Cytotoxic naphthoquinones from Arnebia densiflora (Nordm.) Ledeb and determining new apoptosis inducers

Targeting NQO1/GPX4-mediated ferroptosis by plumbagin suppresses in vitro and in vivo glioma growth

BACKGROUND

Ferroptosis has attracted increasing interest in cancer therapy. Emerging evidences suggest that naturally occurring naphthoquinones exhibit potent anti-glioma effects via various mechanisms.

METHODS

The anti-glioma effects of plumbagin were evaluated by in vitro and in vivo experiments. Anti-glioma mechanism of plumbagin was studied by proteomics, flow cytometry, MDA assay, western blot, and RT-PCR. Gene knockdown/overexpression, molecular docking, PharmMappper database, and coimmunoprecipitation were used to study the targets of plumbagin.

RESULTS

Plumbagin showed higher blood-brain barrier penetration ability than that of lapachol and shikonin and elicited significant growth inhibitory effects in vitro and in vivo. Ferroptosis was the main mechanism of plumbagin-induced cell death. Mechanistically, plumbagin significantly downregulated the protein and mRNA levels of xCT and decreased GPX4 protein levels. NAD(P)H quinone dehydrogenase 1 (NQO1) was revealed as a plumbagin predictive target using PharmMappper database and molecular docking. Plumbagin enhanced NQO1 activity and decreased xCT expression, resulting in NQO1-dependent cell death. It also induced GPX4 degradation via the lysosome pathway and caused GPX4-dependent cell death.

CONCLUSIONS

Plumbagin inhibited in vitro and in vivo glioma growth via targeting NQO1/GPX4-mediated ferroptosis, which might be developed as a novel ferroptosis inducer or anti-glioma candidate.

β-acetoxyisovaleryl alkannin (AAN-II) from Alkanna tinctoria promotes the healing of pressure-induced venous ulcers in a rabbit model through the activation of TGF-β/Smad3 signaling

Alkannin-based pharmaceutical formulations for improving wound healing have been on the market for several years. However, detailed molecular mechanisms of their action have yet to be elucidated. Here, we investigated the potential roles of AAN-II in improving the healing of pressure-induced venous ulcers using a rabbit model generated by combining deep vein thrombosis with a local skin defect/local skin defect. The extent of healing was evaluated using hematoxylin and eosin (HE) or vimentin staining. Rabbit skin fibroblasts were cultured for AAN-II treatment or TGFB1-sgRNA lentivirus transfection. ELISA was used to evaluate the levels of various cytokines, including IL-1β, IL-4, IL-6, TNF-α, VEGF, bFGF, TGF-β and PDGF. The protein levels of TGF-β sensors, including TGF-β, Smad7 and phosphor-Smad3, and total Smad3, were assayed via western blotting after TGF-β knockout or AAN-II treatment. The results show that, for this model, AAN-II facilitates ulcer healing by suppressing the development of inflammation and promoting fibroblast proliferation and secretion of proangiogenic factors. AAN-II enhances the activation of the TGF-β1-Smad3 signaling pathway during skin ulcer healing. In addition, the results demonstrate that AAN-II and TGF-β have synergistic effects on ulcer healing. Our findings indicate that AAN-II can promote healing of pressure-induced venous skin ulcers via activation of TGF-β-Smad3 signaling in fibroblast cells and provide evidence that could be used in the development of more effective treatments.

Phytochemical constituents, distributions and traditional usages of Arnebia euchroma: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The present study has indicated phytochemical composition, distribution and ethno-medicinal uses of Arnebia euchroma (Royle) I.M. Johnst, which is commonly known as "Ratanjot" in the Indian subcontinent. It has widely been used in the traditional systems of the Unani, Ayurvedic and Chinese medicines recipes due to its anti-fungal and anti-microbial properties. Instead, the gap of earlier studies is well defined that will be helpful for researchers to carry out more analysis and increase medicinal importance of this plant.

AIM OF STUDY

The main aim of this review study is to demonstrate the phytochemical composition and traditional ethno-medicinal uses of A. euchroma all over the world. Earlier studies related to this plant have been discussed in the present study and on that basis, future perspective of A. euchroma is also proposed.

MATERIALS AND METHODS

The information of A. euchroma has been gathered from various electronic database, reference books and available literature.

RESULTS

The study has indicated that Arnebia euchroma owing to anti-microbial and anti-inflammatory properties is used in the traditional medicines and pharmaceutical industries for the treatment of hair problems, remitting, chronic diseases, burnt limbs, cough and cold, etc., and besides as a vegetable colorant and dyeing of cloths. The important phytochemical constituents viz., shikonin, acetyl-shikonin, iso-butyryl-shikonin, β,β-di-methylacryl-shikonin, isovaleryl-shikonin, β-hydroxy-isovaleryl-shikonin, deoxy-shikonin, isobutyl-shikonin, arnebinone, arnebin-7, stigmasterol, etc., isolated from the roots of Arnebia euchroma are used for curing various harmful diseases.

CONCLUSIONS

The earlier studies have confirmed that Arnebia euchroma is having wound healing, anti-microbial and anti-bacterial properties and thus used for the treatment of several diseases. Although, a little works is done on the experimental study regarding anti-HIV, anti-cancer diseases, etc., so there is a requirement of more exploration via analytical studies on phytochemical compounds to treat such diseases. Moreover, the information of its clinical and pharmacokinetics uses is also limited. Therefore, further research is needed to understand bioavailability and pharmacokinetics of this species. In-situ and ex-situ conservations for the management of this endangered species are also lacking in the Himalayan perspective. Such studies will emphasize to explore the possibilities for its conservation and development of agro-technological protocol.

Naphthoquinone Derivatives Isolated from Plants: Recent Advances in Biological Activity

Naturally occurring naphthoquinones (NQs) comprising highly reactive small molecules are the subject of increasing attention due to their promising biological activities such as antioxidant, antimicrobial, apoptosis-inducing activities, and especially anticancer activity. Lapachol, lapachone, and napabucasin belong to the NQs and are in phase II clinical trials for the treatment of many cancers. This review aims to provide a comprehensive and updated overview on the biological activities of several new NQs isolated from different species of plants reported from January 2013 to January 2020, their potential therapeutic applications and their clinical significance.