Table 2 List of antioxidants with potential therapeutic effects against brain tumors

Vitamin A

It is essential for human body functioning; it protects against DNA damage and OS; it acts as an antioxidant and exhibits capacity to relieve oxidation stress; and it prevents the risk of tumor formation.

Vitamin C

It is essential for maintaining proper functioning of various tissues and organs including central nervous system (CNS); it helps in maintaining the metabolism of CNS; it exhibits chemopreventive potential against gliomas; and it acts as an antioxidant and attenuates redox insult.

Vitamin E

It plays several functions in the human body; it acts as an antioxidant and attenuates redox insult; it is effective as chemopreventive agent; and it regulates antioxidant enzymes in various brain tumors.

Curcumin

It protects from developing gliomas; it can eliminate a large variety of cancer cells; it regulates different signaling pathways; it decreases the malignant properties of GBM stem cells by ROS induction (prooxidant property); it endorses autophagy; it reduces metastasis and invasion; it induces G2/M cell cycle arrest phenomenon; and it activates the apoptotic pathways.

Resveratrol

It modulates different signaling pathways; it inhibits viability, proliferation, and migration of cancer cells; it shows ability to accumulate in target organs or cells of tumor location; it acts as a chemosensitizer and increases potential therapeutic efficacy of chemotherapeutic drugs through various mechanisms; it increases ROS level (prooxidant property) in cancer cells; and it induces apoptosis in several cancerous cells via ROS production, increasing mitochondrial membrane permeability, and p53, BAX and caspase activation, etc.

Genistein

It exhibits neuroprotective properties; it exhibits therapeutic properties against brain, bone, and heart defects, as well as postmenopausal cancers; it induces protection against memory impairment by decreasing OS; it enhances cholinergic neurotransmission; it exhibits antioxidants properties and shows chemopreventive potential; it attenuates neuroinflammation and enhances chemopreventive potential against brain tumor development; it increases the expression of neuroprotective genes (CBP, CREB, IGF-1, BDNF and ERK) and inhibit gene involved in pathological events; and it also exhibits chemotherapeutic potential (prooxidant property) simultaneously.

MnSOD

It scavenges superoxide radicals and prevent tumorigenesis; and it modulates the AP-1-mediated cell proliferation pathways and p53-mediated apoptosis.

Cu-ZnSOD

It scavenges superoxide radicals and prevents tumorigenesis; and it exhibits prooxidant effects of increasing ROS production resulting in induction of OS, which leads to apoptosis activation and tissue injury.

Catalase

It is an antioxidant enzyme that converts H₂O₂ to water and molecular oxygen; it prevents tumorigenesis and cell proliferation by reducing OS

GSH

It is an antioxidant cellular metabolite and prevent tumorigenesis; it prevents the redox imbalance; it can modulate different signaling pathways; and it also regulates other cellular functions.