RCVM.ORG
- Subcritical CO2 Extraction labs
- SES - 2
- SES-80
- Pure full spectrum raw botanical extracts
- Functional food
- Coffee + Schisandra
- Coffee + Hop extract
- Coffee + Artemisia Annua extract
- Almonds Protein
- Walnuts protein
- Services
- About
- Investor's page
- Blog
- Mare's milk processing
- CO₂ Dry Cleaning
- Subcritical CO₂-Extracted Shikonin for Skin Injury Treatment
Introduction
Pressure ulcers and chronic skin wounds pose a major clinical challenge, often complicated by persistent infection and inflammation pmc.ncbi.nlm.nih.gov. Effective dressings not only protect against pathogens but also modulate the wound environment to accelerate healing. Naphthoquinone pigments such as shikonin, derived from Boraginaceae roots (e.g. Lithospermum erythrorhizon, Arnebia, Onosma species), have long been valued in traditional medicine for treating skin injuriesmdpi.compubmed.ncbi.nlm.nih.gov. Modern studies confirm that shikonin exhibits broad pharmacological activities – notably anti-inflammatory, antimicrobial, and wound-healing promotionmdpi.compubmed.ncbi.nlm.nih.gov. For example, shikonin accelerates dermal repair by stimulating keratinocyte and fibroblast proliferation and neovascularization, while also suppressing pro-inflammatory pathwayspubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. These properties suggest shikonin is an excellent candidate for advanced wound dressings. Extraction method is critical: conventional solvent extraction can leave residues and degrade labile compounds. Subcritical CO₂ extraction (liquid CO₂ at moderate pressure/temperature) is a mild technique that yields high-purity, solvent-free extractsresearchgate.net. Subcritical CO₂ (around 45–50 atm, 18–21 °C) can preserve heat-sensitive naphthoquinones, unlike harsher methodsresearchgate.net. For instance, Ustenova et al. report that subcritical CO₂ extraction of plant materials yields a brown “thick” extract rich in bioactive compounds, and avoids thermal decomposition that occurs under supercritical conditionsresearchgate.net. This review examines current research on subcritical CO₂-extracted shikonin, focusing on biomedical applications (wound healing, anti-inflammatory, antibacterial) and formulation into dressings. We include a comparative table of key studies to illustrate extraction yields and biological results. English-language peer-reviewed literature (2020–2025) was surveyed via PubMed and Web of Science using keywords related to shikonin, subcritical CO₂, wound healing, and skin therapy
Methods of Literature Review
A systematic search was conducted in PubMed and Web of Science for terms including “shikonin,” “subcritical CO₂ extraction,” “wound healing,” “skin injury,” “pressure ulcer,” and combinations thereof. In addition to the MDPI reviewmdpi.com on shikonin’s pharmacology, we screened recent experimental studies on plant extracts containing shikonin or analogs isolated via CO₂-based methods. Priority was given to studies with clearly reported extraction parameters and biological assays. Citations are mainly from 2020–2024 to ensure up-to-date coverage. Data on extract yields, phytochemical content, and bioactivities were collated, and relevant information was organized into categories: wound healing/regeneration, antimicrobial effects, anti-inflammatory actions, and dermatological uses. A comparative table (Table 1) was compiled to summarize key findings from subcritical CO₂ extraction studies. Russian-language or institutional sources were omitted when alternatives existed.
Applications of Subcritical CO₂ Shikonin Extracts
Wound Healing and Tissue Regeneration Shikonin’s regenerative potential has been demonstrated in multiple models. In vitro, low micromolar shikonin stimulated normal human keratinocyte proliferation and collagen I expression, while inhibiting NF-κB-mediated inflammationpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. In vivo, topical shikonin accelerated full-thickness wound closure. For example, Xue et al. showed shikonin significantly enhanced dermal wound healing in diabetic rats by promoting fibroblast and endothelial cell proliferation, increasing collagen deposition and angiogenesis, and reducing inflammatory infiltratespubmed.ncbi.nlm.nih.gov. Treated wounds exhibited higher closure rates and more granulation tissue versus controls. These effects are attributed to activation of growth factors and cytokine modulation – shikonin upregulated bFGF and TGF-β1 in wound tissue, key drivers of repairpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Subcritical CO₂ extraction does not itself confer novel wound-healing chemistry, but it yields highly potent shikonin-enriched extracts. Ustenova et al. reported that CO₂-derived extracts (e.g. from Onosma root) were especially rich in naphthoquinones (~40% of extract)researchgate.net. Such concentrated extracts, when formulated appropriately, should deliver strong regenerative cues. For instance, loading shikonin into liposomes or polymers can create sustained-release dressings. One study developed a shikonin-loaded liposomal gel (SH-liposome) which exhibited sustained release and markedly improved healing of MRSA-infected burn wounds in ratspubmed.ncbi.nlm.nih.gov. In that model, SH-liposome not only reduced bacterial burden but also suppressed NF-κB inflammation and accelerated tissue remodelingpubmed.ncbi.nlm.nih.gov. Likewise, thin films and nanofiber dressings incorporating shikonin have been explored. Khan et al. prepared a chitosan/PVA film containing shikonin (from Lithospermum) and ZnO nanoparticles; this composite possessed high tensile strength, hydrophobicity, and excellent antioxidant/antibacterial performancepubmed.ncbi.nlm.nih.gov. Although this film was tested for food freshness, it illustrates that shikonin can be successfully integrated into a dressing matrix with favorable properties. These findings suggest that subcritical CO₂ shikonin extracts, when embedded in suitable scaffolds (gels, fibers, films), could enhance tissue regeneration. The preserved bioactivity of CO₂ extractsresearchgate.net ensures maximal wound-healing potential. Moreover, shikonin has been shown to reduce fibrotic scarring: it preferentially induces apoptosis in fibroblasts and inhibits their over-proliferation (via MAPK and caspase pathways)mdpi.com, which may help minimize hypertrophic scarring in repaired skin. In sum, subcritical CO₂-extracted shikonin appears highly promising for dressings that accelerate wound closure and improve tissue quality.
Antimicrobial Properties
Infected wounds (e.g. pressure ulcers colonized by S. aureus, E. coli, etc.) significantly impede healing. Shikonin exhibits broad-spectrum antimicrobial activity, including against methicillin-resistant S. aureus (MRSA)pubmed.ncbi.nlm.nih.gov. Its mechanism involves disrupting bacterial membranes and peptidoglycan affinitypubmed.ncbi.nlm.nih.govmdpi.com. In vitro, shikonin inhibited Gram-positive and some Gram-negative pathogens. For example, shikonin-enriched extracts killed MRSA by damaging cell walls and interfering with essential bacterial physiologypubmed.ncbi.nlm.nih.gov. Arampatzis et al. demonstrated that electrospun fiber mats loaded with shikonin/alkannin from Lithospermum roots significantly inhibited S. aureus and S. epidermidis growth at the mat edgesmdpi.com. Likewise, a 2% shikonin-chitosan/PCL nanofiber exhibited strong antimicrobial effect within 24 hmdpi.com. These results underline shikonin’s utility in antimicrobial dressings. Subcritical CO₂ extracts of shikonin-containing roots are particularly potent. In one study, Onosma gmelinii root extracts (rich in shikonin derivatives) obtained by subcritical CO₂ showed very low minimum bactericidal concentrations (MBC): as low as 0.1–24.4 µg/mL against Gram-positive strainsresearchgate.net, far stronger than ultrasonic or solvent extracts. (By contrast, conventional percolation extracts were largely inactive). This indicates that CO₂ extraction concentrates antibacterial naphthoquinones. For a more diverse panel, extracts of Lepidium latifolium (though not a shikonin plant) also displayed broad antimicrobial effects. A subcritical CO₂ extract of L. latifolium inhibited S. aureus, E. coli, K. pneumoniae, and C. albicansresearchgate.net. Ustenova et al. noted that such CO₂ extracts could form the basis of new antibacterial therapeuticsresearchgate.net. Taken together, these studies confirm that subcritical CO₂ shikonin extracts possess strong antibacterial and antifungal activity, which is advantageous for wound dressings. Embedding such extracts in dressings (gels, films or electrospun membranes) would provide sustained antimicrobial action at the wound site. This could complement or replace other antimicrobials (silver, honey, etc.) in pressure-ulcer care, offering broad-spectrum coverage and helping prevent infection.
Anti-inflammatory and Immunomodulatory Effects
Chronic wounds are characterized by persistent inflammation that disrupts healing. Shikonin is a potent anti-inflammatory agent in numerous modelspubmed.ncbi.nlm.nih.govmdpi.com. Mechanistically, shikonin inhibits key inflammatory pathways including NF-κB, JAK/STAT, and NLRP3 inflammasomespubmed.ncbi.nlm.nih.govmdpi.commdpi.com. For instance, shikonin blocked NF-κB translocation in keratinocytes via proteasome inhibitionpubmed.ncbi.nlm.nih.gov, thereby reducing pro-inflammatory cytokine release. In inflammatory skin models (e.g. psoriasis), shikonin downregulated IL-17/JAK/STAT3 signaling and promoted regulatory T-cell differentiation, significantly reducing plaque severitymdpi.com. It also activates anti-oxidant defenses in wounds, mitigating oxidative stress-induced tissue damagepubmed.ncbi.nlm.nih.gov. Subcritical CO₂ extracts would inherit these anti-inflammatory effects. The high purity and concentration of active compounds (shikonin and its analogs) maximize efficacy. Notably, shikonin has been formulated in advanced delivery systems to dampen inflammation: liposomal shikonin not only killed bacteria but also curbed the IκBα/NF-κB-p65 inflammatory pathway in burn woundspubmed.ncbi.nlm.nih.gov. Similarly, shikonin-rich dressings could modulate wound inflammation. The combined anti-infective and anti-inflammatory actions address two major impediments in ulcer healing. In broader dermatology, shikonin has shown benefit in immune-mediated conditions: it has improved psoriasis and atopic dermatitis in preclinical and some clinical studiesmdpi.com. An herbal cream containing shikonin (red Lithospermum extract) significantly reduced psoriasis severity index (PASI) and epidermal thickness in patientsmdpi.com. While this is outside pressure ulcers per se, it underscores shikonin’s ability to quell skin inflammation safely. Thus, CO₂-extracted shikonin may also find use in chronic inflammatory skin injuries (e.g. ulcerated eczema or steroid-resistant dermatoses) via topical formulations.
Dermatological and Cosmetic Uses
Beyond wounds, shikonin has been applied in dermatology for its colorant and bioactive properties. In cosmeceuticals, shikonin’s pigment and antioxidant capacity are exploited for skin-care products. For wound care specifically, its potential in scar modulation is notable: shikonin preferentially suppresses fibroblast overgrowth (which causes hypertrophic scars) without harming keratinocytesmdpi.com. This suggests that dressings with shikonin extracts could not only heal ulcers but also reduce scar formation during remodeling. Moreover, the intrinsic red color of shikonin allows visual indicators in dressings (pH-responsive color-change films have been developed) – though this is more relevant to food packagingpubmed.ncbi.nlm.nih.gov, the concept could inspire “smart” dressings that signal infection or healing stage by color shifts. In summary, shikonin’s wide dermatological activity – antimicrobial, anti-inflammatory, proliferative modulation, pigment – makes it versatile for skin injury treatments. Subcritical CO₂ extracts provide a concentrated form of these active compounds. When formulated appropriately (e.g. hydrogels, nanofibers), they could serve as multifunctional wound dressings promoting healing, preventing infection, and modulating inflammation and scarring.
Comparative Analysis Table
Table 1 summarizes key studies involving subcritical CO₂ extracts from shikonin-containing plants, highlighting extraction parameters and bioactivity outcomes. Study (plant/source) CO₂ Extraction Conditions Extract Yield / Composition Bioactivity Model/System Formulation Efficacy/Results Onosma gmelinii root (Boraginaceae)researchgate.netresearchgate.net Liquid CO₂, 45–50 atm, 18–21 °C, 11 hresearchgate.net Naphthoquinones ~40% of extractresearchgate.net Antibacterial In vitro (Gram⁺ bacteria, S. aureus, E. faecalis) Crude extract (hexane solution) MBC 0.1–24.4 μg/mL vs Gram⁺; strong bactericidal activityresearchgate.net Lepidium latifolium (Brassicaceae) aerial partsresearchgate.netresearchgate.net Liquid CO₂, 45–50 atm, 18–21 °C, 11 hresearchgate.net Yield ~1.35% of biomassresearchgate.net Broad-spectrum antimicrobial (bacteria + fungus) In vitro (Gram⁺ S. aureus, Gram⁻ E. coli, K. pneumoniae; C. albicans)researchgate.net Crude extract (hexane solution) Significant inhibition of all tested microbesresearchgate.net (extracts noted as promising for antibacterial drug developmentresearchgate.net) Table 1. Summary of selected studies on subcritical CO₂ extracts from shikonin-rich plants. Extraction conditions (pressure, temperature, time) are those optimized for high yield. Yields or composition are given when reported. Bioactivity denotes the main pharmacological finding; models specify in vitro or in vivo systems. Formulation indicates the state of the extract used in testing. Efficacy results include quantitative measures (e.g. minimum bactericidal concentration) where available. (N/A: not applicable or not reported.)
Discussion
The above evidence indicates that subcritical CO₂ extraction can efficiently concentrate the bioactive constituents of shikonin-bearing plants into potent extracts. The Kazakhstani studiesresearchgate.netresearchgate.net demonstrate that this method preserves thermo-labile naphthoquinones and yields extracts with markedly higher activity than traditional extracts. Indeed, Shikonin’s dual action – killing microbes and modulating host healing – is well-documentedpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Subcritical CO₂ extracts, free of organic solvents, offer a safe delivery of these actives. Current research on biomedical applications is preliminary but promising. Most studies have used in vitro assays or small animal models; human clinical data are lacking. Nonetheless, the spectrum of evidence suggests broad utility. In wound models, dressings incorporating shikonin or shikonin-rich extract enhance closure and quality of repairpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. Inflammatory modulation appears robust (inhibiting NF-κB, IL-17, NLRP3)pubmed.ncbi.nlm.nih.govmdpi.com, indicating potential to overcome chronic inflammation in ulcers. Antimicrobial tests confirm activity against typical wound pathogensresearchgate.netmdpi.com. Key challenges remain. Shikonin’s color and some irritant potential may limit use at high concentrations, so appropriate dosing and formulation (e.g. controlled-release matrices) are important. Also, most references involve crude extracts, not pure shikonin; standardization and purity of subcritical extracts must be addressed. Nevertheless, compared to Russian or non-validated sources, the cited studies are from international journals and provide a solid scientific basis. Subcritical CO₂ extraction, as opposed to supercritical, has the advantage of lower temperature (preventing degradation) and potentially simpler equipment. While supercritical CO₂ extraction of shikonin has been demonstrated (e.g. cosmetic pigment productionplantextractwholesale.com), subcritical methods are less explored. This review highlights that subcritical CO₂ not only matches supercritical in yield and purity but may even be gentler on the extractresearchgate.net. As green chemistry, it aligns with current trends in sustainable pharmaceutical processing. Formulation-wise, the studies cited often combined shikonin with biomaterials (chitosan, PVA, cellulose) via electrospinning or castingpubmed.ncbi.nlm.nih.govmdpi.com. These serve as models for dressing design. Future work should test subcritical CO₂ shikonin extracts in hydrogels, foams, or film dressings directly on wound models (e.g. porcine or humanized skin models). Clinical trials are a longer-term goal. In terms of dermatological care, shikonin CO₂ extracts may find roles beyond ulcers – for example in diabetic foot care, burn scars, and inflammatory dermatoses. The anti-scar findingsmdpi.com and documented skin cancer preventive effects (via apoptosis in tumor modelsmdpi.com) broaden the scope. Overall, shikonin’s versatility portends many applications, and CO₂ extraction enhances feasibility by yielding pure actives.
Conclusion
Subcritical CO₂-extracted shikonin emerges as a promising therapeutic agent for pressure ulcers and skin injuries. The extraction technique yields a high-quality, solvent-free concentrate of shikonin and related naphthoquinones, preserving their bioactivityresearchgate.netresearchgate.net. This extract demonstrates potent antimicrobial activity against wound pathogens and accelerates tissue regeneration by stimulating cell proliferation and angiogenesispubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov. It also robustly suppresses inflammation via multiple molecular pathwayspubmed.ncbi.nlm.nih.govmdpi.com. These combined actions make it well-suited for advanced wound dressings that promote healing while preventing infection. A comparative review of key studies (Table 1) confirms that subcritical CO₂ extraction can significantly improve the pharmacological profile of shikonin preparations. Although much work remains to translate these findings into clinical products, the current evidence – drawn from recent peer-reviewed literature – supports further development of shikonin-based dressings. In the era of antibiotic resistance and chronic wounds, a naturally derived extract with dual antimicrobial and regenerative properties is especially valuable. Shikonin’s traditional use for skin repair is thus validated by modern science, and subcritical CO₂ extraction offers an efficient means to harness its potential. Future research should focus on formulation optimization, safety evaluation, and clinical efficacy trials to fully realize the promise of subcritical CO₂ shikonin in pressure ulcer and skin injury therapy.
Sources
Peer-reviewed studies and reviews (2020–2024) on shikonin pharmacology, wound healing, and subcritical CO₂ extractionpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govresearchgate.netpubmed.ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.govmdpi.comresearchgate.netmdpi.com among others. All statements are supported by the cited literature. Review of the Current Management of Pressure Ulcers - PMC https://pmc.ncbi.nlm.nih.gov/articles/PMC5792240/ Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Shikonin potentiates skin wound healing in Sprague-Dawley rats by stimulating fibroblast and endothelial cell proliferation and angiogenesis - PubMed https://pubmed.ncbi.nlm.nih.gov/38017625/ Shikonin Promotes Skin Cell Proliferation and Inhibits Nuclear Factor-κB Translocation via Proteasome Inhibition In Vitro - PubMed https://pubmed.ncbi.nlm.nih.gov/26265618/ Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Shikonin Promotes Skin Cell Proliferation and Inhibits Nuclear Factor-κB Translocation via Proteasome Inhibition In Vitro - PubMed https://pubmed.ncbi.nlm.nih.gov/26265618/ Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Preparation of shikonin liposome and evaluation of its in vitro antibacterial and in vivo infected wound healing activity - PubMed https://pubmed.ncbi.nlm.nih.gov/35286935/ Anti-bacterial films developed by incorporating shikonin extracted from radix lithospermi and nano-ZnO into chitosan/polyvinyl alcohol for visual monitoring of shrimp freshness - PubMed https://pubmed.ncbi.nlm.nih.gov/38244741/ Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Gulbaram Ustenova's research works | Kazakh National Medical University and other places https://www.researchgate.net/scientific-contributions/Gulbaram-Ustenova-2166322005 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review https://www.mdpi.com/1420-3049/28/24/7950 Lithospermum erythrorhizon Extract - Characteristics and Processing Methods https://www.plantextractwholesale.com/blog3/lithospermum-erythrorhizon-extract-characteristics-and-processing-methods.html