The effectiveness of synthetic methoxylated isoflavones in delivering to the skin and alleviating psoriasiform lesions via topical absorption

The anti-inflammatory activity of flavonoids and alkaloids from Sophora flavescens alleviates psoriasiform lesions: Prenylation and methoxylation beneficially enhance bioactivity and skin targeting

The herb Sophora flavescens displays anti-inflammatory activity and can provide a source of antipsoriatic medications. We aimed to evaluate whether S. flavescens extracts and compounds can relieve psoriasiform inflammation. The ability of flavonoids (maackiain, sophoraflavanone G, leachianone A) and alkaloids (matrine, oxymatrine) isolated from S. flavescens to inhibit production of cytokine/chemokines was examined in keratinocytes and macrophages. Physicochemical properties and skin absorption were determined by in silico molecular modeling and the in vitro permeation test (IVPT) to establish the structure-permeation relationship (SPR). The ethyl acetate extract exhibited higher inhibition of interleukin (IL)-6, IL-8, and CXCL1 production in tumor necrosis factor-α-stimulated keratinocytes compared to the ethanol and water extracts. The flavonoids demonstrated higher cytokine/chemokine inhibition than alkaloids, with the prenylated flavanones (sophoraflavanone G, leachianone A) led to the highest suppression. Flavonoids exerted anti-inflammatory effects via the extracellular signal-regulated kinase, p38, activator protein-1, and nuclear factor-κB signaling pathways. In the IVPT, prenylation of the flavanone skeleton significantly promoted skin absorption from 0.01 to 0.22 nmol/mg (sophoraflavanone G vs. eriodictyol). Further methoxylation of a prenylated flavanone (leachianone A) elevated skin absorption to 2.65 nmol/mg. Topical leachianone A reduced the epidermal thickness in IMQ-treated mice by 47%, and inhibited cutaneous scaling and cytokine/chemokine overexpression at comparable levels to a commercial betamethasone product. Thus, prenylation and methoxylation of S. flavescens flavanones may enable the design of novel antipsoriatic agents.

Lipid-based nanoformulation optimization for achieving cutaneous targeting: niosomes as the potential candidates to fulfill this aim

The present study screened the utility of topically-applied nanoformulations to target the drugs/actives into the skin reservoir with the reduction of possible systemic absorption. The lipid-based nanoformulations selected in this study included solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), nanoemulsions (NEs), liposomes, and niosomes. We loaded flavanone and retinoic acid (RA) as the penetrants. The prepared nanoformulations were assessed for their average diameter, polydispersity index (PDI), and zeta potential. An in vitro permeation test (IVPT) was utilized to determine the skin delivery into/across pig skin, atopic dermatitis (AD)-like mouse skin, and photoaged mouse skin. We found an increased skin absorption of lipid nanoparticles following the increase of solid lipid percentage in the formulations (SLNs > NLCs > NEs). The use of liposomes even reduced the dermal/transdermal selectivity (S value) to lessen the cutaneous targeting. The niosomes resulted in significantly greater RA deposition and reduced permeation in the Franz cell receptor compared to the other nanoformulations. The S value of the RA delivery via stripped skin was increased by 26-fold in the niosomes compared to the free RA. The dye-labeled niosomes displayed a strong fluorescence in the epidermis and upper dermis through the visualization of fluorescence and confocal microscopies. The cyanoacrylate skin biopsy manifested greater hair follicle uptake of the niosomes compared to the free penetrants by 1.5 to three-fold. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay indicated an increase in antioxidant ability from 55% to 75% after flavanone entrapment in the niosomes. In the activated keratinocytes, the niosomal flavanone could suppress the overexpressed CCL5 to the baseline control because of the facile cell internalization. After the formulation optimization, the niosomes with higher phospholipid amount had a superior effect in delivering penetrants into the skin reservoir, with limited permeation to the receptors.

The elucidation of structure-activity and structure-permeation relationships for the cutaneous delivery of phytosterols to attenuate psoriasiform inflammation

Phytosterols have been reported to exert anti-inflammatory activity. This study aimed to investigate the capacity of campesterol, β-sitosterol, and stigmasterol on the mitigation of psoriasiform inflammation. We also tried to establish structure-activity and structure-permeation relationships for these plant sterols. To support this study, we first approached the in silico data of the physicochemical properties and the molecular docking of phytosterols with stratum corneum (SC) lipids. The anti-inflammatory activity of the phytosterols was explored in the activated keratinocytes and macrophages. Using the activated keratinocyte model, a significant inhibition of IL-6 and CXCL8 overexpression by phytosterols was detected. A comparable inhibition level was found for the three phytosterols tested. The macrophage-based study showed that the anti-IL-6 and anti-CXCL8 activities of campesterol were greater than those of the other compounds, which indicated that a phytosterol structure without a double bond on C₂₂ and with methyl moiety on C₂₄ was more effective. The conditioned medium of phytosterol-treated macrophages decreased STAT3 phosphorylation in the keratinocytes, suggesting the inhibition of keratinocyte hyperproliferation. β-sitosterol was the penetrant with the highest pig skin absorption (0.33 nmol/mg), followed by campesterol (0.21 nmol/mg) and stigmasterol (0.16 nmol/mg). The therapeutic index (TI) is a parameter measured by multiplying the cytokine/chemokine suppression percentage with skin absorption for anticipating the anti-inflammatory activity after topical delivery. β-sitosterol is a potential candidate for treating psoriatic inflammation due to having the greatest TI value. In this study, β-sitosterol attenuated epidermal hyperplasia and immune cell infiltration in the psoriasis-like mouse model. The psoriasiform epidermis thickness could be reduced from 92.4 to 63.8 μm by the topical use of β-sitosterol, with a downregulation of IL-6, TNF-α, and CXCL1. The skin tolerance study manifested that the reference drug betamethasone but not β-sitosterol could generate barrier dysfunction. β-sitosterol possessed anti-inflammatory activity and facile skin transport, showing the potential for development as an anti-psoriatic agent.