Anti-inflammatory and cytotoxic 2-arylbenzofurans from Morus wittiorum

Structures, activities, and putative biosynthetic pathways of characteristic polyphenolic compounds from Morus plants: A review

Morus plants played a pivotal role in ancient Chinese sericulture and silk production, which served as critical components of economy and culture. Besides, many parts of mulberry trees, including roots, leaves, stems, and fruits, hold various medicinal value, and have been utilized in traditional medicine for thousands of years. The chemical composition of mulberry has been reported in many literatures, while the characteristic compounds have not been systematically summarized. In this review, we focused on the polyphenolic compounds in mulberry, including flavonoids, 2-arylbenzofurans, and Diels-Alder (D-A) adducts, and summarized their structural features, structure-activity relationships, and potential biosynthetic pathways. The results revealed a characteristic class of 2'-hydroxylated flavonoids and stilbenes which played an important role in the biosynthesis of downstream 2-arylbenzofurans and D-A adducts in mulberry but had been overlooked by most studies. The prenylated modifications of different compounds were also discussed and their function as precursors of D-A adducts was emphasized. We also describe the effects of different modifications on biological activities. Besides, the chemical composition of Morus was most similar to that of Artocarpus in the Moraceae family in that they had almost identical characteristic compounds. Finally, a putative total biosynthetic pathway of D-A adducts in mulberry was proposed based on structure derivation and combination of verified reactions. This review contributes to the understanding of the biological activity and biosynthesis of the characteristic components of Morus plants.

Benzofuran as a promising scaffold for the synthesis of novel antimicrobial agents

INTRODUCTION

The benzofuran moiety constitutes a main component of enormous biologically active natural and synthetic heterocycles. Such heterocycles have distinctive therapeutic potential and are employed in various clinical drugs. A number of publications have dealt with the synthesis and extraction of benzofuran-based heterocycles to investigate their antimicrobial potential.

AREAS COVERED

This review describes the antimicrobial activity of various natural and synthetic benzofuran scaffolds. The antimicrobial activity of benzofurans is thoroughly investigated against several bacterial (Gram-positive and Gram-negative) and fungal microorganisms compared with several reference antibiotic drugs. The effects of the electronic nature of substituents on the activity of benzofurans through SAR study were reported. This article also highlights the recent natural and synthetic benzofuran-based organic molecules between 2019-2022 that have had success in terms of their antimicrobial activity.

EXPERT OPINION

Many of the described benzofurans are promising candidates as antimicrobial agents based on their activity. Most used antibiotics target infections caused by the gram-positive pathogen S. aureus. Interestingly, most of the described benzofurans are promising inhibitors against S. aureus with either equipotent or more potent activity than the reference antibiotic drugs. These findings will encourage medicinal chemists to explore these new avenues for human health promotion to reduce suffering.

Synthesis and biological evaluation of 2-arylbenzofuran derivatives as potential anti-Alzheimer's disease agents

Alzheimer's disease (AD) is a type of progressive dementia caused by degeneration of the nervous system. A single target drug usually does not work well. Therefore, multi-target drugs are designed and developed so that one drug can specifically bind to multiple targets to ensure clinical effectiveness and reduce toxicity. We synthesised a series of 2-arylbenzofuran derivatives and evaluated their in vitro activities. 2-Arylbenzofuran compounds have good dual cholinesterase inhibitory activity and β-secretase inhibitory activity. The IC50 value of compound 20 against acetylcholinesterase inhibition (0.086 ± 0.01 µmol·L-1) is similar to donepezil (0.085 ± 0.01 µmol·L-1) and is better than baicalein (0.404 ± 0.04 µmol·L-1). And most of the compounds have good BACE1 inhibitory activity, of which 3 compounds (8, 19 and 20) show better activity than baicalein (0.087 ± 0.03 µmol·L-1). According to experimental results, 2-arylbenzofuran compounds provide an idea for drug design to develop prevention and treatment for AD.

Caralluma europaea (Guss.) N.E.Br.: Anti-Inflammatory, Antifungal, and Antibacterial Activities against Nosocomial Antibiotic-Resistant Microbes of Chemically Characterized Fractions

Caralluma europaea (Guss.) N.E.Br.: (C. europaea) is a wild medicinal plant belonging to the family Apocynaceae. It is commonly used in traditional medicines for treating several diseases. The present work aims to evaluate the anti-inflammatory, antibacterial, and antifungal potentials of C. europaea fractions including hydro ethanol (ET CE), n-butanol (But CE), and polyphenol (Poly CE). The chemical composition of hydroethanol, n-butanol, and polyphenol-rich fractions from C. europaea were determined using GC-MS after silylation. The anti-inflammatory effect of hydroethanol, n-butanol, and polyphenol-rich fractions was studied by carrageenan-induced paw edema. Antibacterial and antifungal activities of hydroethanol, n-butanol, and polyphenol-rich fractions against Gram-positive bacteria, Gram-negative bacteria, and yeasts were assessed using the disc diffusion and micro-dilution assays. The findings of the chemical characterization affirmed the presence of interesting bioactive compounds in C. europaea fractions. The polyphenol-rich fraction was the best inhibitor of edema by75.68% after 6 h of treatment. The hydroethanol fraction was the most active against both bacteria and yeasts. This study contributes to society as it provides potential bioactive compounds in C. europaea extract, which may help in fighting nosocomial antibiotic-resistant microbes.

Natural source, bioactivity and synthesis of benzofuran derivatives

Benzofuran compounds are a class of compounds that are ubiquitous in nature. Numerous studies have shown that most benzofuran compounds have strong biological activities such as anti-tumor, antibacterial, anti-oxidative, and anti-viral activities. Owing to these biological activities and potential applications in many aspects, benzofuran compounds have attracted more and more attention of chemical and pharmaceutical researchers worldwide, making these substances potential natural drug lead compounds. For example, the recently discovered novel macrocyclic benzofuran compound has anti-hepatitis C virus activity and is expected to be an effective therapeutic drug for hepatitis C disease; novel scaffold compounds of benzothiophene and benzofuran have been developed and utilized as anticancer agents. Novel methods for constructing benzofuran rings have been discovered in recent years. A complex benzofuran derivative is constructed by a unique free radical cyclization cascade, which is an excellent method for the synthesis of a series of difficult-to-prepare polycyclic benzofuran compounds. Another benzofuran ring constructed by proton quantum tunneling has not only fewer side reactions, but also high yield, which is conducive to the construction of complex benzofuran ring systems. This review summarizes the recent studies on the various aspects of benzofuran derivatives including their important natural product sources, biological activities and drug prospects, and chemical synthesis, as well as the relationship between the bioactivities and structures.

Isolation of naturally occurring novel isoflavonoids: an update

This review covers the literature concerning the isolation and identification of new naturally occurring isoflavonoids from Leguminosae and non-Leguminous species between 2012–2017.

Four New Flavonoids with α-Glucosidase Inhibitory Activities from Morus alba var. tatarica

Four new flavonoids, mortatarins A-D (1-4, resp.), along with eight known flavonoids (5-12) were isolated from the root bark of Morus alba var. tatarica. Their structures were established on the basis of spectroscopic data analysis, and the absolute configuration of 4 was determined by analysis of its CD spectrum. All isolates were tested for inhibitory activities against α-glucosidase. Compounds 4, 7, and 8 exhibited a significant degree of inhibition with IC50 values of 5.0 ± 0.3, 7.5 ± 0.5, and 5.9 ± 0.2 μM, respectively.

Identification and Determination of the Polyhydroxylated Alkaloids Compounds with α-Glucosidase Inhibitor Activity in Mulberry Leaves of Different Origins

Mulberry leaves have commonly been utilized in China as a herbal medicine for the treatment of diabetes for thousands of years. To evaluate the quality, an ultra-high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF/MS) method was developed for identification of polyhydroxylated alkaloids with α-glucosidase inhibitor activity in mulberry leaf. As a result, five alkaloid compounds were identified or tentatively characterized. Among them, the compound 1-deoxynojirimycin (DNJ) was selected as the most typical and active chemical marker and quantified using an improved high performance liquid chromatography (HPLC) normal phase coupled with evaporative light scattering detector (ELSD) method. The developed method was fully validated in terms of linearity, sensitivity, precision and repeatability, as well as recovery, and subsequently applied to evaluate twenty-nine batches of mulberry leaves from different collections. From the analytical data it was discovered that the average content of DNJ is 1.53 mg/g, while the total contents of DNJ in the 29 mulberry leaf sample ranged from 0.20 to 3.88 mg/g, which suggested remarkable differences, although it reached the highest levels in early August. These data may provide an important reference for the quality of mulberry leaves used as herbal medicine for the treatment of diabetes or as a material to obtain the DNJ of α-glucosidase inhibitor or as a functional food.

The latest review on the polyphenols and their bioactivities of Chinese Morus plants

The mulberry tree (Morus alba) plays a key role in agriculture, and its different parts have been used as popular Traditional Chinese Medicines for thousands of years. There are 16 species belonging to the Morus genus. Among them, 11 species distribute in China, most of which have been used as the substitutes of M. alba in local provinces. This review summarizes the structural characters of polyphenols, the main components in Morus, including Diels-Alder-type adducts, flavonoids, 2-arylbenzofurans, and stilbenes, and also their related bioactivities in the last 10 years.

Natural stilbenoids: distribution in the plant kingdom and chemotaxonomic interest in Vitaceae

Stilbenoids, a family of polyphenols known for the complexity of their structure and for their diverse biological activities, occur with a limited but heterogeneous distribution in the plant kingdom. The most prominent stilbene containing plant family, the Vitaceae, represented by the famous wine producing grape vines Vitis vinifera L., is one of the richest sources of novel stilbenes currently known, together with other families, such as Dipterocarpaceae, Gnetaceae and Fabaceae. This review focuses on the distribution of stilbenes and 2-arylbenzofuran derivatives in the plant kingdom, the chemical structure of stilbenes in the Vitaceae family and their taxonomic implication.