major component. This paper reported the evaluation of the protective effects of MSBE and mangiferin against the toxicity induced in HepG2 cells by tert-butyl hydroperoxide or amiodarone.

METHOD

Nuclear morphology, cell viability, intracellular calcium concentration and reactive oxygen species (ROS) production were measured by using a high-content screening multiparametric assay.

KEY FINDINGS

MSBE and mangiferin produced no toxicity below 500 mg/ml doses. A marked recovery in cell viability, which was reduced by the toxicants, was observed in cells pre-exposed to MSBE or mangiferin at 5-100 mg/ml doses. We also explored the possible interaction of both products over P-glycoprotein (P-gp). MSBE and mangiferin above 100 mg/ml inhibited the activity of P-gp in HepG2 cells.

CONCLUSIONS

MSBE and mangiferin showed cytoprotective effects of against oxidative damage and mitochondrial toxicity induced by xenobiotics to human hepatic cells but it seemed that other constituents of the extract could contribute to MSBE protective properties. In addition, the drug efflux should be taken into account because of the inhibition of the P-gp function observed in those cells exposed to both natural products.

Antimutagenic properties of Mangifera indica L. stem bark extract and evaluation of its effects on hepatic CYP1A1

Mangifera indica stem bark extract (MSBE) is a Cuban natural product which has shown strong antioxidant properties. In this work, the antimutagenic effect of MSBE was tested against 10 well-known mutagens/carcinogens in the Ames test in the absence or presence of metabolic fraction (S9). The chemical mutagens tested included: cyclophosphamide, mitomycin C, bleomycin, cisplatin, dimethylnitrosamine (DMNA), benzo[a]pyrene (BP), 2-acetylaminofluorene (2-AAF), sodium azide, 1-nitropyrene (1-NP) and picrolonic acid. Protective effects of the extract were also evaluated by comparing the efficiency of S9 fraction obtained from rats treated during 28 days with oral doses of MSBE (50-500 mg/kg) with that obtained from rats treated with vehicle (control) to activate bleomycin and cyclophosphamide in the Ames test. MSBE concentrations between 50 and 500 μg/plate significantly reduced the mutagenicity mediated by all the chemicals tested with the exception of sodium azide. Higher mutagenicity was found when bleomycin and cyclophosphamide (CP) were activated by control S9 than by MSBE S9. In addition, inhibition of CYP1A1 microsomal activity was observed in the presence of MSBE (10-20 μg/ml). We can conclude that besides its potent antioxidant activity previously reported, MSBE may also exert a chemoprotective effect due to its capacity to inhibit CYP activity.

Evaluation of genotoxicity and DNA protective effects of mangiferin, a glucosylxanthone isolated from Mangifera indica L. stem bark extract

Mangiferin is a glucosylxantone isolated from Mangifera indica L. stem bark. Several studies have shown its pharmacological properties which make it a promising candidate for putative therapeutic use. This study was focused to investigate the in vitro genotoxic effects of mangiferin in the Ames test, SOS Chromotest and Comet assay. The genotoxic effects in bone marrow erythrocytes from NMRI mice orally treated with mangiferin (2000 mg/kg) were also evaluated. Additionally, its potential antimutagenic activity against several mutagens in the Ames test and its effects on CYP1A1 activity were assessed. Mangiferin (50-5000 μg/plate) did not increased the frequency of reverse mutations in the Ames test, nor induced primary DNA damage (5-1000 μg/mL) to Escherichia coli PQ37 cells under the SOS Chromotest. It was observed neither single strand breaks nor alkali-labile sites in blood peripheral lymphocytes or hepatocytes after 1h exposition to 10-500 μg/mL of mangiferin under the Comet assay. Furthermore, micronucleus studies showed mangiferin neither induced cytotoxic activity nor increased the frequency of micronucleated/binucleated cells in mice bone marrow. In short, mangiferin did not induce cytotoxic or genotoxic effects but it protect against DNA damage which would be associated with its antioxidant properties and its capacity to inhibit CYP enzymes.

Hepatoprotective and antioxidant activity of standardized herbal extracts

BACKGROUND

Phyllanthus emblica, Camellia sinensis, Mangifera indica, Punica granatum, and Acacia catechu have been shown to possess widespread pharmacological application against multitude of diseases namely cancer, diabetes, liver disorders, and oxidative stress.

OBJECTIVE

We evaluated the hepatoprotective activity of the standardized herbal extracts against tert-butyl hydroperoxide (t-BH) induced toxicity and their mechanism of hepatoprotective action in human hepatocarcinoma cells (HepG2 cell line).

MATERIALS AND METHODS

The hepatoprotective activity was studied by observing the effect of these herbal extracts on t-BH induced reduction in cell viability of HepG2 cells. In addition, the reducing power of the extracts and their ability to scavenge free radicals were evaluated using two antioxidant assay systems: cell free [oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid)] (ABTS)] and cell based [cellular antioxidant activity (CAA)].

RESULTS AND DISCUSSION

The results obtained showed that these extracts possess significant hepatoprotective activity. This may indicate that the plant extracts contain compounds, which can remove toxic metabolites following t-BH induced toxicity. The extracts exhibited significant antioxidant property as evident by the Trolox values and effective scavenging of DPPH and ABTS radicals. The extracts also demonstrated inhibition of AAPH-induced fluorescence in HepG2 cells. These results indicate the ability of the plant extracts to protect the liver cells from chemical-induced damage, which might be correlated to their radical scavenging potential.

CONCLUSION

This study demonstrates that these extracts have potential hepatoprotective activity which is mainly attributed to the antioxidant potential, which might occur by reduction of lipid peroxidation and cellular damage.

Antimicrobial, antiproliferative and proapoptotic activities of extract, fractions and isolated compounds from the stem of Erythroxylum caatingae plowman

In the study, we have examined the antitumor and antimicrobial activities of the methanol extract, the fractions, a fraction of total alkaloids and two alkaloids isolated from the stem of Erythroxylum caatingae Plowman. All test fractions, except the hexane fractions, showed antimicrobial activity on gram-positive bacteria and fungi. The acetate: methanol (95:5), acetate, chloroform and hexane fractions show the highest cytotoxicity activity against the NCI-H292, HEp-2 and K562 cell lines using MTT. The absence of hemolysis in the erythrocytes of mice was observed in these fractions and 6β-Benzoyloxy-3α-(3,4,5- trimethoxybenzoyloxy) tropane (catuabine B). Staining with Annexin V-FITC and JC-1 was used to verify the mechanism of action of the compounds of E. caatingae that showed cytotoxicity less than 30 μg/mL in leukemic cells. After 48 h of incubation, we observed that the acetate: methanol (95:5), acetate, and chloroform fractions, as well as the catuabine B, increased in the number of cells in early apoptosis, from 53.0 to 74.8%. An analysis of the potential of the mitochondrial membrane by incorporation of JC-1 showed that most cells during incubation of the acetate: methanol (95:5) and acetate fractions (63.85 and 59.2%) were stained, suggesting the involvement of an intrinsic pathway of apoptosis.

Photoprotecting action and phytochemical analysis of a multiple radical scavenger lipophilic fraction obtained from the leaf of the seagrass Thalassia testudinum

The apolar fraction F1 of Thalassia testudinum was chemically characterized by gas chromatography-mass spectrometry, which led to the identification of 43 metabolites, all of them reported for the first time in the genus Thalassia. More than 80% of the F1 composition was constituted by aromatic metabolites including the major components 1,1-bis(p-tolyl)ethane (6.0%), 4,4'-diisopropylbiphenyl (4.8%) and a 1,1-bis(p-tolyl)ethane isomer (4.7%). This lipophilic fraction was assayed for its antioxidant effects and skin protective action. In vitro assays showed that F1 strongly scavenged DPPH* (IC(50) 312.0 ± 8.0 μg mL(-1)), hydroxyl (IC(50) 23.8 ± 0.5 μg mL(-1)) and peroxyl radical (IC(50) 6.6 ± 0.3 μg mL(-1) ), as well as superoxide anion (IC(50) 50.0 ± 0.7 μg mL(-1)). Also, F1 markedly inhibited the spontaneous lipid peroxidation (LPO) in brain homogenates (IC(50) 93.0 ± 6.0 μg mL(-1)) and the LPS-stimulated nitrite generation on RAW624.7 macrophages (58.6 ± 3.2%, 400 μg mL(-1)). In agreement with these findings, its topical application at 250 and 500 μg cm(-2) strikingly reduced skin damage on mice exposed to acute UVB radiation by 45% and 70%, respectively and significantly attenuated the LPO developed following the first 48 h after acute exposure to UVB irradiation, as manifested by the decreased malondialdehide level and by the increased of reduced gluthatione content. Our results suggest that F1 may contribute to skin repair by attenuating oxidative stress due to its antioxidant activity.

Novel antihypertensive hexa- and heptapeptides with ACE-inhibiting properties: from the in vitro ACE assay to the spontaneously hypertensive rat

Bioactive ACE inhibiting peptides are gaining interest in hypertension treatment. We have designed and screened six synthetic heptapeptides (PACEI48 to PACEI53) based on two hexapeptide leads (PACEI32 and PACEI34) to improve ACE inhibitory properties and assess their antihypertensive effects. ACE activity was assayed in vitro and ex vivo. Selected peptides were administered to spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. In vitro cytotoxicity was assessed with the MTT reduction test. The six heptapeptides at low micromolar concentration produced different degrees of in vitro inhibition of ACE activity using the synthetic substrate HHL or the natural substrate angiotensin I; and ex vivo inhibition of ACE-dependent, angiotensin I-induced vasoconstriction, but not angiotensin II-induced vasoconstriction. Oral administration of the hexapeptide PACEI32L, and the heptapeptides PACEI50L and PACEI52L, induced reductions in systolic blood pressure lasting up to 3h in SHRs but not in WKY rats. Intravenous injection of PACEI32L and PACEI50L, but not PACEI52L, induced acute transient reductions in mean blood pressure of SHRs. d-Amino acid peptides showed five-fold less ACE inhibitory potency, no inhibitory effect on angiotensin I-induced vasoconstriction, and antihypertensive effect in SHRs after i.v. injection, but not after oral administration. The toxicity of peptides to reduce the viability of cultured cells was in the millimolar range. In conclusion, we have obtained novel rationally designed heptapeptides with improved ACE inhibitory properties when compared to lead hexapeptides. One selected hexapeptide and two heptapeptides show oral antihypertensive effects in SHRs and appear safe in cytotoxicity assays.

In vitro modulation of ABCB1/P-glycoprotein expression by polyphenols from Mangifera indica

Many plant compounds are able to modulate the activity and/or the expression of the major multidrug transporter ABCB1/P-glycoprotein (P-gp). In this study, mango (Mangifera indica L.) stem bark extract (MSBE), its main polyphenol mangiferin and the mangiferin aglycone derivative norathyriol, as well as catechin, gallic acid and quercetin, were investigated for their potential ability to influence ABCB1 gene and P-gp expression in HK-2 cells, a proximal tubule line constitutively expressing this transporter. Western blot analysis demonstrated a concentration-dependent decrease in P-gp in cells cultured in the presence of MSBE for 72 h. Gallic acid and quercetin also decreased the levels of P-gp at all studied concentrations, whereas catechin was almost ineffective. However, in cells exposed to mangiferin (10-200 microM), the P-gp amount showed a concentration- and time-dependent increase, being 2-fold higher than the controls after 72 h. Norathyriol (5 microM) induced P-gp, but the effect decreased at higher concentrations. The changes in the P-gp protein amount were correlated with relative changes in the ABCB1 mRNA content and with the efflux activity of the transporter. The transcriptional inhibitor 1-d-ribofuranosylbenzimidazole (DRB) contrasted the increased expression of ABCB1 by mangiferin, suggesting that the increase could be due to transcriptional up-regulation of ABCB1 mRNA. Mangiferin-treated cells overexpressing the transporter were protected against the cytotoxicity of the known P-gp substrate cyclosporine A. However, the opposite effect was not observed in cells pretreated with MSBE. These results demonstrate that MSBE and mango polyphenols, already shown in our previous studies to influence P-gp activity, may also interact with ABCB1/P-gp at the expression level. In particular, we show for the first time that the main mango polyphenol mangiferin up-regulates this multidrug transporter. The molecular mechanisms and the consequences of these effects, including the possibility of interactions with conventional drugs or other herbal constituents, remain to be elucidated.