Inactivation Mechanism of Algal Chlorophyll by Allelochemical Quercetin.

Cyanobacteria harmful algal blooms (CyanoHABs) are a global concern. Application of allelochemicals is a promising solution for cyanobacteria control, due to its high efficiency, low cost and ecological safety. Flavonoids (natural polyphenols produced by aquatic plants) are reported capable of effectively inhibiting the growth of algae; however, the molecular mechanism of algae chlorophyll inactivation is still unclear. In this study, quercetin was used as a typical flavonoid, to investigate the inactivation effect of allelochemical on Microcystis aeruginosa chlorophyll a. The absorption and fluorescence spectra showed that chlorophyll reacted with quercetin to form pheophytin, and the formation rate of pheophytin increased with increasing quercetin concentration (1 × 10-5-1 × 10-2 M). FTIR spectra and DFT calculation showed that Mg2+ complexed with the 3-OH and 4-C = O groups in the quercetin ring C so that chlorophyll was inactivated due to the loss of Mg2+ ions. Overall, this study revealed that quercetin inactivated chlorophyll a of cyanobacteria by capturing Mg2+ ions, providing insights into the molecular mechanisms of algal bloom control by allelochemicals.

Modulation of drug resistance in Staphylococcus aureus by 132-hydroxy-(132-R/S)-pheophytin isolated from Sargassum polyceratium.

Efflux pumps are integral parts of the bacterial plasma membrane that are responsible for many cases of antibiotic resistance. Modulators of drug resistance are regarded as the most suitable new antibacterial therapies. We evaluated the extracts of Sargassum polyceratium and the isolated compound pheophytin (Sp-1) for antibiotic modifying activity in strains of Staphylococcus aureus with efflux pump. The minimum inhibitory concentrations (MICs) for norfloxacin, tetracycline and erythromycin were determined by the microdilution broth method, in the absence and presence of the extract at a sub-inhibitory concentration (MIC/4). The extracts and isolated compounds showed no significant antimicrobial activity, but they changed the antibiotic activity, decreasing bacterial resistance by 2 to 4x. Using a checkerboard method, it was also possible to observe the synergistic effect (ΣFIC ≤ 0.5) between Sp-1 and the antibiotics erythromycin and norfloxacin. The results indicate that the seaweed Sargassum polyceratium and pheophytin are potential sources of an antibiotic adjuvant that modulates bacterial resistance, acting as a putative efflux pump inhibitor.

Formulation of Ethyl Cellulose Microparticles Incorporated Pheophytin A Isolated from Suaeda vermiculata for Antioxidant and Cytotoxic Activities.

BACKGROUND: This study is designed to discover a method for delivering an efficient potent pheophytin a (pheo-a) into more absorbed and small polymeric ethyl cellulose (EC) microparticles. METHODS: Silica gel and Sephadex LH-20 columns were used to isolate pheo-a from the chloroform extract of the edible plant, Suaeda vermiculata. Pheo-a was incorporated into EC microparticles using emulsion-solvent techniques. The antioxidant activity of pheo-a microparticles was confirmed by the level of superoxide radical (SOD), nitric oxide (NO), and reducing power (RP) methods. Meanwhile, the cytotoxic effect of the product was investigated on MCF-7 cells using MTT assay. RESULTS: Pheo-a was isolated from S. vermiculata in a 12% concentration of the total chloroform extract. The structures were confirmed by NMR and IR spectroscopic analysis. The formulated microparticles were uniform, completely dispersed in the aqueous media, compatible as ingredients, and had a mean diameter of 139 ± 1.56 µm as measured by a particle size analyzer. Pheo-a demonstrated a valuable antioxidant activity when compared with ascorbic acid. The IC50 values of pheo-a microparticles were 200.5 and 137.7 µg/mL for SOD, and NO respectively. The reducing power of pheo-a microparticles was more potent than ascorbic acid and had a 4.2 µg/mL for IC50 value. Pheo-a microparticles did not show notable cytotoxicity on the MCF-7 cell line (IC50 = 35.9 µg/mL) compared with doxorubicin (IC50 = 3.2 µg/mL). CONCLUSIONS: the results showed that water-soluble pheo-a microparticles were prepared with a valuable antioxidant activity in a wide range of concentrations with a noteworthy cytotoxic effect.

Chlorophyll and Chlorophyll Derivatives Interfere with Multi-Drug Resistant Cancer Cells and Bacteria.

Multidrug resistance (MDR) causes challenging tasks in medicine. Human cancer cells, as well as microorganisms, can acquire multiresistance due to the up-regulation of efflux pumps (ABC transporters) and are difficult to treat. Here, we evaluated the effects of chlorophyll, the most abundant pigment on the globe, and its derivative, pheophytin, on cancer cells and methicillin-resistant Staphylococcus aureus (MRSA). We found that both substances have significant reversal effects on multidrug-resistant CEM/ADR5000 cells (RRpheophytin = 3.13, combination index (CI)pheophytin = 0.438; RRchlorophyll = 2.72, CIchlorophyll < 0.407), but not on drug-sensitive CCRF-CEM cells when used in combination with doxorubicin. This indicates that the porphyrins could interact with efflux pumps. Strong synergism was also observed in antimicrobial tests against MRSA when combining ethidium bromide with chlorophyll (FICI = 0.08). As there is a strong need for new drugs in order to reliably treat MDR cells, our research provides potential candidates for further investigation.

Lipopolysaccharide-Induced Nitric Oxide, Prostaglandin E2, and Cytokine Production of Mouse and Human Macrophages Are Suppressed by Pheophytin-b.

Sepsis is an overwhelming systemic response to infection that frequently results in tissue damage, organ failure, and even death. Nitric oxide (NO), prostaglandin E2 (PGE2), and cytokine overproduction are thought to be associated with the immunostimulatory cascade in sepsis. In the present study, we analyzed the anti-inflammatory efficacy of the pheophytin-b on both RAW 264.7 murine macrophage and purified human CD14⁺ monocytes stimulated with lipopolysaccharide (LPS) and elucidated the mechanisms by analyzing the cell signaling pathways known to be activated in sepsis. Pheophytin-b suppressed the overexpression of NO, PGE2, and cytokines in LPS-stimulated macrophages without inducing cytotoxicity. It also reduced NOS2 and COX-2 mRNA and protein levels. The inhibitory effects on NO, PGE2, and cytokine overproduction arose from the suppression of STAT-1 and PI3K/Akt pathways; no changes in NF-κB, MAPK, and AP-1 signaling were detected. Thus, pheophytin-b may represent a potential candidate to beneficially modulate the inflammatory response in sepsis.

Anti-HIV Activity of Ocimum labiatum Extract and Isolated Pheophytin-a.

Ocimum plants are traditionally used to manage HIV/AIDS in various African countries. The effects of Ocimum labiatum extract on HIV-1 protease (PR) and reverse transcriptase (RT) is presented here along with characterization of an identified bioactive compound, achieved through ¹H- and 13C-NMR. The extract's effect on HIV-1 replication was assessed by HIV-1 p24 antigen capture. Cytotoxicity of samples was evaluated using tetrazolium dyes and real-time cell electronic sensing (RT-CES). Ocimum labiatum inhibited HIV-1 PR with an IC50 value of 49.8 ± 0.4 µg/mL and presented weak inhibition (21%) against HIV-1 RT. The extract also reduced HIV-1 replication in U1 cells at a non-cytotoxic concentration (25 µg/mL). The CC50 value of the extract in U1 cells was 42.0 ± 0.13 µg/mL. The HIV-1 PR inhibiting fraction was purified using prep-HPLC and yielded a chlorophyll derivative, pheophytin-a (phy-a). Phy-a inhibited HIV-1 PR with an IC50 value of 44.4 ± 1.5 µg/mL (51 ± 1.7 µM). The low cytotoxicity of phy-a in TZM-bl cells was detected by RT-CES and the CC50 value in U1 cells was 51.3 ± 1.0 µg/mL (58.9 ± 1.2 µM). This study provides the first in vitro evidence of anti-HIV activity of O. labiatum and isolated phy-a, supporting further investigation of O. labiatum for lead compounds against HIV-1.

Pheophytin a isolated from the seagrass Syringodium isoetifolium plausibly blocks umuC proteins of select bacterial pathogens, in silico.

AIMS: This investigation is designed to evaluate the antibacterial efficiency of the noodle grass Syringodium isoetifolium, which is commonly found in the Indian coastal waters. Also, this study characterizes the active compound and predicts the mode of action in silico. METHODS AND RESULTS: Human pathogenic bacteria were treated with crude metabolites of S. isoetifolium. The potent fraction b was analysed by UV/VIS, Spectroscopy RP-HPLC, FT-IR, ESI-Mass and 1 H and 13 C NMRs and determined to be a hydrate of pheophytin a (C55 H74 N4 O6 ). The isolated compound Pheo had MIC values of 6·2 ± 0·7 (Salmonella typhi) and 12·5 ± 0·8 (Escherichia coli and Pseudomonas aeruginosa) µg ml-1 . Molecular docking studies of the compound were done to find the binding sites on the pathogens using a Molegro Virtual Docker platform. Pheo targets umuC proteins by binding compactly to five amino acid residues with interaction energy of -3·66 and a Moldock score of -160·175. CONCLUSIONS: Hence, we conclude that pheophytin a, besides being an accessory photosynthetic pigment, also has proven to be antibacterial against human pathogens. Lesser MIC values with definite binding sites predicted in silico are suggestive of a precise of action for this compound. SIGNIFICANCE AND IMPACT OF THE STUDY: Easy extraction methods of the active compound that has a definite target render this under-explored seagrass a good source of antibacterial compound against human pathogenic bacteria. This learning may favour more researches in this unexplored area to build up Pheo-based natural products as antibiotic therapies.

Pheophytin a inhibits inflammation via suppression of LPS-induced nitric oxide synthase-2, prostaglandin E2, and interleukin-1ß of macrophages.

Inflammation is a serious health issue worldwide that induces many diseases such as sepsis. There has been a vast search for potentially effective drugs to decrease mortality from sepsis. Pheophytin a is a chlorophyll-related compound derived from green tea. We found that pre-treatment with pheophytin a suppressed lipopolysaccharide (LPS)-induced nitric oxide (NO), prostaglandin E2 (PGE2), and interleukin-1ß in RAW 264.7 macrophages. NO synthase-2 (NOS2) and cyclooxygenase-2 (COX-2) expression levels were repressed by pre-treatment with pheophytin a at both the transcriptional and translational levels. Pheophytin a inhibited NOS2 promoter activity, but not its mRNA stability, through extracellular signal-regulated kinase (ERK1/2). This suppression was reversed by ERK1/2 inhibitor (U0126). Pheophytin a reduced signal transducers and activators of transcription 1 (STAT-1) activation, without an obvious influence on activator protein-1 (AP-1) and nuclear factor κB (NF-κB). These results suggest that pheophytin a functions by down-regulating the transcriptional levels of inflammatory mediators and blocking the ERK and STAT-1 pathways.

Pheophytin a and chlorophyll a identified from environmentally friendly cultivation of green pepper enhance interleukin-2 and interferon-γ in Peyer's patches ex vivo.

The oral consumption of capsicum has been reported to increase interleukin (IL)-2 and interferon (IFN)-γ production in Peyer's patches (PP); however, the active components responsible for these effects have not been completely identified. The beneficial biological effects of green peppers cultivated under environmentally friendly farming conditions (ECP), without the use of chemical pesticides, have rarely been compared with those of green peppers cultivated under conventional farming conditions (CCP). Oral administration of ECP extract significantly induced the production of IL-2 and IFN-γ in concanavalin A-treated cells from PP ex vivo; their levels were much higher than those in the CCP extract-treated group. A comparative analysis of the HPLC profiles indicated a 1.7-fold increase of a peak, named EF-1, at 415 nm in the ECP extract. The major component of EF-1 was identified as pheophytin a, which is a chlorophyll a molecule lacking a central Mg(2+) ion, as determined from NMR data. Intake of pheophytin a and chlorophyll a significantly increased IL-2 and IFN-γ production, and the percentage of IL-2- and IFN-γ-producing CD4+ T-cells in PP. Taken together, our data suggest that ECPs produce a higher content of pheophytin a than CCPs, and pheophytin a and chlorophyll a are immune-modulating components in green vegetables.

Phaeophytin analogues from Ligularia knorringiana.

A new phaeophytin, ligulariaphytin A, together with five known phaeophytins, were isolated from the aerial parts of Ligularia knorringiana. The structure of ligulariaphytin A was elucidated as 13¹-hydroxy-13¹,13²-peroxyphaeophorbide A ethyl ester, and the five known compounds were identified as 13²-hydroxyphaeophorbide A ethyl ester, 17³-ethoxyphaeophorbide A, phaeophytin B, phaeophytin A, and phaeophorbide B ethyl ester, respectively, based on spectroscopic analysis and by comparison of their spectral data with those reported previously in the literature. All compounds were evaluated for their in vitro cytotoxic activities against cultured Hela cell, and were found to show only very weak cytotoxicity.

Hydroalcoholic extract of Tagetes minuta L. inhibits inflammatory bowel disease through the activity of pheophytins on the NF-κB signalling pathway.

ETHNO-PHARMACOLOGICAL RELEVANCE: Species of the genus Tagetes are well known for their anti-inflammatory properties. Tagetes minuta "Huacatay" is an endemic species of South America that has been used in traditional medicine since ancient times as a remedy for stomach and intestinal discomfort. AIM OF THE STUDY: The aim of this study is to investigate the anti-inflammatory activity of the aqueous and hydroalcoholic extracts of the Huacatay, identifying the compounds responsible for this activity. MATERIALS AND METHODS: Anti-inflammatory activity of the compounds, fractions and extracts was evaluated in Hs 746T (stomach), HIEC-6 (intestine) and THP-1 (monocytes peripheral blood) cells by measuring their inhibitory capacity against the NF-κB production. RESULTS: Aqueous and hydroalcoholic extracts of Tagetes minuta displayed anti-inflammatory activity in vitro, the hydroalcoholic extract being the most active (IC50 between 59.72 and 66.42 µg/mL) in all cell lines. Bio-guided hydroalcoholic extract fractionation led to the isolation and characterisation of two pheophytins, pheophytin a (1) and 132-hydroxy pheophytin a (2). Both compounds inhibited the production of NF-κB with IC50 values in the low micromolar range, with an IC50 between 12.32 and 16.01 µM for compound 1 and 7.91-9.87 µM for compound 2. CONCLUSIONS: The two pheophytins isolated in this study inhibit the production of NF-κB, thus showing that the traditional anti-inflammatory use of Tagetes minuta can be proved through pharmacological assays. This contributes to understanding the anti-inflammatory activity of the Huacatay extracts and their use in the treatment of stomach and intestinal discomfort.

New Derivatives of Bacteriopurpurin with Thiolated Au (I) Complexes: Dual Darkand Light Activated Antitumor Potency.

BACKGROUND: Conventional antitumor Photosensitizers (PS) are normally low toxic in the dark whereas light activation triggers massive cell death (photodynamic therapy, PDT). OBJECTIVE: To expand the therapeutic potential of PS to dual potency cytocidal agents, taking advantage of the use of bacteriopurpurin for a deeper tissue penetration of light, and suitability of the tetrapyrrolic macrocycle for chemical modifications at its periphery. METHODS: Conjugation of a pro-oxidant thiolate Au (I) moiety to the bacteriopurpurin core and evaluation of cytotoxicity in cell culture and in vivo. RESULTS: New water-soluble derivatives showed micromolar cytotoxicity for cultured human tumor cell lines in the dark, including the subline with an altered drug response due to p53 inactivation. Cellular PDT with the selected conjugate, thiolate Au (I)-dipropoxybacteriopurpurinimide (compound 6) with two triphenylphosphine Au fragments, triggered rapid (within minutes) cell death. Damage to the plasma membrane (necrosis) was a hallmark of cell death by compound 6 both in the dark and upon light activation. Furthermore, one single i.v. injection of compound 6 caused retardation of transplanted syngeneic tumors at the tolerable dose. Illumination of tumors that accumulated compound 6 significantly synergized with the effect of 6 in the dark. CONCLUSION: Complexes of virtually non-toxic, photoactivatable bacteriopurpurin with the gold-containing organic moiety are considered the dual potency antitumor agents, tentatively applicable for intractable tumors.

Bioactivity-guided screening identifies pheophytin a as a potent anti-hepatitis C virus compound from Lonicera hypoglauca Miq.

Chronic hepatitis C virus (HCV) infection is a worldwide public issue. In this study, we performed bioactivity-guided screening of the Lonicera hypoglauca Miq. crude extracts to find for naturally chemical entities with anti-HCV activity. Pheophytin a was identified from the ethanol-soluble fraction of L. hypoglauca that elicited dose-dependent inhibition of HCV viral proteins and RNA expression in both replicon cells and cell culture infectious system. Computational modeling revealed that pheophytin a can bind to the active site of HCV-NS3, suggesting that NS3 is a potent molecular target of pheophytin a. Biochemical analysis further revealed that pheophytin a inhibited NS3 serine protease activity with IC(50)=0.89 microM. Notably, pheophytin a and IFNalpha-2a elicited synergistic anti-HCV activity in replicon cells with no significant cytotoxicity. This study thereby demonstrates for the first time that pheophytin a is a potent HCV-NS3 protease inhibitor and offers insight for development of novel anti-HCV regimens.

Pheophytin Derived Near-Infrared-Light Responsive Carbon Dot Assembly as a New Phototheranotic Agent for Bioimaging and Photodynamic Therapy.

Carbon dots (CDs), a kind of phototheranostic agent with the capability of simultaneous bioimaging and phototherapy [i.e., photodynamic therapy (PDT) or photothermal therapy (PTT)], have received considerable attention because of their remarkable properties, including flexibility for surface modification, high biocompatibility, low toxicity and photo-induced activity for malignant tumor cells. Among numerous carbon sources, it has been found that natural biomass are good candidates for the preparation of CD phototheranostic agents. In this study, pheophytin, a type of Mg-free chlorophyll derivative and also a natural product with low toxicity, was used as a raw carbon source for the synthesis of CDs by using a microwave method. The obtained hydrophobic CDs exhibited a maximum near-infrared (NIR) emission peak at approximately 680 nm, and high singlet oxygen (1 O2 ) generation with a quantum yield of 0.62. The self-assembled CDs from the as-prepared CDs with DSPE-mPEG2000 retained efficient 1 O2 generation. The obtained carbon dot assembly was not only an efficient fluorescence (FL) imaging agent but also a smart PDT agent. Our studies indicated that the obtained hydrophilic CD assembly holds great potential as a new phototheranostic agent for cancer therapy. This work provides a new route for synthesis of CDs and proposes a readily available candidate for tumor treatment.

A natural anticancer pigment,Pheophytin a,from a seagrass acts as a high affinity human mitochondrial translocator protein (TSPO) ligand, in silico, to reduce mitochondrial membrane Potential (∆ψmit) in adenocarcinomic A549 cells.

BACKGROUND: The present investigation looks at the most likely possibilities of usage of a naturally occurring photosynthetic pigment, Pheophytin a, from the seagrass, Syringodium isoetifolium, for plausible use as human TSPO ligand. METHODS: Pheophytin a isolated in our laboratory previously was administered to A549 cell lines in vitro to examine its effects on cell migrations, DNA, cell cycle, Mitochondrial Membrane Potential and gene expressions. In silico tools were used to predict the nature of the compound and target binding. RESULTS: Pheophytin a hadIC50 values of 22.9 ±â€¯5.8 µM for cancerous A549 cell lines, whilst not targeting non-cancerous vero cells [IC50: 183.6 ±â€¯1.92 µM]. Pheophytin a hindered cellular migration, fragmented DNA, arrested cell cycle precisely at S phase, reduced ∆ψmit and directed mRNA expressions toward apoptosis. In silico tools indicate that the compound binds to TSPO with high effectiveness to collapse ∆ψmit(which is proved using wet lab experiments) to promote mitophagy. CONCLUSION: Hence Pheophytin a could be seen as a possible TSPO ligand for targeting metastatic alveolar cancers like A549 via intrinsic apoptotic pathway. GENERAL SIGNIFICANCE: Given the inherent non-toxic nature of the compound and easy extractability from almost all autotrophic eukaryotes, one could be confident to testing in animal models.

Pheophytin analogues from the medicinal lichen Usnea diffracta.

A new pheophytin, (132S, 17S, 18S)-132-hydroxy-20-chloro-ethylpheophorbide a (3), along with two known analogues (1-2) were isolated from the lichen Usnea diffracta Vainio (Parmeliaceae). Among them, compound 3 was a rare C-20-chloro type pheophytin obtained from lichens. Their structures were elucidated by extensive spectroscopic analysis, and all the compounds were obtained for the first time from U. diffracta. Compounds (1-3) were evaluated for their xanthine oxidase (XO) inhibitory activities in vitro, and the results showed that 1-3 possessed significant enzyme inhibitory actions with IC50 values of 46.9 ± 3.8, 75.9 ± 7.4 and 42.1 ± 1.7 µg/mL, respectively.

Synthesis, characterization, and functional properties of chlorophylls, pheophytins, and Zn-pheophytins.

The aims of this study were to synthesize chlorophyll derivatives, pheophytins and Zn-pheophytins, from chlorophylls extracted from spinach, characterize them, and evaluate their antioxidant and anti-inflammatory activities. The chlorophylls isolated from spinach were identified by means of FT-IR and NMR spectroscopies. The synthesis of pheophytins and Zn-pheophytins was confirmed by UV-Vis spectral analyses. The antioxidant activity of chlorophylls, pheophytins, and Zn-pheophytins was studied. The results revealed that the Zn-pheophytins showed the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ß-carotene bleaching activities, followed by chlorophylls and pheophytins. Additionally, Zn-pheophytins showed substantial inhibitory activity against lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells. Furthermore, Zn-pheophytins remarkably suppressed LPS-induced expression of inducible nitric oxide synthase (iNOS) in RAW 264.7 cells and showed no cytotoxicity. Our findings indicated that Zn-pheophytins have strong antioxidant and anti-inflammatory properties and can therefore be a potential source of bioactive compounds for nutraceutical, cosmetic, and pharmaceutical applications.

In vitro anti-diabetic effect of flavonoids and pheophytins from Allophylus cominia Sw. on the glucose uptake assays by HepG2, L6, 3T3-L1 and fat accumulation in 3T3-L1 adipocytes.

BACKGROUND AND PURPOSE: Based on ethno-botanical information collected from diabetic patients in Cuba and firstly reported inhibition of PTP1B and DPPIV enzymes activities, Allophylus cominia (A. cominia) was identified as possible source of new drugs that could be used for the treatment of type 2 diabetes mellitus (T2-DM). EXPERIMENTAL APPROACH: in this study, the activity of the characterised extracts from A. cominia was tested on the glucose uptake using HepG2 and L6 cells, 3T3-L1 fibroblasts and adipocytes as well as their effect on the fat accumulation using 3T3-L1 adipocytes. KEY RESULTS: on 2-NBDG glucose uptake assay using HepG2 and L6 cells, extracts from A. cominia enhanced insulin activity by increasing glucose uptake. On HepG2 cells Insulin EC50 of 93 ± 21nM decreased to 13 ± 2nM in the presence of the flavonoids mixture from A.cominia. In L6 cells, insulin also produced a concentration-dependent increase with an EC50 of 28.6 ± 0.7nM; EC50 decreased to 0.08 ± 0.02nM and 5 ± 0.9nM in the presence of 100µg/ml of flavonoids and pheophytins mixtures, respectively. In 3T3-L1 fibroblasts, insulin had an EC50 of >1000nM that decreased to 38 ± 4nM in the presence of the flavonoids extract. However, in adipocytes, insulin produced a significant concentration-dependent increase and an EC50 of 30 ± 8nM was a further confirmation of the insulin responsiveness of the adipocytes to the insulin. At 100µg/ml, flavonoids and pheophytins extracts decreased fat accumulation in 3T3-L1 adipocytes by two folds in comparison to the control differentiated cells (p < 0.05). The crude extract of A. cominia did not show any enhancement of 2-NBDG uptake by 3T3-L1 adipocytes in the presence or absence of 100nM insulin. In addition, in fully differentiated adipocytes, both extracts produced significant decrease in lipid droplets in the cells and no lipid accumulation were seen after withdrawal of the extracts from the cell growth medium. However, there was no effect of both extracts on total protein concentration in cells as well as on Glut-4 transporters. CONCLUSIONS AND IMPLICATIONS: the pharmacological effects of the extracts from A. cominia observed in experimental diabetic models were shown in this study. A. cominia is potentially a new candidate for the treatment and management of T2-DM.

Pheophytin a, a low molecular weight compound found in the marine brown alga Sargassum fulvellum, promotes the differentiation of PC12 cells.

We identified and characterized a neurodifferentiation compound from the marine brown alga Sargassum fulvellum collected from the Japanese coastline. Several instrumental analyses revealed the compound to be pheophytin a. Pheophytin a did not itself promote neurite outgrowth of PC12 cells. However, when PC12 cells were treated with a low concentration of pheophytin a (3.9 microg/ml) in the presence of a low level of nerve growth factor (10 ng/ml), the compound produced neurite outgrowth similar to that produced by a high level of nerve growth factor (50 ng/ml). Pheophytin a also enhanced signal transduction in the mitogen-activated protein kinase signaling pathway, which is also induced by nerve growth factor. The effect of pheophytin a on neurite outgrowth of PC12 cells was completely blocked by U0126, a representative mitogen-activated protein kinase kinase inhibitor. These results suggest that pheophytin a enhances the neurodifferentiation of PC12 cells in the presence of a low level of nerve growth factor and that this effect is mediated by activation of a mitogen-activated protein kinase signaling pathway.

Identification of chlorophyll molecules with peroxyl radical scavenger capacity in microalgae Phormidium autumnale using ultrasound-assisted extraction.

The identification of chlorophyll molecules with peroxyl radical scavenger capacity in microalgae Phormidium autumnale was determined. The ultrasound-assisted extraction was utilized for obtaining the chlorophyll compounds from biomass. A total of eleven molecules were separated in microalgae chlorophyll extract, with pheophytin a' (371µg·g-1) and chlorophyll a (159.3µg·g-1) as the major ones. The chlorophyll extract was shown to be a potent scavenger of peroxyl radical, being almost 200 times more potent than α-tocopherol. These facts suggest the microalgae Phormidium autumnale as potential source of bioactive tetrapyrrole compounds.