Review of Shikonin and Derivatives: Isolation, Chemistry, Biosynthesis, Pharmacology and Toxicology

Identification, quantification and nutraceutical evaluation of the extracts from Arnebia benthamii roots of Himalayan regions of J&K, India

Arnebia benthamii is one of the important sources of biologically active naphthoquinone pigments. The present study aimed at extraction of shikonin from Arnebia benthamii roots and its characterization. In order to identify and quantify shikonin, the extracts were evaluated using HPLC, LCMS, GCMS, NP-HPTLC and FTIR. Furthermore, nutraceutical evaluation was also done. It was found that the amount of shikonin was very low in the extracts obtained by using aqueous ethanol as it was not detected through chromatographic techniques. However, when hexane was used for extraction, a significant amount of shikonin (4.55 mg/g) was detected. The shikonin showed a linear range from 2-55 µg/mL with LOD and LOQ of 2.65 and 8.02 respectively, with a retention time of 3.64 min. The results of FTIR revealed that hexane extract had the intensity of functional groups similar to that of the standard. The values of DPPH radical inhibition were observed as 82.98 ± 0.01, 65.09 ± 0.23 %, 62.28 ± 0.86 % and 54.09 ± 0.23 % for Std, Ehex, Eus and Evs, respectively. The hexane extract showed the highest antioxidant activity as compared to other samples. Moreover, the hexane extracted shikonin displayed significantly (p > 0.05) high α-amylase and pancreatic lipase inhibition, indicating its high anti-diabetic and anti-lipidemic potential. It can be concluded that hexane is the best solvent for the extraction of shikonin and has better nutraceutical potential compared to ethanolic extracts.

Delivery of natural products via polysaccharide-based nanocarriers for cancer therapy: A review on recent advances and future challenges

Cancer, caused by uncontrolled proliferation of abnormal cells, has long been a global public health issue. For decades, natural products have been proven to be an essential source for novel anticancer drug discovery. But their instability, low solubility and bioavailability, poor targeting impede therapeutic efficacy. With the development of nanotechnology, nanomedicine delivery systems have emerged as promising strategies to improve bioavailability and enhance the therapeutic efficacy of drugs. However, constructing suitable nanocarrier is still a major challenge. Polysaccharides are extensively employed as carrier materials in nanomedicine delivery systems, owing to their unique physicochemical properties, biocompatibility and low immunogenicity. Polysaccharide-based nanomedicine delivery systems show high drug delivery efficiency, controlled drug release, and precise tumor targeting. This paper reviews influencing factors in the construction of polysaccharide-based nanocarriers and the application of polysaccharide-based nanocarriers for the delivery of natural products in treating various cancers. It focuses on their in vitro and in vivo anticancer efficacy and mechanisms. Furthermore, the review contrasts the capabilities and limitations of polysaccharide-based nanocarriers with traditional delivery methods, underlining their potential to enable targeted, reduced toxicity and excellent cancer treatment modalities. Finally, we discuss the current research limitations and future prospects in this emerging field.

Shikonin protects skin cells against oxidative stress and cellular dysfunction induced by fine particulate matter

Shikonin, an herbal naphthoquinone, demonstrates a broad spectrum of pharmacological properties. Owing to increasingly adverse environmental conditions, human skin is vulnerable to harmful influences from dust particles. This study explored the antioxidant capabilities of shikonin and its ability to protect human keratinocytes from oxidative stress induced by fine particulate matter (PM2.5). We found that shikonin at a concentration of 3 µM was nontoxic to human keratinocytes and effectively scavenged reactive oxygen species (ROS) while increasing the production of reduced glutathione (GSH). Furthermore, shikonin enhanced GSH level by upregulating glutamate-cysteine ligase catalytic subunit and glutathione synthetase mediated by nuclear factor-erythroid 2-related factor. Shikonin reduced ROS levels induced by PM2.5, leading to recovering PM2.5-impaired cellular biomolecules and cell viability. Shikonin restored the GSH level in PM2.5-exposed keratinocytes via enhancing the expression of GSH-synthesizing enzymes. Notably, buthionine sulphoximine, an inhibitor of GSH synthesis, diminished effect of shikonin against PM2.5-induced cell damage, confirming the role of GSH in shikonin-induced cytoprotection. Collectively, these findings indicated that shikonin could provide substantial cytoprotection against the adverse effects of PM2.5 through direct ROS scavenging and modulation of cellular antioxidant system.

Systematic bioinformatics analysis reveals the role of shikonin in blocking colon cancer progression by identifying senescence-induced genes

Shikonin, a naturally occurring naphthoquinone compound extracted from comfrey plants, has antitumor, anti-inflammatory, and antimicrobial properties. Cell senescence plays a key role in preventing tumor progression. It is unclear whether shikonin has an effect on cell senescence in colon cancer. In the current study, we first determine the IC50 values of shikonin on colon cancer cell lines HT29 and HCT116. Then, we verified the inhibitory effects of shikonin on the proliferation and migration abilities of colon cancer cell lines HT29 and HCT116 using cell counting kit-8, colony formation, and wound healing assays. Next, we identified a series of potential targets using high-throughput mRNA sequencing and identified 210 upregulated and 296 downregulated genes. KEGG profiling revealed eight downregulated genes associated with cell senescence: CCNB3, IL-1α, CXCL8, CDKN2A, MYC, IGFBP3, SQSTM1, and GADD45G. Among them, CXCL8 and CDKN2A were associated with poor prognosis in patients with colon cancer, suggesting that their downregulation by shikonin could improve patient survival. Furthermore, SA-β-galactosidase staining revealed that the percentage of cellular senescence in colon cancer cells was significantly increased after shikonin treatment. Molecular docking revealed that shikonin suppressed colon cancer progression by blocking CXCL8 activity. Based on these findings, we deem that shikonin might induce senescence and exert antitumor activity in colon cancer cells by downregulating CDKN2A and CXCL8. This provides a new molecular mechanism and potential therapeutic target for shikonin to inhibit colon cancer progression.

High-Altitude Medicinal Plants as Promising Source of Phytochemical Antioxidants to Combat Lifestyle-Associated Oxidative Stress-Induced Disorders

Oxidative stress, driven by reactive oxygen, nitrogen, and sulphur species (ROS, RNS, RSS), poses a significant threat to cellular integrity and human health. Generated during mitochondrial respiration, inflammation, UV exposure and pollution, these species damage cells and contribute to pathologies like cardiovascular issues, neurodegeneration, cancer, and metabolic syndromes. Lifestyle factors exert a substantial influence on oxidative stress levels, with mitochondria emerging as pivotal players in ROS generation and cellular equilibrium. Phytochemicals, abundant in plants, such as carotenoids, ascorbic acid, tocopherols and polyphenols, offer diverse antioxidant mechanisms. They scavenge free radicals, chelate metal ions, and modulate cellular signalling pathways to mitigate oxidative damage. Furthermore, plants thriving in high-altitude regions are adapted to extreme conditions, and synthesize secondary metabolites, like flavonoids and phenolic compounds in bulk quantities, which act to form a robust antioxidant defence against oxidative stress, including UV radiation and temperature fluctuations. These plants are promising sources for drug development, offering innovative strategies by which to manage oxidative stress-related ailments and enhance human health. Understanding and harnessing the antioxidant potential of phytochemicals from high-altitude plants represent crucial steps in combating oxidative stress-induced disorders and promoting overall wellbeing. This study offers a comprehensive summary of the production and physio-pathological aspects of lifestyle-induced oxidative stress disorders and explores the potential of phytochemicals as promising antioxidants. Additionally, it presents an appraisal of high-altitude medicinal plants as significant sources of antioxidants, highlighting their potential for drug development and the creation of innovative antioxidant therapeutic approaches.

Research progress in mechanism of anticancer action of shikonin targeting reactive oxygen species

Excessive buildup of highly reactive molecules can occur due to the generation and dysregulation of reactive oxygen species (ROS) and their associated signaling pathways. ROS have a dual function in cancer development, either leading to DNA mutations that promote the growth and dissemination of cancer cells, or triggering the death of cancer cells. Cancer cells strategically balance their fate by modulating ROS levels, activating pro-cancer signaling pathways, and suppressing antioxidant defenses. Consequently, targeting ROS has emerged as a promising strategy in cancer therapy. Shikonin and its derivatives, along with related drug carriers, can impact several signaling pathways by targeting components involved with oxidative stress to induce processes such as apoptosis, necroptosis, cell cycle arrest, autophagy, as well as modulation of ferroptosis. Moreover, they can increase the responsiveness of drug-resistant cells to chemotherapy drugs, based on the specific characteristics of ROS, as well as the kind and stage of cancer. This research explores the pro-cancer and anti-cancer impacts of ROS, summarize the mechanisms and research achievements of shikonin-targeted ROS in anti-cancer effects and provide suggestions for designing further anti-tumor experiments and undertaking further experimental and practical research.

Phytochemical-mediated modulation of autophagy and endoplasmic reticulum stress as a cancer therapeutic approach

Autophagy and endoplasmic reticulum (ER) stress are conserved processes that generally promote survival, but can induce cell death when physiological thresholds are crossed. The pro-survival aspects of these processes are exploited by cancer cells for tumor development and progression. Therefore, anticancer drugs targeting autophagy or ER stress to induce cell death and/or block the pro-survival aspects are being investigated extensively. Consistently, several phytochemicals have been reported to exert their anticancer effects by modulating autophagy and/or ER stress. Various phytochemicals (e.g., celastrol, curcumin, emodin, resveratrol, among others) activate the unfolded protein response to induce ER stress-mediated apoptosis through different pathways. Similarly, various phytochemicals induce autophagy through different mechanisms (namely mechanistic target of Rapamycin [mTOR] inhibition). However, phytochemical-induced autophagy can function either as a cytoprotective mechanism or as programmed cell death type II. Interestingly, at times, the same phytochemical (e.g., 6-gingerol, emodin, shikonin, among others) can induce cytoprotective autophagy or programmed cell death type II depending on cellular contexts, such as cancer type. Although there is well-documented mechanistic interplay between autophagy and ER stress, only a one-way modulation was noted with some phytochemicals (carnosol, capsaicin, cryptotanshinone, guangsangon E, kaempferol, and δ-tocotrienol): ER stress-dependent autophagy. Plant extracts are sources of potent phytochemicals and while numerous phytochemicals have been investigated in preclinical and clinical studies, the search for novel phytochemicals with anticancer effects is ongoing from plant extracts used in traditional medicine (e.g., Origanum majorana). Nonetheless, the clinical translation of phytochemicals, a promising avenue for cancer therapeutics, is hindered by several limitations that need to be addressed in future studies.

Natural colorant incorporated biopolymers-based pH-sensing films for indicating the food product quality and safety

The current synthetic plastic-based packaging creates environmental hazards that impact climate change. Hence, the topic of the current research in food packaging is biodegradable packaging and its development. In addition, new smart packaging solutions are being developed to monitor the quality of packaged foods, with dual functions as food preservation and quality indicators. In the creation of intelligent and active food packaging, many natural colorants have been employed effectively as pH indicators and active substances, respectively. This review provides an overview of biodegradable polymers and natural colorants that are being extensively studied for pH-indicating packaging. A comprehensive discussion has been provided on the current status of the development of intelligent packaging systems for food, different incorporation techniques, and technical challenges in the development of such green packaging. Finally, the food industry and environmental protection might be revolutionized by pH-sensing biodegradable packaging enabling real-time detection of food product quality and safety.

Pharmacological Significance of Boraginaceae with Special Insights into Shikonin and Its Potential in the Food Industry

Shikonin is a naphthoquinone pigment present in the hairy roots of the plant species from the Boraginaceae family. The compound has been well investigated for its highly efficient medicinal, antioxidant, and antimicrobial properties. Various extraction methodologies have been employed to maximise yield while minimising waste production of shikonin and its derivatives. Despite substantial research on shikonin and Boraginaceae plants, a research gap persists in the food industry and extraction technologies. This review addresses crucial aspects of shikonin deserving of further exploration. It begins by elucidating the attributes of the Boraginaceae plants and their medicinal traits in folklore. It proceeds to focus on the roots of the plant and its medicinal properties, followed by extraction procedures explored in the last fifteen years, emphasising the novel technologies that have been chosen to improve the yield extract while minimising extraction times. Furthermore, this review briefly outlines studies employing cell culture techniques to enhance in vitro shikonin production. Lastly, attention is directed towards research in the food industry, particularly on shikonin-loaded biodegradable films and the antioxidant activity of shikonin. This review concludes by summarising the future potential in food science and prominent research gaps in this field.

Exploring the Pharmacological Potential of Lithospermum officinale L.: A Review of Phytochemicals and Ethnomedicinal Uses

Exploring phytochemicals from ethnomedicinal plants for pharmacological applications is a promising research area. By studying ethnomedicine, researchers can identify plants used for centuries to treat ailments and investigate their phytochemicals. Consequently, phytochemicals can be isolated, characterized, and tested for pharmacological activities, leading to new drug development. This research also helps preserve traditional knowledge and biodiversity. Lithospermum officinale L., found in Eurasia, Argentina (South), Colombia, and the United States, is valued for its medicinal properties, including anti-inflammatory, antioxidant, and antimicrobial effects. The current review emphasizes L. officinale L. as a significant reservoir of bioactive phytochemicals, with alkaloids, quinones, glucosides, phenolics, flavonoids, and lipids identified as the principal metabolites. It also unveils the unexplored potential of this plant for future research endeavors. Continued research on L. officinale L. can unlock its full potential, providing insights into its medicinal uses and contributing to biodiversity preservation.

Comparative Analysis of Shikonin and Alkannin Acyltransferases Reveals Their Functional Conservation in Boraginaceae

Shikonin and its enantiomer, alkannin, are bioactive naphthoquinones produced in several plants of the family Boraginaceae. The structures of these acylated derivatives, which have various short-chain acyl moieties, differ among plant species. The acylation of shikonin and alkannin in Lithospermum erythrorhizon was previously reported to be catalyzed by two enantioselective BAHD acyltransferases, shikonin O-acyltransferase (LeSAT1) and alkannin O-acyltransferase (LeAAT1). However, the mechanisms by which various shikonin and alkannin derivatives are produced in Boraginaceae plants remain to be determined. In the present study, evaluation of six Boraginaceae plants identified 23 homologs of LeSAT1 and LeAAT1, with 15 of these enzymes found to catalyze the acylation of shikonin or alkannin, utilizing acetyl-CoA, isobutyryl-CoA or isovaleryl-CoA as an acyl donor. Analyses of substrate specificities of these enzymes for both acyl donors and acyl acceptors and determination of their subcellular localization using Nicotiana benthamiana revealed a distinct functional differentiation of BAHD acyltransferases in Boraginaceae plants. Gene expression of these acyltransferases correlated with the enantiomeric ratio of produced shikonin/alkannin derivatives in L. erythrorhizon and Echium plantagineum. These enzymes showed conserved substrate specificities for acyl donors among plant species, indicating that the diversity in acyl moieties of shikonin/alkannin derivatives involved factors other than the differentiation of acyltransferases. These findings provide insight into the chemical diversification and evolutionary processes of shikonin/alkannin derivatives.

Phytochemicals against Osteoarthritis by Inhibiting Apoptosis

Osteoarthritis (OA) is a chronic joint disease that causes pathological changes in articular cartilage, synovial membrane, or subchondral bone. Conventional treatments for OA include surgical and non-surgical methods. Surgical treatment is suitable for patients in the terminal stage of OA. It is often the last choice because of the associated risks and high cost. Medication of OA mainly includes non-steroidal anti-inflammatory drugs, analgesics, hyaluronic acid, and cortico-steroid anti-inflammatory drugs. However, these drugs often have severe side effects and cannot meet the needs of patients. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Apoptosis is programmed cell death, which is a kind of physiologic cell suicide determined by heredity and conserved by evolution. Inhibition of apoptosis-related pathways has been found to prevent and treat a variety of diseases. Excessive apoptosis can destroy cartilage homeostasis and aggravate the pathological process of OA. Therefore, inhibition of apoptosis-related factors or signaling pathways has become an effective means to treat OA. Phytochemicals are active ingredients from plants, and it has been found that phytochemicals can play an important role in the prevention and treatment of OA by inhibiting apoptosis. We summarize preclinical and clinical studies of phytochemicals for the treatment of OA by inhibiting apoptosis. The results show that phytochemicals can treat OA by targeting apoptosis-related pathways. On the basis of improving some phytochemicals with low bioavailability, poor water solubility, and high toxicity by nanotechnology-based drug delivery systems, and at the same time undergoing strict clinical and pharmacological tests, phytochemicals can be used as a potential therapeutic drug for OA and may be applied in clinical settings.

Naphthoquinone derivatives as potential immunomodulators: prospective for COVID-19 treatment

Inflammation plays a crucial role in COVID-19, and when it becomes dysregulated, it can lead to severe outcomes, including death. Naphthoquinones, a class of cyclic organic compounds widely distributed in nature, have attracted significant interest due to their potential biological benefits. One such naphthoquinone is 3,5,8-trihydroxy-6-methoxy-2-(5-oxohexa-1,3-dienyl)-naphthanthene-1,4-dione (3,5,8-TMON), a compound produced by fungi. Despite its structural similarity to shikonin, limited research has been conducted to investigate its biological properties. Therefore, the objective of this study was to evaluate the effects of 3,5,8-TMON and its synthetic derivatives in the context of inflammation induced by lipopolysaccharide (LPS) and SARS-CoV-2 infection in vitro using cell cultures. 3,5,8-TMON was obtained by acid treatment of crude extracts of fermentation medium from Cordyceps sp., and two derivatives were accessed by reaction with phenylhydrazine under different conditions. The results revealed that the crude extract of the fungi (C. Ex) inhibited the activity of transcription factor NF-kB, as well as the production of nitric oxide (NO) and interleukin-6 (IL-6) when LPS induced it in RAW 264.7 cells. This inhibitory effect was observed at effective concentrations of 12.5 and 3.12 μg mL-1. In parallel, 3,5,8-TMON and the new derivatives 3 and 4 demonstrated the ability to decrease IL-6 production while increasing TNF, with a specific effect depending on the concentration. These concentration-dependent agonist and antagonist effects were observed in THP-1 cells. Furthermore, 3,5,8-TMON inhibited IL-6 production at concentrations of 12.5 and 3.12 μg mL-1 in Calu-3 cells during SARS-CoV-2 viral infection. These findings present promising opportunities for further research into the therapeutic potential of this class of naphthoquinone in the management of inflammation and viral infections.

Inhibition of Biofilm Formation in Cutibacterium acnes, Staphylococcus aureus, and Candida albicans by the Phytopigment Shikonin

Skin microbiota, such as acne-related Cutibacterium acnes, Staphylococcus aureus, and fungal Candida albicans, can form polymicrobial biofilms with greater antimicrobial tolerance to traditional antimicrobial agents and host immune systems. In this study, the phytopigment shikonin was investigated against single-species and multispecies biofilms under aerobic and anaerobic conditions. Minimum inhibitory concentrations of shikonin were 10 µg/mL against C. acnes, S. aureus, and C. albicans, and at 1-5 µg/mL, shikonin efficiently inhibited single biofilm formation and multispecies biofilm development by these three microbes. Shikonin increased porphyrin production in C. acnes, inhibited cell aggregation and hyphal formation by C. albicans, decreased lipase production, and increased hydrophilicity in S. aureus. In addition, shikonin at 5 or 10 µg/mL repressed the transcription of various biofilm-related genes and virulence-related genes in C. acnes and downregulated the gene expression levels of the quorum-sensing agrA and RNAIII, α-hemolysin hla, and nuclease nuc1 in S. aureus, supporting biofilm inhibition. In addition, shikonin prevented multispecies biofilm development on porcine skin, and the antimicrobial efficacy of shikonin was recapitulated in a mouse infection model, in which it promoted skin regeneration. The study shows that shikonin inhibits multispecies biofilm development by acne-related skin microbes and might be useful for controlling bacterial infections.

(2-Methylbutyryl)shikonin Naturally Occurring Shikonin Derivative Ameliorates the α-MSH-Induced Melanogenesis via ERK1/2 and p38 MAP Kinase-Mediated Down-Regulation of the MITF Transcription Factor

Cutaneous pigmentation is an important phenotypic trait whose regulation, despite recent advances, has yet to be completely elucidated. Melanogenesis, a physiological process of melanin production, is imperative for organism survival as it provides protection against the environmental insults that majorly involve sunlight-induced skin photodamage. However, immoderate melanin synthesis can cause pigmentation disorders associated with a psychosocial impact. In this study, the hypopigmentation effect of (2-methylbutyryl)shikonin, a natural product present in the root extract of Lithospermum erythrorhizon, and the underlying mechanisms responsible for the inhibition of melanin synthesis in α-MSH-stimulated B16F10 cells and C57BL/6J mice was studied. Non-cytotoxic concentrations of (2-methylbutyryl)shikonin significantly repressed cellular tyrosinase activity and melanin synthesis in both in vitro and in vivo models (C57BL/6J mice). (2-Methylbutyryl)shikonin remarkably abolished the protein expression of MITF, tyrosinase, tyrosinase-related protein 1, and tyrosinase-related protein 2, thereby blocking the production of pigment melanin via modulating the phosphorylation status of MAPK proteins, viz., ERK1/2 and p38. In addition, specific inhibition of ERK1/2 attenuated the inhibitory effects of (2-methylbutyryl)shikonin on melanin synthesis, whereas selective inhibition of p38 augmented the inhibitory effect of BSHK on melanin synthesis. Moreover, topical application of (2-methylbutyryl)shikonin on C57BL/6J mouse tails remarkably induced tail depigmentation. In conclusion, with these findings, we, for the first time, report the hypopigmentation effect of (2-methylbutyryl)shikonin via inhibition of cellular tyrosinase enzyme activity, subsequently ameliorating the melanin production, thereby indicating that (2-methylbutyryl)shikonin is a potential natural therapy for hyperpigmentation disorders.

Anoikis and cancer cell differentiation: novel modes of shikonin derivatives anticancer action in vitro

BACKGROUND

Shikonin is a naturally occurring naphthoquinone found in the roots of several genera of the Boraginaceae family, widely known for its numerous biological activities, such as antiinflammatory, antioxidant, antimicrobial and anticancer. In this study, the antitumor effect of six naphthoquinones isolated from the roots of Onosma visianii was evaluated using two cell lines, mouse melanoma B16 and highly aggressive rat glioma cell line C6.

METHODS AND RESULTS

All examined shikonins dose-dependently decreased the viability of tested cells, with compounds 5 and 6 being the most potent ones and hence subjected to further analysis. The diminished viability of B16 melanoma cells was in correlation with detected caspase-mediated apoptosis. Importantly, observed altered cell morphology along with the loss of dividing potential upon exposure to both shikonins implied reprogram of B16 cell phenotype. Elevated expression of myelin basic protein indicated the acquirement of Schwann-like cell phenotype, while detected autophagy might be connected to this phenomenon. On the contrary, upon exposure to both agents, C6 cells underwent specific cell death-anoikis, provoked by detachment from the extracellular matrix and compromised integrin signaling. Oppositely to compound 5, compound 6 realized anoikis in a caspase-independent manner and under sustained ERK1/2 activation, indicating the deviation from standard proanoikis signaling.

CONCLUSIONS

Herein, we have pointed out the diversity and novelty in the mode of action of shikonin derivatives depending on the tumor cell features, which represents a good platform for new investigations of these promising natural compounds.

Shikonin Suppresses Cell Tumorigenesis in Gastric Cancer Associated with the Inhibition of c-Myc and Yap-1

AIM

The study aimed to study the potential roles and mechanisms of shikonin in gastric cancer by network pharmacology and biological experiments.

METHODS

The key genes and targets of shikonin in gastric cancer were predicted by network pharmacology and molecular docking study. The effect of shikonin on the proliferation, migration, and invasion of gastric cancer cells was detected by the CCK8 method, and wound healing and transwell assays. The expression levels of c-Myc and Yap-1 were detected via western blotting in gastric cancer cells after shikonin intervention.

RESULTS

The results of network pharmacology revealed the key target genes of shikonin on gastric cancer cells to be c-Myc, Yap-1, AKT1, etc. GO and KEGG analysis showed regulation of cell migration, proliferation, adhesion, and other biological processes, including the PI3K-Akt signaling pathway, HIF-1 signaling pathway, necroptosis, and other cancer pathways. Molecular docking showed shikonin to be most closely combined with protooncogenes c-Myc and Yap-1. In vitro experiments showed that the proliferation rate, migration, and invasion ability of the gastric cancer cell group decreased significantly after shikonin intervention for 24h. The expression levels of c-Myc and Yap-1 in gastric cancer cells were found to be significantly decreased after shikonin intervention.

CONCLUSION

This study showed protooncogenes c-Myc and Yap-1 to be the core target genes of shikonin on gastric cancer cells. Shikonin may suppress gastric cancer cells by inhibiting the protooncogenes c-Myc and Yap-1. This suggests that shikonin may be a good candidate for the treatment of gastric cancer.

Inhibition of Pyruvate kinase M2 (PKM2) by shikonin attenuates isoproterenol-induced acute myocardial infarction via reduction in inflammation, hypoxia, apoptosis, and fibrosis

Myocardial infarction (MI) is a major cause of mortality and disability globally. MI results from acute or chronic myocardial ischemia characterized by an imbalance of oxygen demand and supply, leading to irreversible myocardial injury. Despite several significant efforts in the understanding of MI, the therapy of MI is not satisfactory due to its complicated pathophysiology. Recently, therapeutic potential of targeting pyruvate kinase M2 (PKM2) has been postulated in several cardiovascular diseases. PKM2 gene knockout and expression studies implicated the role of PKM2 in MI. However, the effects of pharmacological interventions targeting PKM2 have not been investigated in MI. Therefore, in the present study, effect of PKM2 inhibitor has been investigated in the MI along with elucidation of possible mechanism(s). MI in rats was induced by administrations of isoproterenol (ISO) at a dose of 100 mg/kg s.c. for two consecutives days at 24-h interval. At the same time, shikonin (PKM2 inhibitor) was administered at 2 and 4 mg/kg in ISO-induced MI rats. After the shikonin treatment, the ventricular functions were measured using a PV-loop system. Plasma MI injury markers, cardiac histology, and immunoblotting were performed to elucidate the molecular mechanism. Treatment of shikonin 2 and 4 mg/kg ameliorated cardiac injury, reduced infarct size, biochemical alterations, ventricular dysfunction, and cardiac fibrosis in ISO-induced MI. Expression of PKM2 in the ventricle was reduced while PKM1 expression increased in the shikonin treated group, indicating PKM2 inhibition restores PKM1 expression. In addition, PKM splicing protein (hnRNPA2B1 & PTBP1), HIF-1α, and caspase-3 expression were reduced after shikonin treatment. Our findings suggest that pharmacological inhibition of PKM2 with shikonin could be a potential therapeutic strategy to treat MI.

Spectrum-Effect Relationship in Chinese Herbal Medicine: Current Status and Future Perspectives

The quality of Chinese herbal medicine (CHM) directly impacts clinical efficacy and safety. Fingerprint technology is an internationally recognized method for evaluating the quality of CHM. However, the existing quality evaluation models based on fingerprint technology have blocked the ability to assess the internal quality of CHM and cannot comprehensively reflect the correlation between pharmacodynamic information and active constituents. Through mathematical methods, a connection between the "Spectrum" (fingerprint) and the "Effect" (pharmacodynamic data) was established to conduct a spectrum-effect relationship (SER) of CHM to unravel the active component information associated with the pharmacodynamic activity. Consequently, SER can efficiently address the limitations of the segmentation of chemical components and pharmacodynamic effect in CHM and further improve the quality evaluation of CHM. This review focuses on the recent research progress of SER in the field of CHM, including the establishment of fingerprint, the selection of data analysis methods, and their recent applications in the field of CHM. Various advanced fingerprint techniques are introduced, followed by the data analysis methods used in recent years are summarized. Finally, the applications of SER based on different research subjects are described in detail. In addition, the advantages of combining SER with other data are discussed through practical applications, and the research on SER is summarized and prospected. This review proves the validity and development potential of the SER and provides a reference for the development and application of quality evaluation methods for CHM.

An effective antimicrobial strategy of colistin combined with the Chinese herbal medicine shikonin against colistin-resistant Escherichia coli

IMPORTANCE

Infections caused by multidrug-resistant Escherichia coli (MDR E. coli) have become a major global healthcare problem due to the lack of effective antibiotics today. The emergence of colistin-resistant E. coli strains makes the situation even worse. Therefore, new antimicrobial strategies are urgently needed to combat colistin-resistant E. coli. Combining traditional antibiotics with non-antibacterial drugs has proved to be an effective approach of combating MDR bacteria. This study investigated the combination of colistin and shikonin, a Chinese herbal medicine, against colistin-resistant E. coli. This combination showed good synergistic antibacterial both in vivo and in vitro experiments. Under the background of daily increasing colistin resistance in E. coli, this research points to an effective antimicrobial strategy of using colistin and shikonin in combination against colistin-resistant E. coli.

Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review

Currently, skin injuries have a serious impact on people's lives and socio-economic stress. Shikonin, a naphthoquinone compound derived from the root of the traditional Chinese medicine Shikonin, has favorable biological activities such as anti-inflammatory, antibacterial, immunomodulatory, anticancer, and wound-healing-promoting pharmacological activities. It has been reported that Shikonin can be used for repairing skin diseases due to its wide range of pharmacological effects. Moreover, the antimicrobial activity of Shikonin can play a great role in food and can also reduce the number of pathogenic bacteria in food. This paper summarizes the research on the pharmacological effects of Shikonin in recent years, as well as research on the mechanism of action of Shikonin in the treatment of certain skin diseases, to provide certain theoretical references for the clinical application of Shikonin, and also to provides research ideas for the investigation of the mechanism of action of Shikonin in other skin diseases.

Evaluation of combined carbon dots and ciprofloxacin on the expression level of pslA, pelA, and ppyR genes and biofilm production in ciprofloxacin-resistant Pseudomonas aeruginosa isolates from burn wound infection in Iran

OBJECTIVES

Antimicrobial resistance and biofilm formation are increasingly significant public health concerns. This study aimed to examine the antibacterial and antibiofilm properties of carbon dots (C-dots) alone and in combination with antibiotics against biofilm-forming isolates of Pseudomonas aeruginosa.

METHODS

The antibacterial property of C-dots was investigated by broth microdilution method against ATCC PAO1 and P. aeruginosa clinical isolates. The antibacterial effect of the C-dots and ciprofloxacin combination was investigated using the checkerboard method. The antibiofilm effect of the C-dots alone and its combination with ciprofloxacin was evaluated using the microtiter plate method. Subsequently, the toxicity of each agent was tested on L929 fibroblast cells. In the end, the effects of C-dots on the expression levels of pslA, pelA, and ppyR genes were determined using real-time quantitative PCR.

RESULTS

The combination of C-dots and ciprofloxacin exhibited a synergistic effect. Additionally, this compound substantially decreased bacterial growth (P < 0.0001) and inhibited biofilm formation at MIC (96 µg/mL) and sub-MIC (48 µg/mL) concentrations (P < 0.0053, P < 0.01). After being exposed to C-dots at a concentration of 1mg/mL for 24 hours, the survival rate of L929 cells was 87.3%. The expression of genes pslA, pelA, and ppyR, associated with biofilm formation in P. aeruginosa, was significantly reduced upon exposure to C-dots (P < 0.0023).

CONCLUSIONS

The findings demonstrate a promising new treatment method for infections. Furthermore, reducing the dosage of antibiotics can lead to an improvement in the toxic effects caused by dose-dependent antibiotics and antimicrobial activity.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

Shikonin promotes hypertrophic scar repair by autophagy of hypertrophic scar-derived fibroblasts

PURPOSE

To investigate the Shikonin (SHI) induce autophagy of hypertrophic scar-derived fibroblasts (HSFs) and the mechanism of which in repairing hypertrophic scar.

METHODS

This study showed that SHI induced autophagy from HSFs and repaired skin scars through the AMPK/mTOR pathway. Alamar Blue and Sirius red were used to identify cell activity and collagen. Electron microscopy, label-free quantitative proteomic analysis, fluorescence and other methods were used to identify autophagy. The differences in the expression of autophagy and AMPK/mTOR pathway-related proteins after SHI treatment were quantitatively analyzed by Western blots. A quantitative real-time polymerase chain reaction assay was used to detect the expression of LC3, AMPK and ULK after adding chloroquine (CQ) autophagy inhibitor.

RESULTS

After treatment with SHI for 24 hours, it was found that the viability of HSFs was significantly reduced, the protein expression of LC3-II/LC3-I and Beclin1 increased, while the protein expression of P62 decreased. The expression of phosphorylated AMPK increased and expression of phosphorylated mTOR decreased. After the use of CQ, the cell autophagy caused by SHI was blocked. The key genes LC3 and P62 were then reexamined by immunohistochemistry using a porcine full-thickness burn hypertrophic scar model, and the results verified that SHI could induce autophagy in vivo.

CONCLUSIONS

These findings suggested that SHI promoted autophagy of HSFs cells, and the potential mechanism may be related to the AMPK/mTOR signal pathway, which provided new insights for the treatment of hypertrophic scars.

Shikonin Causes an Apoptotic Effect on Human Kidney Cancer Cells through Ras/MAPK and PI3K/AKT Pathways

(1) Background: Shikonin, the main ingredient in Chinese herbal medicine, is described as a novel angiogenesis inhibitor, and its anticancer effects have already been studied. Shikonin and its derivatives induce apoptosis and suppress metastasis, which further enhance the effectiveness of chemotherapy. However, their mechanism of function has not been completely elucidated on human renal cancer cells. (2) Methods: In our study, CAKI-2 and A-498 cells were treated with increasing concentrations (2.5-40 µM) of shikonin, when colony formation ability and cytotoxic activity were tested. The changes in the expression of the main targets of apoptotic pathways were measured by RT-qPCR and Western blot. The intracellular levels of miR-21 and miR-155 were quantified by RT-qPCR. (3) Results: Shikonin exerted a dose-dependent effect on the proliferation of the cell lines examined. In 5 µM concentration of shikonin in vitro elevated caspase-3 and -7 levels, the proteins of the Ras/MAPK and PI3K/AKT pathways were activated. However, no significant changes were detected in the miR-21 and miR-155 expressions. (4) Conclusions: Our findings indicated that shikonin causes apoptosis of renal cancer cells by activating the Ras/MAPK and PI3K/AKT pathways. These effects of shikonin on renal cancer cells may bear important potential therapeutic implications for the treatment of renal cancer.

Shikonin, an inhibitor of inflammasomes, inhibits Epstein-Barr virus reactivation

Epstein-Barr virus (EBV) is a highly prevalent human herpesvirus that persists for life in more than 95% of the adult population. EBV usually establishes an asymptomatic life-long infection, but it is also associated with malignancies affecting B lymphocytes and epithelial cells mainly. The virus alternates between a latent phase and a lytic phase, both of which contribute to the initiation of the tumor process. So far, there is only a limited number of antiviral molecules against the lytic phase, most of them targeting viral replication. Recent studies provided evidence that EBV uses components of the NLRP3 inflammasome to enter the productive phase of its cycle following activation in response to various stimuli. In the present work, we demonstrate that shikonin, a natural molecule with low toxicity which is known to inhibit inflammasome, can efficiently repress EBV reactivation. Similar results were obtained with apigenin and OLT 1177, two other NLRP3 inflammasome inhibitors. It is shown herein that shikonin repressed the transcription of reactivation-induced NLRP3 thereby inhibiting inflammasome activation and EBV lytic phase induction.

Bacterial responses to plant antimicrobials: the case of alkannin and shikonin derivatives

Alkannin, shikonin and their derivatives (A/S) are secondary metabolites produced in the roots of certain plants of the Boraginaceae family such as Lithospermum erythrorhizon Siebold & Zucc. and Alkanna tinctoria (L.) Tausch. These naphthoquinones express anti-cancer, wound healing, and antimicrobial activities. To study the interactions between endophytic bacteria isolated from A. tinctoria and the antimicrobials A/S, endophytic bacteria known to be resistant to the compounds were screened for their effect on A/S in liquid medium. Thereafter, the strain Pseudomonas sp. R-72008, was selected and tested for its ability to modify A/S in nutrient medium and minimal medium with A/S as sole carbon source. Bacterial growth was recorded, and high performance liquid chromatography-diode array and ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry analyses were performed to detect and quantify metabolites. In nutrient medium inoculated with R-72008, a decrease in the amount of A/S monomers initially present was observed and correlated with an increase of A/S oligomers. Moreover, a significant decrease of initial A/S monomers in minimal medium was correlated with bacterial growth, showing for the first time that a bacterial strain, Pseudomonas sp. R-72008, was able to use the naphthoquinones A/S as sole carbon source. This study opens new perspectives on the interactions between bacteria and plant antimicrobials.

Natural Plant-Derived Compounds in Food and Cosmetics: A Paradigm of Shikonin and Its Derivatives

Shikonin and its derivatives are the natural naphthoquinone compounds produced in the roots of the Boraginaceae family. These red pigments have been used for a long time in coloring silk, as food colorants, and in the Chinese traditional system of medicines The resurgence of public interest in natural and plant-based products has led to this category of compounds being in high demand due to their wide range of biological activities including antioxidant, antitumor, antifungal, anti-inflammatory ones. Different researchers worldwide have reported various applications of shikonin derivatives in the area of pharmacology. Nevertheless, the use of these compounds in the food and cosmetics fields needs to be explored more in order to make them available for commercial utilization in various food industries as a packaging material and to enhance their shelf life without any side effects. Similarly, the antioxidant properties and skin whitening effects of these bioactive molecules may be used successfully in various cosmetic formulations. The present review delves into the updated knowledge on the various properties of shikonin derivatives in relation to food and cosmetics. The pharmacological effects of these bioactive compounds are also highlighted. Based on various studies, it can be concluded that these natural bioactive molecules have potential to be used in different sectors, including functional food, food additives, skin, health care, and to cure various diseases. Further research is required for the sustainable production of these compounds with minimum disturbances to the environment and in order to make them available in the market at an economic price. Simultaneous studies utilizing recent techniques in computational biology, bioinformatics, molecular docking, and artificial intelligence in laboratory and clinical trials would further help in making these potential candidates promising alternative natural bioactive therapeutics with multiple uses.

Therapeutic application of natural products: NAD+ metabolism as potential target

BACKGROUND

Nicotinamide adenine dinucleotide (NAD⁺) metabolism is involved in the entire physiopathological process and is critical to human health. Long-term imbalance in NAD⁺ homeostasis is associated with various diseases, including non-alcoholic fatty liver disease, diabetes mellitus, cardiovascular diseases, neurodegenerative disorders, aging, and cancer, making it a potential target for effective therapeutic strategies. Currently, several natural products that target NAD⁺ metabolism have been widely reported to have significant therapeutic effects, but systematic summaries are lacking.

PURPOSE

To summarize the latest findings on the prevention and treatment of various diseases through the regulation of NAD⁺ metabolism by various natural products in vivo and in vitro models, and evaluate the toxicities of the natural products.

METHODS

PubMed, Web of Science, and ScienceDirect were searched using the keywords "natural products sources," "toxicology," "NAD⁺ clinical trials," and "NAD⁺," and/or paired with "natural products" and "diseases" for studies published within the last decade until January 2023.

RESULTS

We found that the natural products mainly include phenols (curcumin, cyclocurcumin, 4-hydroxybenzyl alcohol, salvianolic acid B, pterostilbene, EGCG), flavonoids (pinostrobin, apigenin, acacetin, tilianin, kaempferol, quercetin, isoliquiritigenin, luteolin, silybin, hydroxysafflor yellow A, scutellarin), glycosides (salidroside), quinones (emodin, embelin, β-LAPachone, shikonin), terpenoids (notoginsenoside R1, ginsenoside F2, ginsenoside Rd, ginsenoside Rb1, ginsenoside Rg3, thymoquinone, genipin), pyrazines (tetramethylpyrazine), alkaloids (evodiamine, berberine), and phenylpropanoids (ferulic acid). These natural products have antioxidant, energy-producing, anti-inflammatory, anti-apoptotic and anti-aging effects, which mainly influence the NAMPT/NAD⁺/SIRT, AMPK/SIRT1/PGC-1α, Nrf2/HO-1, PKCs/PARPs/NF-κB, and AMPK/Nrf2/mTOR signaling pathways, thereby regulating NAD⁺ metabolism to prevent and treat various diseases. These natural products have been shown to be safe, tolerable and have fewer adverse effects in various in vivo and in vitro studies and clinical trials.

CONCLUSION

We evaluated the toxic effects of natural products and summarized the available clinical trials on NAD⁺ metabolism, as well as the recent advances in the therapeutic application of natural products targeting NAD⁺ metabolism, with the aim to provide new insights into the treatment of multiple disorders.

The discovery and characterization of AeHGO in the branching route from shikonin biosynthesis to shikonofuran in Arnebia euchroma

Shikonin derivatives are natural naphthoquinone compounds and the main bioactive components produced by several boraginaceous plants, such as Lithospermum erythrorhizon and Arnebia euchroma. Phytochemical studies utilizing both L. erythrorhizon and A. euchroma cultured cells indicate the existence of a competing route branching out from the shikonin biosynthetic pathway to shikonofuran. A previous study has shown that the branch point is the transformation from (Z)-3''-hydroxy-geranylhydroquinone to an aldehyde intermediate (E)-3''-oxo-geranylhydroquinone. However, the gene encoding the oxidoreductase that catalyzes the branch reaction remains unidentified. In this study, we discovered a candidate gene belonging to the cinnamyl alcohol dehydrogenase family, AeHGO, through coexpression analysis of transcriptome data sets of shikonin-proficient and shikonin-deficient cell lines of A. euchroma. In biochemical assays, purified AeHGO protein reversibly oxidized (Z)-3''-hydroxy-geranylhydroquinone to produce (E)-3''-oxo-geranylhydroquinone followed by reversibly reducing (E)-3''-oxo-geranylhydroquinone to (E)-3''-hydroxy-geranylhydroquinone, resulting in an equilibrium mixture of the three compounds. Time course analysis and kinetic parameters showed that the reduction of (E)-3''-oxo-geranylhydroquinone was stereoselective and efficient in presence of NADPH, which determined that the overall reaction proceeded from (Z)-3''-hydroxy-geranylhydroquinone to (E)-3''-hydroxy-geranylhydroquinone. Considering that there is a competition between the accumulation of shikonin and shikonofuran derivatives in cultured plant cells, AeHGO is supposed to play an important role in the metabolic regulation of the shikonin biosynthetic pathway. Characterization of AeHGO should help expedite the development of metabolic engineering and synthetic biology toward production of shikonin derivatives.

IgSF11-mediated phosphorylation of pyruvate kinase M2 regulates osteoclast differentiation and prevents pathological bone loss

Osteoclasts are primary bone-resorbing cells, and receptor-activated NF-kB ligand (RANKL) stimulation is the key driver of osteoclast differentiation. During late-stage differentiation, osteoclasts become multinucleated and enlarged (so-called "maturation"), suggesting their need to adapt to changing metabolic demands and a substantial increase in size. Here, we demonstrate that immunoglobulin superfamily 11 (IgSF11), which is required for osteoclast differentiation through an association with the postsynaptic scaffolding protein PSD-95, regulates osteoclast differentiation by controlling the activity of pyruvate kinase M isoform 2 (PKM2). By using a system that directly induces the activation of IgSF11 in a controlled manner, we identified PKM2 as a major IgSF11-induced tyrosine-phosphorylated protein. IgSF11 activates multiple Src family tyrosine kinases (SFKs), including c-Src, Fyn, and HcK, which phosphorylate PKM2 and thereby inhibit PKM2 activity. Consistently, IgSF11-deficient cells show higher PKM2 activity and defective osteoclast differentiation. Furthermore, inhibiting PKM2 activities with the specific inhibitor Shikonin rescues the impaired osteoclast differentiation in IgSF11-deficient cells, and activating PKM2 with the specific activator TEPP46 suppresses osteoclast differentiation in wild-type cells. Moreover, PKM2 activation further suppresses osteoclastic bone loss without affecting bone formation in vivo. Taken together, these results show that IgSF11 controls osteoclast differentiation through PKM2 activity, which is a metabolic switch necessary for optimal osteoclast maturation.

Liquid-liquid phase separation of protein tau: An emerging process in Alzheimer's disease pathogenesis

Metabolic reactions within cells occur in various isolated compartments with or without borders, the latter being known as membrane-less organelles (MLOs). The MLOs show liquid-like properties and are formed by a process known as liquid-liquid phase separation (LLPS). MLOs contribute to different molecules interactions such as protein-protein, protein-RNA, and RNA-RNA driven by various factors, such as multivalency of intrinsic disorders. MLOs are involved in several cell signaling pathways such as transcription, immune response, and cellular organization. However, disruption of these processes has been found in different pathologies. Recently, it has been demonstrated that protein aggregates, a characteristic of some neurodegenerative diseases, undergo similar phase separation. Tau protein is known as a major neurofibrillary tangles component in Alzheimer's disease (AD). This protein can undergo phase separation to form a MLO known as tau droplet in vitro and in vivo, and this process can be facilitated by several factors, including crowding agents, RNA, and phosphorylation. Tau droplet has been shown to mature into insoluble aggregates suggesting that this process may precede and induce neurodegeneration in AD. Here we review major factors involved in liquid droplet formation within a cell. Additionally, we highlight recent findings concerning tau aggregation following phase separation in AD, along with the potential therapeutic strategies that could be explored in this process against the progression of this pathology.

Unraveling the interaction of copper, cadmium, calcium, and nitrate on phenolics, flavonoids, and shikonin contents of Onosma dichroantha calli by statistical modeling

Increased anthropogenic activities have led to the accumulation of certain minerals to ecotoxic levels in the environment, which could influence the secondary metabolism of plants. Shikonin, an exudate from the roots of Onosma dichroantha, is a secondary metabolite involved in plant defense and invasion success; however, the interactive effects of copper (Cu), cadmium (Cd), calcium (Ca), and nitrate (NO₃) in shikonin biosynthesis and accumulation are not known. Here, the individual, curvilinear, and pairwise effects of these elements on shikonin biosynthesis in callus culture of O. dichroantha have been investigated by means of a statistical modeling approach and multivariate regression analyses. Although the main effects of the examined minerals seemed to be suppressive, their combined interactions could enhance callus growth and secondary metabolism of O. dichroantha. Accordingly, maximum values were recorded for the callus growth index (6.85 at 23.25 μM Cu, 70 mM NO₃, 1 mM Ca, 27.50 μM Cd), total phenolics (24.83 mg gallic acid equivalent at 9.75 μM Cu, 70 mM NO₃, 1 mM Ca, 62.50 μM Cd), total flavonoids (6.12 mg quercetin equivalent at 30 μM Cu, 80 mM NO₃, 1.5 mM Ca, 45 μM Cd), and shikonin (24.33 μg g^-1 FW at 9.75 μM Cu, 70 mM NO₃, 2 mM Ca, 27.5 μM Cd). Overall, these data show that increasing concentrations of the examined minerals in culture medium can markedly influence the secondary metabolism of O. dichroantha cells and suggest that a comparable phenomenon may exist in a wider range of medicinal plants, grown on polluted environments, which may affect their invasive capabilities.

FLI1 accelerates leukemogenesis through transcriptional regulation of pyruvate kinase-L/R and other glycolytic genes

In cancer cells, multiple oncogenes and tumor suppressors control glycolysis to sustain rapid proliferation. The ETS-related transcription factor Fli1 plays a critical role in the induction and progression of leukemia, yet, the underlying mechanism of this oncogenic event is still not fully understood. In this study, RNAseq analysis of FLI1-depleted human leukemic cells revealed transcriptional suppression of the PKLR gene and activation of multiple glycolytic genes, such as PKM1/2. Pharmacological inhibition of glycolysis by PKM2 inhibitor, Shikonin, significantly suppressed leukemic cell proliferation. FLI1 directly binds to the PKLR promoter, leading to the suppression of this inhibitor of glycolysis. In accordance, shRNA-mediated depletion of PKLR in leukemic HEL cells expressing high levels of FLI1 accelerated leukemia proliferation, pointing for the first time to its tumor suppressor function. PKLR knockdown also led to downregulation of the erythroid markers EPOR, HBA1, and HBA2 and suppression of erythroid differentiation. Interestingly, silencing of PKLR in HEL cells significantly increased FLI1 expression, which was associated with faster proliferation in culture. In FLI1-expressing leukemic cells, lower PKLR expression was associated with higher expression of PKM1 and PKM2, which promote aerobic glycolysis. Finally, injection of pyruvate, a known inhibitor of glycolysis, into leukemia mice significantly suppressed leukemogenesis. These results demonstrate that FLI1 promotes leukemia in part by inducing glycolysis, implicates PKLR in erythroid differentiation, and suggests that targeting glycolysis may be an attractive therapeutic strategy for cancers driven by FLI1 overexpression.

Antifungal and Immunomodulatory Ingredients from Traditional Chinese Medicine

Fungal infections have become a growing public health challenge due to the clinical transmission of pathogenic fungi. The currently available antifungal drugs leave very limited choices for clinical physicians to deal with such situation, not to mention the long-standing problems of emerging drug resistance, side effects and heavy economic burdens imposed to patients. Therefore, new antifungal drugs are urgently needed. Screening drugs from natural products and using synthetic biology strategies are very promising for antifungal drug development. Chinese medicine is a vast library of natural products of biologically active molecules. According to traditional Chinese medicine (TCM) theory, preparations used to treat fungal diseases usually have antifungal and immunomodulatory functions. This suggests that if antifungal drugs are used in combination with immunomodulatory drugs, better results may be achieved. Studies have shown that the active components of TCM have strong antifungal or immunomodulatory effects and have broad application prospects. In this paper, the latest research progress of antifungal and immunomodulatory components of TCM is reviewed and discussed, hoping to provide inspiration for the design of novel antifungal compounds and to open up new horizons for antifungal treatment strategies.

Antiallergic Effects of N,N-dicoumaroylspermidine Isolated from Lithospermum erythrorhizon on Mast Cells and Ovalbumin-Induced Allergic Rhinitis

In East Asia, the dried root of Lithospermum erythrorhizon has been utilized as an anti-inflammatory, antipyretic, detoxifying, and anti-inflammatory agent. Recently, we reported that L. erythrorhizon protects against allergic rhinitis; however, the component within L. erythrorhizon that exerts antiallergic activity remains unknown. The purpose of the current study was to isolate and characterize the antiallergic active components in an ethanolic extract of L. erythrorhizon roots. We examined the antiallergic effects of L. erythrorhizon reflux ethanol extracts in an ovalbumin (OVA)-induced allergic rhinitis mouse model, and compared the chemical compounds extracted using the hot reflux and cold extraction methods. Chromatographic separation identified two novel anthraquinones, erythrin A and B, one newly discovered compound from the Lithospermum genus, N1″,N3″-dicoumaroylspermidine, and nineteen other recognized compounds. Their chemical structures were elucidated by single (1D) and 2D analysis of nuclear magnetic resonance (NMR) spectroscopic data, as well as high resolution mass spectrometry. Among the identified compounds, N,N′-dicoumaroylspermidine strongly inhibited the release of β-hexosaminidase, as well as the production of IL-3, IL-4, and IL-13 by IgE-sensitized and BSA-stimulated RBL-2H3 cells. Using the OVA-induced allergic rhinitis mouse model, we showed that N,N′-dicoumaroylspermidine reduced the production of serum OVA-specific IgE and the number of inflammatory cells in nasal lavage fluid. N,N′-dicoumaroylspermidine isolated from L. erythrorhizon exhibits antiallergic properties, making it potentially effective for allergic rhinitis.