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Plants have a pivotal role in ethnopharmacology, and their preparations are in use globally. However, getting down to the structure requires an effective workflow and mostly requires a time-consuming isolation process. Although bioassay-guided approaches are widely popular, they face a massive problem of rediscovery in recent times, especially in plant metabolomics. Mass spectrometry (MS)-based approach incorporated molecular networking via Global Natural Product Social Molecular Networking (GNPS) is considered here for the benefit of the fast screening of secondary metabolites. This study uses direct crude extracts obtained from various parts of the Urtica dioica plant for the characterization of secondary metabolites. The crude extract of the plant initially displayed promising antioxidant and anti-diabetic activities. Then, we employed mass spectrometry-based dereplication to identify the phytochemical components in the extracts. This led to the discovery of 7 unknown and 17 known secondary metabolites, which were further verified with the SIRIUS 4 platform, a computational tool for the annotation of compounds using tandem MS data. On the other hand, chasing the antioxidant activity of methanolic extract of U. dioica leaves, we employed a bioassay-guided isolation approach. With this method, we isolated and characterized compound 13, a known molecule, which possessed strong antioxidant activity without showing much toxicity in the brine shrimp lethality test at the test concentration of 1 mg/mL. With our results, we advocate the MS-based approach as a good starting point for the dereplication of compounds from the complex crude extracts of plants.

Plants have a pivotal role in ethnopharmacology, and their preparations are in use globally. However, getting down to the structure requires an effective workflow and mostly requires a time-consuming isolation process. Although bioassay-guided approaches are widely popular, they face a massive problem of rediscovery in recent times, especially in plant metabolomics. Mass spectrometry (MS)-based approach incorporated molecular networking via Global Natural Product Social Molecular Networking (GNPS) is considered here for the benefit of the fast screening of secondary metabolites. This study uses direct crude extracts obtained from various parts of the

Two compounds, compounds 1 and 2, were isolated from Preussia sp. The molecular structures of both compounds were elucidated by analyzing one-dimensional (1D) and 2D nuclear magnetic resonance data along with high-resolution mass spectrometry data. Compound 1 was obtained as novel in structure, and compound 2 was recently reported elsewhere. Compound 1 did not show antioxidant and antimicrobial activities and brine shrimp toxicity, while compound 2 showed strong antioxidant activity (DPPH reduction capacity; IC50=3 μg/mL) and brine shrimp toxicity (LD50=50 μg/mL).

A total of twenty four lichen species belonging to six families were collected from mountainous region of Nepal. The methanol extracts of each species were tested for antimicrobial and antioxidant activities in vitro . It was found that extracts of twenty one lichen species were active against B. subtilis and seven species were active against S. aureus . Similarly, in DPPH assay, three species Peltigera sp., Cladonia sp., and Canoparmelia sp. showed comparable activity with commercial standard, BHA. In ABTS + assay, extracts of Parmoterma sp., Ramalina sp., Peltigera sp. and Cladonia sp. showed stronger activity than ascorbic acid. The observed data after comparison with previously published reports indicated that the high altitude lichens contain stronger antioxidant and antibacterial constituents. Similarly, the methanol extracts of Heterodermia sp. and Ramalina sp. showed comparable toxicity eff ect with commercial standard berberine chloride indicating a potent source of anticancer drugs.

Ramalin (γ-glutamyl-N′-(2-hydroxyphenyl)hydrazide), a novel compound, was isolated from the methanol–water extract of the Antarctic lichen Ramalina terebrata by several chromatographic methods. The molecular structure of ramalin was determined by spectroscopic analysis. The experimental data showed that ramalin was five times more potent than commercial butylated hydroxyanisole (BHA) in scavenging 1-diphenyl-2-picryl-hydazil (DPPH) free radicals, 27 times more potent in scavenging 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid free radicals (ABTS +) than the vitamin E analogue, trolox, and 2.5 times more potent than BHT in reducing Fe3+ to Fe2+ ions. Similarly, ramalin was 1.2 times more potent than ascorbic acid in scavenging superoxide radicals and 1.25 times more potent than commercial kojic acid in inhibiting tyrosinase enzyme activity, which ultimately leads to whitening of skin cells. Ramalin showed no or very little cytotoxicity in human keratinocyte and fibroblast cells at its antioxidant concentration. Furthermore, ramalin was assessed to determine its antioxidant activity in vivo. One microgram per milliliter ramalin significantly reduced the released nitric oxide (NO) and 0.125 μg/ml ramalin reduced the produced hydrogen peroxide (H2O2) in LPS (lipopolysaccharide)-stimulated murine macrophage Raw264.7 cells. Considering all the data together, ramalin can be a strong therapeutic candidate for controlling oxidative stress in cells.

Antioxidant agents counter reactive oxygen species (ROS) and can be used in cosmetic and medicinal applications. The goal of this study was to evaluate the antioxidant activity of an Antarctic moss species from King George Island (Antarctica), tentatively designated as KSJ-M5. On the basis of morphological characteristics, KSJ-M5 was identified as Sanionia uncinata (Hedw.) Loeske (Amblystegiaceae). The identification was confirmed by comparing the partial sequence of the ITS (internal transcribed spacer) region with that in GenBank. The antioxidant activity of an ethanol extract of KSJ-M5 was evaluated by analyzing its reducing power, superoxide scavenging activity, ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] cation scavenging activity, and DPPH (1,1-diphenyl-2-picrylhydrazyl) free-radical scavenging activity. The reducing power of 1 mg of KSJ-M5 extract was equivalent to 31.9 +/- 0.9 microg (Mean +/- SD, n = 3) of the commercial standard, BHT (butylated hydroxytoluene). IC(50) values of the KSJ-M5 extract for DPPH free-radical scavenging activity, superoxide scavenging activity, and ABTS cation scavenging activity were found as 356 +/- 26.8 microg/mL, 466.2 +/- 43.4 microg/mL, and 181.3 +/- 12.2 microg/mL, respectively. The total phenolic content in 1 mg of KSJM5 extract was equivalent to 12.7 +/- 2.7 microg of pyrocatechol. These results clearly showed that KSJ-M5 could be an important source of natural antioxidant agents for improved medicinal and cosmetic applications.

Antioxidant agents prevent reactive oxygen species, which can cause degenerative diseases. Natural antioxidants are preferred over many synthetic antioxidants, which can be toxic, for therapeutic applications. Five lichen species were collected from King George Island, Antarctica. Antioxidant activities as assessed by DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical and ABTS•+ [2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] radical scavenging capacities were determined and compared with those of commercial standards BHA (butylated hydroxyanisole) and trolox [(±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid]. The results indicated that two lichens exhibited comparatively high antioxidant activities with the remaining three exhibiting less activity. The antioxidant activity was concentration-dependent. When compared, the antioxidant activity of crude extracts from polar lichens to previously published data for tropical and temperate lichen species, we concluded that lichens of Antarctic origin may be the potent sources of strong antioxidant agents. Such species should be explored as novel sources of effective antioxidant metabolites.

Preservation of algal spores of the green seaweed Ulva fasciata and U. pertusa was enhanced by the addition of ampicillin in f/2 medium at 4°C. The viability of preserved spores was determined by a spore germination assay at various time intervals. The germination rate of U. fasciata remained at 5% to 38% for the first five days, dropping to 1% to 6% on the 10th day of storage with various preservation treatments without ampicillin at 4°C during parameter-selecting experiments. In f/2 medium, 53% of U. fasciata spores were still viable on day 5 and 23% on day 10 at 4°C. By adding 100 μg mL−1 ampicillin to f/2 medium, 90% of the spores were viable at day 40 and 61% after 100 days of storage at 4°C. Spores of U. pertusa had lower preservation rates, with viabilities of 70% at day 40 and 32% at day 100. Algal spore preservation was heavily dependent on the bacterial contamination and subsequent degradation in stock solutions.

Two compounds, 2-hydroxymyristic acid (HMA) and cis-9-oleic acid (COA), were isolated from a chloroform extract of the marine bacterium, Shewanella oneidensis SCH0402. In a spectrophotometer-based chemotaxis assay, HMA completely eliminated the optical density (OD) of Alteromonas marina SCH0401 and Bacillus atrophaeus SCH0408, motile, fouling bacteria, at 100 and 1000 µg ml−1, respectively. COA similarly decreased the OD of A. marina and B. atrophaeus by 100% at 1000 µg ml−1. The commercially available, highly toxic anti-fouling compound, tributyltin oxide (TBTO) never reduced the OD of the target bacteria by 100% even at higher concentration. Instead, all the test bacterial cells were killed at higher than 1000 µg ml−1 of concentration. Both HMA and COA inhibited germination of Ulva pertusa spores completely at 10 and 100 µg ml−1, respectively, while TBTO inhibited germination at 0.01 µg ml−1. However, in field assays, both HMA and COA showed anti-fouling activities as potent as TBTO against a wide range of fouling organisms, including micro- and macro-algae, barnacles, and mussels. The average fouling coverage on the surface of the control panel was 93 ± 6% after 1.5 years but no fouling was observed on the surface of the test panel onto which each compound was applied separately. Thus, bacterial repellent compounds can be used as substitutes for potent toxic anti-fouling compounds, resulting in higher standards of environmental safety without loss of anti-fouling performance.

A new fused tetracyclic heterocyclic compound, (4bR,10bR)-4b-hydroxy-10b,12-dihydrodibenzo[c,h][2,6]naphthyridine-5,11(4bH,6H)-dione (1), and a known compound, butyl 2-[(benzoyloxy)methyl]benzoate, spatozoate 2, were isolated from the broth culture of Serratia sp. PAMC 25557. The structure of 1 was determined by analyzing spectroscopic data. Compound 1 did not exhibit antimicrobial activity against Escherichia coli, Staphylococcus aureus, or Candida albicans. In addition, up to 100 μg/ml compound 1 did not show any toxicity against Artemia salina larvae. However, compound 1 showed DPPH free radical scavenging activity (IC50 = 16.7 ± 0.34 μg/ml). This was the first report of spatozoate isolation from bacterial sources.

Extracts from five Antarctic lichens (L3, Stereocaulon alpinum; L5, Ramalina terebrata; L6, Caloplaca sp.; L8, Lecanora sp.; and L17, Caloplaca regalis) were tested for antimicrobial activities against several clinically important microbes by disk diffusion. The minimum inhibitory concentration (MIC) of each extract was determined by a broth dilution method. Extracts from L3, L5, L6 and L8 were active against two Gram(+) strains. B. subtilis was more sensitive to lichen extracts (except L5) than S. aureus. The MIC of lichen extracts against B. subtilis and S. aureus was observed from 36.7 ± 0.3 to 953.8 ± 85.8 μg/mL and 68.5 ± 0.6 to >1000 μg/mL, respectively. Comparisons of MIC values of Antarctic lichen crude extracts to previously published MIC values of some reported lichen metabolites against Gram(+) bacteria indicated that Antarctic lichens might be an enriched source of effective antibacterial agents against clinically relevant Gram(+) species.

Background Several plants are reported to be produced various biological active compounds. Lichens from the extreme environments such as high altitude, high UV, drought and cold are believed to be synthesized unique types of secondary metabolites than the other one. Several human pathogenic bacteria and fungi have been muted into drug resistant strains. Various synthetic antioxidant compounds have posed carcinogenic effects. This phenomenon needs further research for new effective drugs of natural origin. This manuscript aimed to screen new source of biological active compounds from plants of subarctic origin. Results A total of 114 plant species, including 80 species of higher plants, 19 species of lichens and 15 species of mosses, were collected from Oymyakon region of the Republic of Sakha (Yakutia), Russia (63˚20′N, 141˚42′E–63˚15′N, 142˚27′E). Antimicrobial, DPPH free radical scavenging and brine shrimp (Artemia salina) toxicity of all crude extract were evaluated. The obtained result was analyzed and compared with commercial standards. A total of 28 species of higher plants showed very strong antioxidant activity (DPPH IC50, 0.45-5.0 μg/mL), 13 species showed strong activity (DPPH IC50, 5-10 μg/mL), 22 species showed moderate antioxidant activity (DPPH IC50,10-20 μg/mL) and 17 species showed weak antioxidant activity (DPPH IC50 more than 20 μg/mL). Similarly, 3 species of lichen showed strong antioxidant activity, one species showed moderate and 15 species showed weak DPPH reducing activity. In addition, 4 species of mosses showed moderate antioxidant activity and 11 species showed weak antioxidant activity. Similarly, extracts of 51 species of higher plants showed antimicrobial (AM) activity against Staphylococcus aureus and 2 species showed AM activity against Candida albicans. Similarly, 11 species of lichen showed AM activity against S. aureus and 3 species showed AM activity against Escherichia coli. One species of moss showed AM activity against S. aureus. And finally, one species of higher plant Rheum compactum and one species of lichen Flavocetraria cucullata showed the toxicity against Brine shrimp larvae in 100 μg/mL of concentration. Conclusion The experimental results showed that subarctic plant species could be potential sources of various biologically active natural compounds.

The development of new antibacterial compounds is an urgent issue to meet the evolution of resistivity of pathogenic bacteria against the available drugs. The objective of this study was to investigate the antibacterial compounds from the Antarctic lichen species Ramalina terebrata. A total of fi ve compounds, usnic acid, usimine A, usimine B, usimine C, and ramalin, were isolated by bioactivity guided-fractionation of the methanol extract of R. terebrata after several chromatographic procedures. The qualitative antibacterial activities of the crude extract and isolated compounds were determined by the disk diffusion method while the minimum inhibitory concentration (MIC) determination assay gave the quantitative strength of the test samples. All the test samples showed antibacterial activity against Bacillus subtilis. The crude extract and usnic acid showed antibacterial activity against Staphylococcus aureus. The MIC values of the isolated compounds against B. subtilis were in the range of 1 to 26 μg/mL. These observed experimental data showed the strong antibacterial potential of these compounds against B. subtilis.

Antioxidant agents against reactive oxygen species can be used for several cosmetic and medicinal applications. This study’s objective was to evaluate the antioxidant activities of Polytrichastrum alpinum (Hedw.) G. L. Sm. (Polytrichaceae), an Antarctic moss species collected from King George Island (Antarctica). The identifi cation of the moss species was performed on the basis of morphological characteristics and molecular sequencing of the 18S rRNA gene. Two benzonaphthoxanthenones: ohioensins F and G, were isolated from the extract after several chromatographic procedures. The various in vitro antioxidant capacities of a methanolic extract of P. alpinum and the isolated compounds were evaluated by analyzing the scavenging capacities of free radicals of 2,2-azino-bis(3-ethylbenzthiazoline- 6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), the total phenol assay with Folin-Ciocalteu reagent, the ferric ion (Fe3+) reducing power and the nitric oxide (NO) scavenging activity and compared to those of commercial standards for each assay. The experimental data showed that even the crude extract of P. alpinum exhibited potent antioxidant activity. The antioxidant activity was increased two- to seven-fold for the purified compounds. The antioxidant activities of both purified compounds were found to be more or less the same in all experiments. However, the obtained data showed that the Fe3+ reducing power of the purified compounds and crude methanolic extract was almost the same suggesting the presence of other stronger reducing agents in the methanolic extract which could not be isolated in the present experiment. Therefore, further work on the isolation of these stronger antioxidant agents from this moss specimen of the extreme environment is warranted. Developments of laboratory mass culture techniques are anticipated to achieve bulk production of the active constituents for commercial application.

Antioxidant agents counter reactive oxygen species (ROS) and can be used in cosmetic and medicinal applications. The goal of this study was to evaluate the antioxidant activity of an Antarctic moss species from King George Island (Antarctica), tentatively designated as KSJ-M5. On the basis of morphological characteristics, KSJ-M5 was identified as Sanionia uncinata (Hedw.) Loeske (Amblystegiaceae). The identification was confirmed by comparing the partial sequence of the ITS (internal transcribed spacer) region with that in GenBank. The antioxidant activity of an ethanol extract of KSJ-M5 was evaluated by analyzing its reducing power, superoxide scavenging activity, ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] cation scavenging activity, and DPPH (1,1-diphenyl-2-picrylhydrazyl) free-radical scavenging activity. The reducing power of 1 mg of KSJ-M5 extract was equivalent to 31.9 +/- 0.9 microg (Mean +/- SD, n = 3) of the commercial standard, BHT (butylated hydroxytoluene). IC(50) values of the KSJ-M5 extract for DPPH free-radical scavenging activity, superoxide scavenging activity, and ABTS cation scavenging activity were found as 356 +/- 26.8 microg/mL, 466.2 +/- 43.4 microg/mL, and 181.3 +/- 12.2 microg/mL, respectively. The total phenolic content in 1 mg of KSJM5 extract was equivalent to 12.7 +/- 2.7 microg of pyrocatechol. These results clearly showed that KSJ-M5 could be an important source of natural antioxidant agents for improved medicinal and cosmetic applications.

Extracts from five Antarctic lichens (L3, Stereocaulon alpinum; L5, Ramalina terebrata; L6, Caloplaca sp.; L8, Lecanora sp.; and L17, Caloplaca regalis) were tested for antimicrobial activities against several clinically important microbes by disk diffusion. The minimum inhibitory concentration (MIC) of each extract was determined by a broth dilution method. Extracts from L3, L5, L6 and L8 were active against two Gram(+) strains. B. subtilis was more sensitive to lichen extracts (except L5) than S. aureus. The MIC of lichen extracts against B. subtilis and S. aureus was observed from 36.7 +/- 0.3 to 953.8 +/- 85.8 microg/mL and 68.5 +/- 0.6 to1000 microg/mL, respectively. Comparisons of MIC values of Antarctic lichen crude extracts to previously published MIC values of some reported lichen metabolites against Gram(+) bacteria indicated that Antarctic lichens might be an enriched source of effective antibacterial agents against clinically relevant Gram(+) species.

Environmental impacts caused by tin and copper based commercial antifouling (AF) paints were proved to be detrimental to aquatic ecosystems. Therefore, a search of environmental friendly AF compounds to be used in marine paint to protect the surface of maritime developmental structures from the unwanted biofouling is a burning issue of the present time. Commercially available eight organic chemicals--allyl isothiocyanate, beta-myrecene, cis-3-hexenyl acetate, citral, ethyl heptanoate, eugenol, methyl caproate, and octyl alcohol were evaluated forAF activities using both laboratory and field assays. The test chemicals were found to repel the target motile marine bacteria--Alteromonas marina, Bacillus atrophaeus, Roseobactergallaeciensis and Shewanella oneidensis and motile spores of the green alga, Ulva pertusa. The bacterial and Ulva spore repulsion activities of the test chemicals were measured by chemotaxis and agar diffusion methods respectively interestingly these test chemicals were less toxic to the test fouling species. The toxicity of the test chemicals was measured by using antibiotic assay disks against the bacteria and motility test against Ulva spores. Moreover, in field assay, all test chemicals showed a perfect performance ofAF activity showing no fouling during the experimental period of one year Such results and commercial as well as technical feasibility of the test chemicals firmly showed the possibility of using as alternatives of the existing toxic AF agents.

Antioxidant agents against reactive oxygen species can be used for several cosmetic and medicinal applications. Methanol-water (90:10 v/v) extracts of five polar lichen species--namely Stereocaulon alpinum Laurer (Stereocaulaceae); Ramalina terebrata Hook and Taylor (Ramalinaceae); Caloplaca sp. (Teloschistaceae); Lecanora sp. (Lecanoraceae); and Caloplaca regalis (Vain.)Zahlbr (Teloschistaceae) from King George Island (Antarctica)--were analyzed using thin layer chromatography (TLC) followed by a DPPH (2,2-diphenyl-1-picrylhydrazyl) spray technique. The experimental data showed that 33-50% of the major constituents of the test extracts were active antioxidants. Stereocaulon alpinum and R. terebrata showed a higher number (50%) of antioxidant constituents, although their activities were comparatively weak. The strength of antioxidant activity in terms of discoloration of DPPH was shown to be stronger by the constituents of S. alpinum, C. regalis and C. sp. In addition, phenolic content in these Antarctic lichen extracts was in the range of 17-47 mg/g, supporting the antioxidant data of TLC analysis. Thus, these results suggest that Antarctic lichen contains a variety of strong antioxidant constituents. Therefore, further study of the laboratory culture of lichen is warranted to investigate possible commercial production, followed by isolation and characterization of the active antioxidant agents, which can be used against various oxidative stress-related diseases.