Antioxidant activity of Myristica malabarica extracts and their constituents

Exploring apoptotic induction of malabaricone A in triple-negative breast cancer cells: an acylphenol phyto-entity isolated from the fruit rind of Myristica malabarica Lam

Myristica malabarica Lam., commonly known as Malabar nutmeg or false nutmeg, is used in traditional medicine and as a spice. Our exploration focuses on malabaricones, a distinct group of secondary metabolites isolated from the fruit rind of M. malabarica. We investigated the selective cytotoxicity of malabaricones against the triple-negative breast cancer (TNBC) cell line. In particular, malabaricone A (Mal-A) displays heightened toxicity towards TNBC cells (MDA-MB-231), with an IC50 of 8.81 ± 0.03 μM. In vitro fluorimetric assays confirmed the apoptotic capability of Mal-A and its capacity to induce nuclear fragmentation. Additionally, ultrasensitive surface-enhanced Raman spectroscopy confirms DNA fragmentation during cellular apoptosis. Cell cycle analysis indicates arrest during the sub-G0 phase by downregulating key regulatory proteins involved in cell cycle progression. Increased expression levels of caspase 3, 9, and 8 suggest involvement of both extrinsic and intrinsic apoptotic pathways. Finally, assessment of protein expression patterns within apoptotic pathways reveals upregulation of key apoptotic proteins like Fas/FasL, TNF/TNFR1, and p53, coupled with downregulation of several inhibitors of apoptosis proteins such as XIAP, cIAP-2, and Livin. These findings are further verified with in silico molecular docking. Mal-A reveals a strong affinity towards apoptotic proteins, including TNF, Fas, HTRA, Smac, and XIAP, with docking scores ranging from -5.1 to -7.2 kcal mol-1. Subsequently, molecular dynamics simulation confirms the binding stability. This conclusive in vitro evaluation validates Mal-A as a potent phyto-entity against TNBC. To the best of our knowledge, this study represents the first comprehensive anticancer evaluation of Mal-A in TNBC cells.

Malabaricones from the fruit of Myristica cinnamomea King as potential agents against Acanthamoeba castellanii

Acanthamoeba castellanii is an opportunistic free-living amoeba (FLA) pathogen which can cause fatal central nervous system (CNS) infection, granulomatous amoebic encephalitis (GAE) and potentially blinding ocular infection, Acanthamoeba keratitis (AK). Acanthamoeba species remain a challenging protist to treat due to the unavailability of safe and effective therapeutic drugs and their ability to protect themselves in the cyst stage. Natural products and their secondary metabolites play a pivotal role in drug discovery against various pathogenic microorganisms. In the present study, the ethyl acetate extract of Myristica cinnamomea King fruit was evaluated against A. castellanii (ATCC 50492), showing an IC50 of 45.102 ± 4.62 µg/mL. Previously, the bio-guided fractionation of the extract resulted in the identification of three active compounds, namely Malabaricones (A-C). The isolated and thoroughly characterized acylphenols were evaluated for their anti-amoebic activity against A. castellanii for the first time. Among tested compounds, Malabaricone B (IC50 of 101.31 ± 17.41 µM) and Malabaricone C (IC50 of 49.95 ± 6.33 µM) showed potent anti-amoebic activity against A. castellanii trophozoites and reduced their viability up-to 75 and 80 %, respectively. Moreover, both extract and Malabaricones also significantly (p < 0.05) inhibit the encystation and excystation of A. castellanii, while showed minimal toxicity against human keratinocyte cells (HaCaT cells) at lower tested concentrations. Following that, the explanation of the possible mechanism of action of purified compounds were assessed by detection of the state of chromatin. Hoechst/PI 33342 double staining showed that necrotic cell death occurred in A. castellanii trophozoites after 8 h treatment of Malabaricones (A-C). These findings demonstrate that Malabaricones B and C could serve as promising therapeutic options against A. castellanii infections.

Naturally Derived Malabaricone B as a Promising Bactericidal Candidate Targeting Multidrug-Resistant Staphylococcus aureus also Possess Synergistic Interactions with Clinical Antibiotics

The emergence of multidrug-resistant (MDR) superbugs underlines the urgent need for innovative treatment options to tackle resistant bacterial infections. The clinical efficacy of natural products directed our efforts towards developing new antibacterial leads from naturally abundant known chemical structures. The present study aimed to explore an unusual class of phenylacylphenols (malabaricones) from Myristicamalabarica as antibacterial agents. In vitro antibacterial activity was determined via broth microdilution, cell viability, time-kill kinetics, biofilm eradication, intracellular killing, and checkerboard assays. The efficacy was evaluated in vivo in murine neutropenic thigh and skin infection models. Confocal and SEM analyses were used for mechanistic studies. Among the tested isolates, malabaricone B (NS-7) demonstrated the best activity against S. aureus with a favorable selectivity index and concentration-dependent, rapid bactericidal killing kinetics. It displayed equal efficacy against MDR clinical isolates of S. aureus and Enterococci, efficiently clearing S. aureus in intracellular and biofilm tests, with no detectable resistance. In addition, NS-7 synergized with daptomycin and gentamicin. In vivo, NS-7 exhibited significant efficacy against S. aureus infection. Mechanistically, NS-7 damaged S. aureus membrane integrity, resulting in the release of extracellular ATP. The results indicated that NS-7 can act as a naturally derived bactericidal drug lead for anti-staphylococcal therapy.

Malabaricone C, a constituent of spice Myristica malabarica, exhibits anti-inflammatory effects via modulation of cellular redox

The present study primarily focuses on the efficacy of Malabaricone C (Mal C) as an anti-inflammatory agent. Mal C inhibited mitogen-induced T-cell proliferation and cytokine secretion. Mal C significantly reduced cellular thiols in lymphocytes. N-acetyl cysteine (NAC) restored cellular thiol levels and abrogated Mal C-mediated inhibition of T-cell proliferation and cytokine secretion. Physical interaction between Mal C and NAC was evinced from HPLC and spectral analysis. Mal C treatment significantly inhibited concanavalin A-induced phosphorylation of ERK/JNK and DNA binding of NF-κB. Administration of Mal C to mice suppressed T-cell proliferation and effector functions ex vivo. Mal C treatment did not alter the homeostatic proliferation of T-cells in vivo but completely abrogated acute graft-versus-host disease (GvHD)-associated morbidity and mortality. Our studies indicate probable use of Mal C for prophylaxis and treatment of immunological disorders caused due to hyper-activation of T-cells.

Impact of sodium pyrophosphate and static magnetic field on Haematococcus pluvialis: enhancement of astaxanthin accumulation, PAL, and antioxidant enzyme activities

The Haematococcus pluvialis microalga is known as a main source of astaxanthin with a strong antioxidant capacity and low growth rate. The induction of growth and astaxanthin content was established in H. pluvialis alga using a static magnetic field (SMF) and tetrasodium pyrophosphate (NaPP) as an inhibitor of isopentenyl pyrophosphate (precursor of astaxanthin biosynthesis) translocator between cytosol to plastid. NaPP (0.3 mM), SMF (4 mT), and their combinations were applied to the H. pluvialis cell culture. Results showed chlorophyll a and b were induced in H. pluvialis by SMF treatment, but didn't change significantly under NaPP. Astaxanthin content enhanced under NaPP, SMF, and their combination, and the highest astaxanthin content was obtained under NaPP after 21 days (late of stationary phase) of culture. A significant increase in total phenol and flavonoid contents, and activities of phenylalanine ammonia-lyase (PAL) and DPPH were observed under both NaPP and SMF treatments. In contrast to NaPP, SMF decreased H₂O₂ content, which was associated with more activity of SOD and CAT enzymes. These results revealed that NaPP and SMF might stimulate both phenol and astaxanthin biosynthesis pathways by impacting the activity of enzymes, and inhibition of IPP translocation by NaPP didn't affect astaxanthin biosynthesis at the late growth phase of H. pluvialis.

Inhibitory Effects of AF-343, a Mixture of Cassia tora L., Ulmus pumila L., and Taraxacum officinale, on Compound 48/80-Mediated Allergic Responses in RBL-2H3 Cells

The purpose of this study was to determine the antiallergic effects of AF-343, a mixture of natural plant extracts from Cassia tora L., Ulmus pumila L., and Taraxacum officinale, on rat basophilic leukemia (RBL-2H3) cells. The inhibitory effects on cell degranulation, proinflammatory cytokine secretion, and reactive oxygen species (ROS) production were studied in compound 48/80-treated RBL-2H3 cells. The bioactive compounds in AF-343 were also identified by HPLC–UV. AF-343 was found to effectively suppress compound 48/80-induced β-hexosaminidase release, and interleukin (IL)-4 and tumor necrosis factor-α (TNF-α) production in RBL-2H3 cells. In addition, AF-343 exhibited DPPH free radical scavenging effects in vitro (half-maximal inhibitory concentration (IC₅₀) = 105 μg/mL) and potently inhibited compound 48/80-induced cellular ROS generation in a 2′,7′-dichlorofluorescein diacetate (DCFH-DA) assay. Specifically, treatment with AF-343 exerted stronger antioxidant effects in vitro and antiallergic effects in cells than treatment with three single natural plant extracts. Furthermore, AF-343 was observed to contain bioactive compounds, including catechin, aurantio-obtusin, and chicoric acid, which have been reported to elicit antiallergic responses. This study reveals that AF-343 attenuates allergic responses via suppression of β-hexosaminidase release, IL-4 and TNF-α secretion, and ROS generation, perhaps through mechanisms related to catechin, aurantio-obtusin, and chicoric acid. The results indicate that AF-343 can be considered a treatment for various allergic diseases.

Malabaricone C Attenuates Nonsteroidal Anti-Inflammatory Drug-Induced Gastric Ulceration by Decreasing Oxidative/Nitrative Stress and Inflammation and Promoting Angiogenic Autohealing

Aims: Nonsteroidal anti-inflammatory drugs (NSAIDs), among the most commonly used drugs worldwide, are associated with gastrointestinal (GI) complications that severely limit the clinical utility of this essential class of pain medications. Here, we mechanistically dissect the protective impact of a natural product, malabaricone C (Mal C), on NSAID-induced gastropathy. Results: Mal C dose dependently diminished erosion of the stomach lining and inflammation in mice treated with NSAIDs with the protective impact translating to improvement in survival. By decreasing oxidative and nitrative stress, Mal C treatment prevented NSAID-induced mitochondrial dysfunction and cell death; nuclear factor κ-light-chain enhancer of activated B cell induction, release of proinflammatory cytokines and neutrophil infiltration; and disruptions in the vascular endothelial growth factor/endostatin balance that contributes to mucosal autohealing. Importantly, Mal C failed to impact the therapeutic anti-inflammatory properties of multiple NSAIDs in a model of acute inflammation. In all assays tested, Mal C proved as or more efficacious than the current first-line therapy for NSAID-dependent GI complications, the proton pump inhibitor omeprazole. Innovation: Given that omeprazole-mediated prophylaxis is, itself, associated with a shift in NSAID-driven GI complications from the upper GI to the lower GI system, there is a clear and present need for novel therapeutics aimed at ameliorating NSAID-induced gastropathy. Mal C provided significant protection against NSAID-induced gastric ulcerations impacting multiple critical signaling cascades contributing to inflammation, cell loss, extracellular matrix degradation, and angiogenic autohealing. Conclusion: Thus, Mal C represents a viable lead compound for the development of novel gastroprotective agents.

Anti-Helicobacter pylori, Anti-Inflammatory, Cytotoxic, and Antioxidant Activities of Mace Extracts from Myristica fragrans

The aril (mace) of Myristica fragrans, known as Dok-Chan, is a spice that has long been used for treating stomach discomfort, peptic ulcer, and nausea. It is an ingredient in many remedies in Thai traditional medicine, e.g., Ya-Hom-Thep-Bha-Jit, Ya-Hom-Nao-Wa-Kot, and Ya-That-Bun-Job, which are used to treat dyspepsia and other gastrointestinal tract symptoms. The aqueous and ethanolic extracts of mace were used for all tests. Anti-H. pylori activities were determined by the disc diffusion method and agar dilution. Anti-inflammatory activity was determined by the LPS-induced nitric oxide (NO) inhibition in a RAW264.7 cell line, and cytotoxicity was determined against gastric cancer cell lines (Kato III) using the sulphorhodamine B (SRB) assay. The DPPH radical scavenging and ABTS radical cation decolorization assays were used to determine the antioxidant activities. The result found that the ethanolic extract of mace exhibited antimicrobial activity against H. pylori ATCC 43504 and six clinical strains with MIC values of 125–250 μg/ml. The aqueous extract MICs against H. pylori ATCC reference strain and six clinical strains were 500 μg/ml compared with 0.5 μg/ml for the positive control, clarithromycin. The inhibitory effect of LPS-induced NO release and cytotoxic activity of the ethanolic extract had IC₅₀ values of 82.19 μg/ml and 26.06 μg/ml, respectively, and the EC₅₀ values for the DPPH and ABTS antioxidant assays were 13.41 μg/ml and 12.44 μg/ml, respectively. The mace extract also had anticancer properties. In conclusion, the ethanolic mace extract had anti-H. pylori, anti-inflammatory, antioxidant, and anticancer activities. These data support further preclinical and clinical investigation to see if the mace extract could have a role in treating patients with dyspepsia, peptic ulcers, and possibly gastric cancer.

Thiol antioxidants sensitize malabaricone C induced cancer cell death via reprogramming redox sensitive p53 and NF-κB proteins in vitro and in vivo

Specific focus on "redox cancer therapy" by targeting drugs to redox homeostasis of the cancer cells is growing rapidly. Recent clinical studies showed that N-acetyl cysteine (NAC) treatment significantly decreased the metabolic heterogeneity and reduced Ki67 (a proliferation marker) with simultaneous enhancement in apoptosis of tumor cells in patients. However, it is not yet precisely known how thiol antioxidants enhance killing of cancer cells in a context dependent manner. To this end, we showed that a dietary compound, malabaricone C (mal C) generated copious amounts of reactive oxygen species (ROS) and also reduced GSH level in lung cancer cells. Paradoxically, although antioxidants supplementation reduced mal C-induced ROS, thiol-antioxidants (NAC/GSH) restored intracellular GSH level but enhanced DNA DSBs and apoptotic cell death induced by mal C. Our results unraveled two tightly coupled biochemical mechanisms attributing this sensitization process by thiol antioxidants. Firstly, thiol antioxidants enable the "catechol-quinone redox cycle" of mal C and ameliorate ROS generation and bio-molecular damage (DNA and protein). Secondly, thiol antioxidants cause rapid glutathionylation of transcription factors [p53, p65 (NF-κB) etc.], oxidized by mal C, and abrogates their nuclear sequestration and transcription of the anti-apoptotic genes. Furthermore, analyses of the mitochondrial fractions of p53 expressing and silenced cells revealed that cytoplasmic accumulation of glutathionylated p53 (p53-SSG) triggers a robust mitochondrial death process. Interestingly, mutation of redox sensitive cysteine residues at 124, 141 and 182 position in p53 significantly reduces mal C plus NAC mediated sensitization of cancer cells. The preclinical results, in two different tumor models in mice, provides further support our conclusion that NAC is able to sensitize mal C induced suppression of tumor growth in vivo.

Potential of some autochthonous wild plants of Burundi for vegetable oil and valuable compounds production

Twelve species of indigenous plants have been studied in order to valorize some natural resources of Burundi (Eastern Africa) to investigate possibilities of vegetable oil production. Physicochemical properties and oil contents were determined from seeds harvested through five ecogeographic zones. From oilcake extracts, total sugars contents, proteins (TPrC), polyphenolic (TPhC), and flavonoids were quantified using spectrophotometry. Furthermore, antioxidant activity of oilcake extracts was assessed by 2, 2-diphenyl-b-picrylhydrazyl (DPPH) radical-scavenging and ferric reducing antioxidant power (FRAP) assays. All oil contents obtained were found to be quite similar to those of common oleaginous seeds. The two highest were found in Parinari curatellifolia (61.44 ± 4.81% Dry Matter) and Myrianthus arboreus (48.26 ± 5.96% DM). More than half of the species have shown TPrC ranging from 10 to 24% dry matter of oilcake (DM). Brachystegia longifolia was revealed exceptionally stronger antioxidant potential: effectiveness antiradical of 163.06 ± 26.29 mL/μg.min (DPPH assay) and reducing power of 2618.21 ± 161.22 GAE/100 g DM (FRAP assay). TPhC were positively correlated (p < 0.05) to the antioxidant activity. This pioneering work on these wild species highlight the potential for producing vegetable oil and valuable biomolecule sources likely for food, cosmetics, pharmacy and industry.

Phenolic compounds from nutmeg (Myristica fragrans Houtt.) inhibit the endocannabinoid-modulating enzyme fatty acid amide hydrolase

OBJECTIVES

The study aimed to identify nutmeg compounds that indirectly interact with the endocannabinoid system through inhibition of the fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes.

METHODS

Thirteen compounds were screened for FAAH and MAGL inhibition. Compounds demonstrating significant FAAH inhibition were evaluated to determine the halfmaximal inhibitory concentration (IC₅₀ ). The most potent compound was investigated in the elevated plus maze (EPM) rodent anxiety model.

KEY FINDINGS

Three compounds, licarin A (9), 5'-methoxylicarin A (8) and malabaricone C (6) were most active in inhibiting FAAH with IC₅₀ of 7.02 μm ± 2.02, 4.57 μm ± 0.66 and 38.29 μm ± 6.18, respectively. None of the purified compounds showed significant MAGL inhibition. Because of its relative high potency and selectivity, compound 8 was further evaluated in the EPM animal model of anxiety. The compound showed significant increase in number of open arm entries (P < 0.05) when administered at 120 mg/kg dose. No effect was observed on the locomotor activity.

CONCLUSIONS

Results collected introduce active nutmeg compounds as potential leads for further development. Of the three compounds, 8 possesses highest potency and FAAH selectivity as well as anxiolytic activity. Furthermore, in vivo testing in appropriate behavioural animal paradigms is warranted.

Spice-derived phenolic, malabaricone B induces mitochondrial damage in lung cancer cellsviaa p53-independent pathway

The spice-derived phenolic, malabaricone B induces mitochondrial cell death and reduces lung tumor growthin vivo.

Total Syntheses of Malabaricones B and C via a Cross-Metathesis Strategy

The malabaricones A-D belong to the class of diarylnonanoids isolated from the Myristicaceae family of plants. Although malabaricone C displayed various interesting biological activities, its isolation remains tedious due to its close chemical similarity to malabaricones A, B, and D. Therefore, development of an efficient synthesis route has become essential to cater to the need of large amounts of malabaricone C for its pharmacological profiling. So far there is only one report of the synthesis of malabaricone C through a lengthy sequence of reactions. We have developed an efficient and short route for the syntheses of malabaricones B and C, which will also provide a convenient access to all other members of the malabaricone family. Synthesis of an important building block, ω-aryl heptyl bromide, employed in the synthesis was realized by adopting a cross-metathesis reaction as the key step.

Chemical diversity and pharmacological significance of the secondary metabolites of nutmeg (Myristica fragrans Houtt.)

Nutmeg is a valued kitchen spice that has been used for centuries all over the world. In addition to its use in flavoring foods and beverages, nutmeg has been used in traditional remedies for stomach and kidney disorders. The antioxidant, antimicrobial and central nervous system effects of nutmeg have also been reported in literature. Nutmeg is a rich source of fixed and essential oil, triterpenes, and various types of phenolic compounds. Many of the secondary metabolites of nutmeg exhibit biological activities that may support its use in traditional medicine. This article provides an overview of the chemistry of secondary metabolites isolated from nutmeg kernel and mace including common methods for analysis of extracts and pure compounds as well as recent approaches towards total synthesis of some of the major constituents. A summary of the most significant pharmacological investigations of potential drug leads isolated from nutmeg and reported in the last decade is also included.

Crystal structure of an aryl cyclo-hexyl nona-noid, an anti-proliferative mol-ecule isolated from the spice Myristica malabarica

The title compound, C21H26O5, an aryl cyclo-hexyl nona-noid {systematic name: 3,5-dihy-droxy-2-[9-(4-hy-droxy-phen-yl)nona-noyl]cyclo-hexa-2,4-dien-1-one}, extracted from the spice plant Myristica malabarica comprises two ring components, a 4-hy-droxy-phenyl moiety and a 3,5-di-hydroxy-cyclo-hexa-2,4-dienone moiety linked by a nona-noyl chain. The mol-ecule has an extended essentially planar conformation stabilized by an intra-molecular hy-droxy O-H⋯Ocarbon-yl hydrogen bond, giving a dihedral angle between the two ring systems of 6.37 (15)°. The C, O and H atoms associated with one of the hy-droxy groups of the cyclo-hexa-dienone component are disordered over two sets of sites with site occupancies of 0.6972 and 0.3028. In the crystal, hy-droxy O-H⋯O hydrogen bonds to carbonyl O-atom acceptors form large centrosymmetric R22(36) cyclic dimers, which are further extended into supra-molecular one-dimensional ribbon structures along [1-11].

The Blood-Brain Barrier Permeability of Lignans and Malabaricones from the Seeds of Myristica fragrans in the MDCK-pHaMDR Cell Monolayer Model

The blood-brain barrier (BBB) permeability of twelve lignans and three phenolic malabaricones from the seeds of Myristica fragrans (nutmeg) were studied with the MDCK-pHaMDR cell monolayer model. The samples were measured by high-performance liquid chromatography and the apparent permeability coefficients (P_app) were calculated. Among the fifteen test compounds, benzonfuran-type, dibenzylbutane-type and arylnaphthalene-type lignans showed poor to moderate permeabilities with P_app values at 10⁻⁸–10⁻⁶ cm/s; those of 8-O-4′-neolignan and tetrahydrofuran-lignan were at 10⁻⁶–10⁻⁵ cm/s, meaning that their permeabilities are moderate to high; the permeabilities of malabaricones were poor as their P_app values were at 10⁻⁸–10⁻⁷ cm/s. To 5-methoxy-dehydrodiisoeugenol (2), erythro-2-(4-allyl-2,6-dimethoxyphenoxy)-1-(3,4-dimethoxyphenyl)-propan-1-ol acetate (6), verrucosin (8), and nectandrin B (9), an efflux way was involved and the main transporter for 6, 8 and 9 was demonstrated to be P-glycoprotein. The time and concentration dependency experiments indicated the main transport mechanism for neolignans dehydrodiisoeugenol (1), myrislignan (7) and 8 was passive diffusion. This study summarized the relationship between the BBB permeability and structure parameters of the test compounds, which could be used to preliminarily predict the transport of a compound through BBB. The results provide a significant molecular basis for better understanding the potential central nervous system effects of nutmeg.

The variable chemotherapeutic response of Malabaricone-A in leukemic and solid tumor cell lines depends on the degree of redox imbalance

PURPOSE

The 'two-faced' character of reactive oxygen species (ROS) plays an important role in cancer biology by acting as secondary messengers in intracellular signaling cascades, enhancing cell proliferation and survival, thereby sustaining the oncogenic phenotype. Conversely, enhanced generation of ROS can trigger an oxidative assault leading to a redox imbalance translating into an apoptotic cell death. Intrinsically, cancer cells have higher basal levels of ROS which if supplemented by additional oxidative insult by pro-oxidants can be cytotoxic, an example being Malabaricone-A (MAL-A). MAL-A is a plant derived diarylnonanoid, purified from fruit rind of the plant Myristica malabarica whose anti-cancer activity has been demonstrated in leukemic cell lines, the modality of cell death being apoptosis. This study aimed to compare the degree of effectiveness of MAL-A in leukemic vs. solid tumor cell lines.

METHODS

The cytotoxicity of MAL-A was evaluated by the MTS-PMS cell viability assay in leukemic cell lines (MOLT3, K562 and HL-60) and compared with solid tumor cell lines (MCF7, A549 and HepG2); further studies then proceeded with MOLT3 vs. MCF7 and A549. The contribution of redox imbalance in MAL-A induced cytotoxicity was confirmed by pre-incubating cells with an antioxidant, N-acetyl-L-cysteine (NAC) or a thiol depletor, buthionine sulfoximine (BSO). MAL-A induced redox imbalance was quantitated by flow cytometry, by measuring the generation of ROS and levels of non protein thiols using dichlorofluorescein diacetate (CM-H2DCFDA) and 5-chloromethylfluorescein diacetate (CMFDA) respectively. The activities of glutathione peroxidase (GPx), superoxide dismutase, catalase (CAT), NAD(P)H dehydrogenase (quinone 1) NQO1 and glutathione-S-transferase GST were measured spectrophotometrically. The mitochondrial involvement of MAL-A induced cell death was measured by evaluation of cardiolipin peroxidation using 10-N-nonyl acridine orange (NAO), transition pore activity with calcein-AM, while the mitochondrial transmembrane electrochemical gradient (∆ψ(m)) was measured by JC-1, fluorescence being acquired in a flow cytometer. The apoptotic mode of cell death was evaluated by double staining with annexin V-FITC and propidium iodide (PI), cell cycle analysis by flow cytometry and caspase-3 activity spectrophotometrically. The expression of Nrf2 and HO-1 was examined by western blotting.

RESULTS

MAL-A demonstrated a higher degree of cytotoxicity in three leukemic cell lines whose IC50 ranged from 12.70 ± 0.10 to 18.10 ± 0.95 µg/ml, whereas in three solid tumor cell lines, the IC50 ranged from 28.10 ± 0.58 to 55.26 ± 5.90 µg/ml. This higher degree of cytotoxicity in MOLT3, a leukemic cell line was due to a higher induction of redox imbalance, evident by both an increased generation of ROS and concomitant depletion of thiols. This was confirmed by pre-incubation with NAC and BSO, wherein NAC decreased MAL-A induced cytotoxicity by 2.04 fold while BSO enhanced MAL-A cytotoxicity and decreased the IC50 by 5.60 fold. However, in solid tumor cell lines (MCF7 and A549), NAC minimally decreased MAL-A induced cytotoxicity, and BSO increased the IC50 by 1.96 and 2.39 fold respectively. Furthermore, the generation of ROS by MAL-A increased maximally in MOLT3 as the fluorescence increased from 44.28 ± 7.85 to 273.99 ± 32.78, and to a lesser degree in solid tumor cell lines, MCF7 (44.28 ± 14.89 to 207.97 ± 70.64) and A549 (37.87 ± 3.24 to 147.12 ± 38.53). In all three cell lines there was a concomitant depletion of thiols as in MOLT3, the GMFC decreased from 340.65 ± 60.39 to 62.67 ± 11.32, in MCF7 (277.82 ± 50.32 to 100.39 ± 31.93) and in A549 (274.05 ± 59.13 to 83.15 ± 21.43). In MOLT3 as compared to MCF7 and A549, decrease in the activities of GPx, CAT, NQO1 and GST was substantially greater. In all cell lines, the MAL-A induced redox imbalance translated into triggering of initial mitochondrial apoptotic events. Here again, MAL-A induced a higher degree of cardiolipin peroxidation in MOLT3 (67.01%) than MCF7 and A549 (29.15% and 44.30%), as also down regulated the mitochondrial transition pore activity from baseline to a higher extent, GMFC being 48.05 ± 2.37 to 10.70 ± 3.97 (MOLT3), 43.55 ± 3.36 to 15.36 ± 0.60 (MCF7) and 39.58 ± 0.4 to 12.65 ± 1.56 (A549). Perturbation of mitochondrial membrane potential evident by a decrease in the ratio of red/green (J-aggregates/monomers) was 134 fold (14.73/0.11) in MOLT3, 45 fold in MCF7 (20.72/0.46) and 34 fold in A549 (22.01/0.64). The extent of apoptosis using a similar concentration of MAL-A was maximal in MOLT3, wherein a 105 fold increase in annexin V binding was evident (0.83 ± 0.51 to 87.08 ± 9.85%) whereas it increased by 43.11 fold in MCF7 (0.69 ± 0.30 to 29.75 ± 11.79%) and 47.52 fold in A549 (0.61 ± 0.31 to 28.99 ± 17.21%). MAL-A induced apoptosis was also associated with a higher degree of caspase-3 activity in MOLT3 vs. MCF7 or A549 which translated into halting of cell cycle progression, evident by an increment in the sub-G0/G1 population [19.26 fold in MOLT3 (0.95 ± 0.45 vs. 18.30 ± 1.90%), 11.01 fold in MCF7 (0.97 ± 0.37 vs. 10.68 ± 0.69%) and 8.58 fold in A549 (1.06 ± 0.45 vs. 9.10 ± 1.05%)]. MAL-A effectively inhibited Nrf2 and HO-1, more prominently in MOLT3. Furthermore, the decreased expression of Nrf2 in MOLT3 correlated with the decreased activities of NQO1 and GST, suggesting that targeting of the Nrf2 anti-oxidant pathway could be considered.

CONCLUSION

Taken together, MAL-A a pro-oxidant compound is likely to be more effective in leukemias, meriting further pharmacological consideration.

Salt effect on phenolics and antioxidant activities of Tunisian and Canadian sweet marjoram (Origanum majorana L.) shoots

BACKGROUND

Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint.

RESULTS

The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed-phase high-performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans-2-hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L(-1) NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin-3-galactoside and quercetin-3-rhamnoside.

CONCLUSION

Our results confirmed the tolerance of Tunisian O. majorana plants.

Malabaricone-A induces a redox imbalance that mediates apoptosis in U937 cell line

BACKGROUND

The 'two-faced' character of reactive oxygen species (ROS) plays an important role in cancer biology by acting both as secondary messengers in intracellular signaling cascades and sustaining the oncogenic phenotype of cancer cells, while on the other hand, it triggers an oxidative assault that causes a redox imbalance translating into an apoptotic cell death.

PRINCIPAL FINDINGS

Using a tetrazolium [{3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl}-2H-tetrazolium] based cell viability assay, we evaluated the cytotoxicity of a plant derived diarylnonanoid, malabaricone-A on leukemic cell lines U937 and MOLT-3. This cytotoxicity hinged on its ability to cause a redox imbalance via its ability to increase ROS, measured by flow cytometry using 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate and by decreasing glutathione peroxidase activity. This redox imbalance mediated apoptosis was evident by an increase in cytosolic [Ca(2+)], externalization of phosphatidyl serine as also depolarization of the mitochondrial membrane potential as measured by flow cytometry. There was concomitant peroxidation of cardiolipin, release of free cytochrome c to cytosol along with activation of caspases 9, 8 and 3. This led to cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by labeling with 4',6-diamidino-2-phenylindole (DAPI); furthermore, terminal deoxy ribonucleotide transferase catalysed incorporation of deoxy uridine triphosphate confirmed DNA nicking and was accompanied by arrest of cell cycle progression.

CONCLUSIONS

Taken together, compounds like MAL-A having pro-oxidant activity mediate their cytotoxicity in leukemic cells via induction of oxidative stress triggering a caspase dependent apoptosis.

Insulin secretagogue, alpha-glucosidase and antioxidant activity of some selected spices in streptozotocin-induced diabetic rats

Spices are extensively used to enhance the taste and flavor of foods and are known to possess several medicinal properties. Myristica fragrans, Parmelia perlata, Illicium verum, Trachyspermum copticum and Myristica malabarica, the commonly used spices in India were assessed for antidiabetic activity in streptozotocin induced diabetic rats. In the in vitro insulin secretion studies on isolated islets of Langerhans, M. fragrans, T. copticum and M. malabarica showed dose dependent insulin secretion. At 1 mg/ml, P. perlata showed significant in vitro alpha-glucosidase inhibitory activity with IC(50) value of 0.14 mg/ml followed by M. malabarica (0.64 mg/ml), I. verum (0.67 mg/ml), M. fragrans (0.85 mg/ml) and T. copticum (0.92 mg/ml). The DPPH free radical scavenging activity of the extracts at a concentration of 1 mg/ml was as M. malabarica (90.45%), M. fragrans (89.89%), I. verum (87.22%), P. perlata (76.70%) and T. copticum (38.14%). P. perlata showed the highest phenolic content (i.e., 118.5 mg gallic acid equivalents/g) followed by M. malabarica (84.13 mg gallic acid equivalents/g). M. malabarica showed the highest flavonoid content (i.e., 38.35 mg quercetin equivalents/g). Regular use of these spices may prevent postprandial rise in glucose levels through inhibition of intestinal alpha-glucosidase and may maintain blood glucose level through insulin secretagogue action.

Standardized extract of Dicksonia sellowiana Presl. Hook (Dicksoniaceae) decreases oxidative damage in cultured endothelial cells and in rats

AIMS

Aging and a variety of pathologies, including cancer, diabetes, cardiovascular and inflammatory diseases have been associated with reactive oxygen species (ROS), such as superoxide anion (O₂·⁻), hydroxyl radical (·OH) and hydrogen peroxide (H₂O₂) generation. Plant polyphenols bear radical scavenging/antioxidant activity. A phytomedicinal preparation obtained from aerial parts of Dicksonia sellowiana (Dicksoniaceae), a native plant from Central and South America, has been widely used in Brazil against asthma and presents beneficial effects in several other diseases, including cardiovascular disturbance. In this work, we investigated whether Dicksonia sellowiana, which is also known to contain high levels of polyphenols, presents antioxidant activity.

METHODS

The antioxidant activity of the hydroalcoholic extract obtained from Dicksonia sellowiana leaves (HEDS) was investigated by in vitro and in vivo tests.

RESULTS

HEDS (0.1-100 μg/mL) exhibited a strong scavenging activity against all reactive species tested (DPPH, O₂·⁻,·OH and H₂O₂; IC₅₀=6.83±2.05, 11.6±5.4, 2.03±0.4, and 4.8±0.4 μg/mL, respectively). HEDS strongly protected endothelial cells against H₂O₂-induced oxidative stress by mechanisms other than increasing catalase activity. In addition, HEDS protected cell membrane from oxidative damage. HEDS, (20 and 40 mg/kg) inhibited lipid peroxidation in vivo (29.8% and 24.5%, respectively).

CONCLUSIONS

According to our results, we can speculate that the traditional uses of Dicksonia sellowiana for cardiovascular diseases, asthma and skin diseases could be, at least in part, related to the potent antioxidant and endothelial protective activities of the plant.

Regulation of arginase/nitric oxide synthesis axis via cytokine balance contributes to the healing action of malabaricone B against indomethacin-induced gastric ulceration in mice

The role of the arginine-metabolism in the healing action of the Myristica malabarica phenol malabaricone B (mal B) and omeprazole against indomethacin-induced stomach ulceration in mouse was investigated. Indomethacin (18 mg kg- 1) was found to induce maximum stomach ulceration in Swiss albino mice on the 3rd day of its administration, which was associated with reduced arginase activity (30.8%, P < 0.01), eNOS expression, along with increased iNOS expression, total NOS activity (5.55 folds, P < 0.001), NO generation (2.19 folds, P < 0.001), and ratio of pro-/anti-inflammatory cytokines. Besides providing comparable healing as omeprazole (3 mg kg- 1 x 3 days), mal B (10 mg kg- 1 x 3 days, p. o.) shifted the iNOS/NO axis to the arginase/polyamine axis as revealed from the increased arginase activity (51.6%, P < 0.001), eNOS expression, and reduced iNOS expression, total NOS activity (approximately 75%, P < 0.001), and NO level (50.6%, P < 0.01). These could be attributed to a favourable anti/pro inflammatory cytokines ratio, generated by mal B. The healing by omeprazole was however, not significantly associated with those parameters.

Gastroprotective properties of Myristica malabarica against indometacin-induced stomach ulceration: a mechanistic exploration

The healing activity of the methanol extract of the spice rampatri, Myristica malabarica, (RM) and omeprazole against indometacin-induced stomach ulceration has been studied in a mouse model. Treatment with RM (40 mg kg(-1) per day) and omeprazole (3 mg kg(-1) per day) for 3 days could effectively heal the stomach ulceration, as revealed from the ulcer indices and histopathological studies. Compared with the ulcerated group, treatment with RM and omeprazole for 3 days reduced the macroscopic damage score by approximately 72% and 76%, respectively (P<0.001), establishing the efficacy of RM. The extent of ulcer healing offered by 3 days' treatment with RM or omeprazole was better than that observed with natural recovery over 5 and 7 days (P<0.05). The healing capacities of RM and omeprazole could be attributed to their antioxidant activity as well as the ability to enhance the mucin content of the gastric tissues. Both drugs reduced lipid peroxidation (by 42-44%) and protein carbonyl content (by 34%), and augmented non-protein thiol levels beyond normal values. Furthermore, RM improved the mucin level beyond the normal value, while omeprazole restored it to near normalcy.

Angiogenic and cell proliferating action of the natural diarylnonanoids, malabaricone B and malabaricone C during healing of indomethacin-induced gastric ulceration

PURPOSE

To evaluate the plant phenolics, malabaricone B (mal B) and malabaricone C (mal C) in healing stomach ulcer by modulating angiogenesis.

MATERIALS AND METHODS

Male Swiss albino mice, ulcerated with indomethacin (18 mg/kg, p. o., single dose) were treated up to 7 days with different doses of mal B or mal C. The healing capacities of the drugs and their effects on the angiogenic parameters were assessed.

RESULTS

Maximum ulceration, observed on the 3rd day after indomethacin administration was effectively healed by mal B and mal C (each 10 mg/kg, p. o. x 3 days), the latter showing equivalent potency (~78% p < 0.001) as that of Omez (3 mg/kg, p. o. x 3 days) and misoprostol (10 mug/kg, p. o. x 3 days). Compared to the untreated mice, those treated with mal B or mal C respectively for 3 days increased the mucosal EGF level (139 and 178%, p < 0.001), the serum VEGF level (56%, p < 0.01 and 95%, p < 0.001) and microvessels formation (37%, p < 0.05 and 62%, p < 0.01), while reducing the serum endostatin level (37%, p < 0.05 and 61%, p < 0.01). The relative healing capacities of mal B and mal C correlated well with their respective abilities to modulate the angiogenic factors. The healing by Omez and misoprostol was not due to improved angiogenesis.

CONCLUSIONS

The drugs, mal B and mal C could effectively heal indomethacin-induced stomach ulceration in mice by promoting angiogenesis.

Healing properties of malabaricone B and malabaricone C, against indomethacin-induced gastric ulceration and mechanism of action

The healing activity of malabaricone B and malabaricone C, the major antioxidant constituents of the spice Myristica malabarica against the indomethacin-induced gastric ulceration in mice has been studied. The histological indices revealed maximum ulceration on the 3rd day after indomethacin administration, which was effectively healed by malabaricone B, malabaricone C (each 10 mg/kg body weight/day) and omeprazole (3 mg/kg body weight/day) for 3 days. Compared to the untreated ulcerated mice, treatment with malabaricone B, malabaricone C and omeprazole reduced the ulcer indices by 60.3% (P<0.01), 88.4% and 86.1% respectively (P<0.001). All the test samples accelerated ulcer healing than observed in natural recovery even after 7 days. Stomach ulceration reduced the total antioxidant status of plasma by 41% (P<0.05), which was significantly increased by malabaricone B (36%, P<0.01), malabaricone C (61%, P<0.001) and omeprazole (53%, P<0.001). Compared to the ulcerated untreated mice, those treated with malabaricone B reduced the levels of thiobarbituric acid reactive substances and protein carbonyls by 17% and approximately 34% respectively (P<0.05), while malabaricone C and omeprazole reduced the parameters almost equally (approximately 30%, P<0.01, and approximately 40%, P<0.01 respectively). Likewise, all the test samples reduced the oxidation of protein and non-protein thiols significantly (P<0.05). The antioxidant activity of the test samples could partly account their healing capacities. However, the differential potency of them was explainable by considering their relative abilities to modulate mucin secretion, PGE(2) synthesis and expression of EGF receptor and COX isoforms, malabaricone C being most effective in controlling all these factors.

Salinity effects on polyphenol content and antioxidant activities in leaves of the halophyte Cakile maritima

Cakile maritima is a local oilseed halophyte exhibiting potential for secondary metabolite production. In the present study, plant growth, leaf polyphenol content and antioxidant activity were comparatively analyzed in two C. maritima Tunisian accessions (Jerba and Tabarka, respectively sampled from arid and humid bioclimatic stages) under salt constraint. Three-week-old plants were subjected to 0, 100, and 400 mM NaCl for 28 days under glasshouse conditions. A significant variability in salt response was found between both accessions: while Tabarka growth (shoot biomass, leaf expansion) was significantly restricted at 100 and 400 mM NaCl, compared to the control, Jerba growth increased at 100mM before declining at 400 mM NaCl. The better behaviour of Jerba salt-challenged plants, compared to those of Tabarka, may be related to their higher polyphenol content (1.56- and 1.3-fold the control, at 100 and 400 mM NaCl respectively) and antioxidant activity (smaller IC(50) values for both 1,1-diphenyl-2-picrylhydrazyl and superoxide scavenging), associated with lower leaf MDA accumulation (ca. -66% of the control at 100mM NaCl). Taken together, our findings suggest that halophytes may be interesting for production of antioxidant compounds, and that the accession-dependent capacity to induce antioxidative mechanisms in response to salt, may result in a corresponding variability for growth sustainability.

Antipromastigote activity of the malabaricones ofMyristica malabarica (rampatri)

A major problem in the management of visceral leishmaniasis, especially in the Indian subcontinent, is the growing unresponsiveness to conventional antimonial therapy, indicating the urgent need to identify new antileishmanial compounds. This study was undertaken to evaluate the antileishmanial activity of the fruit rind of Myristica malabarica that is used as a spice and is also credited with medicinal properties. The antipromastigote activity of different extracts/fractions of M. malabarica and its constituent diarylnonanoids were evaluated in Leishmania donovani promastigotes (MHOM/IN/83/AG83) using the MTS-PMS assay. Preliminary screening of the ether extract (R1) with its crude methanol fraction (R2) and two fractions (R3 and R4) revealed that R2 had potent leishmanicidal activity (IC(50) 31.0 microg/mL), whereas R3 and R4 showed poor activity. Fractionation of R2 yielded four diarylnonanoids (malabaricones A-D, designated as Mal A, Mal B, Mal C and Mal D, respectively). The IC(50) values of Mal A-D were 16, 22, 27 and >50 microg/mL, respectively. Taken together, the data suggest that the methanol extract of M. malabarica, especially its constituent compounds, Mal A and Mal B, have promising antileishmanial activity meriting further investigations regarding the underlying molecular mechanism(s) of action with a view towards future drug development.

Antioxidant activity of piper betel leaf extract and its constituents

The 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay of the ethanol extracts of three varieties (Bangla, sweet, and Mysore) of Piper betel (pan) revealed the Bangla variety to possess the best antioxidant activity that can be correlated with the total phenolic content and reducing powers of the respective extracts. Column chromatography of the extract of the Bangla variety led to the isolation of chevibetol (CHV), allylpyrocatechol (APC), and their respective glucosides. The HPTLC analyses of the extracts revealed similar chemical profiles in all three P. betel varieties, although the concentrations of CHV and APC were significantly less in the sweet and Mysore varieties. Among the isolated compounds, APC showed the best results in all the in vitro experiments. It could prevent Fe(II)-induced lipid peroxidation (LPO) of liposomes and rat brain homogenates as well as gamma-ray-induced damage of pBR322 plasmid DNA more efficiently than CHV. The superior anti-LPO and radioprotective activities of APC vis-à-vis those of CHV could not be explained by their respective Fe(II) chelation and .OH radical scavenging capacities. The better ability of APC to scavenge O2-. radicals and H2O2 might account for the results.