N-Hydroxypyridone alkaloids,chromone derivatives,and tetrahydroxanthones from the scale-insect pathogenic fungus Orbiocrella sp. BCC 33248

Six new compounds, an N-hydroxypyridone glucoside, orbiocrellin A (1), its aglycone orbiocrellin B (2), chromone glucosides 3 and 4, a dihydrochromone 5a/5b, and a chromone 6, were isolated from the scale-insect pathogenic fungus Orbiocrella sp. BCC 33248. Orbiocrellin A (1) exhibited antimalarial activity against Plasmodium falciparum K1 (IC₅₀ 3.1 μg/mL) while it was non-cytotoxic. In contrast, orbiocrellin B (2) showed both antimalarial (IC₅₀ 2.1 μg/mL) and cytotoxic (NCI-H187 cells, IC₅₀ 0.70 μg/mL) activities.     

Acylphloroglucinol derivatives from the twigs and leaves of Callistemon salignus

Three new acylphloroglucinol derivatives, callisalignones A–C (1–3), six new meroterpenoids, callisalignenes A–F (4–9), along with 18 known analogues (10–27) were isolated from the twigs and leaves of Callistemon salignus. Their structures and absolute configurations were established by comprehensive spectroscopic evidences (NMR, MS, amd electronic circular dichroism calculations). The absolute configurations of callistenones B (13) and H (14) were determined by comparison of their ECD spectra with that of callisalignone B (2). Callisalignones B and C are new adducts of β-triketone and acylphloroglucinol, whereas callisalignenes A–D are new meroterpenoids of acylphloroglucinol and α-phellandrene with different coupling models via hetero-Diels-Alder reaction, respectively. Myrtucommulone D (15) showed significant antibacterial activity against Staphylococcus aureus and three drug resistant S. aureus strains with MIC values of 1.953 and 0.975 μg/mL, respectively. Isomyrtucommulone B (17) displayed remarkable antibacterial activity against Escherichia coli with an MIC value of 0.122 μg/mL. Cytotoxic assay revealed that isomyrtucommulone B (17) was the most active against HCT116 with an IC₅₀ value of 2.09 ± 0.10 μM.     

Halogenated cladosporols produced by the sodium halide-supplemented fermentation of the plant-associated fungus Cladosporium sp. TMPU1621

A new cladosporol derivative, 2-chloro-cladosporol D (6), was isolated together with known cladosporol (1), cladosporols B–D (2–4), and cladosporol F (5) from the culture broth of plant-associated Cladosporium sp. TMPU1621. The structure of 6 was elucidated from spectroscopic analyses including NMR and MS data. The productivity of 6 increased in 3% NaCl-supplemented medium; therefore, fermentation of the producing fungus TMPU1621 with 3% NaBr was investigated, leading to the induced production of a new halogenated cladosporol, 2-bromo-cladosporol D (7). Compound 2 showed the lowest MIC values of 3.13 and 12.5?μg/mL against two MRSA strains, ATCC43300 and ATCC700698, respectively.     

Antimalarial 20-membered macrolides from Streptomyces sp. BCC33756

Two new natural products, samroiyotmycins A (1) and B (2), along with two naturally new novclobiocin 101 (3) and 4-hydroxy-3-(3-methylbut-2-enyl)benzamide (5), and five known substances including neoantimycin, clorobiocin (4), 29-O-methylabierixin, daidzein, and 1-(3-indolyl)-2,3-dihydroxypropan-1-one have been isolated from Streptomyces sp. BCC33756. Their chemical structures were determined based on NMR spectral information and the relative stereochemistry of compound 1 was determined by X-ray crystallographic data. Both samroiyotmycins A and B exhibited antimalarial activity against Plasmodium falciparum K1—multi-drug resistant strain, with IC₅₀ values of 3.65 and 3.16 μg/mL, respectively. Compound 1 was inactive against both cancerous (MCF-7, KB) and non-cancerous (Vero) cells, while compound 2 displayed cytotoxicity against Vero cell with IC₅₀ value of 29.57 μg/mL.     

Isolation of herbicidal compounds,quercetin and β-caryophyllene,from Digera muricata

Synthetic herbicides are available to control weeds but these herbicides have many concerns. Eco-friendly herbicides obtained from plants is a better alternative to synthetic ones. Despite that the herbicidal activity of Digera muricata extracts have been reported but there are no studies regarding the isolation and identification of herbicidal compounds from D. muricata. Herein, we are reporting the identification of two herbicidal compounds from chloroform extract obtained from D. muricata. The chloroform extract was initially tested on the germination and early growth of two weeds; Avena fatua and Melilotus indicus as well as wheat where a significant decline in % age germination and growth of both weeds was observed. Among the 8 different fractions obtained using different chromatographic techniques, fractions 2 and 7 were found to be phytotoxic to both test weeds. The herbicidal efficacy was tested at 200, 150, 100, 50, 25 μg/ml. These two fractions were further purified on Reversed Phase High Pressure Liquid Chromatography (RP-HPLC). Fraction 2 yielded 3 sub-fractions (2A, 2B & 2C), while fraction 7 yielded 2 sub-fractions (7A, 7B). Fraction 2B caused 43%, 53%, and 57% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 50%, 81% and 84%, respectively. Fraction 7A caused 25%, 36%, and 42% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 35%, 62% and 69%, respectively, at 200 μg/ml conc. Cyanazine caused 61% and 50% reduction in seed germination of A. fatua and M. indicus, respectively. The herbicidal effects of these two fractions were found nonsignificant against wheat. Fourier Transform Infrared Spectroscopy (FT-IR), elemental analysis (C,H) and Nuclear Magnetic Resonanace (NMR) analyses of these two fractions depicted the presence of quercetin (Fraction 2B) and β-caryophyllene (Fraction 7A). In post emergence bioassays, the isolated compounds caused significant decrease in the biomass of both weeds. Plasma membrane integrity assays revealed electrolyte leakage in treated leaf discs of both weeds. It was concluded that quercetin and β-caryophyllene isolated from D. muricata exhibited toxicity towards both test weeds without harming wheat.     

New aplysiatoxin derivatives from the Okinawan cyanobacterium Moorea producens

The marine cyanobacterium Moorea producens is a rich source of diverse compounds that possess a variety of biological activities. In the present study, eight new aplysiatoxin derivatives, namely 6, 8–13, and 15, along with aplysiatoxin (1), debromoaplysiatoxin (2), 3-methoxyaplysiatoxin (3), anhydroaplysiatoxin (4), anhydrodebromoaplysiatoxin (5), oscillatoxin B2 (7), and 30-methyloscillatoxin D (14) were isolated and identified from the Okinawan M. producens. In cytotoxicity and diatom growth inhibition tests, the fifteen compounds tested (1–15) showed moderate or no activity at a concentration of 10?μg/mL.     

Bioactive polyketides from the sea fan-derived fungus Penicillium citrinum PSU-F51

Five new polyketides including two benzopyranones (1 and 2), one isochroman (3) and two anthraquinone-citrinin derivatives (4 and 5) were isolated from the sea fan-derived fungus Penicillium citrinum PSU-F51 together with thirteen known compounds. The structures were determined by spectroscopic methods. The anthraquinone-citrinin derivatives are rare natural products. Compound 4 displayed moderate antibacterial activity against both Staphylococcus aureus and methicillin-resistant S. aureus with equal MIC values of 16 μg/mL, while the known coniochaetone A displayed moderate antifungal activity against Candida albicans with MIC value of 16 μg/mL.     

Novel antifungal janthinopolyenemycins A and B from a co-culture of marine-associated Janthinobacterium spp. ZZ145 and ZZ148

Two rare polyketides, named as janthinopolyenemycins A (1) and B (2), were isolated from a co-culture of two marine-sourced bacteria Janthinobacterium spp. ZZ145 and ZZ148. Their structures were established by a combination of extensive NMR spectroscopic analyses, HRESIMS data, and ECD calculation. Both janthinopolyenemycins A and B showed activity in inhibiting the growth of Candida albicans with a MIC value of 15.6?μg/mL and a MBC value of 31. 25?μg/mL.     

Antimalarial and antituberculosis substances from Streptomyces sp. BCC26924

Two new carbazomycin dimers (6 and 7) and 3-hydroxy-1,2-dimethyl-2,3-dihydro-1H-carbazol-4-one (9) together with six known compounds, carbazomycins A-D, cyclomarin C, and pimprinine have been isolated from Streptomyces sp. BCC26924. Carbazomycins B, C, and cyclomarin C exhibited antimalarial activity (against Plasmodium falciparum, K1 multi-drug resistant strain) with IC₅₀ in a range of 0.24-2.37 μg/mL. Cyclomarin C exhibited anti-TB activity with a minimum inhibitory concentration value of 0.10 μg/mL, while carbazomycin D, compound 7, and pimprinine displayed MIC values in a range of 12.5-25.0 μg/mL. In addition, compounds 2, 5, 6, and 7 showed weak cytotoxicity against cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells.     

Modiolin and phthalide derivatives from the endophytic fungus Microsphaeropsis arundinis PSU-G18

One new modiolin, microsphaerodiolin (1), and seven new phthalides, microsphaerophthalides A-G (2-8), together with 12 known compounds were isolated from the endophytic fungus Microsphaeropsis arundinis PSU-G18. Their structures were elucidated by spectroscopic methods. The new 3-oxygenated phthalides are rare natural products. The known 1-(2,5-dihydroxyphenyl)-2-buten-1-one exhibited significant antifungal activity against Microsporum gypseum SH-MU-4 with an MIC value of 8 μg/mL, moderate antimalarial activity with an IC₅₀ value of 9.63 μg/mL and strong radical scavenging potency with the IC₅₀ value of 0.018 mg/mL. The new compounds 2 and 6 showed moderately antifungal activity against M. gypseum SH-MU-4 and Cryptococcus neoformans, respectively, with equal MIC values of 64 μg/mL.     

Synthesis and biological evaluation of 1,4-pentadien-3-one derivatives containing 1,2,4-triazole

A series of new 1,4-pentadien-3-one derivatives containing 1,2,4-triazole moiety were synthesized. The structures of the synthesized compounds were charactered via ¹H NMR, ¹³C NMR and HRMS. Antibacterial bioassays indicated that some of compounds showed potential antibacterial activities against Ralstonia solanacearum (Rs), Xanthomonas oryzae pv. Oryzae (Xoo) and Xanthomonas axonopodis pv. Citri (Xac). Compounds F₈ and F₁₇ showed good in vitro antibacterial activities against Rs, with the EC₅₀ values of 18.6 and 18.6 μg/mL, respectively, which were better than commercial agent bismerthiazol (55.2 μg/mL). Furthermore, compounds F₁₂ and F₁₅ showed good in vitro antibacterial activities against Xoo, with the EC₅₀ values of 10.9 and 17.5 μg/mL, which were better than commercial agent bismerthiazol (69.3 μg/mL). Moreover, compounds F₂, F₉, F₁₆ and F₁₇ showed good in vitro antibacterial activities against Xac, with the EC₅₀ values of 6.6, 5.4, 7.5 and 7.8 μg/mL, respectively, which were better than commercial agent bismerthiazol (54.9 μg/mL). The effect of compound F₉ on Xac bacterial cell membrane rupture was observed by scanning electron microscopy (SEM). In addition, antiviral bioassays indicated that some of compounds showed excellent protection activities against tobacco mosaic virus (TMV). Compounds F₅ and F₁₅ showed good protecting activity against TMV, with the EC₅₀ values of 108.3 and 105.4 μg/mL, respectively, which were better than commercial agent ningnanmycin (214.7 μg/mL). Microscale thermophoresis (MST) also showed that the binding of compound F₂ to TMV coat protein (TMV-CP) yielded a Kd value of 1.260 ± 0.654 μmol/L, which was very close to ningnanmycin (1.058 ± 0.286 μmol/L). Similarly, the molecular docking studies for F₂ and F₅ with TMV-CP (PDB code: 1EI7, ID: 4QGH) indicated that compounds F₂ and F₅ had partially interacted with TMV-CP.     

Pseudoalteromone A: a novel bioactive ubiquinone from a marine bacterium Pseudoalteromonas sp. CGH2XX (Pseudoalteromonadaceae)

A novel ubiquinone derivative, pseudoalteromone A (1), possessing a 9C nor-monoterpenoid moiety was produced from a marine bacterium Pseudoalteromonas sp. CGH2XX. This bacterium is originally isolated from a cultured-type octocoral Lobophytum crassum. The structure of ubiquinone 1 was established by spectroscopic methods. Pseudoalteromone A (1) exhibited significant cytotoxicity toward the MOLT-4 (human acute lymphoblastic leukemia, IC₅₀ = 3.764 μg/mL) cells and displayed a significant inhibitory effect (inhibition rate 45.1%) on the release of elastase by human neutrophils at a concentration of 10 μg/mL.     

Abiestetranes A and B,two unique tetraterpenes from Abies fabri

Abiestetranes A (1) and B (2), two unique tetraterpenes formed by Diels–Alder cycloaddition between a lanostane triterpenoid and a monoterpenoid, were isolated from Abies fabri. Their structures were elucidated by extensive analysis of NMR data. The electronic circular dichroism was utilized to assign the absolute configuration of 1. Compounds 1 and 2 showed significant cytotoxic activities against ZR-75-30 tumor cell with IC₅₀ values of 6.26 and 1.63 μg/mL, respectively.     

Nematicidal quinone derivatives from three Rubia plants

Five new quinone derivatives, rubiasins D-F (1–3), rubialatones A and B (4 and 5), have been isolated from the roots and rhizomes of three Rubia species, Rubia alata, R. wallichiana and R. schumanniana, together with 26 known quinones (6–31). Their structures have been elucidated on the basis of NMR, MS spectra and computational methods. The compounds have been evaluated for their toxicity to the saprophytic nematode Caenorhabditis elegans and the root-knot nematode Meloidogyne incognita. Compounds 1, 6 and 7 showed toxicity to C. elegans with the LC₅₀ values at 8.50, 9.44 and 44.82?μg/mL, respectively; and 6 showed toxicity to M. incognita with the LC₅₀ value at 35.22?μg/mL. Meanwhile, compounds 1 and 6 showed inhibitory effect on egg hatch of C. elegans with the LC₅₀ values at 5.60 and 48.95?μg/mL.     

Abiesanordines A-N: fourteen new norditerpenes from Abies georgei

Fourteen new norditerpenoids (abiesanordines A-N, 1-14), including a novel podocarpene bearing a rare enolic structure (abiesanordine A, 1), were isolated from Abies georgei together with eight known ones. Their structures were determined mainly by detailed analysis of 1D and 2D NMR spectroscopic data including HSQC, DQF COSY, HMBC, and NOESY. All the isolates were tested for inhibitory activities against LPS-induced NO production in RAW264.7 macrophages, abiesanordine I (9) showed the strongest activity with the IC₅₀ value of 17.0 μg/mL. Furthermore, it exhibited no cytotoxicity against RAW264.7 macrophages under the concentration of 50 μg/mL.     

3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

Palmadorin chemodiversity from the Antarctic nudibranch Austrodoris kerguelenensis and inhibition of Jak2/STAT5-dependent HEL leukemia cells

Detailed investigation of the Antarctic nudibranch Austrodoris kerguelenensis has resulted in the isolation of a diverse suite of new diterpenoid glyceride esters (1–16) related to the palmadorins (17–19), including one (palmadorin L (9)) that is the first halogenated diterpene from this well-studied nudibranch. Previous collections of A. kerguelenensis from McMurdo Sound, the Weddell Sea and the Western Antarctic Peninsula have afforded related diterpene glycerides, a natural product class implicated as a chemical defense in nudibranchs. In this paper we describe the isolation, structure elucidation, and stereochemical analysis of sixteen new palmadorins using a combination of one- and two-dimensional NMR techniques. Palmadorin A (17), B (18), D (1), M (10), N (11), and O (12) inhibit human erythroleukemia (HEL) cells with low micromolar IC₅₀'s, and palmadorin M inhibits Jak2, STAT5, and Erk1/2 activation in HEL cells and causes apoptosis, at 5 μM.     

A new spiro-type limonoid from Azadirachta indica A. Juss

A rare spiro-type limonoid spirodione (1) was isolated from the seeds of Azadirachta indica A. Juss. Its structure was elucidated through analysis of the spectroscopic data including HRESIMS, NMR, etc., and the absolute configurations were assigned by comparison of experimental and TDDFT-calculated ECD spectra. 1 showed moderate activities against Staphylococcus aureus ATCC 25922 and S. epidermidis ATCC 12228 with MICs of 16 and 64?μg/mL, respectively.     

Dihydroanthracenone metabolites from the endophytic fungus Diaporthe melonis isolated from Annona squamosa

Chemical investigation of the endophytic fungus Diaporthe melonis, isolated from Annona squamosa, yielded two new dihydroanthracenone atropodiastereomers, diaporthemins A (1) and B (2), together with the known flavomannin-6,6′-di-O-methyl ether (3). The structures of the new compounds were established on the basis of extensive 1D and 2D NMR spectroscopy, as well as by high resolution mass spectrometry and by CD spectroscopy. Compounds 1–3 were tested for their antimicrobial activity against a multi-resistant clinical isolate of Staphylococcus aureus 25697, a susceptible reference strain of S. aureus ATCC 29213 and against Streptococcus pneumoniae ATCC 49619. Compound 3 strongly inhibited S. pneumonia growth with a MIC value of 2 μg/mL, and showed moderate activity against the S. aureus multi-resistant clinical isolate and susceptible reference strain (MIC 32 μg/mL), whereas 1 and 2 were not active against the tested strains.     

Papuamides E and F, Cytotoxic Depsipeptides from the Marine Sponge Melophlus sp

Two known papuamides C (1) and D (2) together with two new depsipeptides, papuamides E (3) and F (4), were isolated from an undescribed sponge of the genus Melophlus collected in the Solomon Islands. The planar structures of the compounds were elucidated on the basis of spectroscopic studies. Papuamides C-F (1-4) showed cytotoxicity against brine shrimp with LD₅₀ values between 92 and 106 μg/mL.