The Natural Products Discovery Center: Release of the First 8490 Sequenced Strains for Exploring Actinobacteria Biosynthetic Diversity.

Actinobacteria, the bacterial phylum most renowned for natural product discovery, has been established as a valuable source for drug discovery and biotechnology but is underrepresented within accessible genome and strain collections. Herein, we introduce the Natural Products Discovery Center (NPDC), featuring 122,449 strains assembled over eight decades, the genomes of the first 8490 NPDC strains (7142 Actinobacteria), and the online NPDC Portal making both strains and genomes publicly available. A comparative survey of RefSeq and NPDC Actinobacteria highlights the taxonomic and biosynthetic diversity within the NPDC collection, including three new genera, hundreds of new species, and ~7000 new gene cluster families. Selected examples demonstrate how the NPDC Portal's strain metadata, genomes, and biosynthetic gene clusters can be leveraged using genome mining approaches. Our findings underscore the ongoing significance of Actinobacteria in natural product discovery, and the NPDC serves as an unparalleled resource for both Actinobacteria strains and genomes.

Anoectochiluszhongshanensis (Orchidaceae), a new species from Guangxi, China.

A new species of Anoectochilus (Orchidaceae) from Guangxi, China, A.zhongshanensis, is described here, which was identified based on phylogenetic studies adopting combined plastid markers (rbcL-matK-trnL-F), morphological observation and chemical analysis. Molecular phylogenetic results support the systematic status of A.zhongshanensis as a new species in Anoectochilus genus. Morphologically, this new species is similar to A.zhejiangensis and A.malipoensis, but differs by its characteristic labellum and column, including the hastate or scalpel-shaped lobes of epichile, forward curved and pinnately divided cristate lobes at both sides of the mesochile and inverted triangle column wings. Furthermore, HPLC-ELSD analysis of these three species revealed the interesting chemotaxonomic difference that the principle and characteristic lactone glycoside in this new species was kinsenoside, rather than its diastereoisomer, goodyeroside A, a major glycoside in A.zhejiangensis and A.malipoensis.

Mechanisms of Epichloë bromicola to Promote Plant Growth and Its Potential Application for Coix lacryma-jobi L. Cultivation.

Endophytic fungi play important roles in regulating plant growth and development and usually used as a promising strategy to enhance the biosynthesis of host valuable secondary metabolite, but the underlying growth-promoting mechanisms are only partly understood. In this study, the wild-type Arabidopsis thaliana seedlings co-cultured with fungal endophyte Epichloë bromicola showed auxin (IAA)-stimulated phenotypes, and the growth-promoting effects caused by E. bromicola were further verified by the experiments of spatially separated co-culture and fungal extract treatment. IAA was detected and identified in the extract of E. bromicola culture by LC-HRMS/MS, whereas 2,3-butanediol was confirmed to be the predominant volatile active compound in the diethyl ether and ethyl acetate extracts by GC-MS. Further study observed that IAA-related genes including synthesis key enzyme genes (CYP79B2, CYP79B3, NIT1, TAA1 and YUCCA1) and controlling polar transport genes (AUX1, BIG, EIR1, AXR3 and ARF1), were highly expressed at different periods after E. bromicola inoculation. More importantly, the introduction of fungal endophyte E. bromicola could effectively promote the growth and accumulation of coixol in Coix under soil conditions. Our study showed that endophytic fungus E. bromicola might be considered as a potential inoculant for improving medicinal plant growth.

Corrigendum to "Quantitative determination of multi-class bioactive constituents for quality assessment of ten Anoectochilus, four Goodyera and one Ludisia species in China" [Chinese Herbal Medicines 12 (2020) 430-439].

[This corrects the article DOI: 10.1016/j.chmed.2020.07.002.].

PtmC Catalyzes the Final Step of Thioplatensimycin, Thioplatencin, and Thioplatensilin Biosynthesis and Expands the Scope of Arylamine N-Acetyltransferases.

The members of the arylamine N-acetyltransferase (NAT) family of enzymes are important for their many roles in xenobiotic detoxification in bacteria and humans. However, very little is known about their roles outside of detoxification or their specificities for acyl donors larger than acetyl-CoA. Herein, we report the detailed study of PtmC, an unusual NAT homologue encoded in the biosynthetic gene cluster for thioplatensimycin, thioplatencin, and a newly reported scaffold, thioplatensilin, thioacid-containing diterpenoids and highly potent inhibitors of bacterial and mammalian fatty acid synthases. As the final enzyme of the pathway, PtmC is responsible for the selection of a thioacid arylamine over its cognate carboxylic acid and coupling to at least three large, 17-carbon ketolide-CoA substrates. Therefore, this study uses a combined approach of enzymology and molecular modeling to reveal how PtmC has evolved from the canonical NAT scaffold into a key part of a natural combinatorial biosynthetic pathway. Additionally, genome mining has revealed the presence of other related NATs located within natural product biosynthetic gene clusters. Thus, findings from this study are expected to expand our knowledge of how enzymes evolve for expanded substrate diversity and enable additional predictions about the activities of NATs involved in natural product biosynthesis and xenobiotic detoxification.

Quantitative determination of multi-class bioactive constituents for quality assessment of ten Anoectochilus, four Goodyera and one Ludisia species in China.

Objective: To establish multi-class bioactive constituents' determination of ten Anoectochilus, four Goodyera and one Ludisia species, and provide reference for the improvement of their quality control. Methods: HPLC-ELSD and phenol-sulphuric acid methods were used for the quantitative determination of lactone glycosides (kinsenoside and its diastereoisomer, goodyeroside A) and polysaccharides, respectively, while an efficient iHPLC-MS/MS method was established for rapid determination of other minor constituents in ten Anoectochilus species and five related species. Results: The contents of kinsenoside, goodyeroside A, polysaccharides and flavonoids varied notably almost in all tested samples, including both wild plants and tissue cultures. In particular, kinsenoside was the major lactone glycoside in A. roxburghii, A. formosanus, A. xingrenensis, A. nandanensis, A. brevilabris and A. burmannicus, whereas goodyeroside A was the predominant constituent in A. lylei, A. longilobus, A. elatus, A. zhejiangensis, G. schlechtendaliana, G. biflora, G. yangmeishanensi, G. repens and Ludisia discolor. Conclusion: Our present study suggested that A. lylei, A. longilobus, A. elatus, A. zhejiangensis, Ludisia discolor and Goodyera species cannot be used as alternatives for A. roxburghii, and goodyeroside A may be reasonably used as a diagnostic marker for distinguishing A. roxburghii from A. lylei, A. longilobus, A. elatus and A. zhejiangensis, Goodyera and Ludisia species. The established method thus could be potentially used for the quality evaluation and control of Anoectochilus and some related species.

The regulatory mechanism of fungal elicitor-induced secondary metabolite biosynthesis in medical plants.

A wide range of external stress stimuli trigger plant cells to undergo complex network of reactions that ultimately lead to the synthesis and accumulation of secondary metabolites. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Throughout evolution, endophytic fungi, an important constituent in the environment of medicinal plants, have known to form long-term stable and mutually beneficial symbiosis with medicinal plants. The endophytic fungal elicitor can rapidly and specifically induce the expression of specific genes in medicinal plants which can result in the activation of a series of specific secondary metabolic pathways resulting in the significant accumulation of active ingredients. Here we summarize the progress made on the mechanisms of fungal elicitor including elicitor signal recognition, signal transduction, gene expression and activation of the key enzymes and its application. This review provides guidance on studies which may be conducted to promote the efficient synthesis and accumulation of active ingredients by the endogenous fungal elicitor in medicinal plant cells, and provides new ideas and methods of studying the regulation of secondary metabolism in medicinal plants.

Flavonoids from Caragana pruinosa roots.

A new pterocarpan derivative, pruinosanone D (1), a new isoflavonoid, pruinosanone E (2), and a new chalcone, pruinosanone F (3), were isolated from Caragana pruinosa roots, along with four known analogues (4-7), identified as 2,4-dihydroxy-3'-methoxy-4'-ethoxychalcone, 7,4-dihydroxyflavanone, butin and scutellaprostin C, respectively. Their structures were elucidated by detailed analyses of NMR, IR, and MS data. The ability of the isolated compounds to prevent nitric oxide (NO) production by LPS-stimulated RAW 264.7 macrophages was also studied. Compound 1 were among the most potent NO production inhibitor, with IC50 value of 0.62µM.

Matrine Exerts a Strong Anti-Arthritic Effect on Type II Collagen-Induced Arthritis in Rats by Inhibiting Inflammatory Responses.

To investigate anti-arthritic effects of matrine isolated from the roots of S. flavescens on type II collagen-induced arthritis (CIA) in rats and to explore its related potential mechanisms, CIA rats were established and administered with matrine (20, 40 or 80 mg/kg/days, for 30 days). Subsequently, blood was collected to determine serum levels of TNF-α, IL-1ß, IL-6, IL-8, IL-17A, IL-10, MMP-2, MMP-3 and MMP-9, and hind paws and knee joints were collected for histopathological examination. Furthermore, indices of the thymus and spleen were determined, and synovial tissues were collected to determine the protein expressions of p-IκB, IκB, Cox-2 and iNOS. Our results indicated that matrine significantly suppressed inflammatory reactions and synovial tissue destruction. Matrine inhibited paw swelling, arthritis indices and weight loss in CIA rats. Additionally, matrine decreased the levels of TNF-α, IL-1ß, IL-6, IL-8, IL-17A, MMP-2, MMP-3 and MMP-9. Matrine also down-regulated expressions of p-IκB, Cox-2, and iNOS but up-regulated IκB in synovial tissues in CIA rats. The results suggested matrine possesses an anti-arthritic effect in CIA rats via inhibiting the release of pro-inflammatory cytokines and proteins that promote the NF-κB pathway.

A Friendly Relationship between Endophytic Fungi and Medicinal Plants: A Systematic Review.

Endophytic fungi or endophytes exist widely inside the healthy tissues of living plants, and are important components of plant micro-ecosystems. Over the long period of evolution, some co-existing endophytes and their host plants have established a special relationship with one and another, which can significantly influence the formation of metabolic products in plants, then affect quality and quantity of crude drugs derived from medicinal plants. This paper will focus on the increasing knowledge of relationships between endophytic fungi and medicinal plants through reviewing of published research data obtained from the last 30 years. The analytical results indicate that the distribution and population structure of endophytes can be considerably affected by factors, such as the genetic background, age, and environmental conditions of their hosts. On the other hand, the endophytic fungi can also confer profound impacts on their host plants by enhancing their growth, increasing their fitness, strengthening their tolerances to abiotic and biotic stresses, and promoting their accumulation of secondary metabolites. All the changes are very important for the production of bioactive components in their hosts. Hence, it is essential to understand such relationships between endophytic fungi and their host medicinal plants. Such knowledge can be well exploited and applied for the production of better and more drugs from medicinal plants.

Phytochemical and Pharmacological Profiles of Three Fagopyrum Buckwheats.

The genus Fagopyrum (Polygonaceae), currently comprising 15 species of plants, includes three important buckwheat species: Fagopyrum esculentum (F. esculentum) Moench. (common buckwheat), Fagopyrum tataricum (F. tataricum) (L.) Gaertn. (tartary buckwheat) and Fagopyrum dibotrys (F. dibotrys) (D. Don) Hara. (perennial buckwheat), which have been well explored due to their long tradition of both edible and medicinal use. This review aimed to present an up-to-date and comprehensive analysis of the phytochemistry and pharmacology of the three Fagopyrum buckwheats. In addition, the scope for future research was also discussed. All available references included in this paper were compiled from major databases, such as MEDLINE, Pubmed, Scholar, Elsevier, Springer, Wiley and CNKI. A total of 106 compounds isolated from three Fagopyrum buckwheats can be mainly divided into six classes: flavonoids, phenolics, fagopyritols, triterpenoids, steroids and fatty acids. Flavonoids and phenolic compounds were considered to be the major active components. Considerable pharmacological experiments both in vitro and in vivo have validated that Fagopyrum buckwheats possess antitumor, anti-oxidant, anti-inflammatory, hepatoprotective, anti-diabetic activities, etc. All reported data lead us to conclude that Fagopyrum buckwheats have convincing medicinal potential. However, further research is needed to explore its bioactive constituents, the relationship to their structural activities and the molecular mechanisms of action.

Medicinal plant cell suspension cultures: pharmaceutical applications and high-yielding strategies for the desired secondary metabolites.

The development of plant tissue (including organ and cell) cultures for the production of secondary metabolites has been underway for more than three decades. Plant cell cultures with the production of high-value secondary metabolites are promising potential alternative sources for the production of pharmaceutical agents of industrial importance. Medicinal plant cell suspension cultures (MPCSC), which are characterized with the feature of fermentation with plant cell totipotency, could be a promising alternative "chemical factory". However, low productivity becomes an inevitable obstacle limiting further commercialization of MPCSC and the application to large-scale production is still limited to a few processes. This review generalizes and analyzes the recent progress of this bioproduction platform for the provision of medicinal chemicals and outlines a range of trials taken or underway to increase product yields from MPCSC. The scale-up of MPCSC, which could lead to an unlimited supply of pharmaceuticals, including strategies to overcome and solution of the associated challenges, is discussed.

Kaempferitrin prevents bone lost in ovariectomized rats.

BACKGROUND: Podocarpium podocarpum (DC.), an edible and medicinal plant popularly used for the treatment of bruises and fracture in Chinese folk medicine, has been proved to possess significant antiosteoporotic effect in our latest research. PURPOSE: Our study aimed to investigate the in vitro and in vivo antiosteoporotic effect of kaempfertrin (KN), a principal flavonoid in P. podocarpum obtained through bio-guided isolation. METHODS: An ovariectomized (OVX) rat model of osteoporosis as well as in vitro osteoblast and osteoclast cell lines were employed to evaluate the antiosteoporotic potency of KN. RESULTS: KN significantly improved the bone mass and microarchitecture in OVX rats, with little estrogen-like side effect compared with estradiol valerate. KN also exhibited stimulatory effect on osteoblastic cells and inhibitory action on osteoclastic cells, which down-regulated the phosphorylation level of I-κB. CONCLUSION: KN possessed significant antiosteoporotic activity. Combined with its limited estrogen-like side effect, KN can be regarded as an idealistic antiosteoporotic candidate for human osteoporosis diseases.

Hepatoprotective activity of total iridoid glycosides isolated from Paederia scandens (lour.) Merr. var. tomentosa.

ETHNOPHARMACOLOGICAL RELEVANCE: Currently, human liver is susceptible to injury caused by alcohol and virus infiltration, resulting in hepatitis, cirrhosis, and even hepatocellular carcinoma. Paederia scandens (Lour.) Merr. var. tomentosa (Rubiaceae) has been used as traditional medicine in Asian countries to treat jaundice, dysentery, and abdominal mass. Furthermore, the abundance of iridoid glycosides in Paederia species indicates their notable hepatoprotective potential. MATERIALS AND METHODS: Total iridoid glycosides (TG) was prepared, and constituents of TG were analyzed by HPLC. TG and silymarin (positive) were orally administered for 15 days. Then, acute liver injury rats was induced by intraperitoneally injection (i.p.) of 10% CCl4 (0.12%, v/v, dissolved in olive oil, 10 mL/kg, body weight). Rats were sacrificed at 16 h after CCl4 injection. Liver tissues and blood were collected. Serum samples were prepared to determine the activities of alanine transaminase (ALT) and aspartate transaminase (AST), whereas liver tissue sections were prepared for the purpose of examining possible liver histopathological changes. In addition, antioxidant enzyme activities in liver tissues were also evaluated. RESULTS: Our results demonstrated that TG significantly decreased the levels of AST and ALT, compared with those in control rats. In addition, pre-treatment of the rats with TG clearly alleviated their liver tissue injuries. What's more, the activities of GSH, GAT and SOD in the groups of TG-treated rats were significantly increased compared with those of rats in the control group, whereas the levels of MDA were decreased. CONCLUSIONS: Our present research indicated that TG possessed notable hepatoprotective activity via decreasing oxidative stress level in liver tissues.

Phytochemical and Pharmacological Profile of Vitex negundo.

The article aims to review all the chemical constituents and pharmacological properties of Vitex negundo L. (Verbenaceae) (VN). VN is an important medicinal plant used as reputed herbal medicine with versatile pharmacological activities in China, India and Japan. A total of 104 referred articles about VN were compiled from major databases and academic publishers, such as MEDLINE, Pubmed, Scholar, Elsevier, Springer, Wiley and CNKI. As a result, a total of 120 compounds isolated from VN can be divided mainly into four classes: flavonoids, lignans, terpenoids and steroids. The crude extracts and purified compounds of VN exhibited promising bioactivities, including anti-nociceptive, antiinflammatory, anti-tumor, anti-oxidant, insecticidal, antimicrobial, anti-androgenic, anti-osteoporotic, anti-cataract, hepatoprotective and anti-hyperglycemic activity. All the reported data lead us to conclude that VN has convincing medicinal potential. However, further researches are needed to explore its bioactive constituents, the structure-activity relationship and their molecular mechanisms of action.

Antiosteoporotic activity and constituents of Podocarpium podocarpum.

Our study aimed to investigate the antiosteoporotic properties of the ethanol extract of Podocarpium podocarpum (DC.) Yang et Huang (PE) in ovariectomized (OVX) rats and to characterize the active constituents. As a result, PE significantly inhibited the increased urinary Ca excretion and activity of bone resorption markers including tartrate-resistant acid phosphatase (TRAP), deoxypyridinoline crosslinks and cathepsin K in OVX rats, whereas exhibited little effects on the body, uterus and vagina weight. Detailed micro-CT analysis showed that PE notably enhanced bone quality, with increased bone mineral content (BMC), bone volume fraction (BVF), connectivity density (CD), tissue mineral content (TMC), tissue mineral density (TMD) and trabecular number (Tb. N), and decreased trabecular separation (Tb. Sp), in OVX animal. Those findings implied that PE had notable antiosteoporotic effect, especially effective in preventing bone resorption, with little side-effects on reproductive tissue. Further chemical investigation led to the isolation of 17 flavonoids, most of which showed significantly stimulatory effect on osteoblastic proliferation, ALP activity and mineralized nodes formation as well as inhibitory effect on osteoclastic TRAP activity in osteoblastic and osteoclastic cells. Our results indicated that PE, with abundant flavonoids, had remarkable antiosteoporotic activity and therefore can be a promising candidate for the treatment of postmenopausal osteoporosis induced by estrogen deficiency through herbal remedy.

Antiinflammatory effects and chemical constituents of Veronicastrum axillare.

Our study aims to ascertain the antiinflammatory activity of Veronicastrum axillare and characterize the bioactive constituents. Antiinflammatory activity of the total extract and different fractions from V. axillare was investigated by employing the xylene-induced mouse ear edema model. As a result, the ethyl acetate (EtOAc) fraction showed the highest antiinflammatory activity in vivo. From the EtOAc fraction and the inactive dichloromethane fraction, a total of five new compounds, axillasides A-C and axillactones A and B, together with four known compounds, procumboside A, buergeriside C1 , indole-3-carboxylic acid and apigenin, were isolated and identified. Their structures were elucidated on the basis of spectroscopic analysis and by comparison of their nuclear magnetic resonance data with those reported in the literature. Procumboside A, a major constituent in EtOAc fraction, showed significant antiinflammatory activity in vivo. Further studies revealed that procumboside A was a potent COX-2 inhibitor, significantly reducing the COX-2 protein level in lipopolysaccharide-stimulated RAW 264.7 macrophages.

Anti-arthritic activity of Xanthium strumarium L. extract on complete Freund׳s adjuvant induced arthritis in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Xanthium strumarium L. fruit (Xanthiu fruit) has been traditionally used as a medicinal herb in China for the treatment of many ailments including rheumatoid arthritis. However, the anti-arthritic activity of Xanthium strumarium fruit has still not been demonstrated. In the present study, we confirmed that the extract of Xanthium strumarium (EXS) prevents rheumatoid arthritis induced by Complete Freund׳s Adjuvant (CFA) in rats. MATERIALS AND METHODS: Male Wistar rats (160±10 g) were immunized by intradermal injection of 0.1 mL of CFA into the left hind metatarsal footpad. EXS was administered orally at a dose of 300 and 75 mg/kg once a day after the induction of adjuvant arthritis. Methotrexate (3 mg/kg, twice a week) was used as a positive control. Paw swelling, arthritic score, body weight loss, spleen index, thymus index, serum cytokines, inflammatory mediators and histological change were measured. The chemical profile of EXS was analyzed by HPLC-DAD. RESULTS: We found that the EXS significantly suppressed paw swelling and arthritic score, increased body weight loss and decreased the thymus index. The overproduction of TNF-α and IL-1ß were remarkably suppressed in the serum of all EXS-treated rats, and in contrast IL-10 was markedly increased. The level of COX-2 and 5-LOX was also decreased with EXS treatment. Ten phenolic acid derivatives were identified from 14 detected peaks by HPLC-DAD with the reference substances and verified by LC-MS. CONCLUSIONS: These results suggest the potential effect of EXS as an anti-arthritis agent towards CFA-induced arthritis in rats. Xanthium strumarium has the potential to be regarded as a candidate for use in general therapeutics and as an immune-modulatory medicine in rheumatoid arthritis.

Therapeutic effects of standardized Vitex negundo seeds extract on complete Freund's adjuvant induced arthritis in rats.

The seeds of Vitex negundo L. (Verbenaceae) have been commonly used as a folk remedy for the treatment of rheumatism and joint inflammation in Traditional Chinese Medicine. This study aimed to evaluate the anti-arthritic activity of the extract of V. negundo seeds (EVNS) using Freund's complete adjuvant (CFA) induced arthritis (AA) in rat model. As a result, EVNS, with abundant phenylnaphthalene-type lignans, significantly inhibited the paw edema, decreased the arthritis score and spleen index, and reversed the weight loss of CFA-injected rats. Histopathological studies showed a marked decrease of synovial inflammatory infiltration and synovial lining hyperplasia in the joints of EVNS-treated animals. The remarkable decrement of serum inflammatory factors (TNF-α, IL-1ß and IL-6) were observed in EVNS-treated rats, whereas, IL-10, an anti-inflammatory cytokine, was found to be significantly increased by EVNS. The expressions of COX-2 and 5-LOX in PBMC were also inhibited by administration of EVNS. Our results demonstrated that V. negundo seeds possessed potential therapeutic effect on adjuvant induced arthritis in rats by decreasing the levels of TNF-α, IL-1ß and IL-6 and increasing that of IL-10 in serum as well as down-regulating the levels of COX-2 and 5-LOX, and therefore may be an effective cure for the treatment of human rheumatoid arthritis.

Anti-allergic rhinitis effect of caffeoylxanthiazonoside isolated from fruits of Xanthium strumarium L. in rodent animals.

The fruits of Xanthium strumarium L. (Asteraceae) have been used extensively in China for treatment of various diseases such as allergic rhinitis (AR), tympanitis, urticaria and arthritis or ozena. This study was designed to systemically investigate the effects of the caffeoylxanthiazonoside (CXT) isolated from fruits of X. strumarium on AR in rodent animals. Animals were orally administered with CXT. Anti-allergic activity of CXT was evaluated by passive cutaneous anaphylaxis test (PCA); acetic acid-induced writhing tests were used to evaluate the analgesic effects of CXT; acetic acid-induced vascular permeability tests were performed to evaluate anti-inflammatory effect of CXT. Then, the model AR in rats was established to evaluate the effects of CXT on AR with the following tests: the sneezing and nasal scratching frequencies, IgE level in serum, and histopathological examinations. Our results demonstrated that CXT had favorable anti-allergic, anti-inflammatory and analgesic effects. Additionally, we found that CXT was helpful to ameliorate the nasal symptoms and to down-regulate IgE levels in AR rats. Thus, we suggested that CXT can be treated as a candidate for treating AR.