Antimicrobial Activity of Xanthohumol and Its Selected Structural Analogues

The objective of this study was to evaluate the antimicrobial activity of structural analogues of xanthohumol 1, a flavonoid compound found in hops (Humulus lupulus). The agar-diffusion method using filter paper disks was applied. Biological tests performed for selected strains of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, fungi (Alternaria sp.), and yeasts (Rhodotorula rubra, Candida albicans) revealed that compounds with at least one hydroxyl group—all of them have it at the C-4 position—demonstrated good activity. Our research showed that the strain S. aureus was more sensitive to chalcones than to the isomers in which the heterocyclic ring C is closed (flavanones). The strain R. rubra was moderately sensitive to only one compound: 4-hydroxy-4’-methoxychalcone 8. Loss of the hydroxyl group in the B-ring of 4’-methoxychalcones or its replacement by a halogen atom (−Cl, −Br), nitro group (−NO2), ethoxy group (−OCH2CH3), or aliphatic substituent (−CH3, −CH2CH3) resulted in the loss of antimicrobial activity towards both R. rubra yeast and S. aureus bacteria. Xanthohumol 1, naringenin 5, and chalconaringenin 7 inhibited growth of S. aureus, whereas 4-hydroxy-4′-methoxychalcone 8 was active towards two strains: S. aureus and R. rubra

A Review on Sources and Pharmacological Aspects of Sakuranetin

Sakuranetin belongs to the group of methoxylated flavanones. It is widely distributed in Polyomnia fruticosa and rice, where it acts as a phytoalexin. Other natural sources of this compound are, among others, grass trees, shrubs, flowering plants, cheery, and some herbal drugs, where it has been found in the form of glycosides (mainly sakuranin). Sakuranetin has antiproliferative activity against human cell lines typical for B16BL6 melanoma, esophageal squamous cell carcinoma (ESCC) and colon cancer (Colo 320). Moreover, sakuranetin shows antiviral activity towards human rhinovirus 3 and influenza B virus and was reported to have antioxidant, antimicrobial, antiinflammatory, antiparasitic, antimutagenic, and antiallergic properties. The aim of this review is to present the current status of knowledge of pro-health properties of sakuranetin

Dihydrochalcones: Methods of Acquisition and Pharmacological Properties—A First Systematic Review

Dihydrochalcones are a class of secondary metabolites, for which demand in biological and pharmacological applications is still growing. They posses several health-endorsing properties and, therefore, are promising candidates for further research and development. However, low content of dihydrochalcones in plants along with their low solubility and bioavailability restrict the development of these compounds as clinical therapeutics. Therefore, chemomicrobial and enzymatic modifications are required to expand their application. This review aims at analyzing and summarizing the methods of obtaining dihydrochalcones and of presenting their pharmacological actions that have been described in the literature to support potential future development of this group of compounds as novel therapeutic drugs. We have also performed an evaluation of the available literature on beneficial effects of dihydrochalcones with potent antioxidant activity and multifactorial pharmacological effects, including antidiabetic, antitumor, lipometabolism regulating, antioxidant, anti-inflammatory, antibacterial, antiviral, and immunomodulatory ones. In addition, we provide useful information on their properties, sources, and usefulness in medicinal chemistry

In Vitro Effect of 8-Prenylnaringenin and Naringenin on Fibroblasts and Glioblastoma Cells-Cellular Accumulation and Cytotoxicity

Gliomas are one of the most aggressive and treatment-resistant types of human brain cancer. Identification and evaluation of anticancer properties of compounds found in plants, such as naringenin (N) and 8-prenylnaringenin (8PN), are among the most promising applications in glioma therapy. The prenyl group seems to be crucial to the anticancer activity of flavones, since it may lead to enhanced cell membrane targeting and thus increased intracellular activity. It should be noted that 8PN content in hop cones is 10 to 100 times lower compared to other flavonoids, such as xanthohumol. In the study presented, we used a simple method for the synthesis of 8PN from isoxanthohumol—O-demethylation, with a high yield of 97%. Cellular accumulation and cytotoxicity of naringenin and 8-prenylnaringenin in normal (BJ) and cancer cells (U-118 MG) was also examined. Obtained data indicated that 8-prenylnaringenin exhibited higher cytotoxicity against used cell lines than naringenin, and the effect of both flavones was stronger in U-118 MG cells than in normal fibroblasts. The anticancer properties of 8PN correlated with its significantly greater (37%) accumulation in glioblastoma cells than in normal fibroblasts. Additionally, naringenin demonstrated higher selectivity for glioblastoma cells, as it was over six times more toxic for cancer than normal cells. Our results provide evidence that examined prenylated and non-prenylated flavanones have different biological activities against normal and cancer cell lines, and this property may be useful in designing new anticancer drugs for glioblastoma therapy

The Health Benefits of Emodin, a Natural Anthraquinone Derived from Rhubarb—A Summary Update

Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is a naturally occurring anthraquinone derivative found in roots and leaves of various plants, fungi and lichens. For a long time it has been used in traditional Chinese medicine as an active ingredient in herbs. Among other sources, it is isolated from the rhubarb Rheum palmatum or tuber fleece-flower Polygonam multiflorum. Emodin has a wide range of biological activities, including diuretic, antibacterial, antiulcer, anti-inflammatory, anticancer and antinociceptive. According to the most recent studies, emodin acts as an antimalarial and antiallergic agent, and can also reverse resistance to chemotherapy. In the present work the potential therapeutic role of emodin in treatment of inflammatory diseases, cancers and microbial infections is analysed

Antimicrobial Activity of Xanthohumol and Its Selected Structural Analogues

The objective of this study was to evaluate the antimicrobial activity of structural analogues of xanthohumol 1, a flavonoid compound found in hops (Humulus lupulus). The agar-diffusion method using filter paper disks was applied. Biological tests performed for selected strains of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, fungi (Alternaria sp.), and yeasts (Rhodotorula rubra, Candida albicans) revealed that compounds with at least one hydroxyl group—all of them have it at the C-4 position—demonstrated good activity. Our research showed that the strain S. aureus was more sensitive to chalcones than to the isomers in which the heterocyclic ring C is closed (flavanones). The strain R. rubra was moderately sensitive to only one compound: 4-hydroxy-4’-methoxychalcone 8. Loss of the hydroxyl group in the B-ring of 4’-methoxychalcones or its replacement by a halogen atom (−Cl, −Br), nitro group (−NO2), ethoxy group (−OCH2CH3), or aliphatic substituent (−CH3, −CH2CH3) resulted in the loss of antimicrobial activity towards both R. rubra yeast and S. aureus bacteria. Xanthohumol 1, naringenin 5, and chalconaringenin 7 inhibited growth of S. aureus, whereas 4-hydroxy-4′-methoxychalcone 8 was active towards two strains: S. aureus and R. rubra

The Spectrum of Pharmacological Actions of Syringetin and Its Natural Derivatives—A Summary Review

Mono- and poly-O-methylated flavonols and their glycoside derivatives belong to the group of natural plant polyphenols with a wide spectrum of pharmacological activities. These compounds are known for their antioxidant, antimutagenic, hepatoprotective, antidiabetic, and antilipogenic properties. Additionally, they inhibit carcinogenesis and cancer development. Having in mind the multidirectional biological activity of methylated flavonols, we would like to support further study on their health-promoting activities; in this review we summarized the most recent reports on syringetin and some of its structural analogues: laricitrin, ayanin, and isorhamnetin. Natural sources and biological potential of these substances were described based on the latest research papers

Recent Advances in Biological Activity, New Formulations and Prodrugs of Ferulic Acid

Trans-ferulic acid (FA) is a derivative of 4-hydroxycinnamic acid, which is found in many food products, fruits and beverages. It has scientifically proven antioxidant, anti-inflammatory and antibacterial properties. However, its low ability to permeate through biological barriers (e.g., the blood–brain barrier, BBB), its low bioavailability and its fast elimination from the gastrointestinal tract after oral administration limit its clinical use, e.g., for the treatment of neurodegenerative diseases, such as Alzheimer’s disease. Therefore, new nanotechnological approaches are developed in order to regulate intracellular transport of ferulic acid. The objective of this review is to summarize the last decade’s research on biological properties of ferulic acid and innovative ways of its delivery, supporting pharmacological therapy