Anti-psoriatic potential of medicinal plants, Alstonia scholaris, Wrightia tinctoria, and Solanum xanthocarpum, using human HaCaT keratinocytes by multi-parametric analysis

Abstract

Ethnopharmacological relevance: Psoriasis, a widespread skin condition impacting over 100 million individuals globally, is characterised by uncontrolled hyperproliferation of keratinocytes, abnormal apoptosis, and excessive secretion of inflammatory cytokines and angiogenic factors. Traditional use of Alstonia scholaris (L.) R.Br., Wrightia tinctoria (Roxb.) R.Br. and Solanum xanthocarpum Schrad. & Wendl. in Ayurveda and Siddha medicinal systems have shown promising anti-inflammatory and wound-healing properties. However, underlying mechanisms of their phytoactivity in addressing psoriasis-like skin inflammation on human keratinocytes remain largely unexplored.

Aim of the study: The study was aimed to investigate anti-psoriatic potential of ethyl acetate and ethanolic extracts of A. scholaris, W. tinctoria and S. xanthocarpum in human keratinocyte cell line (HaCaT).

Material and methods: Ethyl acetate and ethanolic extracts of A. scholaris (ASEA and ASE), W. tinctoria (WTEA and WTE) and S. xanthocarpum (SXEA and SXE) were first subjected to phytochemical screening through high-performance liquid chromatography (HPLC) using their marker compound loganin, kaempferol and chlorogenic acid, respectively. The proliferation inhibition efficiency of these extracts was measured using MTT assay on HaCaT cell line. Subsequently, the apoptotic effect of these extracts on HaCaT cell line was determined by JC-1 and Annexin V assays. Furthermore, IL-8 and RANTES levels were measured in TNF-alpha-induced HaCaT cell line post-treatment with these extracts to determine their anti-inflammatory properties.

Results: ASEA, ASE, WTEA, WTE, SXEA and SXE significantly inhibited proliferation of keratinocytes (HaCaT cells) and resulted in the induction of apoptotic markers (mitochondrial membrane potential and phosphatidyl serine externalization). Additionally, pro-inflammatory markers (IL-8 and RANTES levels) were downregulated in HaCaT cells. The anti-proliferative effects were particularly distinct at higher concentrations (200 μg/mL), with inhibition rates reaching over 85% for W. tinctoria and S. xanthocarpum extracts. In apoptotic assays, notable increases in late apoptotic or necrotic cell populations and significant losses in mitochondrial membrane potential were observed. All extracts markedly reduced the secretion of inflammatory mediators IL-8 and RANTES.

Conclusion: All three plants exerted an anti-psoriatic effect at the cellular level via multiple parameters (anti-proliferative, pro-apoptotic, anti-inflammatory effect). This study provides insight into the mechanism of action of ASEA, ASE, WTEA, WTE, SXEA and SXE and highlights their promising potential for development as herbal therapeutic agents for psoriasis. It emphasizes the need for further pharmacological evaluation and toxicological studies of these extracts.

Keywords: Alstonia scholaris; HaCaT cells; Keratinocytes; Medicinal plants; Psoriasis; Solanum xanthocarpum; Wrightia tinctoria.