Bioactive cis-stilbenoids from the tubers of Scirpus yagara

Stilbenes: Source plants, chemistry, biosynthesis, pharmacology, application and problems related to their clinical Application-A comprehensive review

Stilbenes are some of the important phenolic compounds originating from plant families like Vitaceae, Leguminaceae, Gnetaceae, and Dipterocarpaceae. Structurally, they have a C6-C2-C6 skeleton, usually with two isomeric forms. Stilbenes are biosynthesized due to biotic and abiotic stresses such as microbial infections, high temperatures, and oxidation. This review aims to provide a comprehensive overview of stilbenes' botanical sources, chemistry, biosynthetic pathways, pharmacology, and clinical applications and challenges based on up-to-date data. All included studies were collected from PubMed, ScienceDirect, Google Scholar, and CNKI, and the presented data from these indexed studies were analyzed and summarized. A total of 459 natural stilbene compounds from 45 plant families and 196 plant species were identified. Pharmacological studies also show that stilbenes have various activities such as anticancer, antimicrobial, antioxidant, anti-inflammatory, anti-degenerative diseases, anti-diabetic, neuroprotective, anti-aging, and cardioprotective effects. Stilbene synthase (STS) is the key enzyme involved in stilbene biosynthetic pathways. Studies on the therapeutic application of stilbenes pinpoint that challenges such as low bioavailability and isomerization are the major bottlenecks for their development as therapeutic drugs. Although the medicinal uses of several stilbenes have been demonstrated in vivo and in vitro, studies on the development of stilbenes deserve more attention in the future.

Recent progress on anti-Candida natural products

Candida is an intractable life-threatening pathogen. Candida infection is extremely difficult to eradicate, and thus is the major cause of morbidity and mortality in immunocompromised individuals. Morevover, the rapid spread of drug-resistant fungi has led to significant decreases in the therapeutic effects of clinical drugs. New anti-Candida agents are urgently needed to solve the complicated medical problem. Natural products with intricate structures have attracted great attention of researchers who make every endeavor to discover leading compounds for antifungal agents. Their novel mechanisms and diverse modes of action expand the variety of fungistatic agents and reduce the emergence of drug resistance. In recent decades, considerable effort has been devoted to finding unique antifungal agents from nature and revealing their unusual mechanisms, which results in important progress on the development of new antifungals, such as the novel cell wall inhibitors YW3548 and SCY-078 which are being tested in clinical trials. This review will present a brief summary on the landscape of anti-Candida natural products within the last decade. We will also discuss in-depth the research progress on diverse natural fungistatic agents along with their novel mechanisms.

Stilbenoids: A Natural Arsenal against Bacterial Pathogens

The escalating emergence of resistant bacterial strains is one of the most important threats to human health. With the increasing incidence of multi-drugs infections, there is an urgent need to restock our antibiotic arsenal. Natural products are an invaluable source of inspiration in drug design and development. One of the most widely distributed groups of natural products in the plant kingdom is represented by stilbenoids. Stilbenoids are synthesised by plants as means of protection against pathogens, whereby the potential antimicrobial activity of this class of natural compounds has attracted great interest in the last years. The purpose of this review is to provide an overview of recent achievements in the study of stilbenoids as antimicrobial agents, with particular emphasis on the sources, chemical structures, and the mechanism of action of the most promising natural compounds. Attention has been paid to the main structure modifications on the stilbenoid core that have expanded the antimicrobial activity with respect to the parent natural compounds, opening the possibility of their further development. The collected results highlight the therapeutic versatility of natural and synthetic resveratrol derivatives and provide a prospective insight into their potential development as antimicrobial agents.

Sparstolonin B improves neurological outcomes following intracerebral hemorrhage in mice

Inflammation serves an important role in inducing secondary injury following intracerebral hemorrhage (ICH). It has been demonstrated that sparstolonin B (SsnB) is able to attenuate the lipopolysaccharide-induced inflammatory response in sepsis. Mouse ICH models were used to explore the efficacy of SsnB on the ICH-induced inflammatory response. Mice underwent a working memory version of Morris water maze (MWM) test. They underwent 5 successive days of training consisting of 4 trials each day. The ICH model was established on the last training day. Mice were injected intraperitoneally either with vehicle or SsnB once a day for 3 consecutive days following the establishment of the ICH model. The MWM was used to determine the effect of SsnB on short-term memory following ICH. Neurological deficit scores and brain water content were measured following the MWM. Furthermore, the expression of inflammatory factors and signaling molecules downstream of TLR4 were measured. The results demonstrated that 5 mg/kg SsnB significantly improved the MWM path and time latency (P<0.05). Furthermore, neurological deficit scores were decreased in SsnB-treated mice compared with vehicle-treated mice (P<0.01). Brain water content, levels of inflammatory cytokines and the expression of inflammation-associated proteins were also significantly reduced in the SsnB-treated group (P<0.05). These results indicate that SsnB treatment stimulates short-term neurobehavioral recovery and reduces neurological deficits and this may inhibit the inflammatory response. Therefore, SsnB may attenuate the inflammatory response following ICH.

Structural Modification of Stilbenoids from Acanthopanax leucorrhizus and Their Cytotoxic Activity

A new cis-stilbenoid, 1,9-dihydroxy-10-methoxy-6H-dibenzo[b,f]oxocin-6-one (2) was isolated from the AcOEt extract of the stem barks of Acanthopanax leucorrhizus, along with three known stilbenoids, 9-hydroxy-10-methoxy-6H-dibenzo[b,f]oxocin-6-one (1), 5-O-methyl-(E)-resveratrol 3-O-β-d-glucopyranoside (3), and (E)-resveratrol 3-O-β-d-xylopyranoside (4). Two derivatives (2a and 2b) were synthesized by the structural modification of compound 2, which exhibited certain cytotoxic activities against HT-29 and HeLa cell lines in vitro. All compounds were structurally characterized by comprehensive analysis of their spectroscopic data and comparison with literature information, and evaluated for their cytotoxic activities against three human tumor cell lines (HL-60, HT-29, and HeLa) by the standard MTT assay in vitro. The results showed that derivatives 2a and 2b exhibited strong activities than compounds 2 against HT-29 and HeLa cell lines.

Interleukin-23 Secreted by Activated Macrophages Drives γδT Cell Production of Interleukin-17 to Aggravate Secondary Injury After Intracerebral Hemorrhage

BACKGROUND

Neuroinflammation plays a key role in intracerebral hemorrhage (ICH)-induced secondary brain injury, but the specific roles of peripheral inflammatory cells such as macrophages and lymphocytes remain unknown. The purpose of this study was to explore the roles of macrophages, T lymphocytes, and the cytokines they secrete as potential targets for treating secondary brain injury after ICH.

METHODS AND RESULTS

Our results showed that peripheral macrophages and T lymphocytes successively infiltrated the brain, with macrophage counts peaking 1 day after ICH and T-lymphocyte counts peaking after 4 days. These peaks in cellular infiltration corresponded to increases in interleukin (IL)-23 and IL-17 expression, respectively. We found that hemoglobin from the hematoma activated IL-23 secretion by infiltrating macrophages by inducing the formation of toll-like receptor (TLR) 2/4 heterodimer. This increased IL-23 expression stimulated γδT-cell production of IL-17, which increased brain edema and neurologic deficits in the model mice as a proinflammatory factor. Finally, we found that sparstolonin B (SsnB) could ameliorate brain edema and neurologic deficits in ICH model mice via inhibition of TLR2/TLR4 heterodimer formation, and notably, SsnB interacted with myeloid differentiation factor 88 Arg196.

CONCLUSIONS

Together, our results reveal the importance of the IL-23/IL-17 inflammatory axis in secondary brain injury after ICH and thus provide a new therapeutic target for ICH treatment.

Chemical constituents from the tubers of Scirpus yagara and their anti-inflammatory activities

A new natural compound, dehydrophyllodulcin (1) was isolated from the tubers of Scirpus yagara, together with 11 known compounds. Among them, compounds 2, 5-8, and 10-12 were isolated from this plant for the first time. (1)H NMR, (13)C NMR, and 2D NMR data of compound 1 are first reported in this article, though it was synthesized in 1996. The structures of all compounds were determined by comprehensive analyses of their spectroscopic data and compared with literature information. Moreover, the anti-inflammatory effects of compounds 1, 3, 4, 6, and 9 against inflammatory cytokines production in Lipopolysaccharide - or Pam3csk4-stimulated macrophage RAW264.7 cells were evaluated by Enzyme-linked immunosorbent assay. And these compounds significantly inhibited the tumor necrosis factor (TNF)-α, interleukin (IL)-6 productions in RAW264.7 cells, with IC50 values less than 20 μM.

Determination of sparstolonin B by ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry: application to pharmacokinetic study of sparstolonin B in rat plasma

Sparstolonin B (SsnB), a spontaneous isocoumarin compound isolated from the tuber of Scirpus yagara Ohwi. (Cyperaceae), possesses potent anti-inflammatory and antitumor activity. In the present study, a rapid and simple UHPLC/MS/MS method for determination of SsnB in rat plasma was developed and validated. Plasma samples were pretreated by liquid-liquid extraction with ethyl acetate containing rhein as an internal standard and separated on a C18 column at 35 °C, with a gradient mobile phase consisting of acetonitrile and water containing 0.2% (v/v) formic acid within 2.1 min. MS/MS detection was accomplished in multiple reaction monitoring mode with negative electrospray ionization. The precursor-product ion transitions were m/z 266.9 [M-H](-)  → m/z 211.0 for SsnB and m/z 283.2 [M-H](-)  → m/z 239.0 for IS. The intra- and inter-day precision (RSD) was <8.98% and the accuracy (RE) ranged from -7.40 to 4.50%. The extraction recoveries ranged from 96.28 to 97.30%. The pharmacokinetic parameters were calculated using Win Nonlin53 software. The absolute bioavailability of SsnB was estimated to be 6.98%. The proposed method was successfully applied to a pharmacokinetic study of SsnB in rats after intravenous administration with a dose of 0.5 mg/kg and oral administration at a dose of 5 mg/kg.

Protective effects of the active fraction from the tuber of Scirpus yagara in mouse endotoxin shock model

ETHNOPHARMACOLOGICAL RELEVANCE

Scirpus yagara Ohwi is a perennial, aquatic plant, whose dry tubers have long been used as Traditional Chinese Medicine (TCM) "Sanleng" for the treatment of postpartum abdominal pain, hyperemesis gravidarum, amenorrhea, dyspepsia and several inflammatory related diseases. Although it is known to have anti-inflammatory activities, its mechanism of action on lipopolysaccharide (LPS)-induced inflammation has not yet been identified in detail.This study was designed to investigate the anti-inflammatory activity of the active fraction (AF) from the tuber of Scirpusyagara both in vitro and in vivo.

MATERIALS AND METHODS

RAW264.7 macrophage was incubated for 16h with 1µg/ml of LPS in absence or presence of AF (0, 10, 50 and 100µg/ml) and the secretions of tumor necrosis-alpha (TNF-α) and interleukin-6 (IL-6) in the medium were determined by using an enzyme-linked immunosorbent assay (ELISA). In the in vivo study, mice were orally administrated with AF (50 and 300mg/kg) for three days consecutively. 1h after the last AF administration, the mice were intraperitoneally injected with LPS (15mg/kg), and the life span of LPS-challenged mice were determined. Furthermore, the levels of pro-inflammatory cytokines TNF-α and IL-6 in the serum, lung and liver were measured using ELISA kit, and histological change in lungs was examined by light microscopy. Additionally, the components of AF were analyzed by high performance liquid chromatography (HPLC) using a C18 column.

RESULTS

AF significantly decreased TNF-α and IL-6 production induced by LPS in RAW264.7 macrophage. In LPS-induced mouse endotoxin shock model, AF pre-treatment significantly improved the survival rate of mice. And LPS-induced increases of pro-inflammatory cytokines TNF-α and IL-6 in the serum, lung and liver were markedly suppressed by AF. Moreover, the histopathological examination indicated that AF could significantly attenuate lung tissues injury in endotoxemic mice. In addition, eight compounds (protocatechuic acid, vanillic acid, p-coumaric acid, ferulic acid, methyl-3,6-dihydroxy-2-[2-(2-hydroxyphenyl)-ethynyl] benzoate, sciryagarol I, sparstolonin B, SanLeng diphenyllactone) of AF were quantified by HPLC analysis.

CONCLUSIONS

These results suggested that AF protected mice against LPS-induced lethality by inhibiting the production of multiple cytokines and organ dysfunction. Thus AF may prove beneficial in the prevention and treatment of endotoxin shock.