Stilbenoids from Gnetum macrostachyum Attenuate Human Platelet Aggregation and Adhesion

A Review on the Efficacy of Plant-derived Bio-active Compounds Curcumin and Aged Garlic Extract in Modulating Cancer and Age-related Diseases

Aging is a process characterized by accumulating degenerative changes resulting in the death of an organism. Aging is mediated by various pathways that are directly linked to the individual's lifespan and are shunted for many age-related diseases. Many strategies for alleviating age-related diseases have been studied, which can target cells and molecules. Modern drugs such as Metformin, Rapamycin, and other drugs are used to reduce the effects of age-related diseases. Despite their beneficial activity, they possess some side effects which can limit their applications, mainly in older adults. Natural phytochemicals which have anti-aging activities have been studied by many researchers from a broader aspect and suggested that plant-based compounds can be a possible, direct, and practical way to treat age-related diseases which has enormous anti-aging activity. Also, studies indicated that the synergistic action of phytochemicals might enhance the biological effect rather than the individual or summative effects of natural compounds. Curcumin has an antioxidant property and is an effective scavenger of reactive oxygen species. Curcumin also has a beneficial role in many age-related diseases like diabetes, cardiovascular disease, neurological disorder, and cancer. Aged garlic extracts are also another bioactive component that has high antioxidant properties. Many studies demonstrated aged garlic extract, which has high antioxidant properties, could play a significant role in anti-aging and age-related diseases. The synergistic effect of these compounds can decrease the requirement of doses of a single drug, thus reducing its side effects caused by increased concentration of the single drug.

Stilbenes, a Versatile Class of Natural Metabolites for Inflammation-An Overview

Stilbenes are polyphenolic allelochemicals synthesized by plants, especially grapes, peanuts, rhubarb, berries, etc., to defend themselves under stressful conditions. They are now exploited in medicine for their antioxidant, anti-proliferative and anti-inflammatory properties. Inflammation is the immune system's response to invading bacteria, toxic chemicals or even nutrient-deprived conditions. It is characterized by the release of cytokines which can wreak havoc on healthy tissues, worsening the disease condition. Stilbenes modulate NF-κB, MAPK and JAK/STAT pathways, and reduce the transcription of inflammatory factors which result in maintenance of homeostatic conditions. Resveratrol, the most studied stilbene, lowers the Michaelis constant of SIRT1, and occupies the substrate binding pocket. Gigantol interferes with the complement system. Besides these, oxyresveratrol, pterostilbene, polydatin, viniferins, etc., are front runners as drug candidates due to their diverse effects from different functional groups that affect bioavailability and molecular interactions. However, they each have different thresholds for toxicity to various cells of the human body, and thus a careful review of their properties must be conducted. In animal models of autoinflammatory diseases, the mode of application of stilbenes is important to their absorption and curative effects, as seen with topical and microemulsion gel methods. This review covers the diversity seen among stilbenes in the plant kingdom and their mechanism of action on the different inflammatory pathways. In detail, macrophages' contribution to inflamed conditions in the liver, the cardiac, connective and neural tissues, in the nephrons, intestine, lungs and in myriad other body cells is explored, along with detailed explanation on how stilbenes alleviate the symptoms specific to body site. A section on the bioavailability of stilbenes is included for understanding the limitations of the natural compounds as directly used drugs due to their rapid metabolism. Current delivery mechanisms include sulphonamides, or using specially designed synthetic drugs. It is hoped that further research may be fueled by this comprehensive work that makes a compelling argument for the exploitation of these compounds in medicine.

Oxyresveratrol and Gnetol Glucuronide Metabolites: Chemical Production, Structural Identification, Metabolism by Human and Rat Liver Fractions, and In Vitro Anti-inflammatory Properties

Stilbene metabolites are attracting great interest because many of them exhibit similar or even stronger biological effects than their parent compounds. Furthermore, the metabolized forms are predominant in biological fluids; therefore, their study is highly relevant. After hemisynthesis production, isolation, and structural elucidation, three glucuronide metabolites for oxyresveratrol (ORV) were formed: trans-ORV-4'-O-glucuronide, trans-ORV-3-O-glucuronide, and trans-ORV-2'-O-glucuronide. In addition, two glucuronide metabolites were obtained for gnetol (GN): trans-GN-2'-O-glucuronide and trans-GN-3-O-glucuronide. When the metabolism of ORV and GN is studied in vitro by human and rat hepatic enzymes, four of the five hemisynthesized compounds were identified and quantified. Human enzymes glucuronidated preferably at the C-2' position, whereas rat enzymes do so at the C-3 position. In view of these kinetic findings, rat enzymes have a stronger metabolic capacity than human enzymes. Finally, ORV, GN, and their glucuronide metabolites (mainly at the C-3 position) decreased nitric oxide, reactive oxygen species, interleukin 1β, and tumor necrosis factor α production in lipopolysaccharide-stimulated macrophages.

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.

Wound Management Property of a Hydroethanolic Leaf Extract of Cnestis ferruginea DC

Objective

To establish the wound management property of a hydroethanolic Cnestis ferruginea leaf extract (CFHE).

Materials and Methods

The wound area was measured after excision at the dorsal part of the Albino rats, and after treatment with 5–15% w/w CFHE ointments for 14 days. Absorbances of platelet-rich plasma treated with 0.8–100 mg/mL CFHE and an aggregating agent were spectrophotometrically determined in an in vitro platelet aggregation test. Wound tissue histopathology of CFHE ointment-treated animals revealed angiogenesis, reepithelialization, deposition of collagen, and granular tissue formation in wound tissues. Reduction in thigh oedema and pain threshold, in 7-day-old chicks, were assessed by carrageenan-induced oedema and Randall-Sellito pressure models, respectively. By the Agar diffusion method, bacterial growth inhibition by a 15% w/w CFHE ointment was investigated on Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus. Aureus, and Streptococcus pyogenes.

Results

All concentrations of CFHE ointment significantly reduced (p < 0.0001) wound area by 29–41% posttreatment. CFHE (1.6–100 mg/ml) promoted platelet aggregation (p ≤ 0.0001) by 37–67% (IC₅₀: 3.1–6.2 mg/ml). There were improved wound tissue reepithelization, fibroblast proliferation, angiogenesis, and collagen deposition with 15% CFHE ointment treatment. CFHE ointment significantly (p ≤ 0.0001) and dose-dependently reduced thigh oedema and showed a significant (p ≤ 0.05) analgesic effect. In vitro, 15% CFHE ointment caused >100% growth inhibition of selected bacteria.

Conclusion

The hydroethanolic leaf extract of Cnestis ferruginea possesses wound healing, platelet aggregation, anti-inflammatory, analgesic, and antimicrobial properties and, hence, could be effective in the management of open and some closed wounds.

Macrostachyols A-D, oligostilbenes from Gnetum macrostachyum inhibited in vitro human platelet aggregation

Introduction: Gnetum macrostachyum is a known Thai medicinal plant as a source of bioactive oligostilbenes, which possess platelet inhibitory activities. The study aimed to evaluate the in vitro human platelet aggregation inhibitory activities of macrostachyols A-D (compounds 1-4) isolated from the roots of G. macrostachyum. Methods: The in vitro human platelet aggregation assay was assayed with a 96-well microtiter plate format. The well-known aggregating agents were used to investigate the possible mechanism of inhibition, including adenosine diphosphate (ADP), arachidonic acid (AA), thromboxane A2 analog (U-46619), collagen, thrombin, and thrombin receptor-activating peptide-6 (TRAP-6). Results: Compound 1 was more potent than ibuprofen (positive control) on the adenosine diphosphate- induced platelet aggregation assay (P < 0.05). Compound 3 was more potent than 1, 2, and 4 (P < 0.05), but all active oligostilbenes were less potent than the positive control (P < 0.05) on the arachidonic acid-induced platelet aggregation assay. The oligostilbenes 1, 2, 3, and 4 also displayed the inhibitory effects on the U-46619-induced platelet aggregation. The tetrameric stilbenes 1 was the only compound that exhibited inhibitory effects on thrombin-induced platelet aggregation without TRAP-6 mediated platelet aggregation. Conclusion: The findings revealed the inhibitory effects of oligostilbenes on human platelet aggregation through a target-specific experimental design. It suggests that oligostilbenes from this plant might be applied as antiplatelet aggregation agents in platelet hyperreactivity- related diseases.

Studies toward the Total Synthesis of Parvifolals A/B: An Intramolecular o-Quinone Methide [4 + 2]-Cycloaddition To Construct the Central Tetracyclic Core

Two different approaches funded upon the intramolecular [4 + 2]-cycloaddition of in situ generated o-quinone methides have been explored to construct the central tetracyclic core of parvifolals A/B. At the outset, a cross-pinacol coupling of 2-formyl tri-O-methyl resveratrol with 4-methoxysalicylaldehyde followed by acid treatment was found to provide the desired tetracyclic core with an internal olefin. The requisite pendant aryl group has been introduced by a Pd-catalyzed direct coupling of corresponding diazonium salt.

Biological Activities of Stilbenoids

Stilbenoids are a group of naturally occurring phenolic compounds found in various plant species. They share a common backbone structure known as stilbene, but differ in the nature and position of substituents. Stilbenoids are classified as phytoalexins, which are antimicrobial compounds produced de novo in plants to protect against fungal infection and toxins. In this review, the biological effects of stilbenoids such as resveratrol, pterostilbene, gnetol and piceatannol are discussed. Stilbenoids exert various biological activities ranging from cardioprotection, neuroprotection, anti-diabetic properties, depigmentation, anti-inflammation, cancer prevention and treatment. The results presented cover a myriad of models, from cell culture to animal studies as well as clinical human trials. Although positive results were obtained in most cell culture and animal studies, further human studies are needed to substantiate beneficial effects of stilbenoids. Resveratrol remains the most widely studied stilbenoid. However, there is limited information regarding the potential of less common stilbenoids. Therefore, further research is warranted to evaluate the salutary effects of various stilbenoids.

Natural remedies used by Bunong people in Mondulkiri province (Northeast Cambodia) with special reference to the treatment of 11 most common ailments

ETHNOPHARMACOLOGICAL RELEVANCE

In this paper we present a comprehensive ethnomedicinal study conducted in Mondulkiri province. Traditional knowledge about natural medicine (plants, animals, mushrooms) was investigated in Cambodia's largest indigenous community: the Bunong people. The survey aims to document the medicinal plant use of this ethnic, by focusing on the eleven most frequent diseases encountered in the area, in order to highlight species that could be recommended in public health programs.

MATERIALS AND METHODS

During the years 2013 and 2014, 202 villagers were interviewed in 28 villages from the five districts in Mondulkiri. Two types of methodology were employed: (1) an ethnobotanical field survey (walk-in-the-wood interviews) and (2) semi-structured household interviews with a special emphasis on the treatment of 11 most common ailments encountered in the area. Medicinal plants and mushrooms were collected and identified together with medicinal animals. The factor informant consensus (FIC) and fidelity level (FL) were calculated.

RESULTS

Bunong people use a total of 214 plants belonging to 72 families, 1 mushroom and 22 animal species in their traditional healthcare practices in order to treat 51 different ailments. Among the medicinal plants, Fabaceae was the most predominant family; Chromolaena odorata (L.) R.M. King and H.Rob. (Asteraceae), Zingiber montanum (J.Koenig) Link ex A.Dietr. (Zingiberaceae) and Kalanchoe pinnata (Lam.) Pers. (Crassulaceae) were the most cited medicinal plants; and four ailments (cold/fever, diarrhea, postpartum disorders and stomachache) were described as major ailments in the community. The root was the most important part of plants used, and decoction was the most cited method of preparation. During our survey, we also discovered a "new to science" plant species called Ardisia mondulkiriensis Hul and Chassagne, and we recorded for the second time the plant species recently described, Solanum sakhanii Hul.

CONCLUSION

Most of the species reported for the treatment of the 11 most frequent ailments have already been proven to be efficient and safe. Furthermore, 10 plant species are reported for the first time as medicinal and some of them are widely used in the community. Further pharmacological and phytochemical investigations should be undergone to assess the pharmaceutical potential of these species. While undergoing considerable changes, Bunong people have maintained extensive traditional medicine knowledge. As this indigenous hill tribe depend mainly on natural remedies for their daily healthcare, environmental preservation is of high importance for the community.

Naturally active oligostilbenes

Many naturally occurring oligostilbenes have drawn considerable attention because of their intricate structures and diverse biological activities. In recent years, oligostilbene bioactivities have become a popular research topic worldwide. Although these bioactivities are known to be extensive and several summaries on the activities of the compounds have been published, a comprehensive and systematic summary on active oligostilbenes is unavailable. From January 2005 to December 2013, a large number of active oligostilbenes and corresponding new bioactivities were reported in the literature. This review mainly focuses on the diverse bioactivities of oligostilbenes with various backbones.

Antioxidant Phytochemicals for the Prevention and Treatment of Chronic Diseases

Overproduction of oxidants (reactive oxygen species and reactive nitrogen species) in the human body is responsible for the pathogenesis of some diseases. The scavenging of these oxidants is thought to be an effective measure to depress the level of oxidative stress of organisms. It has been reported that intake of vegetables and fruits is inversely associated with the risk of many chronic diseases, and antioxidant phytochemicals in vegetables and fruits are considered to be responsible for these health benefits. Antioxidant phytochemicals can be found in many foods and medicinal plants, and play an important role in the prevention and treatment of chronic diseases caused by oxidative stress. They often possess strong antioxidant and free radical scavenging abilities, as well as anti-inflammatory action, which are also the basis of other bioactivities and health benefits, such as anticancer, anti-aging, and protective action for cardiovascular diseases, diabetes mellitus, obesity and neurodegenerative diseases. This review summarizes recent progress on the health benefits of antioxidant phytochemicals, and discusses their potential mechanisms in the prevention and treatment of chronic diseases.

Preclinical Pharmacokinetics and Pharmacodynamics and Content Analysis of Gnetol in Foodstuffs

Studies were undertaken to evaluate the bioavailability in rats and content analysis of gnetol in Gnetum gnemon products reported to contain gnetol and to examine the pharmacological properties of gnetol in in vitro models including anti-inflammatory/analgesic, antidiabetic, anti-adipogenesis, and anticancer activity. Male Sprague-Dawley rats were cannulated and dosed either intravenously with gnetol (10 mg/kg) or orally (100 mg/kg). Various methanolic extractions of G. gnemon products were quantified. Gnetol's effect on cell viability in selected cell lines with or without inflammatory stimulus was assessed. α-Amylase and α-glucosidase inhibition was evaluated. Cyclooxygenase (COX)-1, COX-2, and histone deacetylase inhibition and adipogenesis inhibition were examined. After oral and intravenous administration, gnetol was detected in both serum and urine as the parent compound and as a glucuronidated metabolite. The bioavailability of gnetol was determined to be 6%. Gnetol is rapidly glucuronidated and is excreted in urine and via nonrenal routes. Gnetol was found to exist as an aglycone and as a glycoside in G. gnemon products. Gnetol showed concentration-dependent reductions in cell viability in cancer cell lines with greatest activity in colorectal cancer and potent COX-1, histone deacetylase, and weak COX-2 activities along with limited reduction in inflammation. Gnetol also possessed concentration-dependent alpha-amylase, alpha-glucosidase, and adipogenesis activities. Pretreatment of mice with gnetol was able to increase the latency period to response in analgesia models.

Highly Potent Oligostilbene sbLOX-1 Inhibitor from Gnetum macrostachyum

Isolated oligostilbenes from G. macrostachyum exhibited sbLOX-1 inhibitory activity with IC50 values ranging from 0.14–11.91 μM. Of these oligostilbenoids, 12 (IC0 0.14±0.01 μM), 10 (IC0 0.33±0.11 μM), 11 (IC50 0.49±0.05 μM) and 7 (IC50 1.03 ± 0.43 μM) were more active than nordihydroguaiaretic acid (NDGA) ( P < 0.05) which was the positive control. The enzyme kinetic analysis revealed that 7 and 11 inhibited sbLOX-1 noncompetitively with K i values of 11.2 and 71.4 nM. Compound 10 inhibited sbLOX-1 through mixed-competitive mechanisms ( K i = 13.8 nM and K' i 56.7 nM). Moreover, 12 was an uncompetitive inhibitor with a K i value of 0.8 nM. The inhibitory activity of oligostilbenes did not result from the antioxidant property, as demonstrated by DPPH and 13-HPOD scavenging assays. These compounds also showed ferric reducing capabilities, but had no effect in a Fe3+-bound sbLOX-1 model, as indicated by UV spectrophotometric and CD spectroscopic studies.

Anti-platelet activity of erythro-(7S,8R)-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan from Myristica fragrans

Platelets play a critical role in pathogenesis of cardiovascular disorders and strokes. The inhibition of platelet function is beneficial for the treatment and prevention of these diseases. In this study, we investigated the anti-platelet activity of erythro-(7S,8R)-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (EATN), a neolignan isolated from Myristica fragrans, using human platelets. EATN preferentially inhibited thrombin- and platelet-activating factor (PAF)-induced platelet aggregation without affecting platelet damage in a concentration-dependent manner with IC50 values of 3.2 ± 0.4 and 3.4 ± 0.3 μM, respectively. However, much higher concentrations of EATN were required to inhibit platelet aggregation induced by arachidonic acid. EATN also inhibited thrombin-induced serotonin and ATP release, and thromboxane B2 formation in human platelets. Moreover, EATN caused an increase in cyclic AMP (cAMP) levels and attenuated intracellular Ca(2+) mobilization in thrombin-activated human platelets. Therefore, we conclude that the inhibitory mechanism of EATN on platelet aggregation may increase cAMP levels and subsequently inhibit intracellular Ca(2+) mobilization by interfering with a common signaling pathway rather than by directly inhibiting the binding of thrombin or PAF to their receptors. This is the first report of the anti-platelet activity of EATN isolated from M. fragrans.