Study on Marine actinomycetes and analysis of their secondary metabolites

Actinomycetes are relatively prevalent bacteria in the ocean,constituting 9% of the total number of marine bacteria.The advancement of science and technology has led to a more profound exploration of marine actinomycetes.These studies hold immense significance in comprehending the distribution and adaptation of marine actinomycetes within the oceanic environment,as well as uncovering new secondary metabolites.Based on differing lifestyles,marine actinomycetes can be categorized as free-living or co-epiphytic.The activity and metabolism of actinomycetes vary across diverse marine settings,including the deep sea,benthic regions,and marine organisms.Due to their distinctive biological traits and genetic background,these marine actinomycetes inevitably generate metabolites possessing unique structures.Research methodologies concerning marine actinomycetes predominantly encompass traditional pure culture techniques,molecular biology approaches,and the integration of metagenomics and bioinformatics.The exploration of varied methodologies proves pivotal for the analysis of metabolite processes.Through the cultivation of marine actinomycetes,numerous compounds featuring novel structures and significant activities have been isolated,furnishing a substantial foundation for new drug investigations.These encompass,but are not restricted to,peptides,antibiotics,terpenoids,ketones,quinones,macrolides,and pigments.The potential applications of marine actinomyces and their secondary metabolites extend beyond antibacterial and anti-tumor effects,exhibiting promising prospects in antifungal and antiviral domains.This paper provides a comprehensive review of the classification,resources,research methodologies,and habitats of marine actinomycetes.Furthermore,it delves into the classification of secondary metabolites and their functional activities,facilitating a more exhaustive analysis of the secondary metabolites produced by marine actinomycetes.

A perspective review on the biosynthesis of plant-based secondary metabolites and their application as potent drugs

Many phytochemicals and their derived metabolites produced by plants are extensively employed in commercial goods,pharmaceutical products as well as in the environmental and medicalfields.However,these secondary metabolites obtained from plants are in low amounts,and it is difficult to synthesize them at the industrial level.Despite these challenges,they may be utilized for a variety of medicinal products that are either available in the market or are being researched and tested.Secondary metabolites are complex compounds that exhibit chirality.Further,under controlled conditions with elicitors,desired secondary metabolites may be produced from plant cell cultures.This review emphasizes the various aspects of secondary metabolites including their types,synthesis,and applications as medicinal products.The article aims to promote the use of plant secondary metabolites in the management and treatment of various diseases.

Metabolic and transcriptomic analyses elucidate a novel insight into the network for biosynthesis of carbohydrate and secondary metabolites in the stems of a medicinal orchid Dendrobium nobile

Dendrobium nobile is an important medicinal and nutraceutical herb.Although the ingredients of D.nobile have been identified as polysaccharides,alkaloids,amino acids,flavonoids and bibenzyls,our understanding of the metabolic pathways that regulate the synthesis of these compounds is limited.Here,we used transcriptomic and metabolic analyses to elucidate the genes and metabolites involved in the biosynthesis of carbohydrate and several secondary metabolites in the stems of D.nobile.A total of 1005 metabolites and 31,745 genes were detected in the stems of D.nobile.The majority of these metabolites and genes were involved in the metabolism of carbohydrates(fructose,mannose,glucose,xylulose and starch),while some were involved in the metabolism of secondary metabolites(alkaloids,β-tyrosine,ferulic acid,4-hydroxybenzoate and chrysin).Our predicted regulatory network indicated that five genes(AROG,PYK,DXS,ACEE and HMGCR) might play vital roles in the transition from carbohydrate to alkaloid synthesis.Correlation analysis identified that six genes(ALDO,PMM,BGLX,EGLC,XYLB and GLGA) were involved in carbohydrate metabolism,and two genes(ADT and CYP73A) were involved in secondary metabolite biosynthesis.Our analyses also indicated that phosphoenol-pyruvate(PEP) was a crucial bridge that connected carbohydrate to alkaloid biosynthesis.The regulatory network between carbohydrate and secondary metabolite biosynthesis established will provide important insights into the regulation of metabolites and biological systems in Dendrobium species.

Plant-derived secondary metabolites as the main source of efflux pump inhibitors and methods for identification

The upsurge of multiple drug resistance(MDR)bacteria substantially diminishes the effectiveness of antibiotic arsenal and therefore intensifies the rate of therapeutic failure.The major factor in MDR is efflux pump-mediated resistance.A unique pump can make bacteria withstand a wide range of structurally diverse compounds.Therefore,their inhibition is a promising route to eliminate resistance phenomenon in bacteria.Phytochemicals are excellent alternatives as resistance-modifying agents.They can directly kill bacteria or interact with the crucial events of pathogenicity,thereby decreasing the ability of bacteria to develop resistance.Numerous botanicals display noteworthy efflux pumps inhibitory activities.Edible plants are of growing interest.Likewise,some plant families would be excellent sources of efflux pump inhibitors(EPIs)including Apocynaceae,Berberidaceae,Convolvulaceae,Cucurbitaceae,Fabaceae,Lamiaceae,and Zingiberaceae.Easily applicable methods for screening plant-derived EPIs include checkerboard synergy test,berberine uptake assay and ethidium bromide test.In silico highthroughput virtual detection can be evaluated as a criterion of excluding compounds with efflux substrate-like characteristics,thereby improving the selection process and extending the identification of EPIs.To ascertain the efflux activity inhibition,real-time PCR and quantitative mass spectrometry can be applied.This review emphasizes on efflux pumps and their roles in transmitting bacterial resistance and an update plant-derived EPIs and strategies for identification.

Evaluation of quantitative variation of secondary metabolites in Bergenia ciliata(Haw.)using high performance thin layer chromatography

Dear Editor： Therapeutically active metabolite contents in a med- icinal plant vary in nature, which may impact on its therapeutic efficacy. Bergenia （Saxifragaceae） is an evergreen perennial herb widely distributed in Central and East Asia with about 30 species reported worldwide. It grows at a range of altitudes from the Khasia hills at 400 feet to the temperate Himalayas from Kashmir to Bhutan at 7,000-10,000 feet. Its distribution over a wide range of altitudinal zones makes it a good candidate for studying variations in its metabolic profiles under different climatic conditions. Bergenin （C-glycoside of 4-O-methyl gallic acid） has been identified as a potent active secondary metabolite in Bergenia and other therapeutically active constituents including, among others, gallic acid （3,4,5 trihydroxybenzoic acid）, （＋） catechin, and gallicin （Fig. 1）.

Bioactivity Determination and Control Effect Evaluation of Three Plant Secondary Metabolites against Semiaphis heraclei

[Objective] The paper was to clarify the bioactivity of trans-2-hexenal,oregano oil and thyme oil against Semiaphis heraclei and the synergistic effect of orange peel essential oil and organosilicon on the aphidicidal activity of the three agents.[Method] With S.heraclei,the dominant species of aphids in Lonicera japonica thunb.,as the test insect,the bioactivity and control effect were evaluated by the method of leaf dipping and foliar spraying.[Result] The indoor toxicity of thyme oil was the highest,with the LC_(50) of 1.793 mg/L.Adding additives significantly increased the toxicity of the agents to S.heraclei.Among them,trans-2-hexenal+OSi,oregano oil+OSi and thyme oil+OSi had obvious synergistic effects,with the toxicity coefficients of 1.80,1.48 and 1.45,respectively.Field test showed that the corrected control effect of thyme oil was the highest after con-ventional spraying,and the toxicities of the three agents were higher than that of the control group at 7 d post spraying.Under the condition of 20%reduction of three agents and adding organosilicon,the control effect was increased by about 10% at 1 d post spraying,which was higher than that of the control group at 4 d post spraying,and reached over 98% at 14 d post spraying.[Conclusion] Thyme oil has the highest toxicity and control effect on S.heraclei.Three agents combined with organosilicon have the obvious effect of reducing the quantity and increasing the efficiency,which has the potential for further development.

Changes of main secondary metabolites in leaves of Ginkgo biloba in response to ozone fumigation

To investigate the effect of elevated 03 on the accumulation of main secondary metabolites in leaves of Ginkgo biloba L., four-year- old trees were exposed in open-top chambers with ambient air and the air with twice ambient 03 concentration in Shenyang in 2006. Elevated 03 increased the concentrations of terpenes, but decreased the concentrations of phenolics in G. biloba leaves. The results showed that secondary compounds from G. biloba leaves responded to the elevated 03 exposure in a different way when compared to previous studies which showed elevated 03 increased the concentrations of phenolics but had no effect on the terpenes in leaves of other deciduous trees. Furthermore, reduced synthesis of phenolics may decrease the resistance of G. biloba to 03 and other environmental factors. On the other hand, the induced synthesis of terpenes may enhance the antioxidant abilities in G. biloba leaves at the end of 03 fumigation.

Research Progress of Medicinal Secondary Metabolites and Gene Cloning of Dendrobium officinale

Dendrobium officinale is one of the most precious medicinal plants in China. Its main medicinal ingredients are its secondary metabolites. However,it has the characteristics of limited sources,low active ingredient content and high cost,limiting the use of D. officinale.Studying the network structure and rate-limiting steps of secondary metabolites of medicinal components of D. officinale,analyzing the secondary metabolic synthesis process,mastering the production rules of its medicinal components and carrying out gene cloning or biosynthesis,etc.are of great significance for the rational development and utilization of D. officinale resources. This paper briefly reviews the progress of the research on the secondary metabolites of D. officinale,including the detection and identification of metabolites and the identification and cloning of key metabolic enzymes.

Isolation and characterization of secondary metabolites from the mangrove plant Rhizophora mucronata

Objective:To evaluate the antibacterial activity of foliar extracts of Rhizophora mucronnata(R. mucronata) against pathogens belonging to human origin and to identify the compound hitherto unprecedented in nature by GC-MS analysis.Methods:Soxhlet extraction method was used to get the corresponding extracts of ethanol,petroleum ether,acetone,methanol and ethyl acetate.The antimicrobial activities of the organic solvent extracts on the various test organisms using agar well diffusion technique were carried out.Ethyl acetate extract exhibited promising antimicrobial activity and hence minimum inhibitory concentration(MIC) was performed for the same.Column chromatography was done for partial purification of crude extract and fractions were analyzed by GC-MS.Results:A column chromatographic fractionation of the extracts and further UV visible and GS-MS analysis suggested the active principle compound were a mixture of squalene(19.19%),n-Hexadecanoic acid(6.59%),phytol(4.74%).2-cyclohexane-l- one, 4-hydroxy-3,5,(4.20%) and oleic acid(2.88%).Conclusions:The results are good enough to serve to transform the practice of research in this sub field across a range of different benefit streams that include drug development.By and large this type of structure analyses are most important as aids to more rational decision taking in safety models versus effectiveness.In general,structural data provide prima facie support for drug hypothesis.

Identification and Bioactivities of Secondary Metabolites Derived from Endophytic Fungi Isolated from Ethnomedicinal Plants of Tujia in Hubei Province:A Review

Tujia is a national minority,inhabiting in the mountainous Wuling area in China.Since 1978,Tujia medicine has been studied,summarized and developed,leading to numerous achievements by Chinese researchers,such as the publishing of approximately 30 monographs of Tujia medicine.These publications are focused on summarizing and improving the theory of Tujia medicine and developing clinical therapies from this system of medicine.The shortage of natural medicinal plants used in Tujia medicine has created the need to discover new resources to replace them and protect endangered natural plant species.Endophytic fungi are one of the conservation options,are considered a source of new bioactive natural products,and are a renewable and inexhaustible source of new drugs and agrochemicals.This review summarizes 260 compounds from endophytic fungi that have been previously isolated from the medicinal plants of Tujia.These compounds include steroids,terpenoids,meroterpenoids,polyketides,alkaloids,peptides,aliphatic compounds,aromatic compounds,and heterocyclic compounds.

Diversity of Secondary Metabolites from Two Antarctic Microbes Rhodococcus sp. NJ-008 and <i>Pseudomonas</i>sp. NJ-011

Diversity analysis on secondary metabolites of Antarctic microbes, Rhodococcus sp. NJ-008 and Pseudomonas sp. NJ-011, together with the structural elucidation of some purified compounds, has been carried out for understanding of their chemical constituents. The methanol extracts of Rhodococcus sp. NJ-008 and Pseudomonas sp. NJ-011 were subjected to HPLC-TOF MS test for diversity analysis on secondary metabolites, respectively. The chemical constituents of NJ-011 are mainly N-containing compounds including some alkaloids and short polypeptides, while those of NJ-008 are not N-containing ones. Three compounds were also isolated and identified from extract of NJ011 by different column chromatography and preparative HPLC, and their structures were elucidated as b-carboline (1), 3-benzylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione (2) and 3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione (3) by comparison of TOF MS, 1Hand 13C-NMR data with those reported. More microbial material of Pseudomonas sp. NJ-011 should be needed for exploration of the minor constituents with complicated structures.

Algicidal activities of secondary metabolites of marine macroalgal-derived endophytic fungi

Red tide occurrs frequently and causes signi?cant damage to the environment and human health. As a result, development of new effcient and environment friendly red-tide microalgae inhibitors has gained increasing attention in recent times. Algicolous endophytic fungi with unique habitats are promising sources for active agents owing to their abundant secondary metabolites and distinguished activities. In this study, the algicidal activities of 49 marine macroalgal-derived endophytic fungi against phytoplankton Alexandrium tamarense, Prorocentrum donghaiense, Heterosigma akashiwo, and Chattonella marina were examined using 96-well microplate. Four fungal strains, including Aspergillus wentii(pt-1), A. ustus(cf-42),and A. versicolor(dl-29, pt-20), exhibited potent algicidal activities. A total of 32 pure compounds isolated from these fungi were noted to possess dif ferent degrees of algicidal activities. Of those, 11 compounds comprising ?ve anthraquinones, two terpenoids, and four steroids showed high 24-h inhibition rates for the four red tide algae, with 24 h EC_(50) values ranging from 0.01 to 14.29 μg/mL. Among them, compound1(1,5-dihydroxy-3-methoxy-7-methylanthraquinone) presented the strongest activity against H. akashiwo,and could decrease its chlorophyll a(Chl a) and superoxide dismutase contents and increase the soluble protein, malondialdehyde, and peroxidase contents. These results suggested that the identi?ed anti-algal compound might inhibit the growth of red tide algae by weakening photosynthesis(reducing Chl a content),destroying cell membrane, and damaging the antioxidant system.

Effect of salinity on the growth,biological activity and secondary metabolites of some marine fungi

The study investigated the effects of salinity on growth, antimicrobial activities and secondary metabolites of 47 marine filamentous fungi isolated from the East China Sea near the western shore of the Taiwan Straits. The results indicate that NaCl promoted the growth up to 91.5% of test strains. However, only 14.9% of them showed a significant increase of antimicrobial activity against Candida albicans. When incubated in different concentrations of NaCl, the colony growth, antimicrobial activities and composition of secondary metabolites of the strain Ty01b-8 of Penicillium sp. varied. Treatment with KCl also showed a similar effect. An alkaloid isolated from the fermentation broth of Ty01b-8 was identified as chrysogine, inhibition activity of which against Hela cells was 15.05% at 20μg/ml, and yield was 4.4 and 4.9 times higher in 3 percent and 6 percent NaCl treatments, respectively, compared with the non-salt culture condition. These findings prove that salinity is an important factor influencing growth and secondary metabolites of some marine fungi, which can be used to screen for new metabolites from marine fungi, and to enhance their metabolites production in industrial fermentation.

The Bioactive Secondary Metabolites from Talaromyces species

The focus of this review is placed on the chemical structures from the species of the genus Talaromyces reported with reference to their biological activities.221 secondary metabolites,including 43 alkaloids and peptides,88 esters,31 polyketides,19 quinones,15 steroid and terpenoids,and 25 other structure type compounds,have been included,and 66 references are cited.

Effects of Barium Stress in Brassica juncea and Cakile maritima:The Indicator Role of Some Antioxidant Enzymes and Secondary Metabolites

Soil contamination by toxic trace metal elements,like barium(Ba),may stimulate various undesirable changes in the metabolic activity of plants.The plant responses are fast and with,direct or indirect,generation of reactive oxygen species(ROS).To cope with the stress imposed by the ROS production,plants developed a dual cellular system composed of enzymatic and non-enzymatic players that convert ROS,and their by-products,into stable nontoxic molecules.To assess the Ba stress response of two Brassicaceae species(Brassica juncea,a glycophyte,and Cakile maritime,a halophyte),plants were exposure to different Ba concentrations(0,100,200,300 and 500µM).The plants response was evaluated through their morphology and development,the determination of plant leaves antioxidant enzymatic activities and by the production of plants secondary metabolites.Results indicated that the two Brassicaceae species have the ability to survive in an environment containing Ba(even at 500µM).The biomass production of C.maritima was slightly affected whereas an increase in biomass B.juncea was noticed.The stress imposed by Ba activated the antioxidant defense system in the two species,noticed by the changes in the leaves activity of catalase(CAT),ascorbate peroxidase(APX)and guaicol peroxidase(GPX),and of the secondary metabolites,through the production of total phenols and flavonoids.The enzymatic response was not similar within the two plant species:CAT and APX seem to have a more important role against the oxidative stress in C.maritima while in B.juncea is GPX.Overall,total phenols and flavonoids production was more significant in the plants aerial part than in the roots,of the both species.Although the two Brassicaceae species response was different,in both plants catalytic and non-catalytic transformation of ROS occurs,and both were able to overcome the Ba toxicity and prevent the cell damage.

The comparative analysis and identification of secondary metabolites between Tibet wild and cultivated pomegranates(Punica granatum L.)in China

Secondary metabolites are closely related to the nutritional quality and health functions of plants.We investigated the secondary metabolites of both wild(n=23)and cultivated(n=27)pomegranate plants(Punica granatum L.)growing in China.The total flavonoid(TF)and tannin(TT)contents from the peel and juice were determined and the secondary metabolites in the peel(ZLP)and juice(ZLZ)of‘Zela 4’were identified using liquid chromatography–electrospray ionization tandem mass spectrometry(LC–ESI-MS/MS).Analysis of variance(P<0.05)showed that there were significant differences in the TF content of peel(TF(P))and juice(TF(J)),and the TT content of peel(TT(P))and juice(TT(J))among different pomegranate accessions.Pearson correlation analysis showed that latitude and altitude might be the main environmental factors affecting TF and TT contents in pomegranates.In this study,279 secondary metabolites were identified in the ZLP and ZLZ.In addition,we report for the first time 227 secondary metabolites in pomegranates.Using orthogonal partial least squares discriminant analysis,90 differential metabolites were identified in ZLP and ZLZ.In addition,we screened eight specific germplasms(high-TF(P),‘Junyong 3’;low-TF(P),‘Yanzhihong’;high-TF(J),‘Zela 4’;low-TF(J),‘Yudazi’,high-TT(P),‘Junyong 4’;low-TT(P),‘Anba 1’;high-TT(J),‘Yeba 1’;and low-TT(J),‘Baihuayushizi’).The results of our study provide a reference for the development and utilization of wild pomegranate resources and pomegranate breeding in China.

Evaluation of Some Secondary Metabolites and Determination of the Antioxidant Potential of Different Extracts from the Plant of <i>Pteridium aquilinum</i>

The present study aims to make an evaluation of some secondary metabolites and determination of the antioxidant potential of P. aquilinum plant extracts obtained by means of a simple and rapid TLC method. The latter revealed the presence of terpenes, sterols, steroids, flavonoids, polyphenols, saponins, sugars and amino acids. The evaluation of the potential antioxidant was assessed on phenolic and flavonoid compounds. These compounds’ dosages revealed different levels, but the highest antioxidant activity was found in the hydro-ethanol extract followed by the aqueous extract. Among the two families of evaluated antioxidants, phenolic compounds were found to be higher in the hydro-ethanolic extract (75.18 mgEAG/gMS), followed by the aqueous extract (66.78 mgEAG/gMS) and lower in the ethanolic extract (12.39 mgEAG/gMS). Whereas flavonoids, less significantly elevated, showed values of 2.58 mgECa/gMS for the hydro-ethanolic extract, 2.24 mgECa/gMS for the aqueous extract and 1.58 mgECa/gMS for the ethanolic extract. However, the antiradical activity was also evaluated. Contrary to the antioxidant activity, the most important antiradical activity was observed on the hydroethanolic extract with a rate of 3.61 mg/mL, then a weak activity on the aqueous and ethanolic extracts respectively 6.18 mg/mL and 15.81 mg/mL, then less important on the aqueous and hydro-ethanolic extracts respectively at levels of 6.18 mg/mL and 3.61 mg/mL.

Nitrogen Sources Affect Streptolydigin Production and Related Secondary Metabolites Distribution of Streptomyces lydicus AS 4.2501

The effects of nitrogen sources on streptolydigin production and distribution of secondary metabolites were investigated for flask cultured S.lydicus AS 4.2501.When peptone,asparamide,and glutamic acid were ex- amined as the nitrogen source,respectively,liquid chromatography-mass spectrometry(LC-MS)and photodiode array(PDA)analyses revealed the formation of two analogues of streptolydigin in the fermentation broth.When soybean meal was used as the source of nitrogen,three analogues of streptolydigin were detected.The use of am- monium sulfate as a source of nitrogen resulted in a lower pH value of the fermentation system,thus inhibiting streptolydigin biosynthesis and changing the metabolic profiling.Among the nitrogen sources that were made use of,glutamic acid was most favorable to the formation of streptolydigin.Simultaneously,this study also showed that the changing nitrogen sources resulted in altering the production and relative ratios of streptolydigin and its analogues.

Antimicrobial secondary metabolites from marine gastropod egg capsules and egg masses

Marine organisms have attracted special attention in the last three decades for their ability to produce interesting pharmacological active compounds.Even though all marine organisms have the potential to produce antimicrobial secondary metabolites,the gastropod has the vital sources of secondary metabolites particularly their egg capsule which has the promising antimicrobial secondary metabolites.In the present review,we intend to focus on marine secondary metabolites from marine gastropod egg capsule.The following compounds i.e.Kabiramid C,Aplysianin E, Aplysianin A,Thisaplysianin E and Tyrian purple have been documented in egg capsule of various gastropod and most of the antimicrobial secondary metabolites have not been isolated from the egg capsule because of the odious,and complex chemical structure.Stability of the compounds is unknown.