Investigation of pharmacokinetics and immunogenicity of magnetosomes.

Magnetosomes are iron oxide or iron sulphide nano-sized particles surrounded by a lipid bilayer synthesised by a group of bacteria known as magnetotactic bacteria (MTB). Magnetosomes have become a promising candidate for biomedical applications and could be potentially used as a drug-carrier. However, pharmacokinetics and immunogenicity of the magnetosomes have not been understood yet which preclude its clinical applications. Herein, we investigated the pharmacokinetics of magnetosomes including Absorption, Distribution, Metabolism, and Elimination (ADME) along with its immunogenicity in vitro and in vivo. The magnetosomes were conjugated with fluorescein isothiocyanate (Mag-FITC) and their conjugation was confirmed through fluorescence microscopy and its absorption in HeLa cell lines was evaluated using flow cytometry analysis. The results revealed a maximum cell uptake of 97% at 200 µg/mL concentration. Further, the biodistribution of Mag-FITC was investigated in vivo by a bioimaging system using BALB/c mice as a subject at different time intervals. The Mag-FITC neither induced death nor physical distress and the same was eliminated post 36 h of injection with meagre intensities left behind. The metabolism and elimination analysis were assessed to detect the iron overload which revealed that magnetosomes were entirely metabolised within 48-h interval. Furthermore, the histopathology and serum analysis reveal no histological damage with the absence of any abnormal biochemical parameters. The results support our study that magnetosomes were completely removed from the blood circulation within 48-h time interval. Moreover, the immunogenicity analysis has shown that magnetosomes do not induce any inflammation as indicated by reduced peaks of immune markers such as IL 1ß, IL 2, IL 6, IL8, IFN γ, and TNF α estimated through Indirect ELISA. The normal behaviour of animals with the absence of acute or chronic toxicities in any organs declares that magnetosomes are safe to be injected. This shows that magnetosomes are benign for biological systems enrouting towards beneficial biomedical applications. Therefore, this study will advance the understanding and application of magnetosomes for clinical purposes.

Diversity and Biotechnological Potential of Marine Actinomycetes from India.

Actinomycetes are potential antibiotic producers that have been isolated from various terrestrial ecosystems and are exploited for their bioactive compounds. On the contrary, the marine environments were less explored and the research on marine actinomycetes had gained momentum only for the past three decades. Marine actinomycetes are one of the most significant producers of diverse groups of secondary metabolites and provide a huge scope for pharmaceutical and other industries. These organisms are proved to be important, both biotechnologically and economically considering their global presence. The marine ecosystem in India is less explored for the isolation of actinomycetes and several ecological niches are left unattended. Compared to the global scenario, the contribution from Indian researchers towards the isolation and exploitation of marine actinomycetes from the Indian sub-continent is noteworthy. Exploration of actinomycetes from these ecosystems will certainly yield new species and metabolites. Considering the declining rate of drug discovery from terrestrial actinomycetes, the marine counterparts, especially from unexplored regions from the Indian coast will hold a promising way ahead. Apart from drugs, these organisms are reported for the production of different industrially important enzymes like cellulase, amylase, protease, lipase, etc. They are also used in environmental applications, agriculture, and aquacultures sectors. With the rapid advancement in the study of actinomycetes from different marine sources in India, new metabolites are being discovered which have an important role from the economic and industrial point of view. As the world is witnessing newer diseases such as Sars-Cov 2 and the pandemic due to its demands drugs and other metabolites are increasing day by day. Therefore, the necessity for the quest for unique and rare marine actinomycetes is enhancing too. This review highlights the research on marine actinomycetes in India and also the challenges associated with its research.

Detection of white spot syndrome virus in seafood samples using a magnetosome-based impedimetric biosensor.

White spot syndrome virus (WSSV) is a significant threat to the aquaculture sector, causing mortality among crabs and shrimps. Currently available diagnostic tests for WSSV are not rapid or cost-effective, and a new detection method is therefore needed. This study demonstrates the development of a biosensor by functionalization of magnetosomes with VP28-specific antibodies to detect WSSV in seafood. The magnetosomes (1 and 2 mg/ml) were conjugated with VP28 antibody (0.025-10 ng/µl), as confirmed by spectroscopy. The magnetosome-antibody conjugate was used to detect the VP28 antigen. The binding of antigen to the magnetosome-antibody complex resulted in a change in absorbance. The magnetosome-antibody-antigen complex was then concentrated and brought near a screen-printed carbon electrode by applying an external magnetic field, and the antigen concentration was determined using impedance measurements. The VP28 antigen (0.025 ng/µl) bound more efficiently to the magnetosome-VP28 antibody complex (0.025 ng/µl) than to the VP28 antibody (0.1 ng/µl) alone. The same assay was repeated to detect the VP28 antigen (0.01 ng/µl) in WSSV-infected seafood samples using the magnetosome-VP28 antibody complex (0.025 ng/µl). The WSSV in the seafood sample was also drawn toward the electrode due to the action of magnetosomes controlled by the external magnetic field and detected using impedance measurement. The presence of WSSV in seafood samples was verified by Western blot and RT-PCR. Cross-reactivity assays with other viruses confirmed the specificity of the magnetosome-based biosensor. The results indicate that the use of the magnetosome-based biosensor is a sensitive, specific, and rapid way to detect WSSV in seafood samples.

Discovery of novel tetrahydrobenzo[b]thiophene-3-carbonitriles as histone deacetylase inhibitors.

The discovery and development of isoform-selective histone deacetylase (HDAC) inhibitor is a challenging task because of the sequence homology among HDAC enzymes. In the present work, novel tetrahydro benzo[b]thiophene-3-carbonitrile based benzamides were designed, synthesized, and evaluated as HDAC inhibitors. Pharmacophore modeling was our main design strategy, and two novel series of tetrahydro benzo[b]thiophene-3-carbonitrile derivatives with piperidine linker (series 1) and piperazine linker (series 2) were identified as HDAC inhibitors. Among all the synthesised compounds, 9h with 4-(aminomethyl) piperidine linker and 14n with piperazine linker demonstrated good activity against human HDAC1 and HDAC6, respectively. Both the compounds also exhibited good antiproliferative activity against several human cancer cell lines. Both these compounds (9h and 14n) also induced cell cycle arrest and apoptosis in U937 and MDA-MB-231 cancer cells. Overall, for the first time, this research discovered potent isoform-selective HDAC inhibitors using cyclic linker instead of the aliphatic chain and aromatic ring system, which were reported in known HDAC inhibitors.

Magnetosome mediated oral Insulin delivery and its possible use in diabetes management.

Our study investigates the effect of magnetosome mediated oral Insulin delivery on diabetic induced rat models. The study involves the development of Magnetosome-Insulin (MI) conjugates by direct and indirect (by means of PEG) coupling method and further characterized by microscopic and spectroscopic analysis. The in vivo oral delivery of magnetosome-Insulin conjugate against streptozotocin-induced rat models and its efficiency was investigated. The impact of MI showed a remarkable change in the reduction of FBG levels up to 65% than the standard (Insulin). Similarly, the serum parameters: triglycerides (43.81%), AST&ALT (39.4 and 57.2%), total cholesterol (43.8%) showed significant changes compared to the diabetic control. The histological results of MI treated rats were found similar to control rats. Thus, these significantly notable results on diabetic rats depicts that magnetosomes can be employed as a potential approach and a very promising alternative for the parenteral route of Insulin delivery.

Diversity of Uncultured Magnetospirillum sp. from the Sediments of South Kerala Sedimentary Basin, India.

Studies on the geographic distribution of Magnetotactic bacteria (MTB) revealed their ubiquitous presence in diverse habitats on all continents. However, little is known about MTB inhabitation in the Indian coastal ecosystem. Here, we investigate the diversity of Magnetospirillum sp. from the iron mineral sediments deposit of the South Kerala sedimentary basin, India using culture-independent methods. The collected sediment samples were analysed for the presence of nitrate (zinc reduction), sulphide (cline method), Fe2+, total iron (ferrozine assay) and iron minerals (XRD analysis). Based on the geochemical measurements, the sediment possesses major factors such as nutrients, pH, temperature and chemical gradients in metabolic accessible form for MTB. The cubo-octahedral crystals of the magnetosome are also evident from the TEM micrographs of magnetically enriched sediment. CARD-FISH analysis showed the presence of Magnetospirillum in all the six samples analysed. Phylogenetic analysis based on 16S rRNA gene library showed that the clones belong to the class Alphaproteobacteria and are members of the genus Magnetospirillum. The results of the species-specific PCR study are consistent with CARD-FISH analysis and the identified uncultured Magnetospirillum were morphologically and phylogenetically similar to the isolates from diverse habitat. The identification of Magnetospirillum from Indian coast supports the hypothesis of wide geographic distribution of these bacteria.

Immobilisation of lipase enzyme onto bacterial magnetosomes for stain removal.

Lipase was immobilized onto bacterial magnetosomes using glutaraldehyde cross-linking and confirmed by Fourier transform infrared spectrometry (FT-IR) and Scanning electron microscopy (SEM). Enzyme activity of immobilised lipase as well as free lipase was estimated by the release of p-nitro phenol due to the hydrolysis of p-nitro phenyl acetate (pNPA). The immobilisation yield of lipase onto magnetosome was found to be 88 %. The optimal pH (7) and temperature (40 °C) for activity was standardised and found to be similar to free lipase. The stored immobilized lipase maintained higher activity even after 30 days at a temperature of 4 °C whereas compared to free lipase. Immobilized lipase found to have removed vegetable oil stain and showed higher cleaning efficiency when compared to free lipase. The results suggest that bacterial magnetosome displays great potential as a support material for the immobilization of industrial enzymes such as lipase.

Comparative ecotoxicity assessment of magnetosomes and magnetite nanoparticles.

Magnetite nanoparticles (MNPs) are gaining attention because of their biomedical, environmental and industrial applications. However, they have limited uses because of ecotoxicity. On contrast, bacterially synthesized MNPs such as magnetosomes are found to be biocompatible and less toxic due to the lipid bilayer membrane found around magnetite. In this context, this study compares the physio-chemical properties and toxicology effects of MNPs and magnetosomes in different models such as human red blood cells, macrophage cell lines (RAW 264.7), onion root tips (Allium cepa), Artemia salina (A. salina) and zebrafish embryo (Danio rerio). MNPs showed 38.59% hemolysis whereas the maximum hemolysis induced by magnetosomes was 7.03% for the same concentration (250 µg/ml). The cytotoxicity of MNPs and magnetosomes were 36.01% and 13.4%, respectively, at 250 µg/ml. Onion root tip assay revealed high toxicity when treated with MNPs than magnetosomes. The MNPs were further tested for its toxicity against A. salina and 50% mortality rate was observed. Similarly, notable malformation was seen in zebrafish embryo treated with MNPs. However, magnetosomes did not exhibit any mortality and malformation in A. salina and zebrafish embryo. The study revealed that magnetosomes are safe and do not cause any potential risk to environment compared to synthetic MNPs.Abbreviation: MNPs: Magnetic nanoparticles; ATCC: American Type Culture Collection; MTB: Magnetotactic bacteria; MSR-1: Magnetospirillum gryphiswaldense; DSMZ: Deutsche Sammlung von Mikroorganismen und Zellkulturen; MSGM: Magnetospirillum growth medium; D-PBS: Dulbecco phosphate buffer saline; RBC: Red blood cells; SEM: Scanning electron microscopy; HRTEM: High-resolution transition electron microscope; FTIR: Fourier transform infrared spectroscopy; XRD: X-ray powder diffraction; AFM: Atomic-force microscopy; ZP: Zeta Potential; PSD: Particle Size Distribution; EDX: Energy-dispersive X-ray spectroscopy; PBS: Phosphate buffer saline; DMEM: Dulbecco's modified eagle medium; HEPES: (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid); MTT:3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide; DMSO: Dimethyl sulfoxide; ROS: Reactive oxygen species.

Corrigendum to "Biodegradation of PAHs by Burkholderia sp. VITRSB1 Isolated from Marine Sediments".

[This corrects the article DOI: 10.1155/2015/867586.].

Methanolic Extract of Costus pictus D. DON Induces Cytotoxicity in Liver Hepatocellular Carcinoma Cells Mediated by Histone Deacetylase Inhibition.

BACKGROUND: Leaves of Costus pictus D. Don, (insulin plant) are used as dietary supplement for the treatment of diabetes. OBJECTIVE: The antidiabetic activity of this plant is well documented, but its activity on different cell types and mechanism remains unknown. Thus, the present study evaluates the cytotoxicity of C. pictus methanolic extract (CPME) against various cancer and normal cells. MATERIALS AND METHODS: Dried leaves of C. pictus were extracted using methanol and were subjected to histone deacetylase (HDAC) inhibition and toxicity studies. RESULTS: The CPME displayed a selective toxicity toward tested cancer cells in a dose- and time-dependent manner. CPME exhibited significant cytotoxicity on Liver hepatocellular carcinoma cells (Hep G2) (half maximal inhibitory concentration IC50 = 6.7 mg/ml). Since CPME demonstrates both antidiabetic, anticancer activity, and HDAC enzyme play a detrimental role in both the complications, we have evaluated the CPME-induced HDAC regulation on Hep G2 cell lines. CPME showed a notable HDAC inhibition (55%). Furthermore, CPME did not show any genotoxicity or membrane instability at the tested concentrations. CONCLUSION: CPME demonstrates selective cytotoxicity toward tumor cells at a lower concentration through HDAC inhibition. SUMMARY: C. pictus is used as munching supplementary food for the treatment of diabetesCPME selectively induces cytotoxicity in cancer cells leaving normal cells healthySelective toxicity to cancer cells are attributed by the inhibition of HDAC enzymeCPME did not show any genotoxicity and membrane instability in blood cellsCPME could be potential source of HDAC inhibitor. Abbreviations used: A549: Human lung carcinoma cells, CPME: Costus pictus methanolic extract, DMEM: Dulbecco's modified eagle's medium, DMSO: Dimethyl sulfoxide, ELISA: Enzyme-linked immunosorbent assay, 5-FU: 5-Fluorouracil, Hep G2: Liver hepatocellular carcinoma cells, HEK-293: Human embryonic kidney cells, Hela: Human cervical carcinoma cells, HT-29: Human colorectal adenocarcinoma cells, HDAC: Histone deacetylase, IC50: Half maximal inhibitory concentration, MCF-7: Human breast adenocarcinoma cells, MDA-MB-435S: Human breast cancer cells, MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide, NFF: Neonatal foreskin fibroblasts, PHA: Phytohemagglutinin, PBS: Phosphate buffer saline, RPMI-1640: Roswell Park Memorial Institute Medium.

Antioxidant and Antiproliferative Activity of Asparagopsis taxiformis.

BACKGROUND: Asparagopsis taxiformis (Rhodophyta) is a species of red algae belonging to the family Bonnemaisoniaceae. The objective of the present study was to evaluate antioxidant and antiproliferative activity of four fractions (petroleum ether, chloroform, ethyl acetate, and methanol) of A. taxiformis. MATERIALS AND METHODS: The red seaweed, A. taxiformis was collected from Mandapam Coastal Region, Gulf of Mannar, Tamil Nadu. Epiphytes present in algal extracts were cleaned and washed with seawater and fresh water. In vitro antioxidant activity was determined by hydrogen peroxide scavenging, ferric reducing antioxidant power, superoxide radical, metal-chelating activity, and phosphomolybdenum reduction assay. Further, the cytotoxic activity was evaluated using brine shrimp lethality assay. This method is rapid, reliable, inexpensive, and convenient as compared to other cytotoxicity assays. Gallic acid, ethylenediaminetetraacetic acid, ascorbic acid, and quercetin were used as reference antioxidant compounds. RESULTS: Reducing power of chloroform extract increased with increasing concentration of the extract. The radical scavenging activity of extracts was in the following order: ascorbic acid > methanol > chloroform > petroleum ether > ethyl acetate. Highest metal-chelating activity was observed in petroleum ether fractions (63%). Reduction of Mo (VI) to Mo (V) increased in methanol extract (27%) at 100 µg/ml. Moreover, all fractions had an inhibitory effect on the formation of hydroxyl radicals. Results showed that ethyl acetate, methanol, and petroleum ether fractions exhibited potent cytotoxic activity with median lethal concentration values of 84.33, 104.4, and 104.4 µg/ml, respectively. CONCLUSION: Thus, the results showed that red algae possess strong antioxidant and cytotoxic activity that suggests their possible use in the development of pharmaceutical drugs. SUMMARY: Various fractions of red algae Asparagopsis taxiformis was evaluated for in vitro antioxidant and antiproliferative studies. All results indicate potential use of red algae for drug development. Abbreviations Used: Mo: Molybdenum, AlCl3.H2O: Aluminum chloride, NaNO2: Sodium nitrite, NaOH: Sodium hydroxide, H2O2: Hydrogen peroxide, NADH: Nicotinamide adenine dinucleotide, NBT: Nitroblue tetrazolium chloride, PMS: Phenyl methanesulfonate, FeCl2: Ferrous chloride.

Toxicity assessment of magnetosomes in different models.

Magnetosomes are nanosized iron oxide particles surrounded by lipid membrane synthesized by magnetotactic bacteria (MTB). Magnetosomes have been exploited for a broad range of biomedical and biotechnological applications. Due to their enormous potential in the biomedical field, its safety assessment is necessary. Detailed research on the toxicity of the magnetosomes was not studied so far. This study focuses on the toxicity assessment of magnetosomes in various models such as Human RBC's, WBC's, mouse macrophage cell line (J774), Onion root tip and fish (Oreochromis mossambicus). The toxicity in RBC models revealed that the RBC's are unaltered up to a concentration of 150 µg/ml, and its morphology was not affected. The genotoxicity studies on WBC's showed that there were no detectable chromosomal aberrations up to a concentration of 100 µg/ml. Similarly, there were no detectable morphological changes observed on the magnetosome-treated J774 cells, and the viability of the cells was above 90% at all the tested concentrations. Furthermore, the magnetosomes are not toxic to the fish (O. mossambicus), as no mortality or behavioural changes were observed in the magnetosome-treated groups. Histopathological analysis of the same reveals no damage in the muscle and gill sections. Overall, the results suggest that the magnetosomes are safe at lower concentration and does not pose any potential risk to the ecosystem.

Vegetable Peel Waste for the Production of ZnO Nanoparticles and its Toxicological Efficiency, Antifungal, Hemolytic, and Antibacterial Activities.

Zinc oxide (ZnO) nanoparticles (NPs) are important materials when making different products like sun screens, textiles, and paints. In the current study, the photocatalytic effect of prepared ZnO NPs from Moringa oleifera (M. oleifera) was evaluated on degradation of crystal violet (CV) dye, which is largely released from textile industries and is harmful to the environment. Preliminarily, ZnO NP formation was confirmed using a double beam ultraviolet visible (UV-Vis) spectrophotometer; further, the NP size was estimated using XRD analysis and the functional group analysis was determined using Fourier transform infrared (FT-IR) spectroscopy. The morphology of the synthesized NPs was found to be a hexagonal shape using SEM and TEM analysis and elemental screening was analyzed using EDX. ZnO NPs were shown sized 40-45 nm and spherical in shape. The degradation percentage of ZnO NPs was calculated as 94% at 70 min and the rate of the reaction -k = 0.0282. The synthesized ZnO NPs were determined for effectiveness on biological activities such as antifungal, hemolytic, and antibacterial activity. ZnO NPs showed good antifungal activity against Alternaria saloni and Sclerrotium rolfii strains. Further, we have determined the hemolytic and antibacterial activity of ZnO NPs and we got successive results in antibacterial and hemolytic activities.

Magnetotactic bacteria and magnetosomes - Scope and challenges.

Geomagnetism aided navigation has been demonstrated by certain organisms which allows them to identify a particular location using magnetic field. This attractive technique to recognize the course was earlier exhibited in numerous animals, for example, birds, insects, reptiles, fishes and mammals. Magnetotactic bacteria (MTB) are one of the best examples for magnetoreception among microorganisms as the magnetic mineral functions as an internal magnet and aid the microbe to move towards the water columns in an oxic-anoxic interface (OAI). The ability of MTB to biomineralize the magnetic particles (magnetosomes) into uniform nano-sized, highly crystalline structure with uniform magnetic properties has made the bacteria an important topic of research. The superior properties of magnetosomes over chemically synthesized magnetic nanoparticles made it an attractive candidate for potential applications in microbiology, biophysics, biochemistry, nanotechnology and biomedicine. In this review article, the scope of MTB, magnetosomes and its challenges in research and industrial application have been discussed in brief. This article mainly focuses on the application based on the magnetotactic behaviour of MTB and magnetosomes in different areas of modern science.

1,2,4-Triazolo-quinazoline-thiones: Non-conventional synthetic approach, study of solvatochromism and antioxidant assessment.

A non-conventional methodology has been utilized for the synthesis of a series of 1,2,4-triazolo-quinazoline-thiones (2a-l). Here the reaction was carried out between 1,2,4-triazolo-quinazolinones (1a-l), in the presence of 1,4-dioxane. The mixture was irradiated under microwave (100W) for 7min to obtain targeted molecules (2a-l). All the synthesized molecules were confirmed by (1)H, (13)C NMR and HRMS. The solvatochromic property (absorption spectra) of compounds (2a-l) in solvents of different polarities was studied. The compounds (2a-l) were further subjected for their in vitro free radical screening using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and also screened for their in vitro anti-fungal property against Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger). The results from free radical scavenging assay showed promising activity for compounds 2a, e-i, whereas compound 2d showed significant antioxidant activity when compared to ascorbic acid. In vitro anti-fungal study showed that the 1,2,4-triazolo-quinazoline-thiones (2a-l) had significant activity against A. flavus and A. niger compared with widely used antifungal agent Fluconazole.

Isolation and characterization of Magnetospirillum from saline lagoon.

Magnetotactic bacteria (MTB) are aquatic prokaryotes that orient themselves to earth's magnetic field with the help of intracellular organelle magnetosomes. Although many species of MTB have been identified, the isolation of MTB is a challenging task due to the lack of systematic isolation procedure and/or commercial media. In this study, we are reporting the isolation of magnetotactic spirillum from the Pulicat lagoon, India using a systematic and selective procedure. Sampling site was chosen on the basis of physicochemical properties of the ecosystem and the catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) analysis of sediment samples. In the current study, a combination of techniques including 'capillary racetrack' Purification and gradient cultivation resulted in the isolation of magnetotactic spirilla from aquatic sediments. Based on the 16S rRNA gene sequence analysis, the strain was identified as Magnetospirillum and was designated as Magnetospirillum sp. VITRJS1. The genes responsible for magnetosome formation (mamA, B, E, F, K, M, O, P, Q, T) were successfully detected using PCR amplification. The presence of cbbM gene confirmed that the isolate is chemolithoautotroph and utilises reduced sulphur as an electron source. Furthermore, magnetosomes extracted from VITRJS1 found to be cubo-octahedral in shape and 45 nm in size. Our results indicate that the systematic procedure using sediment analysis, CARD-FISH, and a combination of isolation methods enables the selective and rapid isolation of MTB from aquatic sediment sample.

Biodegradation of PAHs by Burkholderia sp. VITRSB1 Isolated from Marine Sediments.

The polycyclic aromatic hydrocarbons (PAHs) pollution to the environment is a major threat to the living organisms, and hence the degradation of these PAHs is necessary. Studies on PAHs degrading bacteria have focussed on terrestrial microbes and the potential of marine derived microbes is undermined. Herein we report the isolation and characterization of PAHs degrading Burkholderia sp. from lagoon sediments collected at the Southern coast of India. The strain was Gram negative, rod-shaped, motile, and ∼2-5 µm in length. Based on the phylogenetic data the strain was identified as Burkholderia and designated as VITRSB1. Initial PAHs degradation ability of the strain was assessed using basal salt medium supplemented with diesel, kerosene, toluene, aniline, naphthalene, and phenol. The strain was found to be effectively degrading kerosene, diesel, toluene, and aniline even at higher concentration (1%). However, naphthalene and aniline were degraded only at lower concentration (0.1%) and phenol, camphor, and DAP inhibited the growth of the strain. Furthermore, the degraded end products of the PAHs were determined using FTIR. Notably, none of the end products were found to be toxic to the biosphere. Our results indicate that the isolated Burkholderia sp. could be a prospective candidate for the effective degradation of selective PAHs.

Marine Actinomycetes as potential source for histone deacetylase inhibitors and epigenetic modulation.

UNLABELLED: In the light of important detrimental role of aberrant histone deacetylases (HDAC) production during various clinical complications, development of therapeutically effective and specific inhibitors of HDAC is critically important. This study deals with the screening for HDAC inhibitors from marine Actinomycetes. The isolation of Actinomycetes from 22 sediment samples along the Southern Coast of India yielded 186 strains including Streptomyces, Nocardipsis, evaluated for HDAC inhibition using HeLa cells. Among the 186 isolates, 10 strains have shown moderate to strong inhibition. The maximum inhibition (61%) was seen with strain VITKSM06 and least inhibition (31%) was seen with strain VITSJT03. The MTT cell proliferation assay using HeLa cell line showed significant cytotoxicity with an IC50 of 5·9 µg ml(-1) by VITKSM06-derived metabolite and 26·2 µg ml(-1) by VITSJT03. The compound treated HeLa cells displayed an altered morphology and condensed chromatin which may be due to HDAC inhibition. Based on the phylogenetic analysis, the potential strains were identified as Nocardiopsis sp VITKSM06, Streptomyces sp VITAKS1 and Streptomyces sp VITRSM02. This study reveals the importance of screening marine Actinomycetes for the discovery of potential novel HDAC inhibitors of therapeutic importance. SIGNIFICANCE AND IMPACT OF THE STUDY: Histone deacetylases (HDAC) are epigenetic enzymes that regulate the deacetylation in lysine group on a histone, and thus regulate the gene expression. The HDAC inhibitors are reported to promote apoptosis on tumour cells, thus become clinically important drug target. Several studies have addressed the identification of putative HDAC inhibitors as therapeutic agents for cancer and until now those cleared phase III human trials are very limited. This study attempts to investigate the chemical diversity found in marine Actinomycetes towards negative HDAC modulation, which could be used individually or in combination as anti-cancerous and other therapeutic measure.

Alpha-amylase Inhibition and Antioxidant Activity of Marine Green Algae and its Possible Role in Diabetes Management.

AIM: In the continuing search for safe and efficient antidiabetic drug, marine algae become important source which provide several compounds of immense therapeutic potential. Alpha-amylase, alpha-glucosidase inhibitors, and antioxidant compounds are known to manage diabetes and have received much attention recently. In the present study, four green algae (Chaetomorpha aerea, Enteromorpha intestinalis, Chlorodesmis, and Cladophora rupestris) were chosen to evaluate alpha-amylase, alpha-glucosidase inhibitory, and antioxidant activity in vitro. MATERIALS AND METHODS: The phytochemical constituents of all the extracts were qualitatively determined. Antidiabetic activity was evaluated by inhibitory potential of extracts against alpha-amylase and alpha-glucosidase by spectrophotometric assays. Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl, hydrogen peroxide (H2O2), and nitric oxide scavenging assay. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out to determine the major compound responsible for its antidiabetic action. RESULTS: Among the various extracts screened, chloroform extract of C. aerea (IC50 - 408.9 µg/ml) and methanol extract of Chlorodesmis (IC50 - 147.6 µg/ml) showed effective inhibition against alpha-amylase. The extracts were also evaluated for alpha-glucosidase inhibition, and no observed activity was found. Methanol extract of C. rupestris showed notable free radical scavenging activity (IC50 - 666.3 µg/ml), followed by H2O2 (34%) and nitric oxide (49%). Further, chemical profiling by GC-MS revealed the presence of major bioactive compounds. Phenol, 2,4-bis (1,1-dimethylethyl) and z, z-6,28-heptatriactontadien-2-one were predominantly found in the methanol extract of C. rupestris and chloroform extract of C. aerea. CONCLUSION: Our results demonstrate that the selected algae exhibit notable alpha-amylase inhibition and antioxidant activity. Therefore, characterization of active compounds and its in vivo assays will be noteworthy. SUMMARY: Four green algae were chosen to evaluate alpha-amylase, alpha-glucosidase inhibitory, and antioxidant activity in vitro C. aerea and Chlorodesmis showed significant inhibition against alpha-amylase, and C. rupestris showed notable free radical scavenging activityNo observed activity was found against alpha-glucosidaseGC-MS analysis of the active extracts reveals the presence of major compounds which gives an insight on the antidiabetic and antioxidant activity of these algae. Abbreviations used: DPPH: 2,2-diphenyl-1-picrylhydrazyl, BHT: Butylated hydroxytoluene, GC-MS: Gas chromatography-mass spectrometry.

Inhibitory potential of Turbinaria ornata against key metabolic enzymes linked to diabetes.

One of the therapeutic approaches in treating diabetes is to reduce postprandial hyperglycemia by inhibiting major carbohydrate hydrolyzing enzymes. In the present study, crude extracts of marine seaweed, Turbinaria ornata, were tested for their antidiabetic potential using enzyme inhibitory assays (α-amylase, α-glucosidase, and dipeptidyl peptidase-IV). Among the tested extracts, methanol and acetone extracts showed significant inhibitory effects on α-amylase (IC50 250.9 µg/mL), α-glucosidase (535.6 µg/mL), and dipeptidyl peptidase-4 (55.2 µg/mL), respectively. Free radical scavenging activity of these extracts was analyzed using DPPH assay (65%). Extracts were tested for in vitro toxicity using DNA fragmentation assay, haemolytic assay, and MTT assay. None of the extracts showed toxicity in tested models. Furthermore, GC-MS analysis of lead extracts showed the presence of major compounds, hentriacontane, z, z-6, 28-heptatriactontadien-2-one, 8-heptadecene, and 1-heptacosanol. Our findings suggest that Turbinaria ornata can be used as a potential source for further in vivo studies in controlling hyperglycemia.