Effect of topical application of capsaicin and its related compounds on dermal insulin-like growth factor-I levels in mice and on facial skin elasticity in humans

Photoprotective activities of Capsosiphon fulvescens in UVB-induced SKH-1 mice and human keratinocytes

Capsosiphon fulvescens (CF) is a green alga widely consumed in East Asian countries, particularly in Korea. It has a rich composition of vitamins, minerals, dietary fibers, and bioactive compounds, which contribute to its multiple therapeutic properties. Its application ranges from acting as an antioxidant and anti-inflammatory agent to supporting the skin system. Despite these benefits of CF, the effects and mechanisms of action related to photoaging of the skin have not yet been elucidated. To investigate the photoprotective effects of CF against photoaging, both animal (SKH-1 mouse) and cell models (HaCaT cell line) were used in this study. As a result, administering the CF extract over a period of 10 weeks, which included times of Ultraviolet B (UVB) exposure, significantly reduced erythema and various UVB-induced skin changes, such as wrinkle formation, and the thickening of the epidermis and dermis, as well as alterations in the length and depth of wrinkles. Furthermore, our investigation into CF extract's antiwrinkle properties revealed its efficacy in enhancing skin hydration and collagen content, counteracting the collagen depletion and moisture loss induced by UVB radiation. Also, the fact that the levels of p-ERK, p-p38, and p-JNK proteins went down shows that the CF extract might have a controlling effect on the MAPK signaling pathways. Our findings suggest that CF holds significant potential for preventing photoaging, providing a foundation for the development of functional foods or botanical drugs targeting skin aging and related skin disorders. PRACTICAL APPLICATION: This research proved that Capsosiphon fulvescen, a green alga widely consumed in East Asian countries, provides photoprotective activities against UV-induced skin aging. Therefore, Capsosiphon fulvescen can be utilized as functional foods or botanical drugs targeting skin aging and related skin disorders.

Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners

In this narrative review, we sought to provide a comprehensive overview of the mechanisms underlying cutaneous senescence, framed by the twelve traditional hallmarks of aging. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. We also examined how topical interventions targeting these hallmarks can be integrated with conventional aesthetic medicine techniques to enhance skin rejuvenation. The potential of combining targeted topical therapies against the aging hallmarks with minimally invasive procedures represents a significant advancement in aesthetic medicine, offering personalized and effective strategies to combat skin aging. The reviewed evidence paves the way for future advancements and underscores the transformative potential of integrating scientifically validated interventions targeted against aging hallmarks into traditional aesthetic practices.

Evaluation of the Safety and Effectiveness of Nutritional Supplements for Treating Hair Loss: A Systematic Review

Importance

Despite the widespread use of nutritional supplements and dietary interventions for treating hair loss, the safety and effectiveness of available products remain unclear.

Objective

To evaluate and compile the findings of all dietary and nutritional interventions for treatment of hair loss among individuals without a known baseline nutritional deficiency.

Evidence Review

The MEDLINE, Embase, and CINAHL databases were searched from inception through October 20, 2021, to identify articles written in English with original findings from investigations of dietary and nutritional interventions in individuals with alopecia or hair loss without a known baseline nutritional deficiency. Quality was assessed with Oxford Centre for Evidence Based Medicine criteria. Outcomes of interest were disease course, both objectively and subjectively measured. Data were evaluated from January 3 to 11, 2022.

Findings

The database searches yielded 6347 citations to which 11 articles from reference lists were added. Of this total, 30 articles were included: 17 randomized clinical trials (RCTs), 11 clinical studies (non-RCT), and 2 case series studies. No diet-based interventional studies met inclusion criteria. Studies of nutritional interventions with the highest-quality evidence showed the potential benefit of Viviscal, Nourkrin, Nutrafol, Lamdapil, Pantogar, capsaicin and isoflavone, omegas 3 and 6 with antioxidants, apple nutraceutical, total glucosides of paeony and compound glycyrrhizin tablets, zinc, tocotrienol, and pumpkin seed oil. Kimchi and cheonggukjang, vitamin D3, and Forti5 had low-quality evidence for disease course improvement. Adverse effects were rare and mild for all the therapies evaluated.

Conclusions and Relevance

The findings of this systematic review should be interpreted in the context of each study's design; however, this work suggests a potential role for nutritional supplements in the treatment of hair loss. Physicians should engage in shared decision-making by covering the potential risks and benefits of these treatments with patients experiencing hair loss. Future research should focus on larger RCTs with active comparators.

Influence of Capsaicin on Inflammatory Cytokines Induced by Lipopolysaccharide in Myoblast Cells Under In vitro Environment

BACKGROUND

ellular damage initiated by reactive oxygen species (ROS) is the main cause of numerous severe diseases and therefore for this reason, the natural antioxidants have note worthy significance in human health. Capsaicin possesses noteworthy analgesic and anti-inflammatory properties. It also possesses healing effects for treatment of arthritis, diabetic neuropathy, gastric lesions, and cardiac excitability that is why it is incorporated in creams and gels.

OBJECTIVE

The present study was carried out to estimate the in vitro antioxidant and ROS scavenging activities of capsaicin against muscle precursor cells. Till date, no investigation has been carried out to study the effect of capsaicin on myoblasts.

MATERIALS AND METHODS

Herein, the cytotoxicity was induced by endotoxin lipopolysaccharide (LPS) to analyze the effect of capsaicin on LPS induced inflammation and apoptosis on muscle cells. To find out the toxicity of endotoxin, myoblasts were exposed to different concentrations of LPS, viability and morphology was checkedby the means of CCK-8 test and microscopy, respectively. Apoptotic cell death was examined by fluorescence staining. Additionally, LPS-induced apoptosis was determined by mRNAexpression of calpain, caspase-3 and tumor necrosisfactor alpha (TNF-α), and were quantified by qRT-PCR.

RESULTS

The outcome of the presentstudy demonstrated that LPS stimulation generatestoxicity in dose-dependent manner. Pre-treatmentof myoblasts with capsaicin can considerably alleviate LPS-induced inflammation.

CONCLUSION

In conclusion, this study indicates that dietetic supplementation of capsicum may help to alleviate/reduce the inflammatory effects and is therefore potent source of natural antioxidant agent which can be utilized to control muscle related diseases, such as myotube atrophy.

SUMMARY

In the present study cytotoxicity was induced by LPS to analyze the effect of capsaicin on LPS induced inflammation and apoptosis on muscle cells.The results of this investigation demonstrated that LPS stimulation generates toxicity in dose dependent manner. Pre-treatment of myoblasts with capsaicin can considerably reduce LPS induced inflammation.It has been concluded on the basis of results that the dietetic supplementation of capsicum may help to minimize inflammatory effects and are potent sources of natural antioxidants which can be utilized to control muscle related diseases such as atrophy. Abbreviation used: AMP: Adenosine monophosphate, AO/EB: Acridine orange / Ethidium bromide, ATL: T-cell leukemi, CAP: Capsaicin, CCK-8: Cell counting Kit-8, CLSM: Laser Scanning Microscopy, DCF-DA: 2', 7'-dichlorofluorescein diacetate, DMEM: Dulbecco's modified Eagle's medium, DPPH: α, α-diphenyl-β-picrylhydrazyl, FBS: Fetal bovine serum, KA: Kainic acid, LPS: Lipopolysaccharide, MDA: Malondialdehyde, NF-κB: Nuclear factor kgene binding, PBS: Phosphate buffer saline, pNA: p-nitroanilide, RNW: RNase free water, ROS: Reactive oxygen species, TNF-α: Tumor necrosis factor alpha, TRPV1: Transient receptor potential vanilloid 1.

Capsaicin-loaded vesicular systems designed for enhancing localized delivery for psoriasis therapy

The aim of the current investigation is to evaluate the potential of capsaicin (CAP)-containing liposomes, niosomes and emulsomes in providing localized and controlled delivery, to improve the topical delivery of drug. CAP-bearing systems were prepared by the film hydration method and compared through various in vitro and in vivo parameters. The TEM photographs suggested that the carrier systems were spherical in shape and nanometric in size range. Skin retention studies of CAP from in vitro and in vivo experiments revealed significantly higher accumulation of drug in the case of the emul-gel formulation. Based on the results, we concluded that the emul-gel may be a potential approach for the topical delivery of CAP, for an effective therapy for psoriasis.

Different responses of galanin and calcitonin gene-related peptide to capsaicin stimulation on dorsal root ganglion neurons in vitro

Both galanin (Gal) and calcitonin gene-related peptide (CGRP) are sensory neuropeptides which expressed in dorsal root ganglion (DRG) neurons and are involved in nociceptive processing. Capsaicin (CAP) influences nociceptive processing via influencing the expression of sensory neuropeptides in primary sensory neurons. However, little is known about the alterations of Gal and CGRP expression at the same condition stimulated by CAP. In the present study, primary cultured DRG neurons were used to determine the different responses of Gal and CGRP to CAP stimulation. DRG neurons were cultured for 48 hours and then exposed to CAP (2 μmol/L), capsazepine (CPZ) (2 μmol/L) plus CAP (2 μmol/L), or extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor PD98059 (10 μmol/L) plus CAP (2 μmol/L) for an additional 24hours. The DRG neurons were continuously exposed to culture media as a control. After that, the levels of Gal mRNA and CGRP mRNA of DRG neurons were determined using real time-PCR analysis. Gal and CGRP expression in situ was detected by an immunofluorescent labeling technique. The levels of phosphorylated-ERK1/2 (pERK1/2) protein were detected using a Western blot assay. The results showed that CAP evoked increases of Gal and its mRNA and decreases of CGRP and its mRNA in DRG neurons. Administration of either CPZ or PD98059 blocked the effects of CAP. These data indicate that Gal and CGRP shared different responses to CAP stimulation. Gal and CGRP may have different effects in nociceptive processing during neurogenic inflammation.

Activation of the human transient receptor potential vanilloid subtype 1 by essential oils

Transient receptor potential vanilloid subtype 1 (TRPV1) is a non-selective cation channel activated by capsaicin. TRPV1 is expressed not only on human sensory neurons but also on human epidermal and hair follicle keratinocytes. Therefore, TRPV1 could have the potential to be a therapeutic target for skin disorders. To search for novel TRPV1 agonists, we screened 31 essential oils by using human TRPV1-expressing HEK293 cells. TRPV1 was activated by 4 essential oils: rose, thyme geraniol, palmarosa, and tolu balsam. The dose-response curves for TRPV1 activation by the essential oils revealed a rank order potency [the half-maximal effective concentration (EC(50))] of rose>palmarosa>thyme geraniol>tolu balsam, and rank order efficiency (% activity in response to 1 microM capsaicin) of tolu balsam>rose>palmarosa>thyme geraniol. Moreover, the dose-response curves for TRPV1 activation by citronellol (main constituent of rose oil) and geraniol (main constituent of thyme geraniol and palmarosa oils) were consistent with the potency and efficiency of each essential oil. In contrast, benzyl cinnamate and benzyl benzoate (main constituent of tolu balsam oil) and geranyl acetate (main constituent of thyme geraniol oil) did not show TRPV1 activity. In this first-of-its-kind study, we successfully investigated the role of some essential oils in promoting human TRPV1 activation, and also identified two monoterpenes, citronellol and geraniol, as new human TRPV1 agonists.

Effect of topical application of raspberry ketone on dermal production of insulin-like growth factor-I in mice and on hair growth and skin elasticity in humans

Sensory neurons release calcitonin gene-related peptide (CGRP) on activation. We recently reported that topical application of capsaicin increases facial skin elasticity and promotes hair growth by increasing dermal insulin-like growth factor-I (IGF-I) production through activation of sensory neurons in mice and humans. Raspberry ketone (RK), a major aromatic compound contained in red raspberries (Rubus idaeus), has a structure similar to that of capsaicin. Thus, it is possible that RK activates sensory neurons, thereby increasing skin elasticity and promoting hair growth by increasing dermal IGF-I production. In the present study, we examined this possibility in mice and humans. RK, at concentrations higher than 1 microM, significantly increased CGRP release from dorsal root ganglion neurons (DRG) isolated from wild-type (WT) mice and this increase was completely reversed by capsazepine, an inhibitor of vanilloid receptor-1 activation. Topical application of 0.01% RK increased dermal IGF-I levels at 30 min after application in WT mice, but not in CGRP-knockout mice. Topical application of 0.01% RK increased immunohistochemical expression of IGF-I at dermal papillae in hair follicles and promoted hair re-growth in WT mice at 4 weeks after the application. When applied topically to the scalp and facial skin, 0.01% RK promoted hair growth in 50.0% of humans with alopecia (n=10) at 5 months after application and increased cheek skin elasticity at 2 weeks after application in 5 females (p<0.04). These observations strongly suggest that RK might increase dermal IGF-I production through sensory neuron activation, thereby promoting hair growth and increasing skin elasticity.

Use of serum insulin-like growth factor-I levels to predict psychiatric non-response to donepezil in patients with Alzheimer's disease

OBJECTIVE

Insulin-like growth factor-I (IGF-I) deficiency may be involved in cognitive deficits seen with aging and in neurodegenerative diseases such as Alzheimer's disease (AD). This study was aimed at investigating whether non-responder to donepezil could be predicted using decreased serum levels of IGF-I in AD patients.

DESIGN

This study involved 106 elderly subjects: 50 patients with AD and 56 age-matched controls without dementia. In patients with AD, donepezil was given orally 3 mg/day for 4 weeks and 5 mg/day for another 12 weeks. AD patients were divided into responders and non-responders based on the changes in mini-mental state examination (MMSE) scores before and 16 weeks after treatment with donepezil. Serum levels of IGF-I and atherogenic biomarkers were determined.

RESULTS

Before treatment with donepezil, there was a significant positive correlation between serum IGF-I levels and the MMSE scores in all subjects. Serum IGF-I levels and the MMSE scores were significantly lower in AD patients than in non-demented controls and were the lowest in non-responders to donepezil. Atherogenic biomarkers (LDL cholesterol, triglycerides, lipoprotein(a), lipid peroxide, apolipoprotein E, and glucose levels) did not differ significantly among these groups. On multiple logistic regression, non-responders to donepezil showed decreased serum IGF-I levels <110 ng/ml and MMSE scores <15 points before treatment.

CONCLUSIONS

These findings suggest that decreased levels of serum IGF-I combined with MMSE scores before treatment could predict non-responders to donepezil among AD patients, which may be a simple and practical method for selecting patients expected to show a response to treatment.

Effect of capsaicin on plasma and tissue levels of insulin-like growth factor-I in spontaneously hypertensive rats

OBJECTIVE

Plasma levels of insulin-like growth factor-I (IGF-I), an important substance for maintaining cardiovascular homeostasis, are lower in spontaneously hypertensive rats (SHR) than in normotensive Wistar Kyoto rats (WKY). Calcitonin gene-related peptide (CGRP) increases IGF-I production in vitro and in vivo, suggesting that stimulation of sensory neurons might increase the production of IGF-I in SHR.

DESIGN

Levels of CGRP and IGF-I in plasma, kidneys and heart in WKY and SHR and cellular cyclic AMP levels in dorsal root ganglion neurons (DRGs) isolated from WKY and SHR were measured by an ELISA-based method.

RESULTS

Levels of CGRP and IGF-I in plasma, kidneys and heart of SHR were about half of those of WKY. Administration of capsaicin significantly increased levels of CGRP and IGF-I in plasma and tissues of SHR to the levels in WKY and these increases were completely reversed by pretreatment with capsazepine, an inhibitor of vanilloid receptor-1 activation. CGRP release and cellular levels of cAMP in DRGs isolated from SHR were significantly lower than those in DRGs isolated from WKY. Capsaicin increased both CGRP release and cellular cAMP levels in DRGs isolated from SHR to the levels in DRGs isolated from WKY.

CONCLUSIONS

Sensory neuron activation might be lower in SHR than in WKY probably due to decreased production of cAMP in sensory neurons, explaining why IGF-I levels in plasma and tissues are lower in SHR than in WKY.

Administration of capsaicin and isoflavone promotes hair growth by increasing insulin-like growth factor-I production in mice and in humans with alopecia

OBJECTIVE

Insulin-like growth factor-I (IGF-I) plays an important role in hair growth. Capsaicin activates vanilloid receptor-1, thereby increasing the release of calcitonin gene-related peptide (CGRP) from sensory neurons, and CGRP has been shown to increase IGF-I production. We recently reported that isoflavone, a phytoestrogen, increases production of CGRP by increasing its transcription in sensory neurons. These observations raise the possibility that administration of capsaicin and isoflavone might promote hair growth by increasing IGF-I production. In the present study, we examined this possibility in mice and humans with alopecia.

DESIGN

Dermal IGF-I levels, immunohistochemical expression of IGF-I in the skin and hair regrowth were examined after capsaicin and isoflavone administration to wild-type (WT) mice and CGRP-knockout mice. Plasma levels of IGF-I and promotion of hair growth were evaluated in 48 volunteers with alopecia after administration of capsaicin and isoflavone for 5 months.

RESULTS

Subcutaneous administration of capsaicin significantly increased dermal IGF-I levels at 30 min after administration in WT mice (p < 0.01), but not in CGRP-knockout mice. Dermal levels of IGF-I were significantly higher in WT mice administered capsaicin and isoflavone for 4 wks than in those administered capsaicin alone for 4 wks (p < 0.01) and in those administered neither of them (p < 0.01). Immunohistochemical expression of IGF-I at dermal papillae in hair follicles was increased in WT mice administered capsaicin and isoflavone and in those administered capsaicin alone at 4 wks. Hair regrowth was clearly more accelerated in WT mice administered capsaicin and isoflavone for 4 wks than in those administered capsaicin alone for 4 wks and in those administered neither of them. Plasma levels of IGF-I were significantly increased from baseline levels in 31 volunteers with alopecia at 5 months after oral administration of capsaicin (6 mg/day) and isoflavone (75 mg/day) (p < 0.01), while they were not increased in 17 volunteers with alopecia administered placebo. The number of volunteers with alopecia who showed promotion of hair growth at 5 months after administration was significantly higher among volunteers administered capsaicin and isoflavone (20/31: 64.5%) than among those administered placebo (2/17: 11.8%) (p < 0.01).

CONCLUSIONS

These observations strongly suggested that combined administration of capsaicin and isoflavone might increase IGF-I production in hair follicles in the skin, thereby promoting hair growth. Such effects of capsaicin and isoflavone might be mediated by sensory neuron activation in the skin.