Cheng-Jian Zheng

Recent developments and future prospects of antimicrobial metabolites produced by endophytes

Endophytes, found ubiquitous in all plant species in the world, contribute to their host plants by producing plenty of substances that provide protection and ultimately survival value to the plant. Many researches have proven that endophyte is a new and potential source of novel natural products for exploitation in modern medicine, agriculture and industry. So far, a great number of novel natural products possessing antimicrobial activities have been isolated from endophytes. It is believed that screening for antimicrobial compounds from endophytes is a promising way to overcome the increasing threat of drug resistant strains of human and plant pathogen. Antimicrobial metabolites isolated from endophytes belong to diverse structural classes, including: alkaloids, peptides, steroids, terpenoids, phenols, quinones, and flavonoids. In this review, many well-studied areas are presented and examples will be given to discuss the structure of compounds isolated from endophytes extracts with antimicrobial activities and show the wide variety of approaches taken within the field. These achievements would provide the opportunity to utilize endophytes as a new source for production of antibiotics.

Antiosteoporotic Activity of Anthraquinones from Morinda officinalis on Osteoblasts and Osteoclasts

Bioactivity-guided fractionation led to the successful isolation of antiosteoporotic components, i.e. physicion (1), rubiadin-1-methyl ether (2), 2-hydroxy-1-methoxy- anthraquinone (3), 1,2-dihydroxy-3-methylanthraquinone (4), 1,3,8-trihydroxy-2-methoxy- anthraquinone (5), 2-hydroxymethyl-3-hydroxyanthraquinone (6), 2-methoxyanthraquinone (7) and scopoletin (8) from an ethanolic extract of the roots of Morinda officinalis. Compounds 4-8 are isolated for the first time from M. officinalis. Among them, compounds 2 and 3 promoted osteoblast proliferation, while compounds 4, 5 increased osteoblast ALP activity. All of the isolated compounds inhibited osteoclast TRAP activity and bone resorption, and the inhibitory effects on osteoclastic bone resorption of compounds 1 and 5 were stronger than that of other compounds. Taken together, antiosteoporotic activity of M. officinalis and its anthraquinones suggest therapeutic potential against osteoporosis.

Elicitors from the endophytic fungus Trichoderma atroviride promote Salvia miltiorrhiza hairy root growth and tanshinone biosynthesis

Biotic elicitors can be used to stimulate the production of secondary metabolites in plants. However, limited information is available on the effects of biotic elicitors from endophytic fungi on their host plant. Trichoderma atroviride D16 is an endophytic fungus isolated from the root of Salvia miltiorrhiza and previously reported to produce tanshinone I (T-I) and tanshinone IIA (T-IIA). Here, the effects of extract of mycelium (EM) and the polysaccharide fraction (PSF), produced by T. atroviride D16, on the growth and secondary metabolism of S. miltiorrhiza hairy roots are reported. The results indicated that both EM and PSF promoted hairy root growth and stimulated the biosynthesis of tanshinones in hairy roots. EM slightly suppressed the accumulation of phenolic acids, while PSF had no significant influence on the accumulation of these compounds. When comparing the effects of EM versus PSF, it was concluded that PSF is one of the main active constituents responsible for promoting hairy root growth, as well as stimulating biosynthesis of tanshinones in the hairy root cultures. Moreover, the transcriptional activity of genes involved in the tanshinone biosynthetic pathway increased significantly with PSF treatment. Thus, PSF from endophytic T. atroviride D16 affected the chemical composition of the host plant by influencing the expression of genes related to the secondary metabolite biosynthetic pathway. Furthermore, treatment with PSF can be effectively utilized for large-scale production of tanshinones in the S. miltiorrhiza hairy root culture system.

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

Abstract 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.

Anti-inflammatory diterpenes from the seeds of Vitex negundo.

Phytochemical investigation of a dichloromethane-soluble extract of Vitexnegundo seeds led to the isolation of five labdane diterpenes, negundoins A-E (1-5), a 9,10-seco-abietane diterpene, negundoin F (6), a sandaracopimara-7,15-diene diterpene, negundoin G (7), and two known diterpene derivatives (8, 9). Their chemical structures were elucidated by detailed spectroscopic analyses on the basis of NMR, IR, and MS data. The anti-inflammatory effects of metabolites 1-7 were also evaluated in vitro. Compounds 3 and 5 were among the most potent inhibitors on nitric oxide production by LPS-stimulated RAW 264.7 macrophages, with IC(50) values of 0.12 and 0.23 microM, respectively. Further studies revealed that compounds 3 and 5 (5 microM) significantly reduced the levels of the iNOS protein to 0.40+/-0.13% and 41.02+/-6.02%, respectively, and COX-2 protein to 2.06+/-0.53% and 26.40+/-7.43%, respectively.

Nitric oxide scavenging lignans from Vitex negundo seeds.

A new phenyldihydronaphthalene-type lignan, vitexdoin A (1), a new phenylnaphthalene-type lignan alkaloid, vitedoamine B (2), four new phenylnaphthalene-type lignans, vitexdoins B-E (3-6), and four known lignan derivatives (7-10) were isolated from Vitex negundo seeds. Their structures were elucidated by detailed analyses of NMR, IR, and MS data. The ability of the isolates to prevent nitric oxide (NO) production by LPS-stimulated RAW 264.7 macrophages in a concentration-dependent manner was also studied. Compounds 5, 6, and 9 were among the most potent NO production inhibitors, with IC(50) values of 0.13, 0.15, and 0.11 microM, respectively. The introduction of free hydroxy groups plays a vital role in the potency of these compounds.

Analgesic, anti-inflammatory and antipyretic activities of the petroleum ether fraction from the ethanol extract of Desmodium podocarpum

ETHNOPHARMACOLOGICAL RELEVANCE Desmodium podocarpum is a plant that has been used in the folk medicine to treat febrile diseases, cough and bleeding wounds. However, there is no scientific basis or reports in the modern literature regarding its effectiveness as an analgesic, anti-inflammatory and antipyretic agent. AIMS OF THE STUDY The objective of this study is to evaluate the analgesic, anti-inflammatory and antipyretic activities of the petroleum ether fraction (PEF) from the ethanol extract of Desmodium podocarpum. MATERIALS AND METHODS PEF (50, 100, 200 mg/kg) was estimated for its pharmacological properties by using the acetic acid-induced writhing test, the hot plate test, the Carrageenan-induced rat paw edema model, the dimethylbenzene-induced mouse inflammation model, and the lipopolysaccharide (LPS)-induced rat fever model. In addition, the acute toxicity of PEF was also studied. RESULTS PEF significantly and dose-dependently inhibited the writhing responses in mice, increased reaction time of mice in the hot plate test, reduced carrageenan-induced paw edema in rats and the dimethylbenzene-induced ear edema in mice, and attenuated LPS-induced fever in rats. No death of mice was observed when orally administered PEF up to 4.2 g/kg. CONCLUSIONS These findings suggest that PEF possesses evident analgesic, anti-inflammatory and antipyretic activities, and has a favorable safety, which supports the use of Desmodium podocarpum as an analgesic, anti-inflammatory and antipyretic drug in the folk medicine.

Bioactivity-guided fractionation for analgesic properties and constituents of Vitex negundo L. seeds.

This study was undertaken to ascertain the analgesic properties of Vitex negundo L. seeds and to isolate and characterize the active constituents. Among the 80% ethanol extract and some fractions with different polarity, the acetoacetate fraction showed the highest anti-nociceptive activity in acetic acid-induced writhing test in ICR mice. The analgesic bioguided isolation of the acetoacetate fraction yielded two major lignans: 6-hydroxy-4-(4-hydroxy-3-methoxy-phenyl)-3-hydroxymethyl-7-methoxy-3,4-dihydro-2-naphthaldehyde (1) and vitedoamine A (2). Given orally, compound (1), which was more productive, produced significant inhibitions on chemical nociception induced by intraperitoneal acetic acid and subplantar formalin injections and exhibited notable anti-inflammatory activities in dimethyl benzene-induced ear edema test in a dose-dependent manner. Since co-administration of naloxone fails to antagonize the analgesic activity of compound (1) in the formalin test, we suggest that compound (1) possesses potent analgesic effects which are most likely to be mediated by its anti-inflammatory activity rather than through opioid receptor system and therefore could partially explain the anti-nociceptive effect of V. negundo L. seeds.

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.

The genus Desmodium (Fabaceae)-traditional uses in Chinese medicine, phytochemistry and pharmacology.

ETHNOPHARMACOLOGICAL RELEVANCE Plants of the genus Desmodium (Fabaceae), such as Desmodium styracifolium (Osbeck) Merr. and Desmodium gyrans (L. f.) DC., have a long history of medical use in Traditional Chinese Medicine to treat various ailments including rheumatism, pyrexia, dysentery, wounds, cough, malaria, hepatitis, hemoptysis, etc. In the theory of Traditional Chinese Medicine, most species have the effect of relieving internal heat or fever, neutralizing toxins, inhibiting pain, invigorating blood circulation, suppressing cough and alleviating dyspnea. MATERIALS AND METHODS A bibliographic investigation was accomplished by analyzing secondary sources including Chinese Herbal Classics, and worldwide accepted scientific databases (Pubmed, Scopus and Web of Science, SciFinder) were scrutinized for the available information on the ethnopharmacological uses in Chinese medicine, phytochemistry, pharmacology and toxicology of Desmodium species. RESULTS The genus Desmodium is a large member of the Papilionaceae (Fabaceae) family. It contains about 350 plant species used for both feeding stuffs and herbal medicines, of which only about 30 species have been phytochemically or pharmacologically investigated. Desmodium plant extracts, as well as the active principles, have been experimentally studied for their anti-inflammatory, cytotoxic, antidiabetic, antinephrolithic, antibacterial, and nootropic activities in vitro or in vivo. And so far, a total of 212 compounds have been isolated from 15 Desmodium species and characterized mainly as flavonoids and alkaloids, followed by terpenoids, steroids, phenols, phenylpropanoids, glycosides and a number of volatile oils. The remaining unrevealed species are recorded chiefly in Asia and Africa being used in empirical treatment for various diseases. CONCLUSIONS Desmodium species have long been used in TCM to treat various ailments. Available scientific references revealed that the traditional medical uses of some important Desmodium species in TCM have been evaluated by modern pharmacological studies. As literature demonstrated, flavonoids and alkaloids are perhaps responsible for most of the activities shown by the plants of this genus. Further studies are still required to reveal the structure-activity relationship of these active constituents.