Nitrogen-containing non-steroidal secondary metabolites of Solanum, Cyphomandra, Lycianthes and Margaranthus

Of the 49 species of Solanum studied, cuscohygrine has been detected in 25, solamine and related amines in 17 and solamine-derived amides in 16. Five species of Cyphomandra examined all contained both amines and amides. From roots of Margaranthus solanaceus cuscohygrine has been isolated which probably occurs, too, in roots of Lycianthes rantonnettii. The distribution of these compounds throughout the taxa could be of chemotaxonomic value.     

Chemical constituents from Potentilla fragarioides L

Phytochemical investigation on Potentilla fragarioides L. has led to the identification of twelve compounds including β-sitosterol (1), β-daucosterol (2), ursolic acid (3), pomolic acid (4), swinhoeic acid (5), (1-p-hydroxy-cis-cinnamoyl)cinnamic acid (6), trans-caffeoylisocitric acid (7), trans-caffeic acid (8), quercetin (9), quercetin-3-O-β-D-glucuronide (10), (+)-catechin (11) and 3-O-methylellagic acid-4′-O-ɑ-L-rhamnopyranoside (12). Among them, compounds 4–7 were first identified from the genus Potentilla. And the other compounds except compounds 8 and 11 were found in Potentilla fragarioides for the first time. Chemotaxonomic significance of these compounds was discussed.     

Utilization of dissolved organic phosphorus by different groups of phytoplankton taxa

The utilization of nine dissolved organic phosphorus (DOP) compounds by five bloom-causing phytoplankton species was studied under batch culture conditions. The DOP compounds included were adenosine 5-triphosphate (ATP), adenosine 5-monophosphate (AMP), cytidine 5-monophosphate (CMP), guanosine 5-monophosphate (GMP), uridine 5-monophosphate (UMP), glucose-6-phosphate (G6P), sodium glycerophosphate (GYP), 4-nitrophenyl phosphate (NPP), and triethyl phosphate (TEP), and the phytoplankton taxa were Skeletonema costatum, Prorocentrum micans, Alexandrium tamarense, Chattonella marina, and Heterosigma akashiwo. The four flagellate taxa, P. micans, A. tamarense, C. marina, and H. akashiwo, grew well under various DOP regimes. P. micans and C. marina were the most capable of using DOP compounds, sustaining better growth on a majority of nucleotides (ATP, AMP, CMP, GMP, and UMP) and phosphomonoesters (G6P and GYP) than in inorganic phosphorus (P) controls. A. tamarense and H. akashiwo showed equivalent growth in most organic and inorganic P cultures, while the diatom species, S. costatum, could only utilize AMP and GMP. Furthermore, A. tamarense and C. marina could endure N, P-depleted conditions. Among the nine DOP compounds tested, the nucleotide compounds had the highest nutritional value for algal cell growth, while TEP could not sustain growth as the sole source of P. These results suggest that enhanced DOP utilization and the endurance of nutrient-limitation by harmful flagellate taxa offer their competitive advantages, which may account for the frequent occurrence of their blooms in coastal waters.     

Urinary Levels of N-Nitroso Compounds in Relation to Risk of Gastric Cancer: Findings from the Shanghai Cohort Study

BackgroundN-Nitroso compounds are thought to play a significant role in the development of gastric cancer. Epidemiological data, however, are sparse in examining the associations between biomarkers of exposure to N-nitroso compounds and the risk of gastric cancer.MethodsA nested case-control study within a prospective cohort of 18,244 middle-aged and older men in Shanghai, China, was conducted to examine the association between urinary level of N-nitroso compounds and risk of gastric cancer. Information on demographics, usual dietary intake, and use of alcohol and tobacco was collected through in-person interviews at enrollment. Urinary levels of nitrate, nitrite, N-nitroso-2-methylthiazolidine-4-carboxylic acid (NMTCA), N-nitrosoproline (NPRO), N-nitrososarcosine (NSAR), N-nitrosothiazolidine-4-carboxylic acid (NTCA), as well as serum H. pylori antibodies were quantified in 191 gastric cancer cases and 569 individually matched controls. Logistic regression method was used to assess the association between urinary levels of N-nitroso compounds and risk of gastric cancer.ResultsCompared with controls, gastric cancer patients had overall comparable levels of urinary nitrate, nitrite, and N-nitroso compounds. Among individuals seronegative for antibodies to H. pylori, elevated levels of urinary nitrate were associated with increased risk of gastric cancer. The multivariate-adjusted odds ratios for the second and third tertiles of nitrate were 3.27 (95% confidence interval = 0.76–14.04) and 4.82 (95% confidence interval = 1.05–22.17), respectively, compared with the lowest tertile (P for trend = 0.042). There was no statistically significant association between urinary levels of nitrite or N-nitroso compounds and risk of gastric cancer. Urinary NMTCA level was significantly associated with consumption of alcohol and preserved meat and fish food items.ConclusionThe present study demonstrates that exposure to nitrate, a precursor of N-nitroso compounds, may increase the risk of gastric cancer among individuals without a history of H. pylori infection.     

A multifaceted approach to identify non-specific enzyme inhibition: Application to Mycobacterium tuberculosis shikimate kinase

Single dose high-throughput screening (HTS) followed by dose-response evaluations is a common strategy for the identification of initial hits for further development. Early identification and exclusion of false positives is a cost-saving and essential step in early drug discovery. One of the mechanisms of false positive compounds is the formation of aggregates in assays. This study evaluates the mechanism(s) of inhibition of a set of 14 compounds identified previously as actives in Mycobacterium tuberculosis (Mt) cell culture screening and in vitro actives in Mt shikimate kinase (MtSK) assay. Aggregation of hit compounds was characterized using multiple experimental methods, LC-MS, ¹HNMR, dynamic light scattering (DLS), transmission electron microscopy (TEM), and visual inspection after centrifugation for orthogonal confirmation. Our results suggest that the investigated compounds containing oxadiazole-amide and aminobenzothiazole moieties are false positive hits and non-specific inhibitors of MtSK through aggregate formation.     

Unveiling antimicrobial activity of microalgae Chlorella sorokiniana (UKM2), Chlorella sp. (UKM8) and Scenedesmus sp. (UKM9)

Microalgae represent promising sources of bioactive compounds for pharmaceutical and industrial applications. The emergence of antibiotic resistant bacteria leads to the need to explore new cost-effective, safe, and potent bioactive compounds from the microalgae. This study aimed to investigate the potential of local microalgae for their antimicrobial properties and bioactive compounds. Three local microalgae namely Chlorella sorokiniana (UKM2), Chlorella sp. UKM8, and Scenedesmus sp. UKM9 biomass methanol extracts (ME) were prepared and tested against Gram-positive and Gram-negative bacteria. Chlorella sp. UKM8-ME showed the highest antibacterial activity. UKM8-ME minimum inhibitory concentrations were in the range of 0.312 to 6.25 mg/mL. Cytotoxicity evaluation using MTT assay showed that the microalgae methanolic extracts did not exhibit cytotoxicity against Vero-cells. The UKM8-ME was mainly containing 28 compounds from the Gas Chromatography-Mass Spectrometry (GC–MS) analysis. Major compounds of UKM8-ME included phenol (18.5%), hexadecanoic acid (18.25%), phytol (14.43%), 9,12-octadecadienoic acid (13.69%), and bicyclo[3.1.1]heptane (7.23%), which have been previously described to possess antimicrobial activity. Hence, Chlorella sp. (UKM8) methanol extracts showed promising antibacterial activity. More comprehensive studies are required to purify these antimicrobial compounds and develop our understanding on their mechanism in UKM8-ME to unleash their specific potential.     

Malyngamide 4, a new lipopeptide from the Red Sea marine cyanobacterium Moorea producens (formerly Lyngbya majuscula)

In our continuing effort to discover new drug leads from Red Sea marine organisms, a sample of the marine cyanobacterium Moorea producens (previously Lyngbya majuscula) was investigated. Bioassay-directed purification of a tumor cell-growth inhibitory fraction of the organic extract of the Red Sea cyanobacterium afforded a new compound, malyngamide 4 (1), together with five previously reported compounds, malyngamide A (2) and B (3), (S)-7-methoxytetradec-4(E)-enoic acid (lyngbic acid, 4), aplysiatoxin (5) and debromoaplysiatoxin (6). Assignment of the planar structures of these compounds was based on extensive analysis of one- and two-dimensional NMR spectra and high-resolution mass spectrometric data. The isolated compounds were evaluated for their inhibitory activity against three cancer cell lines. In addition, the antibacterial activity of the compounds against Mycobacterium tuberculosis H₃₇Rv ATCC 27294 (H₃₇Rv) was evaluated. Lyngbic acid (4) was the most active against M. tuberculosis, while malyngamides 4 (1) and B (3) moderately inhibited the cancer cell lines. The other compounds were deemed inactive at the test concentrations.     

Isolation and identification of antimicrobial secondary metabolites from Bacillus cereus associated with a rhabditid entomopathogenic nematode

The cell-free culture filtrate of Bacillus cereus associated with an entomopathogenic nematode, Rhabditis (Oscheius) sp., exhibited strong antimicrobial activity. The ethyl acetate extract of the bacterial culture filtrate was purified by silica gel column chromatography to obtain six bioactive compounds. The structure and absolute stereochemistry of these compounds were determined based on extensive spectroscopic analyses (LCMS, FABMS, ¹H NMR, ¹³C NMR, ¹H ?¹H COSY, ¹H ?¹³C HMBC) and Marfey’s method. The compounds were identified as cyclo(D-Pro-D-Leu), cyclo(L-Pro-D-Met), cyclo (L-Pro-D-Phe), cyclo (L-Pro-L-Val), 3,5-dihydroxy-4-ethyl-trans-stilbene, and 3,5-dihydroxy-4-isopropylstilbene, respectively. Compounds recorded antibacterial activity against all four tested bacteria strains of Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. 3,5-dihydroxy-4-isopropylstilbene recorded activity only against Gram-positive bacteria while cyclo(L-Pro-L-Val) recorded no antibacterial activity. Best antibacterial activity was recorded by 3,5-dihydroxy-4-ethyl-trans-stilbene (4 μg/ml) against Escherichia coli. The six compounds recorded significant antifungal activities against five fungal strains tested (Aspergillus flavus, Candida albicans, Fusarium oxysporum, Rhizoctonia solani and Penicillium expansum) and they were more effective than bavistin, the standard fungicide. The activity of cyclo(D-Pro-D-Leu), cyclo(L-Pro-D-Met), 3,5-dihydroxy-4-ethyl-trans-stilbene, and 3,5-dihydroxy-4-isopropylstilbene against Candida albicans was better than amphotericin B. To the best of our knowledge, this is the first report of antifungal activity of the bioactive compounds against the plant pathogenic fungi Fusarium oxysporum, Rhizoctonia solani, and Penicillium expansum. We conclude that the Bacillus cereus strain associated with entomopathogenic nematode is a promising source of natural bioactive secondary metabolites which may receive great benefit as potential sources of new drugs in the agricultural and pharmacological industry.     

A theoretical interpretation for M/F ratio index in electroantennogram of the American cockroach

• 1.1. In addition to the sexually active and inactive general odorous compounds for which behavioral activity and M/F I evaluations (male/female I value) have been done, several compounds were evaluated here for M/F I value.
• 2.2. To the reference M/F I value of camphor (1.0), the values were estimated to be 1.5–6.9 for sexually active compounds, and 0.5–1.4 for general odorous compounds having interaction with a sex pheromone receptor (SPR).
• 3.3. A theoretical interpretation was made for M/F I on the basis of the interaction of the compounds to general odor receptor (GOR) and SPR, and the resulting M/F I values.
• 4.4. In the M/F I interpretation, affinity and intrinsic activity of the compounds to SPR were newly introduced as factors.
• 5.5. It was assumed theoretically that EAG response due to the interaction of intrinsic activity of the compounds caused various electric responses (negative-, zero- and positive-signed responses), when the compounds had affinity to SPR.
• 6.6. Intrinsic activity of the sexually active compounds was expected to be a main factor to govern their pheromone activity, ie. M/F I values.

     

Chemical constituents of the roots of Eupatorium chinense and their anti-inflammatory activities

In this study, three new compounds (1-3), together with fifteen known ones (4-18) were isolated from a petroleum ether extract of the roots of Eupatorium chinense. The structures of new compounds were elucidated by 1D, 2D nuclear magnetic resonance (NMR), circular dichroism spectrum (CD), mass spectrum (MS) along with other spectroscopy methods. In addition, twelve compounds were evaluated in vitro for their anti-inflammatory activities, while compounds 3 and 5 exhibited moderate activities with inhibition rates of 23.08 % and 25.19 %, respectively.     

Aldose reductase inhibitory compounds from extracts of Dipsacus asper

Amethanolic extract of Dipsacus asper, having anti-diabetic activity, was examined as a possible aldose reductase (ALR2) inhibitor, a key enzyme involved in diabetic complications. Bioactivity guided fractionation led to the isolation of ten compounds, ursolic acid (1), oleanolic acid-3-O-α-L-arabinopyranoside (2), daucosterol (3), hederagenin-3-O-α-L-arabinopyranoside (4), sweroside(5), caffeic acid (6), esculetin (7), protocatechualdehyde (8), loganin (9), and vanilic acid (10) from the ethyl acetate fraction of D. asper methanol extract. Among them, compounds 4, 6, 7, and 8 exhibited inhibitory effects on aldose reductase, with IC₅₀ values of 23.70, 16.71, 34.36, and 21.81 μM, respectively. This is the first report on the isolation of these compounds from D. asper, and the ALR2 inhibitory activity of hederagenin-3-O-α-L-arabinopyranoside. These results suggest the successful use of the extract of D. asper for ameliorating diabetic complications.     

FT-IR and GC-MS analyses of potential bioactive compounds of cow urine and its antibacterial activity

The main emphasis of this study was to identify the bioactive compounds responsible for antibacterial activity of Badri cow urine isolated by thin layer chromatography. The most effective bioactive fraction was analysed by FT-IR and GC-MS analyses. Among the four major fractions (EW1, EW2, CA1 and CA2) obtained by TLC profiling, EW1 was found most active against bacterial strains viz., Listeria monocytogenes (MTCC657), Staphylococcus aureus (MTCC7443), Pseudomonas aeruginosa (MTCC424), Klebsiella pneumoniae (MTCC432) and Salmonella typhi (MTCC733). However, Escherichia coli (MTCC118), was found resistant to all the fractions. In FT-IR spectroscopy, functional groups like alcohol, amide, alkene, alkyl halide, polysulfide and phosphate ions were identified. The GC-MS analysis of EW1 fraction exhibited the presence of 12 compounds, of which 1-heneicosanol was found as the major compound. These compounds might be responsible synergistically or individually for antibacterial activity of cow urine. Nine elements namely sodium (Na), calcium (Ca), chromium (Cr), iron (Fe), magnesium (Mg), aluminium (Al), potassium (K) and zinc (Zn), Gold (Au) were measured by ICP-MS analysis.     

Synthesis and urease inhibitory potential of benzophenone sulfonamide hybrid in vitro and in silico

This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC₅₀ value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC₅₀?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by ¹H NMR, ¹³C NMR, EI-MS and FAB-MS spectroscopic techniques.     

Extraction and characterization of volatile compounds and fatty acids from red and green macroalgae from the Romanian Black Sea in order to obtain valuable bioadditives and biopreservatives

Three species of macroalgae, Ceramium virgatum (Rhodophyta), Ulva intestinalis, and Cladophora vagabunda (Chlorophyta), harvested from the Romanian Black Sea coast, were studied as sources of valuable compounds that could be used as additives and biopreservatives. Volatile compounds including hexanal (11.2 %), octane (9.8 %), nonanal (7.0 %), octanal (6.7 %), 2,5,5-trimethyl-2-hexene (4.7 %), 3-hexen-2-one (4 %), and o-cymene (3.6 %) were identified as the major components in the biomass extract of C. vagabunda. In C. virgatum, the major volatile components were 3-hexen-2-one (27.9 %), acetone (12.4 %), hexanal (3.4 %), and o-cymene (2.7 %). The major volatile compounds of U. intestinalis were hexanal (14.6 %), trichloromethane (7.3 %), nonanal (5.6 %), 3-hexen-2-one (5.3 %), and octanal (3.1 %). Some of these compounds have industrial applications as additives in the food, pharmaceutical, or cosmetics industries. The U. intestinalis extract had a greater content of mono- and polyunsaturated fatty acids around 46.0 % as compared with 42.0 % for C. vagabunda and 31.9 % for C. virgatum. The most abundant fatty acids were palmitic acid (C16:0), arachidonic acid (C20:4n-6), and oleic acid (C18:1ω-9cis). The antimicrobial effect of fatty acid extracts was tested against four pathogenic bacteria. The minimum inhibitory concentrations of C. vagabunda, C. virgatum, and U. intestinalis fatty acids extracts were 1.8, 3.8, and 3.8 mg mL^?1, respectively, for all bacterial strains. This study can help the efforts of finding new, value-added uses for natural marine resources.     

Phytochemicals from the aerial parts of Ligularia thomsonii and their radical scavenging activity

Phytochemical investigation of the aerial parts of Ligularia thomsonii has led to the isolation of three new phenylpropanoid glucosides ligularoside I (1), ligularoside II (2) and ligularoside III (3) along with nine known compounds; cinnamic acid (4), 3-phenylpropanoic acid (5), 3,4,5-trihydroxybenzoic acid (6), 4-hydroxybenzoic acid (7), p-coumaric acid (8), caffeic acid (9), 3,4-dihydroxybenzoic acid (10), kaempferol 3-O-β-d-glucopyranoside (11) and 3,5-di-O-caffeoylquinic acid (12), hitherto unreported from L. thomsonii. Their chemical structures were elucidated by spectroscopic analysis and chemical transformation. All these compounds were tested for antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Among them, compounds 9, 10 and 12 showed significant antioxidant activity against DPPH radicals with IC₅₀ of 19.6, 23.3 and 8.9 μm, respectively.     

Repellent activity of alligator pepper, Aframomum melegueta, and ginger, Zingiber officinale, against the maize weevil, Sitophilus zeamais

The repellent activity of alligator pepper, Aframomum melegueta, and ginger, Zingiber officinale (Zingiberaceae), against the maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae), was investigated in four-way olfactometer bioassays. Results showed that vacuum distilled A. melegueta and Z. officinale extracts were repellent towards adult S. zeamais both in the absence and the presence of maize, Zea mays, grains. Bioassay-guided liquid chromatographic fractionation of the distillates showed that fractions containing oxygenated compounds accounted for the repellent activity. Coupled gas chromatography-mass spectrometry (GC-MS), followed by GC peak enhancement and enantioselective GC using authentic compounds, identified 3 major compounds in the behaviourally active fractions of A. melegueta and Z. officinale to be (S)-2-heptanol, (S)-2-heptyl acetate and (R)-linalool in a ratio of 1:6:3, and 1,8-cineole, neral and geranial in a ratio of 5.48:1:2.13, respectively. The identification of these behaviourally active compounds provides the scientific basis for the observed repellent properties of A. melegueta and Z. officinale, and demonstrates the potential for their use in stored-product protection at the small-scale farmer level in Africa.     

Chemical composition of essential oils of four Eucalyptus species and their phytotoxicity on silverleaf nightshade (Solanum elaeagnifolium Cav.) in Australia

Phytotoxicity and chemical composition of essential oils from four selected Eucalyptus species in Australia were investigated. Essential oils had stronger inhibitory effects on germination and seedling growth of silverleaf nightshade (Solanum elaeagnifolium Cav.) when compared with a commercial eucalyptus oil and with 1,8-cineole. E. salubris oil had the highest inhibition index for silverleaf nightshade germination, root growth and shoot growth, while E. spathulata had the lowest inhibitory effect except root growth. Gas chromatography-mass spectrometry analysis revealed 56 compounds present in E. salubris oil, with 1,8-cineole (57.6?%), ??-pinene (10.9?%) and p-cymene (8.3?%) predominant. E. dundasii oil contained 55 identified compounds with 1,8-cineole (65.5?%) and ??-pinene (19.9?%) being the richest fractions. There were 56 compounds identified from E. brockwayii oil with ??-pinene (31.1?%), isopentyl isovalerate (20.2?%) and 1,8-cineole (16.9?%) as the most abundant components. E. spathulata oil contained 60 compounds, predominantly 1,8-cineole (52.9?%) and ??-pinene (31.0?%). Further study is required to determine the phytoxicity of the individual identified compounds on silverleaf nightshade and whether the observed phytotoxicity is attributable to a single compound or to the synergistic effects of several compounds.     

Avocado seeds (Persea americana cv. Criollo sp.): Lipophilic compounds profile and biological activities

This study aimed to evaluate the volatile or lipophilic chemical profiling and the biological activities of avocado (Persea americana cv. Criollo sp.) seed extracts. Chemical profile of volatile compounds (GC/MS), antioxidant properties (phenolic compounds, DPPH radical scavenging activities and reducing power), and antimicrobial activity (Salmonella Typhimurium and Staphylococcus aureus) of avocado (Persea americana cv. Criollo sp.) seed extracts (ethanol and acetone) were characterized. Sixteen volatile chemical compounds were determined, including isoprenoid derivatives (estragole), esters of fatty acids (linoleic and linolenic acids), and their derivatives (9,12-Octadecadien-1-ol and 9,12,15-Octadecatrien-1-ol). Acetone was the best solvent to obtain volatile compounds from avocado seed; this extract also showed a higher reducing power (56.35 mg AAE/100 g). Maximum S. aureus and S. Typhimurium log reductions were 4.0 ± 0.3 and 1.8 ± 0.3 at the highest amount used (2000 mg/L), without significant effect (p < 0.05) of the solvent used. According to the results of the volatile chemical profiling of avocado (Persea americana cv. Criollo sp.) seed extracts, they can have potential application as antioxidant (212.75 and 183.75 mg Trolox/100 g) and antimicrobial additives.     

Synthesis and antifungal activity of imidazo[1,2-b]pyridazine derivatives against phytopathogenic fungi

A series of 3,6-disubstituted imidazo[1,2-b]pyridazine derivatives have been synthesized and characterized with spectroscopic analyses. The antifungal activities of these compounds against nine phytopathogenic fungi were evaluated by the mycelium growth rate method. The in vitro antifungal bioassays indicated that most of compounds displayed excellent and broad-spectrum antifungal activities. Especially, compounds 4a, 4c, 4d, 4l and 4r exhibited 1.9–25.5 fold more potent than the commercially available fungicide hymexazol against Corn Curvalaria Leaf Spot (CL), Alternaria alternate (AA), Pyricularia oryzae (PO) and Alternaria brassicae (AB) strains. Structure-activity relationship analysis showed that the enhanced antifungal activity is significantly affected by the substituents on the benzene ring and pyridazine ring.