Addition of β-lactoglobulin produces water-soluble shikonin

Inhibitory Effects of Shikonin Dispersion, an Extract of Lithospermum erythrorhizon Encapsulated in β-1,3-1,6 Glucan, on Streptococcus mutans and Non-Mutans Streptococci

Shikonin is extracted from the roots of Lithospermum erythrorhizon, and shikonin extracts have been shown to have inhibitory effects on several bacteria. However, shikonin extracts are difficult to formulate because of their poor water solubility. In the present study, we prepared a shikonin dispersion, which was solubilized by the inclusion of β-1,3-1,6 glucan, and analysed the inhibitory effects of this dispersion on Streptococcus mutans and non-mutans streptococci. The shikonin dispersion showed pronounced anti-S. mutans activity, and inhibited growth of and biofilm formation by this bacterium. The shikonin dispersion also showed antimicrobial and antiproliferative effects against non-mutans streptococci. In addition, a clinical trial was conducted in which 20 subjects were asked to brush their teeth for 1 week using either shikonin dispersion-containing or non-containing toothpaste, respectively. The shikonin-containing toothpaste decreased the number of S. mutans in the oral cavity, while no such effect was observed after the use of the shikonin-free toothpaste. These results suggest that shikonin dispersion has an inhibitory effect on S. mutans and non-mutans streptococci, and toothpaste containing shikonin dispersion may be effective in preventing dental caries.

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.

Combined Shikonin-Loaded MPEG-PCL Micelles Inhibits Effective Transition of Endothelial-to-Mesenchymal Cells

Introduction

Shikonin is well known for its anti-inflammatory activity in cardiovascular diseases. However, the application of shikonin is limited by its low water solubility and poor bioavailability. Methoxy poly (ethylene glycol)-b-poly (ε-caprolactone) (MPEG-PCL) is considered a promising delivery system for hydrophobic drugs. Therefore, in this study, we prepared shikonin-loaded MPEG-PCL micelles and investigated their effect on endothelial-to-mesenchymal transition (EndMT) induced by inflammatory cytokines.

Methods

Shikonin was encapsulated in MPEG-PCL micelles using an anti-solvent method and the physiochemical characteristics of the micelles (particle size, zeta potential, morphology, critical micelle concentration (CMC), drug loading and encapsulation efficiency) were investigated. Cellular uptake of micelles in human umbilical vein endothelial cells (HUVECs) was evaluated using fluorescence microscopy. In vitro EndMT inhibition was explored in HUVECs by quantitative real-time PCR analysis.

Results

The average particle size of shikonin-loaded MPEG-PCL micelles was 54.57±0.13 nm and 60 nm determined by dynamic light scattering and transmission electron microscopy, respectively. The zeta potential was −6.23±0.02 mV. The CMC of the micelles was 6.31×10⁻⁷mol/L. The drug loading and encapsulation efficiency were 0.88±0.08% and 43.08±3.77%, respectively. The MPEG-PCL micelles significantly improved the cellular uptake of cargo with low water solubility. Real-time PCR analysis showed that co-treatment with TNF-α and IL-1β successfully induced EndMT in HUVECs, whereas this process was significantly inhibited by shikonin and shikonin-loaded MPEG-PCL micelles, with greater inhibition mediated by the shikonin-loaded MPEG-PCL micelles.

Conclusion

Shikonin-loaded MPEG-PCL micelles significantly improved the EndMT-inhibiting effect of the free shikonin. MPEG-PCL is suitable for use more generally as a lipophilic drug carrier.

Interactions between stipuol enantiomers and human serum albumin

Natural polyacetylenes occur in food and herbal plants, have a wide range of bioactivities, and are recognized as important nutraceuticals. Stipuol is a natural polyacetylene present in the edible plant Panax notoginseng. The present study was aimed to study interactions of rac-stipuol and its enantiomers with human serum albumin (HSA) using multi-spectroscopic, molecular modeling and microscale thermophoresis. Steady-state and time-resolved fluorescence spectra manifest that the fluorescence quenching mechanism is mainly static in type. The bindings of (S)-stipuol, (R)-stipuol, rac-stipuol lead to some microenvironmental and slight conformational changes of HSA. Competitive ligand displacement experiments and molecular modeling studies revealed that stipuol enantiomers bind to HSA at subdomain III (site IIA). The calculated values of K_a and K_d showed that (R)-stipuol had a stronger binding affinity than (S)-stipuol. The results are informative for use of stipuol as a nutraceutical to improve human health.

Shikonin, a naphthalene ingredient: Therapeutic actions, pharmacokinetics, toxicology, clinical trials and pharmaceutical researches

BACKGROUND

Shikonin is one of the major phytochemical components of Lithospermum erythrorhizon (Purple Cromwell), which is a type of medicinal herb broadly utilized in traditional Chinese medicine. It is well established that shikonin possesses remarkable therapeutic actions on various diseases, with the underlying mechanisms, pharmacokinetics and toxicological effects elusive. Also, the clinical trial and pharmaceutical study of shikonin remain to be comprehensively delineated.

PURPOSE

The present review aimed to systematically summarize the updated knowledge regarding the therapeutic actions, pharmacokinetics, toxicological effects, clinical trial and pharmaceutical study of shikonin.

METHODS

The information contained in this review article were retrieved from some authoritative databases including Web of Science, PubMed, Google scholar, Chinese National Knowledge Infrastructure (CNKI), Wanfang Database and so on, till August 2021.

RESULTS

Shikonin exerts multiple therapeutic efficacies, such as anti-inflammation, anti-cancer, cardiovascular protection, anti-microbiomes, analgesia, anti-obesity, brain protection, and so on, mainly by regulating the NF-κB, PI3K/Akt/MAPKs, Akt/mTOR, TGF-β, GSK3β, TLR4/Akt signaling pathways, NLRP3 inflammasome, reactive oxygen stress, Bax/Bcl-2, etc. In terms of pharmacokinetics, shikonin has an unfavorable oral bioavailability, 64.6% of the binding rate of plasma protein, and enhances some metabolic enzymes, particularly including cytochrome P450. In regard to the toxicological effects, shikonin may potentially cause nephrotoxicity and skin allergy. The above pharmacodynamics and pharmacokinetics of shikonin have been validated by few clinical trials. In addition, pharmaceutical innovation of shikonin with novel drug delivery system such as nanoparticles, liposomes, microemulsions, nanogel, cyclodextrin complexes, micelles and polymers are beneficial to the development of shikonin-based drugs.

CONCLUSIONS

Shikonin is a promising phytochemical for drug candidates. Extensive and intensive explorations on shikonin are warranted to expedite the utilization of shikonin-based drugs in the clinical setting.

Transdermal delivery of Chinese herbal medicine extract using dissolvable microneedles for hypertrophic scar treatment

Hypertrophic scars are unfavorable skin diseases characterized by excessive collagen deposition. Although systemic treatments exist in clinic to manage hypertrophic scars, they pose significant side effects and tend to lose efficacy over prolonged applications. Traditional Chinese medicine (TCM) offers as a promising candidate to treat pathological scars. A large number of TCMs have been studied to show anti-scarring effect, however, the natural barrier of the skin impedes their penetration, lowering its therapeutic efficacy. Herein, we reported the use of dissolvable hyaluronic acid (HA) microneedles (MNs) as a vehicle to aid the transdermal delivery of therapeutic agent, a model TCM called shikonin for the treatment of hypertrophic scars. Here, shikonin was mixed with HA to make MNs with adequate mechanical strength for skin penetration, making its dosage controllable during the fabrication process. The therapeutic effect of the shikonin HA MNs was studied in vitro using HSFs and then further verified with quantitative reverse transcriptase polymerase chain reaction. Our data suggest that the shikonin HA MNs significantly reduce the viability and proliferation of the HSFs and downregulate the fibrotic-related genes (i.e., TGFβ1, FAP-α and COL1A1). Furthermore, we observed a localized therapeutic effect of the shikonin HA MNs that is beneficial for site-specific treatment.

Evaluation of the inhibition risk of shikonin on human and rat UDP-glucuronosyltransferases (UGT) through the cocktail approach

Shikonin, a natural red colorant, is widely used for food garnishment and cosmetic ingredient in the world. Shikonin also possesses a variety of pharmacological actions, including anti-inflammation and anti-cancer activities. However, little is known about its effects on the UDP-glucuronosyltransferases (UGT) activity. Therefore, the aim of this study was to evaluate the effect of shikonin on the UGT1A1, UGT1A3, UGT1A6, UGT1A9 and UGT2B7 activities via the human and rat liver microsomal assay and cocktail approach. The results showed shikonin inhibited human and rat liver microsomal UGT activity only in a dose-dependent manner. The further enzyme kinetic studies demonstrated that shikonin was not only a competitive inhibitor of human UGT1A1, UGT1A9, and UGT2B7, but also presented competitive inhibition on rat UGT1A1 and AZTG reactions. In conclusion, shikonin as a reversible inhibitor of UGT enzyme has a high-risk potential to cause the possible toxicity, especially drug-drug or food-drug interactions.

Successful in vivo hyperthermal therapy toward breast cancer by Chinese medicine shikonin-loaded thermosensitive micelle

The Chinese traditional medicine Shikonin is an ideal drug due to its multiple targets to tumor cells. But in clinics, improving its aqueous solubility and tumor accumulation is still a challenge. Herein, a copolymer with tunable poly(N-isopropylacrymaide) and polylactic acid block lengths is designed, synthesized, and characterized in nuclear magnetic resonance. The corresponding thermosensitive nanomicelle (TN) with well-defined core-shell structure is then assembled in an aqueous solution. For promoting the therapeutic index, the physical-chemistry properties of TNs including narrow size, low critical micellar concentration, high serum stability, tunable volume phase transition temperature (VPTT), high drug-loading capacity, and temperature-controlled drug release are systematically investigated and regulated through the fine self-assembly. The shikonin is then entrapped in a degradable inner core resulting in a shikonin-loaded thermosensitive nanomicelle (STN) with a VPTT of ~40°C. Compared with small-molecular shikonin, the in vitro cellular internalization and cytotoxicity of STN against breast cancer cells (Michigan Cancer Foundation-7) are obviously enhanced. In addition, the therapeutic effect is further enhanced by the programmed cell death (PCD) specifically evoked by shikonin. Interestingly, both the proliferation inhibition and PCD are synergistically promoted as T > VPTT, namely the temperature-regulated passive targeting. Consequently, as intravenous injection is administered to the BALB/c nude mice bearing breast cancer, the intratumor accumulation of STNs is significantly increased as T > VPTT, which is regulated by the in-house developed heating device. The in vivo antitumor assays against breast cancer further confirm the synergistically enhanced therapeutic efficiency. The findings of this study indicate that STN is a potential effective nanoformulation in clinical cancer therapy.

Shikonin Suppresses NLRP3 and AIM2 Inflammasomes by Direct Inhibition of Caspase-1

Shikonin is a highly lipophilic naphtoquinone found in the roots of Lithospermum erythrorhizon used for its pleiotropic effects in traditional Chinese medicine. Based on its reported antipyretic and anti-inflammatory properties, we investigated whether shikonin suppresses the activation of NLRP3 inflammasome. Inflammasomes are cytosolic protein complexes that serve as scaffolds for recruitment and activation of caspase-1, which, in turn, results in cleavage and secretion of proinflammatory cytokines IL-1β and IL-18. NLRP3 inflammasome activation involves two steps: priming, i.e. the activation of NF-κB pathway, and inflammasome assembly. While shikonin has previously been reported to suppress the priming step, we demonstrated that shikonin also inhibits the second step of inflammasome activation induced by soluble and particulate NLRP3 instigators in primed immortalized murine bone marrow-derived macrophages. Shikonin decreased NLRP3 inflammasome activation in response to nigericin more potently than acetylshikonin. Our results showed that shikonin also inhibits AIM2 inflammasome activation by double stranded DNA. Shikonin inhibited ASC speck formation and caspase-1 activation in murine macrophages and suppressed the activity of isolated caspase-1, demonstrating that it directly targets caspase-1. Complexing shikonin with β-lactoglobulin reduced its toxicity while preserving the inhibitory effect on NLRP3 inflammasome activation, suggesting that shikonin with improved bioavailability might be interesting for therapeutic applications in inflammasome-mediated conditions.

The evidence for natural therapeutics as potential anti-scarring agents in burn-related scarring

Though survival rate following severe thermal injuries has improved, the incidence and treatment of scarring have not improved at the same speed. This review discusses the formation of scars and in particular the formation of hypertrophic scars. Further, though there is as yet no gold standard treatment for the prevention or treatment of scarring, a brief overview is included. A number of natural therapeutics have shown beneficial effects both in vivo and in vitro with the potential of becoming clinical therapeutics in the future. These natural therapeutics include both plant-based products such as resveratrol, quercetin and epigallocatechin gallate as examples and includes the non-plant-based therapeutic honey. The review also includes potential mechanism of action for the therapeutics, any recorded adverse events and current administration of the therapeutics used. This review discusses a number of potential 'treatments' that may reduce or even prevent scarring particularly hypertrophic scarring, which is associated with thermal injuries without compromising wound repair.

Exploratory, Phase II Controlled Trial of Shiunko Ointment Local Application Twice a Day for 4 Weeks in Ethiopian Patients with Localized Cutaneous Leishmaniasis

The clinical efficacy and safety of Shiunko ointment (phase II clinical trial) was investigated in 40 Ethiopian patients with cutaneous leishmaniasis. Patients were randomized to receive treatment with Shiunko ointment or placebo (n = 20, each), applied on the lesion twice a day for 4 weeks. Clinicoparasitological assessments were performed before treatment, weekly for 4 weeks, and then 4, 8, and 12 weeks after the end of treatment. A marked reduction in lesion size was observed on week 16 of treatment in the Shiunko compared with placebo group (69% and 22% reduction, resp.). The overall rate of lesion reduction during the four weeks of treatment was significantly faster in the Shiunko group. Shiunko provided significant effect on wound closure in patients with ulcerated lesion. The clinical efficacy and tolerability of Shiunko were comparable to placebo with regard to its clinicoparasitological response (cure rate and parasitological clearance). Results of this preliminary study may suggest that Shiunko could be useful as adjuvant or as complementary treatment, not as alternatives to current treatment. Its attractive action includes fast lesion healing with a significantly smaller lesion at week 16 of treatment compared with placebo. In addition, its action was promoted in ulcerative lesions.