Structural and biological diversity of natural p-terphenyls

Selective C-H Borylation of Polyaromatic Compounds Enabled by Metal-Arene π-Complexation

The undirected Ir-catalyzed C-H borylation usually occurs preferentially at the least hindered and more acidic C-H bond of the aromatic ring. In the case of polyaromatic compounds possessing multiple unbiased and sterically accessible C-H bonds, the site selectivity for the nondirected C-H borylation is low. Here, we report the dramatic effect exerted by the π-complexation of a chromium tricarbonyl unit on the aromatic ring in the context of Ir-catalyzed C-H borylation. Competition experiments demonstrate that the C-H bonds of an aromatic ring bound to the chromium tricarbonyl unit react on average two orders in magnitude faster toward the C-H borylation than the unbound arenes. This enables an unprecedented C-H borylation with high site selectivity of the aromatic ring π-complexed with a chromium tripod in a series of organic polyaromatic compounds. Besides, the drastic enhancement of the reactivity of C-H bonds induced by the chromium tripod allows the C-H borylation to occur at room temperature with the substrate as a limiting reagent. The DFT studies indicate that the oxidative addition of the C-H bonds has lower activation barriers when the arenes are complexed with a chromium tricarbonyl unit, explaining the observed exceptional site selectivity. This study will further spearhead the development of nondirected C-H borylation with a bimetallic system to harness the effect of the noncovalent metal-arene π-type interactions on the reactivity and the selectivity of the C-H functionalization.

Semisynthesis of Nocarterphenyl A and Its Analogues

p-Terphenyl compounds are known to possess a diverse range of biological activities, making the synthesis of novel p-terphenyl derivatives a significant research objective. In this study, we report the first synthesis of nocarterphenyl A (1), characterized by a thiazole-fused p-terphenyl framework. Furthermore, we synthesized 18 additional analogs, including the naturally occurring compound 5-methoxy-4,7-bis(4-methoxyphenyl)benzo[d]thiazol-6-ol (9), employing a similar synthetic approach. Notably, compounds 12, 13, 15-17, and 19 demonstrated potent inhibitory effects against protein tyrosine phosphatase 1B (PTP1B), exhibiting IC50 values ranging from 2.2 to 7.9 μM, which are lower than that of oleanolic acid (13.2 μM). Additionally, compound 14 was found to inhibit α-glucosidase from human colorectal adenocarcinoma (Caco-2) cells with an IC50 value of 10.4 μM, which is also lower than that of acarbose (11.2 μM).

Exploring the molecular tapestry of Sarcodon secondary metabolites: chemical structures, activities, and biosynthesis

Sarcodon mushrooms are esteemed as a rare and highly valuable resource for both culinary and medicinal purposes. Ancient medical classics have documented their beneficial effects on conditions such as indigestion, loss of appetite, and neurological disorders. Modern phytochemical research into their secondary metabolites has led to the discovery of numerous bioactive compounds with significant biological activities. Despite notable achievements in the study of the chemical composition and bioactivity of Sarcodon mushrooms, a comprehensive understanding of these findings has been lacking. This review provides an exhaustive summary of the advancements in the phytochemistry of Sarcodon mushrooms, as well as the biological and pharmacological activities of the isolated compounds and crude extracts derived from Sarcodon over the past nine decades. A total of 100 secondary metabolites isolated from these mushrooms have been classified into five major categories based on their chemical structures, which exhibit bioactivities such as anti-tumour, neurotrophic, and neuroprotective, antioxidant, anti-inflammatory, antimicrobial, and hypoglycaemic properties. The aim of this study is to establish a scientific foundation for future research in drug discovery, biotechnological development, and the exploration of functional foods involving Sarcodon mushrooms.

Photoreaction products of extract from the fruiting bodies of Polyozellus multiplex

Photochemical reactions are powerful tools for synthesizing organic molecules. The input of energy provided by light offers a means to produce strained and unique molecules that cannot be assembled using thermal protocols, allowing for the production of immense molecular complexity in a single chemical step. Furthermore, unlike thermal reactions, photochemical reactions do not require active reagents such as acids, bases, metals, or enzymes. Photochemical reactions play a central role in green chemistry. This article reports the isolation and structure determination of four new compounds (1-4) from the photoreaction products of the Polyozellus multiplex MeOH ext. The structures of the new compounds were elucidated using MS, IR, comprehensive NMR measurements and microED. The four compounds were formed by deacetylation of polyozellin, the main secondary metabolite of P. multiplex, and addition of singlet oxygen generated by sunlight. To develop drugs for treating Alzheimer's disease (AD) on the basis of the amyloid cascade hypothesis, the compounds (1-4) obtained by photoreaction were evaluated for BACE1 inhibitory activity. The hydrolysates (5 and 6) of polyozellin, the main secondary metabolites of P. multiplex, were also evaluated. The photoreaction products (3 and 4) and hydrolysates (5 and 6) of polyozellin showed BACE1 inhibitory activity (IC50: 2.2, 16.4, 23.3, and 5.3 μM, respectively).

Discovery of New Antimicrobial Metabolites in the Coculture of Medicinal Mushrooms

Bioactivity screening revealed that the antifungal activities of EtOAc extracts from coculture broths of Trametes versicolor SY630 with either Vanderbylia robiniophila SY341 or Ganoderma gibbosum SY1001 were significantly improved compared to that of monocultures. Activity-guided isolation led to the discovery of five aromatic compounds (1-5) from the coculture broth of T. versicolor SY630 and V. robiniophila SY341 and two sphingolipids (6 and 7) from the coculture broth of T. versicolor SY630 and G. gibbosum SY1001. Tramevandins A-C (1-3) and 17-ene-1-deoxyPS (6) are new compounds, while 1-deoxyPS (7) is a new natural product. Notably, compound 2 represents a novel scaffold, wherein the highly modified p-terphenyl bears a benzyl substituent. The absolute configurations of those new compounds were elucidated by X-ray diffraction, ECD calculations, and analysis of physicochemical constants. Compounds 1, 2, and 5-7 exhibited different degrees of antimicrobial activity, and the antifungal activities of compounds 6 and 7 against Candida albicans and Cryptococcus neoformans are comparable to those of fluconazole, nystatin, and sphingosine, respectively. Transcriptome analysis, propidium iodide staining, ergosterol quantification, and feeding assays showed that the isolated sphingolipids can extensively downregulate the late biosynthetic pathway of ergosterol in C. albicans, representing a promising mechanism to combat antibiotic-resistant fungi.

p-Terphenyl and Diphenyl Ether Derivatives from the Marine-Derived Fungus Aspergillus candidus HM5-4

Two undescribed p-terphenyl derivatives, asperterphenylcins A-B (1-2), and two undescribed diphenyl ether derivatives, asperdiphenylcins A-B (3-4), together with three previously described p-terphenyl derivatives-4″-deoxyterprenin (5), terphenyllin (6), and 3″-hydroxyterphenyllin (7)-were obtained from the solid-rice culture of the marine-derived fungus Aspergillus candidus HM5-4, which was isolated from sponges from the South China Sea. Their structures were elucidated by HRESIMS data and NMR spectroscopic analysis. Compound 1 showed a strong inhibitory effect on Neoscytalidium dimidiatum, with an inhibition circle diameter of 31.67 ± 2.36 mm at a concentration of 10.0 µg/disc. Compounds 5 and 7 displayed cytotoxic activity against human chronic myeloid leukemia cells (K562), human liver cancer cells (BEL-7402), human gastric cancer cells (SGC-7901), human non-small cell lung cancer cells (A549) and human HeLa cervical cancer cells, with IC50 values ranging from 3.32 to 60.36 µM, respectively. Compounds 2, 6 and 7 showed potent inhibitory activity against α-glucosidase, with IC50 values of 1.26 ± 0.19, 2.16 ± 0.44 and 13.22 ± 0.55 µM, respectively.

Biosynthesis of p-Terphenyls in Aspergillus ustus Implies Enzymatic Reductive Dehydration and Spontaneous Dibenzofuran Formation

p-Terphenyls contain a central benzene ring substituted with two phenyl residues at its para positions. Heterologous expression of a biosynthetic gene cluster from Aspergillus ustus led to the formation of four new p-terphenyl derivatives. Gene deletion experiments proved the formation and reductive dehydration of the terphenylquinone atromentin, followed by O-methylation and prenylation. Spontaneous dibenzofuran formation led to the final products. These results provide new insights into the biosynthesis of p-terphenyls in fungi and dibenzofuran formation in the biosynthesis of numerous natural products.

Structurally various p-terphenyls with neuraminidase inhibitory from a sponge derived fungus Aspergillus sp. SCSIO41315

Guided by Global Natural Products Social molecular networking, 14 new p-terphenyl derivatives, asperterphenyls A-N (1-14), together with 20 known p-terphenyl derivatives (15-34), were obtained from a sponge derived fungus Aspergillus sp. SCSIO41315. Among them, new compounds 2-8 and 15-17 were ten pairs of enantiomers. Comprehensive methods such as chiral-phase HPLC analysis, ECD calculations and X-ray diffraction analysis were applied to determine the absolute configurations. Asperterphenyls B (2) and C (3) represented the first reported natural p-terphenyl derivatives possessing a dicarboxylic acid system. Asperterphenyl A (1) displayed neuraminidase inhibitory activity with an IC₅₀ value of 1.77 ± 0.53 µM and could efficiently inhibit infection of multiple strains of H1N1 with IC₅₀ values from 0.67 ± 0.28 to 1.48 ± 0.60 µM through decreasing viral plaque formation in a dose-dependent manner, which suggested that asperterphenyl A (1) might be exploited as a potential antiviral compound in the pharmaceutical fields.

p-Terphenyl glucosides from the culture broth of Phlebiopsis castanea

A new p-terphenyl derivative, hydroxystrepantibin D (1), was isolated along with two known p-terphenyls (2 and 3) from the culture broth of Phlebiopsis castanea. These compounds were isolated using silica gel column chromatography, reversed-phase medium-pressure liquid chromatography, Sephadex LH-20 column chromatography, and preparative HPLC. Their structures were determined based on spectroscopic methods. These compounds exhibited free radical scavenging activities with IC₅₀ values in the range from 22.2 to 158.4 μM against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical and in the range from 161.1 to 356.1 μM against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

Binding of Vialinin A and p-Terphenyl Derivatives to Ubiquitin-Specific Protease 4 (USP4): A Molecular Docking Study

The para-terphenyl derivative vialinin A (Vi-A), isolated from Thelephora fungi, has been characterized as a potent inhibitor of the ubiquitin-specific protease 4 (USP4). Blockade of USP4 contributes to the anti-inflammatory and anticancer properties of the natural product. We have investigated the interaction of Vi-A with USP4 by molecular modeling, to locate the binding site (around residue V98 within the domain in USP segment) and to identify the binding process and interaction contacts. From this model, a series of 32 p-terphenyl compounds were tested as potential USP4 binders, mainly in the vialinin, terrestrin and telephantin series. We identified 11 compounds presenting a satisfactory USP4 binding capacity, including two fungal products, vialinin B and aurantiotinin A, with a more favorable empirical energy of USP4 interaction (ΔE) than the reference product Vi-A. The rare p-terphenyl aurantiotinin A, isolated from the basidiomycete T. aurantiotincta, emerged as a remarkable USP4 binder. Structure-binding relationships have been identified and discussed, to guide the future design of USP4 inhibitors based on the p-terphenyl skeleton. The docking study should help the identification of other protease inhibitors from fungus.

Comprehensive characterization of polycyclic aromatic hydrocarbon emissions from heavy-duty diesel vehicles utilizing GC × GC-ToF-MS

Comprehensive characterization of diesel vehicle emitted polycyclic aromatic hydrocarbon (PAH) emissions is yet to achieve due to the limitation of analytical methods. Therefore, we herein developed a two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) method and quantified the total PAHs from diesel vehicles based on their characteristic fragments and mass spectral patterns. Overall, the emission factors (EFs) of total PAHs (gas + particle) are observed to range from 4.1 ± 2.5 mg km^-1 to 51.4 ± 22.2 mg km^-1 under cold-start and hot-start conditions for one China IV and two China VI heavy-duty diesel vehicles (HDDVs), of which the un-speciated PAHs account for more than 97%. Gaseous PAHs (g-PAHs) are dominated by three-ring PAHs, whereas particulate PAHs (p-PAHs) are dominated by two-ring PAHs. The total PAHs partition significantly into the gas phase for whole fleets and cycles, except that five-ring PAHs partition almost completely into the particle phase. The aftertreatment technologies (e.g., diesel particulate filter, DPF) significantly reduce the total PAH emissions by 49.8 ± 33.2%. The minimum toxic equivalency factors (TEFs) are deployed to estimate the toxicity of the total PAHs. Much higher toxicity is obtained than those in previous studies, indicating that the PAH toxicity of diesel vehicle emissions might be largely underestimated.

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

Two novel diarylcyclopentenones daturamycin A and B (1 and 2), and one new p-terphenyl daturamycin C (3), along with three known congeners (4-6), were isolated from a rhizosphere soil-derived Streptomyces sp. KIB-H1544. The structures of new compounds were elucidated via a joint use of spectroscopic analyses and single-crystal X-ray diffractions. Compounds 1 and 2 belong to a rare class of tricyclic 6/5/6 diarylcyclopentenones, and compounds 3-6 possess a C-18 tricyclic aromatic skeleton. The biosynthetic gene cluster of daturamycins was identified through gene knockout and biochemical characterization experiments and the biosynthetic pathway of daturamycins was proposed.

Anti-inflammatory and anticancer p-terphenyl derivatives from fungi of the genus Thelephora

Fungi from the genus Thelephora have been exploited to identify bioactive compounds. The main natural products characterized are para-terphenyl derivatives, chiefly represented by the lead anti-inflammatory compound vialinin A isolated from species T. vialis and T. terrestris. Different series of p-terphenyls have been identified, including vialinins, ganbajunins, terrestrins, telephantins and other products. Their mechanism of action is not always clearly identified, and different potential molecule targets have been proposed. The lead vialinin A functions as a protease inhibitor, efficiently targeting ubiquitin-specific peptidases USP4/5 and sentrin-specific protease SENP1 which are prominent anti-inflammatory and anticancer targets. Protease inhibition is coupled with a powerful inhibition of the cellular production of tumor necrosis factor TNFα. Other mechanisms contributing to the anti-inflammatory or anti-proliferative action of these p-terphenyl compounds have been invoked, including the formation of cytotoxic copper complexes for derivatives bearing a catechol central unit such vialinin A, terrestrin B and telephantin O. These p-terphenyl compounds could be further exploited to design novel anticancer agents, as evidenced with the parent compound terphenyllin (essentially found in Aspergillus species) which has revealed marked antitumor and anti-metastatic effects in xenograft models of gastric and pancreatic cancer. This review shed light on the structural and functional diversity of p-terphenyls compounds isolated from Thelephora species, their molecular targets and pharmacological properties.

Bioactive Terphenyls Isolated from the Antarctic Lichen Stereocaulon alpinum

Three p-terphenyls (2–4)—2-hydroxy-3,5-dimethoxy-p-terphenyl (2), 2-hydroxy-3,6-dimethoxy-p-terphenyl (3), and 2,3,5,6-tetramethoxy-p-terphenyl (4)—were isolated for the first time as natural products along with seven known compounds (1, 5–10) from the Antarctic lichen Stereocaulon alpinum. Structures of the new compounds were elucidated by comprehensive analyses of 1D and 2D NMR and HREIMS experiments. Compound 3 exhibited cytotoxicity against HCT116 cells with the IC₅₀ value of 3.76 ± 0.03 μM and also inhibited NO production in LPS-induced RAW264.7 macrophages with the IC₅₀ value of 22.82 ± 0.015 μM.

Non-peptide secondary metabolites from poisonous mushrooms: overview of chemistry, bioactivity, and biosynthesis

Covering: up to June 2021A wide variety of mushrooms have traditionally been recognized as edible fungi with high nutritional value and low calories, and abundantly produce structurally diverse and bioactive secondary metabolites. However, accidental ingestion of poisonous mushrooms can result in serious illnesses and even death. Chemically, mushroom poisoning is associated with secondary metabolites produced in poisonous mushrooms, causing specific toxicity. However, many poisonous mushrooms have not been fully investigated for their secondary metabolites, and the secondary metabolites of poisonous mushrooms have not been systematically summarized for details such as chemical composition and biosynthetic mechanisms. The isolation and identification of secondary metabolites from poisonous mushrooms have great research value since these compounds could be lethal toxins that contribute to the toxicity of mushrooms or could provide lead compounds with remarkable biological activities that can promote advances in other related disciplines, such as biochemistry and pharmacology. In this review, we summarize the structures and biological activities of secondary metabolites identified from poisonous mushrooms and provide an overview of the current information on these metabolites, focusing on their chemistry, bioactivity, and biosynthesis.

Structural diversity and biological activity of natural p-terphenyls

p-Terphenyls are aromatic compounds consisting of a central benzene ring substituted with two phenyl groups, and they are mainly isolated from terrestrial and marine organisms. The central ring of p-Terphenyls is usually modified into more oxidized forms, e.g., para quinone and phenols. In some cases, additional ring systems were observed on the terphenyl-type core structure or between two benzene moieties. p-Terphenyls have been reported to have cytotoxic, antimicrobial, antioxidant and α-glucosidase inhibitory effects. In this review, we will mainly summarize the structural diversity and biological activity of naturally occurring p-Terphenyls referring to the research works published before.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00117-8.

p-Terphenyls as Anti-HSV-1/2 Agents from a Deep-Sea-Derived Penicillium sp

Guided by Global Natural Products Social molecular networking, two p-terphenyl derivatives and one 4,5-diphenyl-2-pyrone analogue, peniterphenyls A-C (1-3), together with five known p-terphenyl derivatives (4-8) and sulochrin (9), were obtained from a deep-sea-derived Penicillium sp. SCSIO41030. Their structures were elucidated using extensive NMR spectroscopic and HRESIMS data and by comparing the information with literature data. Peniterphenyl B (2) represented the first reported natural product possessing a 4,5-diphenyl-substituted 2-pyrone derivative. The p-terphenyl derivatives displayed inhibitory activities against HSV-1/2 with EC₅₀ values ranging from 1.4 ± 0.6 to 9.3 ± 3.7 μM in Vero cells, which showed that they possessed antiviral activities with low cytotoxicity, superior to the current clinical drug acyclovir (EC₅₀ 3.6 ± 0.7 μM). Peniterphenyl A (1) inhibited HSV-1/2 virus entry into cells and may block HSV-1/2 infection through direct interaction with virus envelope glycoprotein D to interfere with virus adsorption and membrane fusion, and thus differs from the nucleoside analogues such as acyclovir. Our study indicated peniterphenyl A (1) could be a promising lead compound against HSV-1/2.

The intriguing chemistry and biology of sulfur-containing natural products from marine microorganisms (1987-2020)

Natural products derived from marine microorganisms have received great attention as a potential resource of new compound entities for drug discovery. The unique marine environment brings us a large group of sulfur-containing natural products with abundant biological functionality including antitumor, antibiotic, anti-inflammatory and antiviral activities. We reviewed all the 484 sulfur-containing natural products (non-sulfated) isolated from marine microorganisms, of which 59.9% are thioethers, 29.8% are thiazole/thiazoline-containing compounds and 10.3% are sulfoxides, sulfones, thioesters and many others. A selection of 133 compounds was further discussed on their structure-activity relationships, mechanisms of action, biosynthesis, and druggability. This is the first systematic review on sulfur-containing natural products from marine microorganisms conducted from January 1987, when the first one was reported, to December 2020.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00101-2.

Neuronal Modulators from the Coral-Associated Fungi Aspergillus candidus

Three new p-terphenyl derivatives, named 4″-O-methyl-prenylterphenyllin B (1) and phenylcandilide A and B (17 and 18), and three new indole-diterpene alkaloids, asperindoles E-G (22-24), were isolated together with eighteen known analogues from the fungi Aspergillus candidus associated with the South China Sea gorgonian Junceela fragillis. The structures and absolute configurations of the new compounds were elucidated on the basis of spectroscopic analysis, and DFT/NMR and TDDFT/ECD calculations. In a primary cultured cortical neuronal network, the compounds 6, 9, 14, 17, 18 and 24 modulated spontaneous Ca²⁺ oscillations and 4-aminopyridine hyperexcited neuronal activity. A preliminary structure-activity relationship was discussed.

Naturally occurring prenylated chalcones from plants: structural diversity, distribution, activities and biosynthesis

Covering: up to July 2020Naturally occurring chalcones carrying up to three modified or unmodified C5-, C10-, and C15-prenyl moieties on both rings A and B as well as at the α- and β-carbons are widely distributed in plants of the families of Fabaceae, Moraceae, Zingiberaceae and Cannabaceae. Xanthohumol and isobavachalcone being the most investigated representatives, exhibit diverse and remarkable biological and pharmacological activities. The present review deals with their structural characters, biological activities and occurrence in the plant kingdom. Biosynthesis of prenylated chalcones and metabolism of xanthohumol are also discussed.

The coupled reaction catalyzed by EchB and EchC lead to the formation of the common 2',3',5'-trihydroxy-benzene core in echosides biosynthesis

p-Terphenyls represent a unique family of aromatic natural products generated by nonribosomal peptide synthetase-like (NRPS-like) enzyme. After formation of p-terphenyl skeleton, tailoring modifications will give rise to structural diversity and various biological activities. Here we demonstrated a two-enzyme (EchB, a short-chain dehydrogenase/reductase (SDR), and EchC, a nuclear transport factor 2 (NTF2)-like dehydratase) participated transformation from dihydroxybenzoquinone core to 2',3',5'-trihydroxy-benzene in the biosynthesis of echosides. Beginning with polyporic acid as substrate, successive steps of reduction-dehydration-reduction cascade catalyzed by EchB-EchC-EchB were concluded after in vivo gene disruption and in vitro bioassay experiments. These findings demonstrated a conserved synthesis pathway of 2',3',5'-trihydroxy-p-terphenyls in bacteria, such as Actinomycetes and Burkholderia. The parallel pathway in fungi has yet to be explored.

Antibacterial p-Terphenyl with a Rare 2,2'-Bithiazole Substructure and Related Compounds Isolated from the Marine-Derived Actinomycete Nocardiopsis sp. HDN154086

Assisted by MS/MS-based molecular networking and X-ray diffraction analysis, five new p-terphenyl derivatives, namely, nocarterphenyls D-H (1-5), were obtained and characterized from the cultures of the marine sediment-derived actinomycete Nocardiopsis sp. HDN154086. The skeleton of nocarterphenyl D (1) was defined to possess a rare 2,2'-bithiazole scaffold, naturally occurring for the first time, and nocarterphenyls E-H (2-5) are p-terphenylquinones with unusual thioether linked fatty acid methyl ester substitutions. Compound 1 showed promising activity against multiple bacteria with MIC values ranging from 1.5 to 6.2 μM, and 2 exhibited notable antibacterial activity against MRSA which surpassed the positive control ciprofloxacin.

p-Terphenyls From Aspergillus sp. GZWMJZ-055: Identification, Derivation, Antioxidant and α-Glycosidase Inhibitory Activities

One new (1) and fifteen known (2–16) p-terphenyls were isolated from a solid culture of the endophytic fungus Aspergillus sp. GZWMJZ-055 by adding the leaves of its host Eucommia ulmoides. Furthermore, nine p-terphenyls (17–25) were synthesized from the main compounds (5–7), among which derivatives 18, 19, 21, 22, and 25 are new p-terphenyls. Compounds 15 and 16 were also, respectively, synthesized from compounds 6 and 7 by oxidative cyclization of air in the presence of silica gel. These p-terphenyls especially those with 4,2′,4″-trihydroxy (4–7, 20, 21) or 4, 4″-dihydroxy-1,2,1′,2′-furan (15, 16) substituted nucleus, exhibited significant antioxidant and α-glucosidase inhibitory activities and lower cytotoxicity to caco-2 cells. The results indicated their potential use as lead compounds or dietary supplements for treating or preventing the diabetes.

The genus Sphingopyxis: Systematics, ecology, and bioremediation potential - A review

The genus Sphingopyxis was first reported in the year 2001. Phylogenetically, Sphingopyxis is well delineated from other genera Sphingobium, Sphingomonas and Novosphingobium of sphingomonads group, family Sphingomonadaceae of Proteobacteria. To date (at the time of writing), the genus Sphingopyxis comprises of twenty validly published species available in List of Prokaryotic Names with Standing in Nomenclature. Sphingopyxis spp. have been isolated from diverse niches including, agricultural soil, marine and fresh water, caves, activated sludge, thermal spring, oil and pesticide contaminated soil, and heavy metal contaminated sites. Sphingopyxis species have drawn considerable attention not only for their ability to survive under extreme environments, but also for their potential to degrade number of xenobiotics and other environmental contaminants that impose serious threat to human health. At present, genome sequence of both cultivable and non-cultivable strains (metagenome assembled genome) are available in the public databases (NCBI) and genome wide studies confirms the presence of mobile genetic elements and plethora of degradation genes and pathways making them a potential candidate for bioremediation. Beside genome wide predictions there are number of experimental evidences confirm the degradation potential of bacteria belonging to genus Sphingopyxis and also the production of different secondary metabolites that help them interact and survive in their ecological niches. This review provides detailed information on ecology, general characteristic and the significant implications of Sphingopyxis species in environmental management along with the bio-synthetic potential.

Polyhydroxy p-Terphenyls from a Mangrove Endophytic Fungus Aspergillus candidus LDJ-5

Six undescribed polyhydroxy p-terphenyls, namely asperterphenyllins A–F, were isolated from an endophytic fungus Aspergillus candidus LDJ-5. Their structures were determined by NMR and MS data. Differing from the previously reported p-terphenyls, asperterphenyllin A represents the first p-terphenyl dimer connected by a C-C bond. Asperterphenyllin A displayed anti-influenza virus A (H1N1) activity and protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with IC₅₀ values of 53 μM and 21 μM, respectively. The anti-influenza virus A (H1N1) activity and protein tyrosine phosphatase 1B (PTP1B) inhibitory activity of p-terphenyls are reported for the first time. Asperterphenyllin G exhibited cytotoxicity against nine cell lines with IC₅₀ values ranging from 0.4 to 1.7 μM. Asperterphenyllin C showed antimicrobial activity against Proteus species with a MIC value of 19 μg/mL.

A one-pot protocol for the fluorosulfonation and Suzuki coupling of phenols and bromophenols, streamlined access to biaryls and terphenyls

A one-pot protocol for the fluorosulfation and Suzuki coupling of phenols is described. The tandem reaction proceeds efficiently at room temperature, and various biaryls and biaryl fluorosulfates were obtained in good to excellent yields. Furthermore, biaryl fluorosulfates were utilized as versatile building blocks for the preparation of terphenyls.

Not all saponins have a greater antiprotozoal activity than their related sapogenins

The antiprotozoal effect of saponins varies according to both the structure of the sapogenin and the composition and linkage of the sugar moieties to the sapogenin. The effect of saponins on protozoa has been considered to be transient as it was thought that when saponins were deglycosilated to sapogenins in the rumen they became inactive; however, no studies have yet evaluated the antiprotozoal effect of sapogenins compared to their related saponins. The aims of this study were to evaluate the antiprotozoal effect of eighteen commercially available triterpenoid and steroid saponins and sapogenins in vitro, to investigate the effect of variations in the sugar moiety of related saponins and to compare different sapogenins bearing identical sugar moieties. Our results show that antiprotozoal activity is not an inherent feature of all saponins and that small variations in the structure of a compound can have a significant influence on their biological activity. Some sapogenins (20(S)-protopanaxatriol, asiatic acid and madecassic acid) inhibited protozoa activity to a greater extent than their corresponding saponins (Re and Rh₁ and asiaticoside and madecassoside), thus the original hypothesis that the transient nature of the antiprotozoal action of saponins is due to the deglycosilation of saponins needs to be revisited.

Natural product diversity from the endophytic fungi of the genus Aspergillus

The endophytic fungus Aspergillus is considered as an enormous source of chemical leads with promising biological activities. Different Aspergillus species have proved their ability to produce plenty of secondary metabolites including butenolides, alkaloids, terpenoids, cytochalasins, phenalenones, ρ-terphenyls, xanthones, sterols, diphenyl ether and anthraquinone derivatives with diverse biological activities, such as anti-cancer, antifungal, anti-bacterial, anti-viral, anti-inflammatory, antitrypanosomal and antileishmanial activities. From January 2015 until December 2019, three hundred and sixty-one secondary metabolites were reported from different endophytic Aspergillus species. This review discusses the isolated secondary metabolites from different endophytic Aspergillus species reported from January 2015 to December 2019 along with their reported biological activities and structural aspects whenever applicable.

Prenylated p-Terphenyls from a Mangrove Endophytic Fungus, Aspergillus candidus LDJ-5

Nine previously undescribed prenylated p-terphenyls, prenylterphenyllins F-J (1, 2, 4-6) and prenylcandidusins D-G (3, 7-9), were isolated from an endophytic fungus, Aspergillus candidus LDJ-5. Their structures were determined from NMR and MS data. Differing from previously reported p-terphenyls, compound 3 represents a rare 6,5,6,6-fused ring system. Compounds 4-6 are antimicrobial, and compounds 1, 4, 6, and 9 are cytotoxic.

Cytotoxic p-Terphenyls from a Marine-Derived Nocardiopsis Species

Three new p-terphenyl derivatives, nocarterphenyls A-C (1-3), along with three known analogues (4-6) were isolated from the marine-derived actinobacterial strain Nocardiopsis sp. OUCMDZ-4936. Their structures were elucidated on the basis of spectroscopic analysis and a single-crystal X-ray diffraction experiment. Compounds 1 and 2 possess a benzothiazole and benzothiazine moiety, respectively, which are rare in the skeleton of p-terphenyls. Nocarterphenyl A (1) showed potent cytotoxic activity against the HL60 and HCC1954 cancer cell lines with the IC₅₀ values of 0.38 and 0.10 μM among 26 human cancer cell lines.

A new p-terphenyl derivative from the fruiting bodies of Sarcodon imbricatus (L.) P. Karst

A new p-terphenyl, 2',3'-diacetoxy-4,5,5',6',4'',5''-hexahydroxy-p-terphenyl (1), along with 12 known compounds were isolated from the fruiting bodies of Sarcodon imbricatus (Bankeraceae). Their structures were confirmed on the basis of extensive spectroscopic analysis and comparison with the spectral data in the literature. Compound 1 exhibited weak cytotoxicity against colon cancer SW480 and leukemia HL-60 cell lines, with IC₅₀ values of 55.02 ± 1.79 μM and 44.71 ± 2.15 μM, respectively.

p-Terphenyls and actinomycins from a Streptomyces sp. associated with the larva of mud dauber wasp

In the course of searching for cytotoxic metabolites from insects associated actinomyces, two new natural p-terphenyl glycosides, strepantibin D (1) and strepantibin E (2), along with terferol (3), actinomycin D (4), actinomycin V (5) and actinomycin V_0β (6), were identified from the fermentation medium of a Streptomyces sp. which was obtained from the larva body of mud dauber wasp. Strepantibin D (1), previously reported as a synthetic derivative of terfestatin A, is firstly isolated as a natural p-terphenyl in this research. Strepantibin D (1) and terferol (3) showed medium cytotoxic activity against breast cancer cells MCF-7, MDA-MB-231 and BT-474. Actinomycins (4-6), especially actinomycin V (5), displayed remarkable cytotoxicity against breast cancer cells, with IC₅₀ values ranging from 0.83 nM to 369.90 nM.

Strepantibins A-C: Hexokinase II Inhibitors from a Mud Dauber Wasp Associated Streptomyces sp

Two new p-terphenyls, strepantibins A and B (1 and 2), along with the first representative of a naturally occurring bisphenyltropone, strepantibin C (3), were characterized from a Streptomyces sp. associated with the larvae of the mud dauber wasp Sceliphron madraspatanum. Their structures were determined by high-resolution electrospray ionization mass spectrometry, NMR, and X-ray crystallography data interpretation. Strepantibins A-C inhibited hexokinase II (HK2) activity and displayed antiproliferative activity against hepatoma carcinoma cells HepG-2, SMMC-7721 and plc-prf-5. In SMMC-7721 cells treated with strepantibin A, the morphological characteristics of apoptosis were observed.

Temperature-controlled sequential Suzuki-Miyaura reactions for preparing unsymmetrical terphenyls

A one-pot protocol of double Suzuki-Miyaura reactions has been developed for the synthesis of unsymmetrical terphenyls. In the absence of a ligand, potassium bromophenyltrifluoroborate reacts with arylboronic acid and then sequentially with a hetero/aryl bromide by controlling the reaction temperature, providing unsymmetrical p- and m-terphenyl compounds in moderate to good overall yields. This protocol provides a convenient and practical approach to unsymmetrical terphenyls under ligand-free and aerobic conditions.

Isolation and Characterization of a Bacterial Strain Capable of Efficient Berberine Degradation

Background: Berberine (BBR) is a pharmaceutical chemical with a broad antibacterial spectrum, and its biological treatment has been of research and practical interest. In this study, a pure bacterial strain B16 was isolated from the activated sludge in a pharmaceutical wastewater treatment plant. The aim of the study is to characterize the properties of the strain B16, especially its BBR degradation capability. Methods: The identification of strain B16 was conducted by visual observation, as well as biochemical and phylogenetic analysis. The degradation kinetics of strain B16 was tentatively described by Haldane model. Results: The strain B16 was 100% determined as a Sphingopyxis sp. The kinetic parameters of BBR degradation by strain B16 were as follows: Vmax 54.73 ± 5.54 mg (g MLSS · h)⁻¹, Km 66.68 ± 8.95 mg L⁻¹, and Ki 43.16 ± 5.92 mg L⁻¹, with an R² of 0.996. Stain B16 exhibited considerable capability of BBR degradation. BBR of initial concentration 40 mg L⁻¹ could be completely degraded in 48 h under optimal conditions. Conclusions: strain B16 was the first pure culture found with the ability to totally mineralize BBR, indicating the potential of B16 application in real industrial processes.

Cytotoxic p-Terphenyls from the Endolichenic Fungus Floricola striata

Eleven new p-terphenyls, floricolins K-U (1-11), together with 13 biosynthetically related known compounds (12-24) were isolated from an endolichenic fungus, Floricola striata. Their structures were elucidated by extensive spectroscopic analyses and single-crystal X-ray diffraction measurements. The newly isolated p-terphenyls inhibited the growth of A2780, MCF-7, and A549 cell lines. Further evaluation for the multidrug resistance (MDR) reversal activity of compound 5 revealed it enhanced the sensitivity of MCF-7/ADR cells toward adriamycin 39-fold at 10 μM through modulating P-glycoprotein-mediated drug exclusion.