PROTAC derivatization of natural products for target identification and drug discovery: Design of evodiamine-based PROTACs as novel REXO4 degraders

INTRODUCTION

Natural products (NPs) play a crucial role in the development of therapeutic drugs. However, it is still highly challenging to identify the targets of NPs. Besides, NPs usually exert their pharmacological activities via acting on multiple targets or pathways, which also poses great difficulties for the target identification of NPs.

OBJECTIVES

Inspired by our continuous efforts in designing drug-like protein degraders, this study introduced a successful example for the target identification and drug discovery of natural products evodiamine by employing PROTAC technology.

METHODS

Taking advantages of proteolysis targeting chimera (PROTAC), herein an integrated strategy combining PROTAC derivatization, quantitative proteomic analysis and binding affinity validation was developed for target identification and drug discovery of antitumor NP evodiamine.

RESULTS

In this study, both highly potent PROTACs and negative controls were designed for quantitative proteomic analysis. Furthermore, REXO4 was confirmed as a direct target of 3-fluoro-10-hydroxylevodiamine, which induced cell death through ROS. In addition, the PROTAC 13c effectively degraded REXO4 both in vitro and in vivo, leading to potent antitumor activities and reduced toxic side effects.

CONCLUSION

In summary, we developed an integrated strategy for the target identification and drug discovery of NPs, which was successfully applied to the PROTAC derivatization and target characterization of evodiamine. This proof-of-concept study highlighted the superiority of PROTAC technology in target identification of NPs and accelerated the process of NPs-based drug discovery, exhibiting broad application in NP-based drug development.

The recent discovery of a promising pharmacological scaffold derived from carvacrol: A review

Carvacrol, called CA, is a dynamic phytoconstituent characterized by a phenol ring abundantly sourced from various natural reservoirs. This versatile scaffold serves as a pivotal template for the design and synthesis of novel drug molecules, harboring promising biological activities. The active sites positioned at C-4, C-6, and the hydroxyl group (-OH) of CA offer fertile ground for creating potent drug candidates from a pharmacological standpoint. In this comprehensive review, we delve into diverse synthesis pathways and explore the biological activity of CA derivatives. We aim to illuminate the potential of these derivatives in discovering and developing efficacious treatments against a myriad of life-threatening diseases. By scrutinizing the structural modifications and pharmacophore placements that enhance the activity of CA derivatives, we aspire to inspire the innovation of novel therapeutics with heightened potency and effectiveness.

Clinical development and informatics analysis of natural and semi-synthetic flavonoid drugs: A critical review

BACKGROUND

Flavonoids are one of the most important metabolites with vast structural diversity and a plethora of potential pharmacological applications, which have drawn considerable attention in the laboratory. Nevertheless, it remains uncertain how many candidates were progressed to clinical application.

AIM OF REVIEW

We carried out a critical review of natural and semi-synthetic flavonoid drugs and candidates undergoing different clinical phases worldwide by applying an adequate search method and conducted a brief cheminformatic and bioinformatic analysis. It was expected that the obtained results might narrow the screening scope and reduce the cost of drug research and development.

KEY SCIENTIFIC CONCEPTS OF REVIEW

To our knowledge, this is the most systematic summarization of flavonoid-based drugs and clinical candidates to date. It was found that a total of 19 flavonoid-based drugs have been approved for the market, and of these, natural flavonoids accounted for 52.6%. Besides, a total of 36 flavonoid-based clinical candidates are undergoing or suspended in different phases, and of these, natural flavonoids account for 44.4%. Thus, natural flavonoids remain the best option for finding novel agents/active templates, and when investigated in conjunction with synthetic chemicals and biologicals, they offer the potential to discover novel structures that can lead to effective agents against a variety of human diseases. Additionally, flavonoid-based marketed drugs have been successful in cardiovascular treatment, and the related drugs account for more than 30% of marketed drugs. However, the use of flavonoids as antineoplastic and immunomodulating agents is not likely for approximately 50% of the candidates suspended in the clinical stage. Interestingly, the marketed drugs covered a broader range of chemical spaces based on size, polarity, and three-dimensional structure compared to the clinical candidates. In addition, flavonoid glycosides with poor oral bioavailability account for 36.8% of the marketed drugs, and thus, they could be thoroughly investigated.

Evo312: An Evodiamine Analog and Novel PKCβI Inhibitor with Potent Antitumor Activity in Gemcitabine-Resistant Pancreatic Cancer

As an obstinate cancer pancreatic cancer (PC) poses a major challenge due to limited treatment options which include resection surgery, radiation therapy, and gemcitabine-based chemotherapy. In cancer cells, protein kinase C βI (PKCβI) participates in diverse cellular processes, including cell proliferation, invasion, and apoptotic pathways. In the present study, we created a scaffold to develop PKCβI inhibitors using evodiamine-based synthetic molecules. Among the candidate inhibitors, Evo312 exhibited the highest antiproliferative efficacy against PC cells, PANC-1, and acquired gemcitabine-resistant PC cells, PANC-GR. Additionally, Evo312 robustly inhibited PKCβI activity. Mechanistically, Evo312 effectively suppressed the upregulation of PKCβI protein expression, leading to the induction of cell cycle arrest and apoptosis in PANC-GR cells. Furthermore, Evo312 exerted an antitumor activity in a PANC-GR cell-implanted xenograft mouse model. These findings position Evo312 as a promising lead compound for overcoming gemcitabine resistance in PC through novel mechanisms.

Natural and synthetic 5-(3'-indolyl)oxazoles: Biological activity, chemical synthesis and advanced molecules

5-(3'-Indolyl)oxazole moiety is a privileged heterocyclic scaffold, embedded in many biologically interesting natural products and potential therapeutic agents. Compounds containing this scaffold, whether from natural sources or synthesized, have demonstrated a wide array of biological activities. This has piqued the interest of synthetic chemists, leading to a large number of reported synthetic approaches to 5-(3'-indolyl)oxazole scaffold in recent years. In this review, we comprehensively overviewed the different biological activities and chemical synthetic methods for the 5-(3'-indolyl)oxazole scaffold reported in the literatures from 1963 to 2024. The focus of this study is to highlight the significance of 5-(3'-indolyl)oxazole derivatives as the lead compounds for the lead discovery of anticancer, pesticidal, antimicrobial, antiviral, antioxidant and anti-inflammatory agents, to summarize the synthetic methods for the 5-(3'-indolyl)oxazole scaffold. In addition, the reported mechanism of action of 5-(3'-indolyl)oxazoles and advanced molecules studied in animal models are also reviewed. Furthermore, this review offers perspectives on how 5-(3'-indolyl)oxazole scaffold as a privileged structure might be exploited in the future.

Facile fabrication of linezolid/strontium coated hydroxyapatite/graphene oxide nanocomposite for osteoporotic bone defect

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ's physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

Antioxidant and anti‑inflammatory effects of esculin and esculetin (Review)

Fraxinus chinensis Roxb is a deciduous tree, which is distributed worldwide and has important medicinal value. In Asia, the bark of Fraxinus chinensis Roxb is a commonly used traditional Chinese medicine called Qinpi. Esculetin is a coumarin compound derived from the bark of Fraxinus chinensis Roxb and its glycoside form is called esculin. The aim of the present study was to systematically review relevant literature on the antioxidant and anti-inflammatory effects of esculetin and esculin. Esculetin and esculin can promote the expression of various endogenous antioxidant proteins, such as superoxide dismutase, glutathione peroxidase and glutathione reductase. This is associated with the activation of the nuclear factor erythroid-derived factor 2-related factor 2 signaling pathway. The anti-inflammatory effects of esculetin and esculin are associated with the inhibition of the nuclear factor κ-B and mitogen-activated protein kinase inflammatory signaling pathways. In various inflammatory models, esculetin and esculin can reduce the expression levels of various proinflammatory factors such as tumor necrosis factor-α, interleukin (IL)-1β and IL-6, thereby inhibiting the development of inflammation. In summary, esculetin and esculin may be promising candidates for the treatment of numerous diseases associated with inflammation and oxidative stress, such as ulcerative colitis, acute lung and kidney injury, lung cancer, acute kidney injury.

Design of Evodiamine-Glucose Conjugates with Improved In Vivo Antitumor Activity

Natural product evodiamine is a multitargeting antitumor lead compound. However, clinical development of evodiamine derivatives was hampered by poor water solubility and limited in vivo antitumor potency. Herein, a series of evodiamine-glucose conjugates were designed by additional targeting glucose transporter-1 (GLUT1). Compared with the lead compound, conjugate 8 exhibited obvious enhancement in water solubility and in vivo antitumor efficacy. Furthermore, the effect of GLUT1 targeting also led to lower cytotoxicity to normal cells. Antitumor mechanism studies manifested that conjugate 8 acted by Top1/Top2 dual inhibition, apoptosis induction, and G2/M cell cycle arrest, which selectively targeted tumor cells with a high expression level of GLUT1. Thus, evodiamine-glucose conjugates showed promising features as potential antitumor agents.

Avenanthramide and β-Glucan Therapeutics Accelerate Wound Healing Via Distinct and Nonoverlapping Mechanisms

Objective: Given the significant economic, health care, and personal burden of acute and chronic wounds, we investigated the dose dependent wound healing mechanisms of two Avena sativa derived compounds: avenanthramide (AVN) and β-Glucan. Approach: We utilized a splinted excisional wound model that mimics human-like wound healing and performed subcutaneous AVN and β-Glucan injections in 15-week-old C57BL/6 mice. Histologic and immunohistochemical analysis was performed on the explanted scar tissue to assess changes in collagen architecture and cellular responses. Results: AVN and β-Glucan treatment provided therapeutic benefits at a 1% dose by weight in a phosphate-buffered saline vehicle, including accelerated healing time, beneficial cellular recruitment, and improved tissue architecture of healed scars. One percent AVN treatment promoted an extracellular matrix (ECM) architecture similar to unwounded skin, with shorter, more randomly aligned collagen fibers and reduced inflammatory cell presence in the healed tissue. One percent β-Glucan treatment promoted a tissue architecture characterized by long, thick bundles of collagen with increased blood vessel density. Innovation: AVN and β-Glucan have previously shown promise in promoting wound healing, although the therapeutic efficacies and mechanisms of these bioactive compounds remain incompletely understood. Furthermore, the healed ECM architecture of these wounds has not been characterized. Conclusions: AVN and β-Glucan accelerated wound closure compared to controls through distinct mechanisms. AVN-treated scars displayed a more regenerative tissue architecture with reduced inflammatory cell recruitment, while β-Glucan demonstrated increased angiogenesis with more highly aligned tissue architecture more indicative of fibrosis. A deeper understanding of the mechanisms driving healing in these two naturally derived therapeutics will be important for translation to human use.

Protective effect of avicularin against lung cancer via inhibiting inflammation, oxidative stress, and induction of apoptosis: an in vitro and in vivo study

The purpose of this research was to investigate whether or not avicularin (AVL) possesses any anticancer properties when tested against lung cancer. In the beginning, the effect that it had on the cellular viability of A549 cells was investigated, and it was discovered that AVL has a considerable negative impact on cellular viability. Following that, an investigation using flow cytometry was carried out to investigate its function in the process of apoptosis and the cell cycle of A549 cells. It has been discovered that AVL significantly promotes apoptosis and stops the cell cycle at the G2/M phase. The colony-forming capacity of A549 cells was observed to be greatly suppressed as the AVL concentration increased compared to the group that received no treatment. In addition to this, the benzo(a)pyrene in vivo model was established in order to investigate the pharmacological value of AVL. The findings revealed that AVL greatly prevented the formation of pro-inflammatory cytokines, in addition to the reduction in oxidative stress, which was evidenced by a reduction in the concentration of TNF-α, IL-1β, IL-6, and MDA with an improvement in the concentration of SOD and GPx, respectively. Our results successfully demonstrated the pharmacological benefit of avicularin against lung cancer, and it has been suggested that it showed a multifactorial effect.

Discovery of a Fungal P450 with an Unusual Two-Step Mechanism for Constructing a Bicyclo[3.2.2]nonane Skeleton

The successful biomimetic or chemoenzymatic synthesis of target natural products (NPs) and their derivatives relies on enzyme discovery. Herein, we discover a fungal P450 BTG5 that can catalyze the formation of a bicyclo[3.2.2]nonane structure through an unusual two-step mechanism of dimerization and cyclization in the biosynthesis of beticolin 1, whose bicyclo[3.2.2]nonane skeleton connects an anthraquinone moiety and a xanthone moiety. Further investigation reveals that BTG5-T318 not only determines the substrate selectivity but also alters the catalytic reactions, which allows the separation of the reaction to two individual steps, thereby understanding its catalytic mechanism. It reveals that the first heterodimerization undergoes the common oxidation process for P450s, while the second uncommon formal redox-neutral cyclization step is proved as a redox-mediated reaction, which has never been reported. Therefore, this work advances our understanding of P450-catalyzed reactions and paves the way for expansion of the diversity of this class of NPs through synthetic biology.

Synthetic Biology-based Construction of Unnatural Perylenequinones with Improved Photodynamic Anticancer Activities

The construction of structural complexity and diversity of natural products is crucial for drug discovery and development. To overcome high dark toxicity and poor photostability of natural photosensitizer perylenequinones (PQs) for photodynamic therapy, herein, we aim to introduce the structural complexity and diversity to biosynthesize the desired unnatural PQs in fungus Cercospora through synthetic biology-based strategy. Thus, we first elucidate the intricate biosynthetic pathways of class B PQs and reveal how the branching enzymes create their structural complexity and diversity from a common ancestor. This enables the rational reprogramming of cercosporin biosynthetic pathway in Cercospora to generate diverse unnatural PQs without chemical modification. Among them, unnatural cercosporin A displays remarkably low dark toxicity and high photostability with retention of great photodynamic anticancer and antimicrobial activities. Moreover, it is found that, unlike cercosporin, unnatural cercosporin A could be selectively accumulated in cancer cells, providing potential targets for drug development. Therefore, this work provides a comprehensive foundation for preparing unnatural products with customized functions through synthetic biology-based strategies, thus facilitating drug discovery pipelines from nature.

Sustainable production of natural products using synthetic biology: Ginsenosides

Synthetic biology approaches offer potential for large-scale and sustainable production of natural products with bioactive potency, including ginsenosides, providing a means to produce novel compounds with enhanced therapeutic properties. Ginseng, known for its non-toxic and potent qualities in traditional medicine, has been used for various medical needs. Ginseng has shown promise for its antioxidant and neuroprotective properties, and it has been used as a potential agent to boost immunity against various infections when used together with other drugs and vaccines. Given the increasing demand for ginsenosides and the challenges associated with traditional extraction methods, synthetic biology holds promise in the development of therapeutics. In this review, we discuss recent developments in microorganism producer engineering and ginsenoside production in microorganisms using synthetic biology approaches.

Total Synthesis of Isoxeniolide A

Isoxeniolide A is a highly strained xenicane diterpenoid of marine origin. This natural product is representative for a subfamily of xenicanes incorporating an allylic hydroxy group in the nine-membered ring; members of this xenicane subfamily so far have not been targeted by total synthesis. Herein, we describe the first asymmetric total synthesis of isoxeniolide A. Key to forming the challenging E-configured cyclononene ring was a diastereoselective intramolecular Nozaki-Hiyama-Kishi reaction. Other important transformations include an enzymatic desymmetrization for absolute stereocontrol, a diastereoselective cuprate addition and the use of a bifunctional vinyl silane building block. Our strategy also permits access to the enantiomer of the natural product and holds potential to access a multitude of xenicane natural products and analogs for structure-activity relationship studies.

Bioactive metabolites reveal the therapeutic consistency of epimedii folium from multi-plant sources for the treatment of kidney-yang deficiency

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedii Folium (Yin-yang-huo in Chinese), a traditional and commonly used herbal medicine (HM), is a representative of multi-plant sources. To date, little is known about the reasons for similar therapeutic effects of this HM from multi-plant sources.

AIM OF THE STUDY

To investigate the underlying reasons for the similar pharmacological effects of Epimedii Folium from two botanical sources (Epimedium koreanum Nakai and Epimedium wushanense T. S. Ying).

MATERIALS AND METHODS

Firstly, the phytochemicals of the extracts of E. koreanum and E. wushanense were systematically analyzed. Meanwhile, their pharmacological effects on kidney-yang deficiency (KYD) syndrome were evaluated in rats induced by hydrocortisone. Subsequently, we proposed a combined effect index (CEI) to assess the effects of two plants on the secretion of testosterone by combing the system exposure of twelve active components in vivo with their regulation activities of testosterone production in vitro. Moreover, the label-free proteomics and Western blot analysis were conducted to evaluate the possible mechanism of Epimedii Folium from two botanical sources.

RESULTS

E. koreanum and E. wushanense exhibited similar pharmacological effects on KYD syndrome with promoting the mating behaviors and testosterone levels of rats, although there is a certain difference in the main components between two plants. The CEI analysis showed that there was no difference (P > 0.05) in the sum of CEIs of two Epimedium, indicating that their similar therapeutic effects are attributed to bioactive metabolites in vivo. Furthermore, Epimedii Folium can regulate testosterone production in rat Leydig cell via reversing expressions of key steroidogenic enzymes, such as steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD).

CONCLUSION

Our results supply critical evidence for the similar pharmacological effects of two Epimedium species, acting by consistent bioactive components directly exposing in vivo, not chemical compositions presenting in herbs. It provides a reasonable scientific basis for understanding of the HMs originated from multi-plant sources for the same clinical application.

CYP1A inhibitors: Recent progress, current challenges, and future perspectives

Mammalian cytochrome P450 1A (CYP1A) are key phase I xenobiotic-metabolizing enzymes that play a distinctive role in metabolic activation or metabolic clearance of a variety of procarcinogens, drugs, and endogenous substances. Human CYP1A subfamily contains two members (hCYP1A1 and hCYP1A2), which are known to catalyze the oxidative activation of some environmental procarcinogens into carcinogenic species. Increasing evidence has demonstrated that CYP1A inhibitor therapies are promising strategies for cancer chemoprevention or overcoming CYP1A-associated drug toxicity and resistance. Herein, we reviewed recent advances in the discovery and characterization of hCYP1A inhibitors, from the discovery approaches to structural features and biomedical applications of hCYP1A inhibitors. The inhibition potentials, inhibition modes, and inhibition constants of all reported hCYP1A inhibitors are comprehensively summarized. Meanwhile, the structural features and structure-activity relationships of different classes of hCYP1A1 and hCYP1A2 inhibitors are analyzed and discussed in depth. Furthermore, the major challenges and future directions for this field are presented and highlighted. Collectively, the information and knowledge presented here will strongly facilitate the researchers to discover and develop more efficacious CYP1A inhibitors for specific purposes, such as chemo-preventive agents or as tool molecules in hCYP1A-related fundamental studies.

Anti-cancer bioprospecting on medicinal plants from Indonesia: A review

The Indonesian archipelago is home to the second largest biodiversity in the world and is inhabited by more than 300 ethnic groups with a total population of more than 270 million. The indigenous population still rely on traditional medicine practices, especially the use of plant-based remedies. Although modern science-based exploration on Indonesian medicinal plants started with the European settlement in the archipelago in the 16th century, it was not until the 1970's that the phytochemistry of Indonesian medicinal plants was recognized for its potency. The need for new cancer cures to increase the quality of human life has led to the bioprospecting of medicinal plants including those of Indonesian origin. Despite published reports on the anticancer potency of Indonesian medicinal plants, to date there has been no comprehensive review on this topic. In this manuscript, we review the phytochemical and pharmacological studies on medicinal plants from Indonesia related to cancer therapy. Established databases (GARUDA, SciFinder, and PubMed) were used to collate data from 1990 to 2022, resulting in the description of 134 medicinal plants and their phytochemical and pharmacological properties including examples containing potent agents against breast, leukaemia, cervix, lung, and colon cancer cell lines based on in vitro bioassays and in vivo evaluation. These findings provide valuable insights into the bioprospecting of Indonesian medicinal plant providing directions for future studies, including the development of new therapeutics, both as botanicals or by using conventional dosage.

γ-Glutamyltranspeptidase-Activated Near-Infrared fluorescent probe for visualization of Drug-Induced liver injury

Drug-induced liver injury (DILI), induced by overdose or chronic administration of drugs, has become the leading cause of acute liver failure. Therefore, an accurate diagnostic method for DILI is critical to improve treatment efficiency. The production of γ-glutamyltranspeptidase (GGT) is closely related to the progression of drug-induced hepatotoxicity. KL-Glu exhibits a prominent GGT-activated NIR fluorescence (734 nm) with a large Stokes shift (137 nm) and good sensitivity/selectivity, making it favorable for real-time detection of endogenous GGT activity. Using this probe, we evaluated the GGT up-regulation under the acetaminophen-induced liver injury model. Moreover, KL-Glu was successfully used to assess liver injury induced by the natural active ingredient triptolide and the effective amelioration upon treatment with N-acetyl cysteine (NAC) or Glutathione (GSH) in cells and in vivo by fluorescent trapping the fluctuation of GGT for the first time. Therefore, the fluorescent probe KL-Glu can be used as a potential tool to explore the function of GGT in the progression of DILI and for the early diagnosis and prognostic evaluation of DILI.

Lipid-based nanoparticle-mediated combination therapy for breast cancer management: a comprehensive review

Breast cancer due to the unpredictable and complex etiopathology combined with the non-availability of any effective drug treatment has become the major root of concern for oncologists globally. The number of women affected by the said disease state is increasing at an alarming rate attributed to environmental and lifestyle changes indicating at the exploration of a novel treatment strategy that can eradicate this aggressive disease. So far, it is treated by promising nanomedicine monotherapy; however, according to the numerous studies conducted, the inadequacy of these nano monotherapies in terms of elevated toxicity and resistance has been reported. This review, therefore, puts forth a new multimodal strategic approach to lipid-based nanoparticle-mediated combination drug delivery in breast cancer, emphasizing the recent advancements. A basic overview about the combination therapy and its index is firstly given. Then, the various nano-based combinations of chemotherapeutics involving the combination delivery of synthetic and herbal agents are discussed along with their examples. Further, the recent exploration of chemotherapeutics co-delivery with small interfering RNA (siRNA) agents has also been explained herein. Finally, a section providing a brief description of the delivery of chemotherapeutic agents with monoclonal antibodies (mAbs) has been presented. From this review, we aim to provide the researchers with deep insight into the novel and much more effective combinational lipid-based nanoparticle-mediated nanomedicines tailored specifically for breast cancer treatment resulting in synergism, enhanced antitumor efficacy, and low toxic effects, subsequently overcoming the hurdles associated with conventional chemotherapy.

Targeted characterization and guided isolation of chemical components in Scrophulariae Radix based on LC-MS

How to achieve rapid characterization and efficient isolation of chemical components from traditional Chinese medicines (TCMs) is what the researchers have been exploring. Herein, a strategy integrated diagnostic ion filtering (DIF) and selected ion recording (SIR)-based screen was firstly proposed and successfully applied for targeted characterization and guided isolation of the chemical components from Scrophulariae Radix, one of TCMs. After acquiring the Q-TOF-MS/MS untargeted data, 128 compounds were characterized based on DIF, a self-built database and comparison of the related literatures, in which 38 compounds were reported for the first time. Subsequently, the SIR method of UPLC-QqQ-MS/MS was adopted to guide the isolation of potential new compounds. Finally, three new compounds together with one known compound with the same skeleton were isolated, and unambiguously elucidated by NMR and acid hydrolysis. These results indicated that this integrated analytical approach is effective and reliable in targeted characterizing chemical components and isolating new compounds from the extract of Scrophulariae Radix.

Activation of a Silent Polyketide Synthase SlPKS4 Encoding the C7-Methylated Isocoumarin in a Marine-Derived Fungus Simplicillium lamellicola HDN13-430

Coumarins, isocoumarins and their derivatives are polyketides abundant in fungal metabolites. Although they were first discovered over 50 years ago, the biosynthetic process is still not entirely understood. Herein, we report the activation of a silent nonreducing polyketide synthase that encodes a C7-methylated isocoumarin, similanpyrone B (1), in a marine-derived fungus Simplicillium lamellicola HDN13-430 by heterologous expression. Feeding studies revealed the host enzymes can change 1 into its hydroxylated derivatives pestapyrone A (2). Compounds 1 and 2 showed moderate radical scavenging activities with ED50 values of 67.4 µM and 104.2 µM. Our discovery fills the gap in the enzymatic elucidation of naturally occurring C7-methylated isocoumarin derivatives.

Biosensor Guided Polyketide Synthases Engineering for Optimization of Domain Exchange Boundaries

Type I modular polyketide synthases (PKSs) are multi-domain enzymes functioning like assembly lines. Many engineering attempts have been made for the last three decades to replace, delete and insert new functional domains into PKSs to produce novel molecules. However, inserting heterologous domains often destabilize PKSs, causing loss of activity and protein misfolding. To address this challenge, here we develop a fluorescence-based solubility biosensor that can quickly identify engineered PKSs variants with minimal structural disruptions. Using this biosensor, we screen a library of acyltransferase (AT)-exchanged PKS hybrids with randomly assigned domain boundaries, and we identify variants that maintain wild type production levels. We then probe each position in the AT linker region to determine how domain boundaries influence structural integrity and identify a set of optimized domain boundaries. Overall, we have successfully developed an experimentally validated, high-throughput method for making hybrid PKSs that produce novel molecules.

Epigallocatechin-3-Gallate Therapeutic Potential in Cancer: Mechanism of Action and Clinical Implications

Cellular signaling pathways involved in the maintenance of the equilibrium between cell proliferation and apoptosis have emerged as rational targets that can be exploited in the prevention and treatment of cancer. Epigallocatechin-3-gallate (EGCG) is the most abundant phenolic compound found in green tea. It has been shown to regulate multiple crucial cellular signaling pathways, including those mediated by EGFR, JAK-STAT, MAPKs, NF-κB, PI3K-AKT-mTOR, and others. Deregulation of the abovementioned pathways is involved in the pathophysiology of cancer. It has been demonstrated that EGCG may exert anti-proliferative, anti-inflammatory, and apoptosis-inducing effects or induce epigenetic changes. Furthermore, preclinical and clinical studies suggest that EGCG may be used in the treatment of numerous disorders, including cancer. This review aims to summarize the existing knowledge regarding the biological properties of EGCG, especially in the context of cancer treatment and prophylaxis.

Bromotyrosine-Derived Metabolites from a Marine Sponge Inhibit Pseudomonas aeruginosa Biofilms

Pseudomonas aeruginosa forms stable biofilms, providing a major barrier for multiple classes of antibiotics and severely impairing treatment of infected patients. The biofilm matrix of this Gram-negative bacterium is primarily composed of three major exopolysaccharides: alginate, Psl, and Pel. Here, we studied the antibiofilm properties of sponge-derived natural products ianthelliformisamines A-C and their combinations with clinically used antibiotics. Wild-type P. aeruginosa strain and its isogenic exopolysaccharide-deficient mutants were employed to determine the interference of the compounds with biofilm matrix components. We identified that ianthelliformisamines A and B worked synergistically with ciprofloxacin to kill planktonic and biofilm cells. Ianthelliformisamines A and B reduced the minimum inhibitory concentration (MIC) of ciprofloxacin to 1/3 and 1/4 MICs, respectively. In contrast, ianthelliformisamine C (MIC = 53.1 µg/mL) alone exhibited bactericidal effects dose-dependently on both free-living and biofilm populations of wild-type PAO1, PAO1ΔpslA (Psl deficient), PDO300 (alginate overproducing and mimicking clinical isolates), and PDO300Δalg8 (alginate deficient). Interestingly, the biofilm of the clinically relevant mucoid variant PDO300 was more susceptible to ianthelliformisamine C than strains with impaired polysaccharide synthesis. Ianthelliformisamines exhibited low cytotoxicity towards HEK293 cells in the resazurin viability assay. Mechanism of action studies showed that ianthelliformisamine C inhibited the efflux pump of P. aeruginosa. Metabolic stability analyses indicated that ianthelliformisamine C is stable and ianthelliformisamines A and B are rapidly degraded. Overall, these findings suggest that the ianthelliformisamine chemotype could be a promising candidate for the treatment of P. aeruginosa biofilms.

Purification and evaluation of 2, 4-di-tert butylphenol (DTBP) as a biocontrol agent against phyto-pathogenic fungi

A fungal strain, Marasmiellus sp (PUK64), isolated from the mangrove forests in Muthupet, Tamil Nadu, East coast of India, along with others were screened for the search of potent bioactive compounds. A phenolic compound, 2,4-di-tert-butylphenol (DTBP), was isolated from the most promising strain PUK64 and its chemical structure was ascertained. DTBP demonstrated remarkable antifungal activity against the phytopathogenic fungi Aspergillus oryzae, Curvularia lunata and Fusarium verticillioides. In an in-vitro experimental setup, DTBP suppressed the growth of all three fungi, among which F. verticillioides was found to be highly susceptible. This effect relates with the inhibition of spore germination and hyphal growth that we observed. DTBP showed high affinity with the F. verticillioides's β-tubulin protein (determined by ligand-protein docking) as compared to the standard fungicide carbendazim (CBZ). Molecular docking and simulation studies of DTBP with target β-tubulin further confirmed the potential of β-tubulin binding in F. verticillioides. To our knowledge, this is the first report on DTBP-mediated biocontrol of phytopathogenic fungi, produced by Marasmiellus sp. PUK64 that can be potent inhibitor of β-tubulin protein of F. verticillioides.

Dietary regulation of peroxisome proliferator-activated receptors in metabolic syndrome

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are a class of ligand-activated nuclear transcription factors, members of the type nuclear receptor superfamily, with three subtypes, namely PPARα, PPARβ/δ, and PPARγ, which play a key role in the metabolic syndrome. In the past decades, a large number of studies have shown that natural products can act by regulating metabolic pathways mediated by PPARs.

PURPOSE

This work summarizes the physiological importance and clinical significance of PPARs and reviews the experimental evidence that natural products mediate metabolic syndrome via PPARs.

METHODS

This study reviews relevant literature on clinical trials, epidemiology, animals, and cell cultures published in NCBI PubMed, Scopus, Web of Science, Google Scholar, and other databases from 2001 to October 2022. Search keywords were "natural product" OR "botanical" OR "phytochemical" AND "PPAR" as well as free text words.

RESULTS

The modulatory involvement of PPARs in the metabolic syndrome has been supported by prior research. It has been observed that many natural products can treat metabolic syndrome by altering PPARs. The majority of currently described natural compounds are mild PPAR-selective agonists with therapeutic effects that are equivalent to synthetic medicines but less harmful adverse effects.

CONCLUSION

PPAR agonists can be combined with natural products to treat and prevent metabolic syndrome. Further human investigations are required because it is unknown how natural products cause harm and how they might have negative impacts.

Cytotoxic and Antibacterial Prenylated Acylphloroglucinols from Hypericum olympicum L

Two new bicyclo[3.3.1]nonane type bicyclic polyprenylated acylphloroglucinol derivatives (BPAPs), olympiforin A and B as well as three known prenylated phloroglucinols, were isolated from the aerial parts of Hypericum olympicum L. The structures of the isolated compounds were established by means of spectral techniques (HRESIMS and 1D and 2D NMR). All compounds were tested on a panel of human tumor (MDA-MB-231, EJ, K-562, HL-60 and HL-60/DOX) and non- tumorigenic (HEK-293 and EA.hy926) cell lines using the MTT assay. All tested compounds exerted significant in vitro cytotoxicity with IC₅₀ values ranging from 1.2 to 24.9 μM and from 0.9 to 34 μM on tumor and non-cancerous cell lines, respectively. Most of the compounds had good selectivity and were more cytotoxic to the tumor cell lines than to the normal ones. A degradation of the precursor caspase 9 for some of the compounds was observed; therefore, the intrinsic pathway of apoptosis is the most likely mechanism of cytotoxic activity. The BPAPs were examined for antibacterial and antibiofilm activity through the broth microdilution method and the protocol of Stepanović. They showed a moderate effect against Enterococcus faecalis and Streptococcus pyogenes but a very profound activity against Staphylococcus aureus with minimum inhibitory concentrations (MIC) in the range of 0.78-2 mg/L. Olympiforin B also had a great effect against methicillin-resistant S. aureus (MRSA) with an MIC value of 1 mg/L and a very significant antibiofilm activity on that strain with a minimum biofilm inhibition concentration (MBIC) value of 0.5 mg/L. The structures of the isolated compounds were in silico evaluated using ADME and drug likeness tests.

Enzymatic Synthesis of Thymol Octanoate, a Promising Hybrid Molecule

Interest in the synthesis and application of thymol esters has increased in recent years due to the numerous applications associated with its biological activities. The enzymatic synthesis of thymol octanoate by esterification of thymol and octanoic acid was explored using soluble lipases and immobilized lipase biocatalysts in solvent-free systems. Candida antarctica lipase B in its soluble form was the most active biocatalyst for this reaction. Different thymol and lipase feeding strategies were evaluated to maximize thymol octanoate production. The results suggest that there could be lipase inhibition by the ester product of the reaction. In this way, the optimal reaction condition was given using a thymol/acid molar ratio of 1:4 mol/mol. Under these conditions the conversion of thymol was close to 94% and the lipase maintained more than 90% of its initial activity after the reaction, showing the potential of the enzyme to be used in successive reaction cycles.

Strengthening microbial cell factories for efficient production of bioactive molecules

High demand of bioactive molecules (food additives, antibiotics, plant growth enhancers, cosmetics, pigments and other commercial products) is the prime need for the betterment of human life where the applicability of the synthetic chemical product is on the saturation due to associated toxicity and ornamentations. It has been noticed that the discovery and productivity of such molecules in natural scenarios are limited due to low cellular yields as well as less optimized conventional methods. In this respect, microbial cell factories timely fulfilling the requirement of synthesizing bioactive molecules by improving production yield and screening more promising structural homologues of the native molecule. Where the robustness of the microbial host can be potentially achieved by taking advantage of cell engineering approaches such as tuning functional and adjustable factors, metabolic balancing, adapting cellular transcription machinery, applying high throughput OMICs tools, stability of genotype/phenotype, organelle optimizations, genome editing (CRISPER/Cas mediated system) and also by developing accurate model systems via machine-learning tools. In this article, we provide an overview from traditional to recent trends and the application of newly developed technologies, for strengthening the systemic approaches and providing future directions for enhancing the robustness of microbial cell factories to speed up the production of biomolecules for commercial purposes.

Structural Simplification of Cryptolepine to Obtain Novel Antifungal Quinoline Derivatives against Phytopathogenic Fungi

A series of quinoline derivatives were designed and synthesized by the structural simplification of cryptolepine and evaluated for their fungicidal activity against six phytopathogenic fungi. Most of these compounds exhibited remarkable activities against Botrytis cinereain vitro. Among them, compounds A18 and L01 showed superior antifungal activity. Significantly, compared to cryptolepine, compound A18 exhibited broad-spectrum inhibitory activities against B. cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani, Phytophthora capsica, Magnaporthe oryzae, and Fusarium graminearum with the respective EC₅₀ values of 0.249, 1.569, 3.915, 0.505, 0.246, and 4.999 μg/mL. Compound L01 displayed the best antifungal activity against B. cinerea with an EC₅₀ value of 0.156 μg/mL. Preliminary mechanistic studies showed that compound A18 could inhibit spore germination, affect the permeability of the cell membrane, increase the content of reactive oxygen species, and affect the morphology of hyphae and cells. Moreover, compound A18 showed excellent in vivo protective effect against B. cinerea, which was more potent than pyrimethanil and equitant to cryptolepine. These results evidenced that compound A18 displayed superior fungicidal activities and could be a potential fungicidal candidate against plant fungal diseases.

Phytotherapy and Drugs: Can Their Interactions Increase Side Effects in Cancer Patients?

BACKGROUND

The use of herbs to treat illnesses was common in all historical eras. Our aim was to describe the phytotherapeutic substances that cancer patients use most commonly, and to determine whether their use can increase side effects.

METHODS

This was a retrospective and descriptive study conducted among older adults actively undergoing chemotherapy, admitted at the Oncology DH Unit (COES) of the Molinette Hospital AOU Città della Salute e della Scienza in Turin (Italy). Data collection was conducted through the distribution of self-compiled and closed-ended questionnaires during chemotherapy treatment.

RESULTS

A total of 281 patients were enrolled. Evaluating retching and sage consumption was statistically significant in multivariate analysis. The only risk factor for dysgeusia was chamomile consumption. Ginger, pomegranate, and vinegar use were retained as mucositis predictors.

CONCLUSIONS

Phytotherapeutic use needs more attention in order to decrease the risks of side effects, toxicity, and ineffective treatment. The conscious administration of these substances should be promoted for safe use and to provide the reported benefits.

Botanical characteristics, chemical components, biological activity, and potential applications of mangosteen

Garcinia mangostana L. (Mangosteen), a functional food, belongs to the Garcinaceae family and has various pharmacological effects, including anti-oxidative, anti-inflammatory, anticancer, antidiabetic, and neuroprotective effects. Mangosteen has abundant chemical constituents with powerful pharmacological effects. After searching scientific literature databases, including PubMed, Science Direct, Research Gate, Web of Science, VIP, Wanfang, and CNKI, we summarized the traditional applications, botanical features, chemical composition, and pharmacological effects of mangosteen. Further, we revealed the mechanism by which it improves health and treats disease. These findings provide a theoretical basis for mangosteen's future clinical use and will aid doctors and researchers who investigate the biological activity and functions of food.

Natural Products Drug Discovery: On Silica or In-Silico?

Natural products have been the most important source for drug development throughout the human history. Over time, the formulation of drugs has evolved from crude drugs to refined chemicals. In modern drug discovery, conventional natural products lead-finding usually uses a top-down approach, namely bio-guided fractionation. In this approach, the crude extracts are separated by chromatography and resulting fractions are tested for activity. Subsequently, active fractions are further refined until a single active compound is obtained. However, this is a painstakingly slow and expensive process. Among the alternatives that have been developed to improve this situation, metabolomics has proved to yield interesting results having been applied successfully to drug discovery in the last two decades. The metabolomics-based approach in lead-finding comprises two steps: (1) in-depth chemical profiling of target samples, e.g. plant extracts, and bioactivity assessment, (2) correlation of the chemical and biological data by chemometrics. In the first step of this approach, the target samples are chemically profiled in an untargeted manner to detect as many compounds as possible. So far, NMR spectroscopy, LC-MS, GC-MS, and MS/MS spectrometry are the most common profiling tools. The profile data are correlated with the biological activity with the help of various chemometric methods such as multivariate data analysis. This in-silico analysis has a high potential to replace or complement conventional on-silica bioassay-guided fractionation as it will greatly reduce the number of bioassays, and thus time and costs. Moreover, it may reveal synergistic mechanisms, when present, something for which the classical top-down approach is clearly not suited. This chapter aims to give an overview of successful approaches based on the application of chemical profiling with chemometrics in natural products drug discovery.

Diversity of Bacterial Secondary Metabolite Biosynthetic Gene Clusters in Three Vietnamese Sponges

Recent reviews have reinforced sponge-associated bacteria as a valuable source of structurally diverse secondary metabolites with potent biological properties, which makes these microbial communities promising sources of new drug candidates. However, the overall diversity of secondary metabolite biosynthetic potential present in bacteria is difficult to access due to the fact that the majority of bacteria are not readily cultured in the laboratory. Thus, use of cultivation-independent approaches may allow accessing "silent" and "cryptic" secondary metabolite biosynthetic gene clusters present in bacteria that cannot yet be cultured. In the present study, we investigated the diversity of secondary metabolite biosynthetic gene clusters (BGCs) in metagenomes of bacterial communities associated with three sponge species: Clathria reinwardti, Rhabdastrella globostellata, and Spheciospongia sp. The results reveal that the three metagenomes contain a high number of predicted BGCs, ranging from 282 to 463 BGCs per metagenome. The types of BGCs were diverse and represented 12 different cluster types. Clusters predicted to encode fatty acid synthases and polyketide synthases (PKS) were the most dominant BGC types, followed by clusters encoding synthesis of terpenes and bacteriocins. Based on BGC sequence similarity analysis, 363 gene cluster families (GCFs) were identified. Interestingly, no GCFs were assigned to pathways responsible for the production of known compounds, implying that the clusters detected might be responsible for production of several novel compounds. The KS gene sequences from PKS clusters were used to predict the taxonomic origin of the clusters involved. The KS sequences were related to 12 bacterial phyla with Actinobacteria, Proteobacteria, and Firmicutes as the most predominant. At the genus level, the KSs were most related to those found in the genera Mycolicibacterium, Mycobacterium, Burkholderia, and Streptomyces. Phylogenetic analysis of KS sequences resulted in detection of two known 'sponge-specific' BGCs, i.e., SupA and SwfA, as well as a new 'sponge-specific' cluster related to fatty acid synthesis in the phylum Candidatus Poribacteria and composed only by KS sequences of the three sponge-associated bacterial communities assessed here.

A New Tetracyclic Bromopyrrole-Imidazole Derivative through Direct Chemical Diversification of Substances Present in Natural Product Extract from Marine Sponge Petrosia (Strongylophora) sp

Chemical diversification of substances present in natural product extracts can lead to a number of natural product-like compounds with a better chance of desirable bioactivities. The aim of this work was to discover unprecedented chemical conversion and produce new compounds through a one-step reaction of substances present in the extracts of marine sponges. In this report, a new unnatural tetracyclic bromopyrrole-imidazole derivative, rac-6-OEt-cylindradine A (1), was created from a chemically diversified extract of the sponge Petrosia (Strongylophora) sp. We also confirmed that 1 originated from naturally occurring (-)-cylindradine A (2) via a new reaction pattern. Moreover, (-)-dibromophakellin (3) and 4,5-dibromopyrrole-2-carboxylic acid (4), as well as 2, were reported herein for the first time in this genus. Studies on the possible reaction mechanism and bioactivities were also conducted. The results indicate that the direct chemical diversification of substances present in natural product extracts can be a speedy and useful strategy for the discovery of new compounds.

Identification of a Novel Curcumin Derivative Influencing Notch Pathway and DNA Damage as a Potential Therapeutic Agent in T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy considered curable by modern clinical management. Nevertheless, the prognosis for T-ALL high-risk cases or patients with relapsed and refractory disease is still dismal. Therefore, there is a keen interest in developing more efficient and less toxic therapeutic approaches. T-ALL pathogenesis is associated with Notch signaling alterations, making this pathway a highly promising target in the fight against T-ALL. Here, by exploring the anti-leukemic capacity of the natural polyphenol curcumin and its derivatives, we found that curcumin exposure impacts T-ALL cell line viability and decreases Notch signaling in a dose- and time-dependent fashion. However, our findings indicated that curcumin-mediated cell outcomes did not depend exclusively on Notch signaling inhibition, but might be mainly related to compound-induced DNA-damage-associated cell death. Furthermore, we identified a novel curcumin-based compound named CD2066, endowed with potentiated anti-proliferative activity in T-ALL compared to the parent molecule curcumin. At nanomolar concentrations, CD2066 antagonized Notch signaling, favored DNA damage, and acted synergistically with the CDK1 inhibitor Ro3306 in T-ALL cells, thus representing a promising novel candidate for developing therapeutic agents against Notch-dependent T-ALL.

A mini-review on synthesis and antiviral activity of natural product oxetanocin A derivatives

Oxetanocin A (Oxt-A), a novel oxetanosyl N-glycoside nucleoside, was isolated from Bacillus megaterium in 1986. It carries an oxetane ring on the sugar moiety of the nucleoside scaffold, which contributes to differences in its structure from those of common tetrahydrofuranyl-based nucleosides. In view of the unique 3D-spatial framework, the complete synthesis of Oxt-A has been achieved by multiple research groups. The pharmacological properties of this natural product have also been broadly investigated by pharmacists and chemists since its discovery. Notably, the potential antiviral effect of Oxt-A has captured attention of researchers in the field of antiviral agent development. Furthermore, epidemic outbreaks caused by viruses have been stimulating the preparation and modification of various Oxt-A analogs over the past few decades. However, none of the studies have overviewed the antiviral efficacies of this naturally occurring scaffold yet. Thus, the present review summarizes the synthesis, structural modification, and antiviral activities of Oxt-A and its derivatives. We believe that these comprehensive descriptions will provide a novel perspective for the discovery of antivirus drugs with well-improved performance and pave newer paths for combating sudden public health issues triggered by viruses in the future.

Metabolites of medicine food homology-derived endophytic fungi and their activities

Medicine food homology (MFH) substances not only provide essential nutrients as food but also have corresponding factors that can prevent and help treat nutritional imbalances, chronic disease, and other related issues. Endophytic fungi associated with plants have potential for use in drug discovery and food therapy. However, the endophytic fungal metabolites from MFH plants and their effects have been overlooked. Therefore, this review focuses on the various biological activities of 108 new metabolites isolated from 53 MFH-derived endophytic fungi. The paper explores the potential nutritional and medicinal value of metabolites of MFH-derived endophytic fungi for food and medical applications. This research is important for the future development of effective, safe, and nontoxic therapeutic nutraceuticals for the prevention and treatment of human diseases.

A Comprehensive Analysis and Anti-Cancer Activities of Quercetin in ROS-Mediated Cancer and Cancer Stem Cells

Reactive oxygen species (ROS) induce carcinogenesis by causing genetic mutations, activating oncogenes, and increasing oxidative stress, all of which affect cell proliferation, survival, and apoptosis. When compared to normal cells, cancer cells have higher levels of ROS, and they are responsible for the maintenance of the cancer phenotype; this unique feature in cancer cells may, therefore, be exploited for targeted therapy. Quercetin (QC), a plant-derived bioflavonoid, is known for its ROS scavenging properties and was recently discovered to have various antitumor properties in a variety of solid tumors. Adaptive stress responses may be induced by persistent ROS stress, allowing cancer cells to survive with high levels of ROS while maintaining cellular viability. However, large amounts of ROS make cancer cells extremely susceptible to quercetin, one of the most available dietary flavonoids. Because of the molecular and metabolic distinctions between malignant and normal cells, targeting ROS metabolism might help overcome medication resistance and achieve therapeutic selectivity while having little or no effect on normal cells. The powerful bioactivity and modulatory role of quercetin has prompted extensive research into the chemical, which has identified a number of pathways that potentially work together to prevent cancer, alongside, QC has a great number of evidences to use as a therapeutic agent in cancer stem cells. This current study has broadly demonstrated the function-mechanistic relationship of quercetin and how it regulates ROS generation to kill cancer and cancer stem cells. Here, we have revealed the regulation and production of ROS in normal cells and cancer cells with a certain signaling mechanism. We demonstrated the specific molecular mechanisms of quercetin including MAPK/ERK1/2, p53, JAK/STAT and TRAIL, AMPKα1/ASK1/p38, RAGE/PI3K/AKT/mTOR axis, HMGB1 and NF-κB, Nrf2-induced signaling pathways and certain cell cycle arrest in cancer cell death, and how they regulate the specific cancer signaling pathways as long-searched cancer therapeutics.

Addressing artifacts of colorimetric anticancer assays for plant-based drug development

Cancer has become the silent killer in less-developed countries and the most significant cause of morbidity worldwide. The accessible and frequently used treatments include surgery, radiotherapy, chemotherapy, and immunotherapy. Chemotherapeutic drugs traditionally involve using plant-based medications either in the form of isolated compounds or as scaffolds for synthetic drugs. To launch a drug in the market, it has to pass through several intricate steps. The multidrug resistance in cancers calls for novel drug discovery and development. Every year anticancer potential of several plant-based compounds and extracts is reported but only a few advances to clinical trials. The false-positive or negative results impact the progress of the cell-based anticancer assays. There are several cell-based assays but the widely used include MTT, MTS, and XTT. In this article, we have discussed various pitfalls and workable solutions.

Marine Compounds for Melanoma Treatment and Prevention

Melanoma is considered a multifactorial disease etiologically divided into melanomas related to sun exposure and those that are not, but also based on their mutational signatures, anatomic site, and epidemiology. The incidence of melanoma skin cancer has been increasing over the past decades with 132,000 cases occurring globally each year. Marine organisms have been shown to be an excellent source of natural compounds with possible bioactivities for human health applications. In this review, we report marine compounds from micro- and macro-organisms with activities in vitro and in vivo against melanoma, including the compound Marizomib, isolated from a marine bacterium, currently in phase III clinical trials for melanoma. When available, we also report active concentrations, cellular targets and mechanisms of action of the mentioned molecules. In addition, compounds used for UV protection and melanoma prevention from marine sources are discussed. This paper gives an overview of promising marine molecules which can be studied more deeply before clinical trials in the near future.

Chemistries and applications of DNA-natural product conjugate

Natural products and their derivatives have made great contributions to chemotherapy, especially for the treatment of tumors and infections. Despite the achievements, natural product-based small molecule drugs usually suffer from side effects, short circulation time, and solubility issue. To overcome these drawbacks, a common approach is to integrate another bio-functional motif into a natural product compound, enabling targeted or synergistic therapy. One of the most promising strategies is to form a DNA-natural product conjugate to improve therapeutic purposes. The incorporated DNA molecules can serve as an aptamer, a nucleic-acid-based congener of antibody, to specifically bind to the disease target of interest, or function as a gene therapy agent, such as immuno-adjuvant or antisense, to enable synergistic chemo-gene therapy. DNA-natural product conjugate can also be incorporated into other DNA nanostructures to improve the administration and delivery of drugs. This minireview aims to provide the chemistry community with a brief overview on this emerging topic of DNA-natural product conjugates for advanced therapeutics. The basic concepts to use the conjugation, the commonly used robust conjugation chemistries, as well as applications in targeted therapy and synergistic therapy of using DNA-natural product conjugates, are highlighted in this minireview. Future perspectives and challenges of this field are also discussed in the discussion and perspective section.

Natural compounds may contribute in preventing SARS-CoV-2 infection: a narrative review

Coronavirus pandemic infection is the most important health issue worldwide. Coronavirus disease 2019 is a contagious disease characterized by severe acute respiratory syndrome coronavirus 2. To date, excluding the possibility of vaccination, against SARS-CoV-2 infection it is possible to act only with supportive care and non-virus-specific treatments in order to improve the patient's symptoms. Pharmaceutical industry is investigating effects of medicinal plants, phytochemical extracts and aromatic herbs to find out natural substances which may act as antiviral drugs. Several studies have revealed how these substances may interfere with the viral life cycle, viral entry, replication, assembly or discharge, as well as virus-specific host targets or stimulating the host immune system, reducing oxidative stress and inflammatory response. A natural compound can be used as a prophylaxis by people professionally exposed to the risk of contagion and/or positive patients not in intensive care. The aim of this paper is to perform a narrative review of current literature in order to summarize the most studied natural compounds and their modes of action.

Chemical diversity, medicinal potentialities, biosynthesis, and pharmacokinetics of anthraquinones and their congeners derived from marine fungi: a comprehensive update

Marine fungi receive excessive attention as prolific producers of structurally unique secondary metabolites, offering promising potential as substitutes or conjugates for current therapeutics, whereas existing research has only scratched the surface in terms of secondary metabolite diversity and potential industrial applications as only a small share of bioactive natural products have been identified from marine-derived fungi thus far. Anthraquinones derived from filamentous fungi are a distinct large group of polyketides containing compounds which feature a common 9,10-dioxoanthracene core, while their derivatives are generated through enzymatic reactions such as methylation, oxidation, or dimerization to produce a large variety of anthraquinone derivatives. A considerable number of reported anthraquinones and their derivatives have shown significant biological activities as well as highly economical, commercial, and biomedical potentialities such as anticancer, antimicrobial, antioxidant, and anti-inflammatory activities. Accordingly, and in this context, this review comprehensively covers the state-of-art over 20 years of about 208 structurally diverse anthraquinones and their derivatives isolated from different species of marine-derived fungal genera along with their reported bioactivity wherever applicable. Also, in this manuscript, we will present in brief recent insights centred on their experimentally proved biosynthetic routes. Moreover, all reported compounds were extensively investigated for their in-silico drug-likeness and pharmacokinetics properties which intriguingly highlighted a list of 20 anthraquinone-containing compounds that could be considered as potential drug lead scaffolds.

LSD1 inhibitors for anticancer therapy: a patent review (2017-present)

INTRODUCTION

Lysine-specific demethylase 1 (LSD1), which belongs to the demethylase of non-histone proteins, is believed to promote cancer cell proliferation and metastasis by modifying histones. LSD1 dysfunction may play a key role in a variety of cancers, such as acute myeloid leukemia and non-small cell lung cancer, indicating that LSD1 is a promising epigenetic target for cancer therapy. Many different types of small molecule LSD1 inhibitors have been developed and shown to inhibit tumor cell proliferation, invasion, and migration, providing a new treatment strategy for solid tumors.

AREAS COVERED

This review summarizes the progress of LSD1 inhibitor research in the last four years, including selected new patents and article publications, as well as the therapeutic potential of these compounds.

EXPERT OPINION

Natural products offer a promising prospect for developing novel potent LSD1 inhibitors, as structural design and activity of irreversible and reversible inhibitors have been continuously optimized since the discovery of the LSD1 target in 2004. The use of "microtubule-binding agents" and "dual-agent combination" has recently become a new anticancer technique, reducing the resistance and adverse reactions of traditional drugs. Several microtubule-binding drugs have been used successfully in clinical practice, providing structural scaffolds and new ideas for the development of safer drugs.

Metabolomics-Driven Exploration of the Antibacterial Activity and Mechanism of 2-Methoxycinnamaldehyde

Methicillin-resistant Staphylococcus epidermidis (MRSE) is one of the most commonly found pathogens that may cause uncontrollable infections in immunocompromised and hospitalized patients. Compounds isolated from cinnamon such as cinnamaldehyde and cinnamic acid showed promising anti-oxidant, anti-tumor, and immunoregulatory effects; more importantly, these compounds also possess promising broad-spectrum antibacterial activity. In this study, the potential antibacterial activity of 2-methoxycinnamaldehyde (MCA), another compound in cinnamon, against MRSE was investigated. Combining the broth microdilution test, live/dead assay, and biofilm formation assay, we found MCA was able to inhibit the proliferation, as well as the biofilm formation of MRSE, indicating MCA could not only affect the growth of MRSE but also inhibit the pathogenic potential of this bacterium. Additionally, the results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that MCA caused morphological changes and the leakage of DNA, RNA, and cellular contents of MRSE. Due to the close relationship between cell wall synthesis, ROS formation, and cell metabolism, the ROS level and metabolic profile of MRSE were explored. Our study showed MCA significantly increased the ROS production in MRSE, and the following metabolomics analysis showed that the increased ROS production may partially be due to the increased metabolic flux through the TCA cycle. In addition, we noticed the metabolic flux through the pentose phosphate pathway (PPP) was upregulated accompanied by elevated ROS production. Therefore, the alterations in cell metabolism and increased ROS production could lead to the damage of the cell wall, which in turn decreased the proliferation of MRSE. In conclusion, MCA seemed to be a promising alternative antimicrobial agent to control MRSE infections.

The Role of m6A RNA Methylation in Cancer: Implication for Nature Products Anti-Cancer Research

N6-methyladenosine (m6A) RNA methylation is identified as the most common, abundant and reversible RNA epigenetic modification in messenger RNA (mRNA) and non-coding RNA, especially within eukaryotic messenger RNAs (mRNAs), which post-transcriptionally directs many important processes of RNA. It has also been demonstrated that m6A modification plays a pivotal role in the occurrence and development of tumors by regulating RNA splicing, localization, translation, stabilization and decay. Growing number of studies have indicated that natural products have outstanding anti-cancer effects of their unique advantages of high efficiency and minimal side effects. However, at present, there are very few research articles to study and explore the relationship between natural products and m6A RNA modification in tumorigenesis. m6A is dynamically deposited, removed, and recognized by m6A methyltransferases (METTL3/14, METTL16, WTAP, RBM15/15B, VIRMA, CBLL1, and ZC3H13, called as “writers”), demethylases (FTO and ALKBH5, called as “erasers”), and m6A-specific binding proteins (YTHDF1/2/3, YTHDC1/2, IGH2BP1/2/3, hnRNPs, eIF3, and FMR1, called as “readers”), respectively. In this review, we summarize the biological function of m6A modification, the role of m6A and the related signaling pathway in cancer, such as AKT, NF-kB, MAPK, ERK, Wnt/β-catenin, STAT, p53, Notch signaling pathway, and so on. Furthermore, we reviewed the current research on nature products in anti-tumor, and further to get a better understanding of the anti-tumor mechanism, thus provide an implication for nature products with anti-cancer research by regulating m6A modification in the future.