Source Of Natural Products Research Articles

Extraction of Bioactive Compounds for Antioxidant, Antimicrobial, and Antidiabetic Applications.

This study was designed to check the potential of secondary metabolites of the selected plants; Citrullus colocynthis, Solanum nigrum, Solanum surattense, Calotropis procera, Agave americana, and Anagallis arvensis for antioxidant, antibacterial, antifungal, and antidiabetic agents. Plant material was soaked in ethanol/methanol to get the crude extract, which was further partitioned via solvent extraction technique. GCMS and FTIR analytical techniques were applied to check the compounds responsible for causing antioxidant, antimicrobial, and antidiabetic activities. It was concluded that about 80% of studied extracts/fractions were active against α-amylase, ranging from 43 to 96%. The highest activity (96.63%) was exhibited by butanol fractions of A. arvensis while the least response (43.65%) was shown by the aqueous fraction of C. colocynthis and the methanol fraction of fruit of S. surattense. The highest antioxidant activity was shown by the ethyl acetate fraction of Anagallis arvensis (78.1%), while aqueous as well as n-hexane fractions are the least active throughout the assay. Results showed that all tested plants can be an excellent source of natural products with potential antimicrobial, antioxidant, and antidiabetic potential. The biological response of these species is depicted as a good therapeutic agent, and, in the future, it can be encapsulated for drug discovery.

Genome-based discovery and total synthesis of janustatins, potent cytotoxins from a plant-associated bacterium.

Host-associated bacteria are increasingly being recognized as underexplored sources of bioactive natural products with unprecedented chemical scaffolds. A recently identified example is the plant-root-associated marine bacterium Gynuella sunshinyii of the chemically underexplored order Oceanospirillales. Its genome contains at least 22 biosynthetic gene clusters, suggesting a rich and mostly uncharacterized specialized metabolism. Here, in silico chemical prediction of a non-canonical polyketide synthase cluster has led to the discovery of janustatins, structurally unprecedented polyketide alkaloids with potent cytotoxicity that are produced in minute quantities. A combination of MS and two-dimensional NMR experiments, density functional theory calculations of 13C chemical shifts and semiquantitative interpretation of transverse rotating-frame Overhauser effect spectroscopy data were conducted to determine the relative configuration, which enabled the total synthesis of both enantiomers and assignment of the absolute configuration. Janustatins feature a previously unknown pyridodihydropyranone heterocycle and an unusual biological activity consisting of delayed, synchronized cell death at subnanomolar concentrations.

A Chloroplast-Localised Fluorescent Protein Enhances the Photosynthetic Action Spectrum in Green Algae

Green microalgae are important sources of natural products and are attractive cell factories for manufacturing high-value products such as recombinant proteins. Increasing scales of production must address the bottleneck of providing sufficient light energy for photosynthesis. Enhancing the photosynthetic action spectrum of green algae to improve the utilisation of yellow light would provide additional light energy for photosynthesis. Here, we evaluated the Katushka fluorescent protein, which converts yellow photons to red photons, to drive photosynthesis and growth when expressed in Chlamydomonas reinhardtii chloroplasts. Transplastomic algae expressing a codon-optimised Katushka gene accumulated the active Katushka protein, which was detected by excitation with yellow light. Removal of chlorophyll from cells, which captures red photons, led to increased Katushka fluorescence. In yellow light, emission of red photons by fluorescent Katushka increased oxygen evolution and photosynthetic growth. Utilisation of yellow photons increased photosynthetic growth of transplastomic cells expressing Katushka in light deficient in red photons. These results showed that Katushka was a simple and effective yellow light-capturing device that enhanced the photosynthetic action spectrum of C. reinhardtii.

Proof-Reading Thioesterase Boosts Activity of Engineered Nonribosomal Peptide Synthetase.

Nonribosomal peptide synthetases (NRPSs) are a vast source of valuable natural products, and re-engineering them is an attractive path toward structurally diversified active compounds. NRPS engineering often requires heterologous expression, which is hindered by the enormous size of NRPS proteins. Protein splitting and docking domain insertion have been proposed as a strategy to overcome this limitation. Here, we have applied the splitting strategy to the gramicidin S NRPS: Despite better production of the split proteins, gramicidin S production almost ceased. However, the addition of type II thioesterase GrsT boosted production. GrsT is an enzyme encoded in the gramicidin S biosynthetic gene cluster that we have produced and characterized for this purpose. We attribute the activity enhancement to the removal of a stalled intermediate from the split NRPS that is formed due to misinitiation. These results highlight type II thioesterases as useful tools for NRPS engineering.

Genomic diversity and biosynthetic capabilities of sponge-associated chlamydiae

Sponge microbiomes contribute to host health, nutrition, and defense through the production of secondary metabolites. Chlamydiae, a phylum of obligate intracellular bacteria ranging from animal pathogens to endosymbionts of microbial eukaryotes, are frequently found associated with sponges. However, sponge-associated chlamydial diversity has not yet been investigated at the genomic level and host interactions thus far remain unexplored. Here, we sequenced the microbiomes of three sponge species and found high, though variable, Chlamydiae relative abundances of up to 18.7% of bacteria. Using genome-resolved metagenomics 18 high-quality sponge-associated chlamydial genomes were reconstructed, covering four chlamydial families. Among these, Candidatus Sororchlamydiaceae shares a common ancestor with Chlamydiaceae animal pathogens, suggesting long-term co-evolution with animals. Based on gene content, sponge-associated chlamydiae resemble members from the same family more than sponge-associated chlamydiae of other families, and have greater metabolic versatility than known chlamydial animal pathogens. Sponge-associated chlamydiae are also enriched in genes for degrading diverse compounds found in sponges. Unexpectedly, we identified widespread genetic potential for secondary metabolite biosynthesis across Chlamydiae, which may represent an unexplored source of novel natural products. This finding suggests that Chlamydiae members may partake in defensive symbioses and that secondary metabolites play a wider role in mediating intracellular interactions. Furthermore, sponge-associated chlamydiae relatives were found in other marine invertebrates, pointing towards wider impacts of the Chlamydiae phylum on marine ecosystems.

Vitamin B3 Triggers Biosynthesis of Secondary Metabolite Dormancy Signals in Streptococcus suis.

Human-associated streptococci have not been viewed as productive sources of natural products. Against expectation, bioinformatic searches recently revealed a large collection of diverse biosynthetic gene clusters coding for ribosomally synthesized and post-translationally modified peptides (RiPPs) in streptococcal genomes. The most abundant of these, the tqq gene cluster, is specific to Streptococcus suis, a burdensome agricultural pathogen and zoonotic agent. Herein, we used high-throughput elicitor screening to identify both small molecule elicitors and products of the tqq cluster. We show that the B3 vitamin niacin effectively elicits the tqq cluster leading to the biosynthesis of a family of RiPP natural products, which we termed threoglucins and characterized structurally. The defining feature of threoglucins is an aliphatic ether bond giving rise to a substituted 1,3-oxazinane heterocycle in the peptide backbone. Isolation of 22 congeners of threoglucins facilitated structure activity relationship studies, demonstrating the requirement for the oxazinane substructure and a Trp-Tyr C-terminal dyad for biological activity, namely antibiotic persistence and allolysis at low and high doses, respectively. Potential therapeutic applications of threoglucins are discussed.

Ultra-high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flightmass spectrometryand molecular networking analysis to investigate the chemodiversity of bioactive extracts of Annona jahnii Saff. fungi from the Brazilian Amazon.

Annona species are of interest for the isolation of bioactive molecules; however, studies of Annona jahnii Saff. are limited. The exploration of bioactive metabolites of endophytes isolated from this species is unprecedented and allows the preservation of the host plant, in addition to enabling the discovery of compounds with promising biological activities. Ethyl acetate extracts from the cultured media of five fungi were obtained. The antioxidant capacity of the extracts was measured using the 1,1-diphenyl-2-picrylhydrazyl free radical method. Antimicrobial activity was determined using the microdilution method in broth in 96-well plates. The exploration of the metabolic profile of the extracts and dereplication of the compounds were performed using ultra-high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (UHPLC/ESI-MS/MS) combined with analysis using molecular networking (MN). A total of 1818 MS features were detected in the five selected extracts, of which 39 compounds were putatively identified. The secondary metabolites with the highest abundance were alkaloids, naphthopyrons, and cytochalasins. Other secondary metabolites include fumonisins, coumarin, and a meroterpenoid. Most of these compounds are related to specific biological properties such as antioxidant, anti-inflammatory, antimicrobial, antiviral, and antitumor activities. Extracts F398 and F403 showed inhibitory activity of the four pathogens tested. Extracts F475 and F506 did not inhibit the growth of Staphylococcus aureus, and F407 did not inhibit the growth of Escherichia coli in addition to having potent antioxidant activity, with IC50 values of 10μg/mL or less. The use of UHPLC/ESI-MS/MS data combined with MN proved useful in the dereplication of bioactive molecules of complex extracts that are still unexplored. These initial investigations should significantly assist in further research and increase the efficiency and speed in the discovery of new sources of secondary metabolites and new natural products.

Traditional Use, Phytochemical Profiles and Pharmacological Properties of Artemisia Genus from Central Asia.

The flora of Kazakhstan is characterized by its wide variety of different types of medicinal plants, many of which can be used on an industrial scale. The Traditional Kazakh Medicine (TKM) was developed during centuries based on the six elements of ancient Kazakh theory, associating different fields such as pharmacology, anatomy, pathology, immunology and food nursing as well as disease prevention. The endemic Artemisia L. species are potential sources of unique and new natural products and new chemical structures, displaying diverse bioactivities and leading to the development of safe and effective phytomedicines against prevailing diseases in Kazakhstan and the Central Asia region. This review provides an overview of Artemisia species from Central Asia, particularly traditional uses in folk medicine and the recent numerous phytochemical and pharmacological studies. The review is done by the methods of literature searches in well-known scientific websites (Scifinder and Pubmed) and data collection in university libraries. Furthermore, our aim is to search for promising and potentially active Artemisia species candidates, encouraging us to analyze Protein Tyrosine Phosphatase 1B (PTP1B), α-glucosidase and bacterial neuraminidase (BNA) inhibition as well as the antioxidant potentials of Artemisia plant extracts, in which endemic species have not been explored for their secondary metabolites and biological activities so far. The main result of the study was that, for the first time, the species Artemisia scopiformis Ledeb. Artemisia albicerata Krasch., Artemisia transiliensis Poljakov, Artemisia schrenkiana Ledeb., Artemisia nitrosa Weber and Artemisia albida Willd. ex Ledeb. due to their special metabolites, showed a high potential for α-glucosidase, PTP1B and BNA inhibition, which is associated with diabetes, obesity and bacterial infections. In addition, we revealed that the methanol extracts of Artemisia were a potent source of polyphenolic compounds. The total polyphenolic contents of Artemisia extracts were correlated with antioxidant potential and varied according to plant origin, the solvent of extraction and the analytical method used. Consequently, oxidative stress caused by reactive oxygen species (ROS) may be managed by the dietary intake of current Artemisia species. The antioxidant potentials of the species A. schrenkiana, A. scopaeformis, A. transiliensis and Artemisia scoparia Waldst. & Kitam. were also promising. In conclusion, the examination of details between different Artemisia species in our research has shown that plant materials are good as an antioxidant and eznyme inhibitory functional natural source.

Affinity selection-mass spectrometry in the discovery of anti-SARS-CoV-2 compounds.

Small molecule therapeutic agents are needed to treat or prevent infections by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), which is the cause of the COVID‐19 pandemic. To expedite the discovery of lead compounds for development, assays have been developed based on affinity selection‐mass spectrometry (AS‐MS), which enables the rapid screening of mixtures such as combinatorial libraries and extracts of botanicals or other sources of natural products. AS‐MS assays have been used to find ligands to the SARS‐CoV‐2 spike protein for inhibition of cell entry as well as to the 3‐chymotrypsin‐like cysteine protease (3CLpro) and the RNA‐dependent RNA polymerase complex constituent Nsp9, which are targets for inhibition of viral replication. The AS‐MS approach of magnetic microbead affinity selection screening has been used to discover high‐affinity peptide ligands to the spike protein as well as the hemp cannabinoids cannabidiolic acid and cannabigerolic acid, which can prevent cell infection by SARS‐CoV‐2. Another AS‐MS method, native mass spectrometry, has been used to discover that the flavonoids baicalein, scutellarein, and ganhuangenin, can inhibit the SARS‐CoV‐2 protease 3CLpro. Native mass spectrometry has also been used to find an ent‐kaurane natural product, oridonin, that can bind to the viral protein Nsp9 and interfere with RNA replication. These natural lead compounds are under investigation for the development of therapeutic agents to prevent or treat SARS‐CoV‐2 infection.

Hairy roots: An untapped potential for production of plant products.

While plants are an abundant source of valuable natural products, it is often challenging to produce those products for commercial application. Often organic synthesis is too expensive for a viable commercial product and the biosynthetic pathways are often so complex that transferring them to a microorganism is not trivial or feasible. For plants not suited to agricultural production of natural products, hairy root cultures offer an attractive option for a production platform which offers genetic and biochemical stability, fast growth, and a hormone free culture media. Advances in metabolic engineering and synthetic biology tools to engineer hairy roots along with bioreactor technology is to a point where commercial application of the technology will soon be realized. We discuss different applications of hairy roots. We also use a case study of the advancements in understanding of the terpenoid indole alkaloid pathway in Catharanthus roseus hairy roots to illustrate the advancements and challenges in pathway discovery and in pathway engineering.

Exploring the Potential of Myrothamnus flabellifolius Welw. (Resurrection Tree) as a Phytogenic Feed Additive in Animal Nutrition.

Simple SummaryThe unregulated use of in-feed antibiotic growth promoters has received widespread condemnation due to an increase in cases of antibiotic-resistant microbes. This has fueled an ever-growing demand for new sources of natural and safe alternative products with minimal impacts on the environment and human health in animal production. Myrothamnus flabellifolius, as a phytogenic feed additive, fits this description, as it is a natural plant containing high amounts of secondary metabolites necessary for cell function, regulation, and protection for improved animal growth, performance, and health. With some limitations towards its use, several processing and combination strategies are available to unlock nutrients and explore its potential in animal production, as described in this review.Myrothamnus flabellifolius (Welw.) is used in African traditional medicine for the treatment of depression and mental disorder, asthma, infectious diseases, respiratory, inflammation, epilepsy, heart, wound, backaches, diabetes, kidney ailments, hypertension, hemorrhoids, gingivitis, shingles, stroke, and skins conditions. The effectiveness of M. flabellifolius is due to the presence of several secondary metabolites that have demonstrated efficacy in other cell and animal models. These metabolites are key in cell regulation and function and have potential use in animal production due to antimicrobial and antioxidant properties, for an improvement in growth performance, feed quality and palatability, gut microbial environment, function, and animal health. The purpose of this review is to provide a detailed account on the potential use of M. flabellifolius in animal nutrition. Limitations towards the use of this plant in animal nutrition, including toxicity, economic, and financial issues are discussed. Finally, novel strategies and technologies, e.g., microencapsulation, microbial fermentation, and essential oil extraction, used to unlock and improve nutrient bioaccessibility and bioavailability are clearly discussed towards the potential use of M. flabellifolius as a phytogenic additive in animal diets.

Purification, Identification, and Properties of a Novel Carotenoid Produced by Arthrobacter sp. QL17 Isolated from Mount Qomolangma.

The genus Arthrobacter is a source of many natural products that are critical in the development of new medicines. Here, we isolated a novel carotenoid from Arthrobacter sp. QL17 and characterized its properties. The carotenoid was extracted with methanol, and purified by column chromatography and semi-preparative HPLC. Based on micrOTOF-Q and NMR analyses, the pigment was chemically characterized as 2,2′-((((1E,3E,5E,7E,9E,11E,13E,15E,17E,19E)-3,7,14,18-tetramethylicosa-1,3,5,7,9,11,13,15,17,19-decaene-1,20-diyl)bis(2,2,4-trimethylcyclohex-3-ene-3,1-diyl)) bis(ethan-2-yl-1-ylidene))bi(propane-1,3-diol), and named arthroxanthin. The biological activities of arthroxanthin were evaluated with DPPH, ABTS and MTT assays. Arthroxanthin exhibited excellent radical scavenging properties, as shown for 2, 20-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-n-(3,2-ethyl-benzothiazole-6-sulfonic acid) ammonium salt (ABTS), respectively, with IC50s of 69.8 and 21.5 µg/mL. It also showed moderate anticancer activities against HepG2, Hela, MDAB-231, SW480, and MKN-45 with IC50 values of 107.6, 150.4, 143.4, 195.9, and 145.5 μg/mL, respectively. Therefore, arthroxanthin derived from Arthrobacter sp. QL17 may be a potent antioxidant and anticancer agent for food and pharmaceutical use.

Medicinal plant cultivation for sustainable use and commercialisation of high-value crops

Many traditional healing systems are based on natural biological resources, and there is a general shift in most parts of the world towards natural medicine, with direct implications on the demand and supply of medicinal plants. This review highlights the economic importance of medicinal plants, their contribution to healthcare systems, and potential opportunities for rural economic development through cultivation. A systematic literature review with specific search terms related to medicinal plants was used to collect scientific and non-scientific information from peer-reviewed literature and grey literature databases. The findings indicate that trade in medicinal plants is increasing, and although they are considered minor crops compared to major food crops, their value is among the highest in the list of traded plants globally. The trade also serves as a revenue source for many rural livelihoods, with women playing a significant role. Medicinal plants contribute to primary health care in many developing countries, and they are also an essential source of modern drug discovery. Cultivation of medicinal plants offers emerging rural farmers an opportunity to grow these plants as new and alternative crops, thus reducing unsustainable wild harvesting and competition with established commercial farmers who mostly focus on food crops. Furthermore, medicinal plant cultivation should be promoted as one of the options for local economic development and sustainability through job creation, the revival of the rural economy, and income generation for small businesses, such as the transport businesses, involved in the value chain. Land accessibility, financial resources, and direct market access for rural communities can elevate their contribution to the industry. Formalisation of the lower levels of the medicinal plant trade is also recommended. Significance: Cultivation is a viable option for biodiversity conservation of medicinal plants and ensuring a goodquality supply of plant materials. Cultivation of medicinal plants – a source of natural products used in product development – can contribute to job creation, income generation, and rural economies in developing countries. This review underlines the importance of medicinal plants in product development, the contribution of the industry to economies of different countries, and the potential for cultivation.

Affinity ultrafiltration and UPLC-HR-Orbitrap-MS based screening of neuraminidase inhibitors from Angelica pubescens

Traditional Chinese medicine is a rich source of natural products and has a long history of use because of its remarkable clinical efficacy. In the present study, the chemical constitutes of Angelica pubescens were studied by ultra high performance liquid chromatography and high-resolution Orbitrap mass spectrometry (UPLC-HR-Orbitrap-MS). A total of 78 compounds were identified and the main composition were coumarins and phenolic acids. Then, the neuraminidase was incubated with extract of Angelica pubescens to screen the neuraminidase inhibitors by affinity ultrafiltration methods. As a result, 13 small molecules were discovered to interact with neuraminidase for the first time. In vitro neuraminidase inhibitory activity of the screened compounds and extract of Angelica pubescens was tested, and isochlorogenic acid C, isochlorogenic acid B, osthole, chlorogenic acid, xanthotoxin, phellopterin and imperatorin were proved to have this activity. In addition, molecular docking analysis was conducted to predict the potential docking position. This study may provide a reference for the medical substance basis in Angelica and the clinical usage of this drug.

Metabolomics-Guided Comparison of Pollen and Microalgae-Based Artificial Diets in Honey Bees.

Managed honey bee colonies used for crop pollination are fed artificial diets to offset nutritional deficiencies related to land-use intensification and climate change. In this study, we formulated novel microalgae diets using Chlorella vulgaris and Arthrospira platensis (spirulina) biomass and fed them to young adult honey bee workers. Diet-induced changes in bee metabolite profiles were studied relative to a natural pollen diet using liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) metabolomics. Untargeted analyses of pollen- and microalgae-fed bees revealed significant overlap, with 248 shared features determined by LC-MS and 87 shared features determined by GC-MS. Further metabolomic commonalities were evident upon subtraction of unique diet features. Twenty-five identified metabolites were influenced by diet, which included complex lipids, essential fatty acids, vitamins, and phytochemicals. The metabolomics results are useful to understand mechanisms underlying favorable growth performance as well as increased antioxidant and heat shock protein gene expression in bees fed the microalgae diets. We conclude that the tested microalgae have potential as sustainable feed additives and as a source of bee health-modulating natural products. Metabolomics-guided diet development could eventually help tailor feed interventions to achieve precision nutrition in honey bees and other livestock animals.

IChip-Inspired Isolation, Bioactivities and Dereplication of Actinomycetota from Portuguese Beach Sediments.

Oceans hold a stunning number of unique microorganisms, which remain unstudied by culture-dependent methods due to failures in establishing the right conditions for these organisms to grow. In this work, an isolation effort inspired by the iChip was performed using marine sediments from Memoria beach, Portugal. The isolates obtained were identified by 16S rRNA gene analysis, fingerprinted using BOX-PCR and ERIC-PCR, searched for the putative presence of secondary metabolism genes associated with polyketide synthase I (PKS-I) and non-ribosomal peptide synthetases (NRPS), screened for antimicrobial activity against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, and had bioactive extracts dereplicated by LC/HRMS. Of the 158 isolated strains, 96 were affiliated with the phylum Actinomycetota, PKS-I and NRPS genes were detected in 53 actinomycetotal strains, and 11 proved to be bioactive (10 against E. coli, 1 against S. aureus and 1 against both pathogens). Further bioactivities were explored using an “one strain many compounds” approach, with six strains showing continued bioactivity and one showing a novel one. Extract dereplication showed the presence of several known bioactive molecules and potential novel ones in the bioactive extracts. These results indicate the use of the bacteria isolated here as sources of new bioactive natural products.

Metabolomic Profiling and Molecular Networking of Nudibranch-Associated Streptomyces sp. SCSIO 001680

Antibiotic-resistant bacteria are the primary source of one of the growing public health problems that requires global attention, indicating an urgent need for new antibiotics. Marine ecosystems are characterized by high biodiversity and are considered one of the essential sources of bioactive chemical compounds. Bacterial associates of marine invertebrates are commonly a source of active medicinal and natural products and are important sources for drug discovery. Hence, marine invertebrate-associated microbiomes are a fruitful resource for excavating novel genes and bioactive compounds. In a previous study, we isolated Streptomyces sp. SCSIO 001680, coded as strain 63, from the Red Sea nudibranch Chromodoris quadricolor, which exhibited antimicrobial and antitumor activity. In addition, this isolate harbors several natural product biosynthetic gene clusters, suggesting it has the potential to produce bioactive natural products. The present study aimed to investigate the metabolic profile of the isolated Streptomyces sp. SCSIO 001680 (strain 63) and to predict their potential role in the host’s survival. The crude metabolic extracts of strain 63 cultivated in two different media were characterized by ultra-high-performance liquid chromatography and high-resolution mass spectrometry. The metabolomics approach provided us with characteristic chemical fingerprints of the cellular processes and the relative abundance of specific compounds. The Global Products Social Molecular Networking database was used to identify the metabolites. While 434 metabolites were detected in the extracts, only a few compounds were identified based on the standards and the public spectral libraries, including desferrioxamines, marineosin A, and bisucaberin, halichoblelide, alternarin A, pachastrelloside A, streptodepsipeptide P1 1B, didemnaketal F, and alexandrolide. This finding suggests that this strain harbors several novel compounds. In addition, the metabolism of the microbiome of marine invertebrates remains poorly represented. Thus, our data constitute a valuable complement to the study of metabolism in the host microbiome.

An N-N linked dimeric indole alkaloid from the marine sponge-associated rare actinomycetes Kocuria sp. S42

Marine derived rare actinomycetes is emerging as one of the new sources for various natural products for further drug discovery. Dimeric indole alkaloids represent a group of structurally diverse natural products and N-N linkage is a special dimerization mode. Here, we report the isolation of 1,1'-([1,1'-biindole]-3,3'-diyl) bis (ethane-1,2-diol), a new tryptophan-derived indole alkaloid from the marine sponge-derived Kocuria sp. S42. The structure was established based on extensive spectroscopic analyses, including nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass (HR-ESI-MS) spectrometry. The new dimeric indole alkaloid via N-N linkage exhibits moderate antimicrobial activity.

Natural Products Inhibitors of Monoamine Oxidases—Potential New Drug Leads for Neuroprotection, Neurological Disorders, and Neuroblastoma

Monoamine oxidase inhibitors (MAOIs) are an important class of drugs prescribed for treatment of depression and other neurological disorders. Evidence has suggested that patients with atypical depression preferentially respond to natural product MAOIs. This review presents a comprehensive survey of the natural products, predominantly from plant sources, as potential new MAOI drug leads. The psychoactive properties of several traditionally used plants and herbal formulations were attributed to their MAOI constituents. MAO inhibitory constituents may also be responsible for neuroprotective effects of natural products. Different classes of MAOIs were identified from the natural product sources with non-selective as well as selective inhibition of MAO-A and -B. Selective reversible natural product MAOIs may be safer alternatives to the conventional MAOI drugs. Characterization of MAO inhibitory constituents of natural products traditionally used as psychoactive preparations or for treatment of neurological disorders may help in understanding the mechanism of action, optimization of these preparations for desired bioactive properties, and improvement of the therapeutic potential. Potential therapeutic application of natural product MAOIs for treatment of neuroblastoma is also discussed.

Changes in antioxidant activity of fresh marine macroalgae from the Canary Islands during air-drying process

Marine macroalgae develop structurally distinct molecules that have been long recognized as an important source of natural products, e.g., bioactive compounds and antioxidants, such as carotenoids, amino acids, proteins, lipids, vitamins and polyphenols, with promising properties as anticoagulant, anti-proliferative and antimicrobial. In this study we analyzed the antioxidant activity of 24 fresh methanolic extracts from marine macroalgae from the Canary Islands. Additionally, the effects of air-drying process in the antioxidant activity were also evaluated. Plant material was collected in three locations on the island of Tenerife. Total antioxidant activity methods included DPPH-free radical scavenging activity and ferrous iron chelating activity. Phytoconstituents evaluated were total carotenoids, proline, phenols, flavonoids and condensed tannins content. Our results indicated that from fresh material, species Cladophora liebetruthii, Dasycladus vermicularis and Dictyopteris polypodioides presented the highest scavenging activity, supported by high correlation with phenolics and flavonoids content, however, in air-dry extracts, Anadyomene saldanhae and D. polypodioides showed the highest antioxidant potential, correlated with a high phenolic compounds content. Asteronema breviarticulatum and D. polypodioides presented a high content of carotenoids in fresh and air-dry state. The highest ferrous iron chelating activity (>60 %) was recorded in extracts from fresh material in Grateloupia imbricata and Lophocladia trichoclados. However, only L. trichoclados was able to maintain this high activity after air-drying supported by a high proline content. A. breviarticulatum was the species that showed the highest condensed tannins content both in fresh and dried extracts. The study revealed that fresh extracts of D. vermicularis, D. polypodioides and L. trichoclados possess promising properties as raw materials to obtain biologically active substances in alimentary and pharmaceutical industry. Besides, these properties were maintained after the air-drying period in the last two species, which makes them species of great interest to be used under drying preservation methods.