Optimal extraction, purification and antioxidant activity of total flavonoids from endophytic fungi of Conyza blinii H. Lév

Advances in Flavonoid Research: Sources, Biological Activities, and Developmental Prospectives

At present, the occurrence of a large number of infectious and non-communicable diseases poses a serious threat to human health as well as to drug development for the treatment of these diseases. One of the most significant challenges is finding new drug candidates that are therapeutically effective and have few or no side effects. In this respect, the active compounds in medicinal plants, especially flavonoids, are potentially useful compounds with a wide range of pharmacological activities. They are naturally present in nature and valuable in the treatment of many infectious and non-communicable diseases. Flavonoids are divided into fourteen categories and are mainly derived from plant extraction, chemical synthesis and structural modification, and biosynthesis. The structural modification of flavonoids is an important way to discover new drugs, but biosynthesis is currently considered the most promising research direction with the potential to revolutionize the new production pipeline in the synthesis of flavonoids. However, relevant problems such as metabolic pathway analyses and cell synthesis protocols for flavonoids need to be addressed on an urgent basis. In the present review, new research techniques for assessing the biological activities of flavonoids and the mechanisms of their biological activities are elucidated and their modes of interaction with other drugs are described. Moreover, novel drug delivery systems, such as nanoparticles, bioparticles, colloidals, etc., are gradually becoming new means of addressing the issues of poor hydrophilicity, lipophilicity, poor chemical stability, and low bioavailability of flavonoids. The present review summarizes the latest research progress on flavonoids, existing problems with their therapeutic efficacy, and how these issues can be solved with the research on flavonoids.

First Natural Yeast Strain Trichosporon asahii HZ10 with Robust Flavonoid Productivity and Its Potential Biosynthetic Pathway

Flavonoids are generally thought to be essential plant natural products with diverse bioactivities and pharmacological effects. Conventional approaches for the industrial production of flavonoids through plant extraction and chemical synthesis face serious economic and environmental challenges. Searching for natural robust flavonoid-producing microorganisms satisfying green and sustainable development is one of the good alternatives. Here, a natural yeast, Trichosporon asahii HZ10, isolated from raw honeycombs, was found to accumulate 146.41 mg/L total flavonoids intracellularly. Also, T. asahii HZ10 represents a broad flavonoid metabolic profiling, covering 40 flavonoids, among which nearly half were silibinin, daidzein, and irigenin trimethyl ether, especially silibinin occupying 21.07% of the total flavonoids. This is the first flavonoid-producing natural yeast strain worldwide. Furthermore, T. asahii HZ10-derived flavonoids represent favorable antioxidant activities. Interestingly, genome mining and transcriptome analysis clearly showed that T. asahii HZ10 possibly evolves a novel flavonoid synthesis pathway for the most crucial step of flavonoid skeleton synthesis, which is different from that in plants and filamentous fungi. Therefore, our results not only enrich the diversity of the natural flavonoid biosynthesis pathway but also pave an alternative way to promote the development of a synthetic biology strategy for the microbial production of flavonoids.

Multicolor Hair Dyeing with Biocompatible Dark Polyphenol Complex-Integrated Shampoo with Reactive Oxygen Species Scavenging Activity

Hair dyeing has become a prevalent lifestyle trend, especially within the fashion industry. However, it possesses disadvantages, such as containing carcinogenic and toxic materials. In this study, we developed a biocompatible hair-dyeing technology using a shampoo with a dark polyphenol complex (DPC), referred to as S-DPC. The DPC was formed from a mixture of gallic acid and [1,1'-biphenyl]-2,2',4,4',5,5'-hexol and used to enhance both the stability of the hair coating and its ability to scavenge reactive oxygen species (ROS). Colloidal DPC particles play a pivotal role in the coating process of various hair dyes, ensuring the uniform coloring of human hair through intermolecular interactions such as hydrogen bonding. Owing to the effect of a polyphenol complex on hair coating, we observed improved antistatic performance and enhanced mechanical strength, resulting in a substantial increase in elongation at the breaking point from 33.74% to 48.85%. The multicolor S-DPC exhibited antioxidant properties, as indicated by its ROS-scavenging ability, including 2,2-diphenyl-1-picrylhydrazyl inhibition (87-89%), superoxide radical scavenging (84-87%), and hydroxyl radical scavenging (95-98%). Moreover, the in vitro analysis of the DPC revealed nearly 100% cell viability in live and dead assays, highlighting the remarkable biocompatibility of the DPC. Therefore, considering its effectiveness and safety, this biomaterial has considerable potential for applications in hair dyeing.

Bioactive compounds and biomedical applications of endophytic fungi: a recent review

Human life has been significantly impacted by the creation and spread of novel species of antibiotic-resistant bacteria and virus strains that are difficult to manage. Scientists and researchers have recently been motivated to seek out alternatives and other sources of safe and ecologically friendly active chemicals that have a powerful and effective effect against a wide variety of pathogenic bacteria as a result of all these hazards and problems. In this review, endophytic fungi and their bioactive compounds and biomedical applications were discussed. Endophytes, a new category of microbial source that can produce a variety of biological components, have major values for study and broad prospects for development. Recently, endophytic fungi have received much attention as a source for new bioactive compounds. In addition, the variety of natural active compounds generated by endophytes is due to the close biological relationship between endophytes and their host plants. The bioactive compounds separated from endophytes are usually classified as steroids, xanthones, terpenoids, isocoumarins, phenols, tetralones, benzopyranones and enniatines. Moreover, this review discusses enhancement methods of secondary metabolites production by fungal endophytes which include optimization methods, co-culture method, chemical epigenetic modification and molecular-based approaches. Furthermore, this review deals with different medical applications of bioactive compounds such as antimicrobial, antiviral, antioxidant and anticancer activities in the last 3 years.

Extraction and purification of antioxidative flavonoids from Chionanthus retusa leaf

In this work, flavonoids from the leaves of Chionanthus retusa were extracted using alcohol, and the extraction yield was optimized by single-factor and orthogonal experiments. Then, the extracted solution with flavonoids was purified via macroporous resin by elution with different concentrations of ethanol. The antioxidative activity of total flavonoid in purified extracted solution was evaluated by detecting its ability to scavenge DPPH free radicals. The results demonstrated that ethanol with a concentration of 60%, ultrasonic power of 140 W, liquid-solid ratio of 25:1 ml g^-1, and water-bath temperature of 80°C were the optimal conditions for the extraction of total flavonoids from C. retusa leaf, achieving a yield of 121.28 mg g^-1. After purification by macroporous resin using different concentrations of ethanol, the highest content of total flavonoids (88.51%) in the extracted solution can be obtained with the 50% ethanol eluant. The results of scavenging DPPH free radicals suggest that the purified flavonoids in the 50% ethanol eluant had the best antioxidant capacity over the flavonoids in other ethanol eluants. In addition, it is confirmed the antioxidant capacity of the extractives was associated with the content of total flavonoids and kinds of flavonoids. These results may provide a feasible pathway to make full use of total flavonoids from C. retusa leaf.

Optimization of Extraction of Compound Flavonoids from Chinese Herbal Medicines Based on Quantification Theory and Evaluation of Their Antioxidant Activity

Plant-derived flavonoids have been attracting increasing research interest because of their multiple health promoting effects, where numerous investigations were carried out on the optimization of extraction and bioactivities. This study aims to optimize the extraction process of compound flavonoids (CFs) from Chinese herbal medicines and detect their antioxidant activity in vitro. CFs were extracted from the raw materials named “medicine food homology,” composed of hawthorn, lotus leaf, tartary buckwheat, cassia seed, Lycium barbarum, and Poria cocos in a mass ratio of 4 :  2 :  2 :  1.5 :  1 :  1. L9 (34) orthogonal design, level effect and engineering average estimation, and quantification theory were utilized to improve the extraction method of CFs, and the predictive model for CFs yield was constructed. The 2,2ʹ-diphenyl-1-picrylhydrazyl (DPPH), 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), hydroxyl radical scavenging rate, and reducing power of CFs were measured. The highest CFs yield was obtained under the following extraction condition: liquid-solid ratio of 35 : 1 mL/g, extraction temperature of 75°C, extraction duration of 75 min, and extraction mode enzyme-assisted extraction. The forecasted yield was 37.62%. The result was accurate and the established prediction equation was reliable (R = 0.95). The antioxidant activity of CFs was significantly positively correlated with the concentration from 0.05 to 0.4 mg/mL. The DPPH, ABTS, hydroxyl radical scavenging abilities, and the reducing power of CFs were 81.82 ± 1.75%, 49.35 ± 0.09%, 89.78 ± 0.66%, and 0.232 ± 0.001 at the concentration of 0.4 mg/mL, respectively. CFs could be exploited as natural antioxidants in pharmaceuticals and functional foods.

Community composition, bacterial symbionts, antibacterial and antioxidant activities of honeybee-associated fungi

Background

Fungi associated with insects represent one potentially rich source for the discovery of novel metabolites. However, a comprehensive understanding of the fungal communities of Apis mellifera ligustica remains elusive.

Results

Here, we investigated the phylogenetic diversity and community composition of honeybee-associated fungi using combination of culture-dependent and culture-independent approaches. A total of forty-five fungi were isolated and purified from the Apis mellifera ligustica, royal jelly, and honeycomb, which belonged to four classes and eleven different genera. Furthermore, 28 bacterial 16S rRNA gene sequences were obtained by PCR from the fungal metagenome. High-throughput sequencing analyses revealed that the fungal communities were more diverse, a total of 62 fungal genera were detected in the honeybee gut by culture-independent method, whereas only 4 genera were isolated by culture-dependent method. Similarly, 247 fungal genera were detected in the honeycomb, whereas only 4 genera were isolated. In addition, we assessed the antibacterial and antioxidant activities of fungal isolates. Most fungal crude extracts obtained from the cultivation supernatant exhibited antioxidant activities. Only two fungal crude extracts displayed moderate activity against Escherichia coli and Staphylococcus aureus. Chemical analysis of Chaetomium subaffine MFFC22 led to the discovery of three known compounds, including cochliodinol (1), emodin (2), chrysophanol (3). Among them, cochliodinol (1) showed intense DPPH radical scavenging activity with the 50% inhibitory concentration (IC₅₀) of 3.06 μg/mL, which was comparable to that of the positive ascorbic acid (IC₅₀ = 2.25 μg/mL). Compound 2 displayed weak inhibitory activities against Micrococcus tetragenus and S. aureus.

Conclusions

This research provided a fundamental clue for the complex interactions among honeybees, fungi, bacterial symbionts, and the effects on the honeybee. Furthermore, the diversity of honeybee-associated fungi had great potential in finding the resource of new species and antioxidants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02580-4.

A multifunctional metal regulator as the potential theranostic agent: Design, synthesis, anti-AD activities and metallic ion sensing properties

Although there is no cure for Alzheimer's disease (AD) due to its complex pathogenesis, early detection and treatment can help delay the development of the disease. So, it is necessary to develop multifunctional metal regulators that can integrate the therapeutics and diagnostics effect against AD. In this work, N-(anthracene-9-ylmethylene)benzohydrazide (probe 1), a fluorescent probe with imine and carbonyl as chelating sites was designed and synthesized. Results showed that 1 had good activities related to AD, such as regulation of metal homeostasis, inhibition of β-amyloid (Aβ) aggregation and scavenging of reactive oxygen species. The selectivity experiment showed that probe 1 had a good recognition effect on Cu²⁺. Fluorescence imaging assay also indicated that probe 1 had a good fluorescence imaging effect on Cu²⁺ in living cells. Furthermore, probe 1 had showed no cytotoxicity and good BBB permeability. These results indicated that probe 1 had potential diagnostic and therapeutic capabilities, and can be used as the multifunctional theranostic agent for AD.