Secondary Metabolites from the Fungus Monascus purpureus and Evaluation of Their Cytotoxic Activity

New polyketides and sesquiterpenoids from the deep-sea sulphide-derived fungus Phoma sp. 3A00413

Phoma fungi are known to produce a diverse range of natural products which possess various biological activities such as antifungal, antimicrobial, insecticidal, cytotoxic, and immunomodulatory effects. In our present study, we have isolated two novel polyketides (1 and 3), one new sesquiterpenoid (2), and eight known compounds (4-11) from the culture of Phoma sp. 3A00413, a deep-sea sulphide-derived fungus. The structures of compounds 1-3 were elucidated using NMR, MS, NMR calculation, and ECD calculation. In vitro antibacterial activities of all the isolated compounds were evaluated against Escherichia coli, Vibrio parahaemolyticus vp-HL, Vibrio parahaemolyticus, Staphylococcus aureus, Vibrio vulnificus, and Salmonella enteritidis. Compounds 1, 7, and 8 exhibited weak inhibition against Staphylococcus aureus growth, while compounds 3 and 7 showed weak inhibition against Vibrio vulnificus growth. Importantly, compound 3 demonstrated exceptional potency against Vibrio parahaemolyticus, with a minimum inhibitory concentration (MIC) of 3.1 μM.

Undescribed Metabolites from an Actinobacteria Acrocarpospora punica and Their Anti-Inflammatory Activity

In an effort to explore bioactive anti-inflammatory compounds from natural Actinobacteria resources from all over Taiwan and various ecological environments, an active strain of Acrocarpospora punica was collected at Taitung County in Taiwan, prepared from soil origin. A bioassay-guided fractionation of the BuOH extract of a culture broth of a new strain of the actinomycete Acrocarpospora punica led to the isolation of five previously undescribed compounds: acrocarpunicains A-F (1-6). The structures were elucidated by 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry. Furthermore, the isolated compounds were subjected to in vitro testing to evaluate their anti-inflammatory activity. Of these isolates, acrocarpunicains A (1), B (2), C (3) and F (6) showed NO inhibitory activity with IC₅₀ values of 9.36 ± 0.25, 10.11 ± 0.47, 5.15 ± 0.18, and 27.17 ± 1.87 μM, stronger than the positive control, quercetin (IC₅₀ = 35.95 ± 2.34 μM). To the best of our knowledge, this is the first report on azaphilone and phenanthrene-type metabolites from the genus Acrocarpospora.

Multivariate Analysis Revealed Ultrasonic-Assisted Extraction Improves Anti-Melanoma Activity of Non-Flavonoid Compounds in Indonesian Brown Algae Ethanol Extract

Indonesia has high biodiversity of algae that are under-utilised due to limitations in the processing techniques. Here, we observed the effect of two different extraction methods (cold maceration and ultrasonic-assisted extraction (UAE)) on multiple variables of Indonesian brown algae ethanol extracts (Sargassum polycystum, Sargassum cristaefolium, Sargassum aquifolium and Turbinaria ornata). The variables observed included metabolites screening by untargeted metabolomics liquid chromatography-high-resolution mass spectrometry (LC-HRMS), observation of total phenolic content (TPC), total flavonoid content (TFC), anti-oxidant and B16-F10 melanoma cells cytotoxicity. UAE extracts had higher extraction yield and TPC, but no TFC difference was observed. UAE extract had more lipophilic compounds, such as fatty acids (Palmitic acid, Oleamide, Palmitoleic acid, Eicosapentaenoic acid, α-Linolenic acid, Arachidonic acid), lipid-derived mediators (11,12-Epoxyeicosatrienoic acid ((±)11(12)-EET)), steroid derivatives (Ergosterol peroxide), lipophilic metabolite (Fucoxanthin), and lipid-soluble vitamins (all-trans-retinol). Principle component analysis (PCA) revealed that TPC, not TFC, in the UAE extracts was correlated with the anti-oxidant activities and cytotoxicity of the extracts towards B16-F10 melanoma cells. This means other non-flavonoid phenolic and lipophilic compounds may have contributed to its bioactivity. These results suggest that out of the two methods investigated, UAE could be a chosen method to extract natural anti-melanogenic agents from brown algae.

Investigations into Chemical Components from Monascus purpureus with Photoprotective and Anti-Melanogenic Activities

Monascus species are asexually or sexually reproduced homothallic fungi that can produce a red colorant, specifically the so-called red yeast rice or Anka, which is used as a food ingredient in Asia. Traditional experiences of using Monascus for treating indigestion, enhancing blood circulation, and health remedies motivate us to investigate and repurpose Monascus-fermented products. Here, two new 5H-cyclopenta[c]pyridine type azaphilones, 5S,6S-monaspurpyridine A (1) and 5R,6R-monaspurpyridine A (2), two new xanthonoids, monasxanthones A and B (3 and 4), one new naphthalenone, monasnaphthalenone (5), and one new azaphilone, monapurpurin (6), along with two known compounds were isolated from the 70% EtOH extract of a citrinin-free domesticated strain M. purpureus BCRC 38110. The phytochemical properties of the xanthonoid and naphthalenone components were first identified from Monascus sp. differently from the representative ingredients of polyketide-derived azaphilones. UVB-induced cell viability loss and reactive oxygen species (ROS) overproduction in human keratinocytes were attenuated by monascuspirolide B (7) and ergosterol peroxide (8), indicating their photoprotective potentials. Ergosterol peroxide (8) decreased the melanin contents and tyrosinase activities of mouse melanocytes, depending on the concentration, suggesting their anti-melanogenic effects. In conclusion, six new and two known compounds were isolated from M. purpureus BCRC 38110, and two of them exhibited dermal protective activities. The results revealed the novel potential of M. purpureus for developing natural cosmeceutics against skin photoaging.

Three new isocoumarin derivatives from the mangrove endophytic fungus Penicillium sp. YYSJ-3

Three new isocoumarin derivatives, (S)-6,8-dihydroxy-5-(methoxymethyl)-3,7-dimethylisochroman-1-one (1), (S)-6,8-dihydroxy-3,5,7-trimethyl-isochroman-1-one (2) and (R)-2-chloro-3-(8-hydroxy-6-methoxy-1-oxo-1H-isochromen-3-yl) propyl acetate (3), along with four known compounds (4-7) were isolated from a mangrove endophytic fungus Penicillium sp. YYSJ-3. Their structures were established on the basis of the extensive spectroscopic data and HR-ESI-MS analysis. The absolute configurations of 1-3 were further determined by X-ray diffraction analysis and optical rotations. Compounds 3, 6 and 7 showed promising inhibitory activity against α-glucosidase, which were stronger than that of the positive control 1-deoxynojirimycin (IC₅₀ 141.2 μmol·L^-1).

Isolation and Structure Elucidation of Secondary Metabolites From an Endophytic Fungus Annulohypoxylon ilanense

Fractionation of the EtOAc-soluble fraction of the liquid fermentation of an endophytic fungus Annulohypoxylon ilanense associated with the wood of medicinal plant Cinnamomum species resulted in the isolation of 1 new α-pyrone, ilanpyrone (1), along with 3 previously identified compounds, 2 to 4. Their structures were elucidated by means of spectroscopic and mass-spectrometric analyses, especially 1D and 2D nuclear magnetic resonance (NMR) spectroscopy as well as high-resolution electrospray ionization mass spectrometry. The isolated compounds were tested for their cytotoxicity against MCF-7, NCI-H460, and SF-268 cell lines using the MTT assay. Among them, compounds 1 and 4 were found to have moderate-to-weak cytotoxic effects against these 3 cell lines in vitro.

New azaphilones and tremulane sesquiterpene from endophytic Nigrospora oryzae cocultured with Irpex lacteus

Five new metabolites belonging to two backbones of pulvilloric acid-type azaphilone and tremulane sesquiterpene were obtained and their structures were determined by spectral analysis. Based on the biogenesis analysis, tremulane sesquiterpenes were obtained from Irpex lacteus by the stimulation of mixed-culture. The antifungal selectivities of metabolites produced by fungus against their co-culture fungus and common pathogens, exhibited competitive interaction of this mix-culture. The tremulane sesquiterpene conocenol B produced by I. lacteus through the induction of Nigrospora oryzae showed selectivity of anti-fungal activity against its co-culture fungus, N. oryzae, with MICs at 16 μg/mL and 128 μg/mL against I. lacteus. The fungus can metabolize these new compounds to inhibit the growth of co-culture fungus while not inhibiting its own growth. Compound 5 was active against acetylcholinesterase (AChE) with a ratio of 35% at the concentration of 50 μM.

Chaetosemins A–E, new chromones isolated from an Ascomycete Chaetomium seminudum and their biological activities

Fifteen polyketide chromones, including four new ones, chaetosemins B–E (2–5), with 4 bearing a new skeleton, and two new natural products, chaetosemin A (1) and (+)-(S)-chaetoquadrin J (14), were isolated from cultures of Chaetomium seminudum.

Isolation and identification of two novel attractant compounds from Chinese cockroach (Eupolyphaga sinensis Walker) by combination of HSCCC, NMR and CD techniques

High-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hextane-ethyl acetate-methanol-water (1.5:1:1.5:1, v/v/v/v) was applied to the isolation and purification of attractants from Chinese cockroach, Eupolyphaga sinensis Walker. Two new attractants with attractant activity towards the male insects were obtained from the extract sample in a one-step separation. Their purities were determined by HPLC. Subsequent MS, NMR and CD analyses have led to the characterization of (R)-3-ethyl-6,8-dihydroxy-7-methyl-3,4-dihydroisochromen-1-one (1) and (R)-6,8-dihydroxy-3,7-dimethyl-3,4-dihydroisochromen-1-one (2), two novel isocumarin type attractants. Based on these results, it is concluded that HSCCC is a viable separation method option for purifying insect attractants, while effectively maintaining the attracting activity of the isolates. This is the first attempt to apply counter-current chromatography technique to separate attractants from Chinese cockroach.

Five new secondary metabolites from Monascus purpureus-fermented Hordeum vulgare and Sorghum bicolor

Long grains of Hordeum vulgare and Sorghum bicolor were individually fermented with Monascus purpureus MTCC 369 under solid state fermentation. The aqueous extract of Monascus which fermented H. vulgare and S. bicolor was found to contain five different new metabolites. Silica gel column chromatography of the aqueous extract with a linear gradient of ethyl acetate, acetonitrile and carbon tetrachloride (v/v) yielded five new metabolites named benzopranyl capriate (9H-1-isoprenyl-benzopyran-5-isopropanoic acid-6-ol-6-n-decanoate), shorghumoic acid (n-octadec-8,11-dien-7α-ol-1-oic acid) and sorghumflavin A (2-n-butyloxo-6-β-hydroxy-7-β-isoprenyl ankaflavin) from Monascus-fermented S. bicolor, while hordeumflavin B (2-n-undecanyloxo-7-β-isoprenyl ankaflavin) and vulgaredilone (2-dodecanyl-7-β isopranyl monoscodilone) from Monascus-fermented H. vulgare.