Dehydroascorbic acid (DHA) is an oxidized form of ascorbic acid. Ascorbic acid is transported in its oxidized form via GLUT1 across the blood-brain barrier. Dehydroascorbic acid delay low-density lipoprotein (LDL) oxidation when added before the initiation of the process, they accelerate the process if added to minimally oxidized LDL. Dehydroascorbic acid is used as biochemical markers of oxidative stress in clinical investigations. Dehydroascorbic acid has been used as a vitamin C dietary supplement.

Sumarotene (also known as Ro 14-9706) is a third-generation retinoid developed by Hoffmann-La Roche, F., und Co. A.-G., as a topical dermatologic agent for the repair of photodamage, antikeratinization, and antiproliferation. Sumarotene shows activity in standard preclinical and pharmacologic models of repair of photodamage, antikeratinization, and antiproliferation. In clinical trials, Sumarotene effectively decreases the number of actinic keratoses. Sumarotene is well-tolerated and most patients have only slight or absent local inflammation.

The monoterpene perillyl alcohol (POH) is a naturally occurring compound derived from citrus fruits, mint, and herbs. It exhibited chemotherapeutic potential against various malignant tumors in preclinical models and was being tested in clinical trials in patients with refractory advanced cancers. POH was formulated in soft gelatine capsules and orally administered to cancer patients several times a day on a continuous basis. However, such clinical trials in humans yielded disappointing results, also because of the large number of capsules that had to be swallowed caused hard-to-tolerate intestinal side effects, causing many patients to withdraw from treatment due to unrelenting nausea, fatigue, and vomiting. The clinical trials in Brazil have explored intranasal POH delivery as an alternative to circumvent the toxic limitations of oral administration. In these trials, patients with recurrent malignant gliomas were given comparatively small doses of POH via simple inhalation through the nose. Results from these studies showed, that this type of long-term, daily chemotherapy was well tolerated and effective. The precise mechanism of action is still undetermined, but it is known, that perillyl alcohol plays an important role in the process of hepatoma cell invasion and migration via decreasing the activity of Notch signaling pathway and increasing E-cadherin expression regulated by Snail. Another possible mechanism is included inhibition of Na/K-ATPase (NKA). The NKA α1 subunit is known to be superexpresses in glioblastoma cells (GBM) and POH acts in signaling cascades associated with NKA can control cell proliferation and/or cellular death.

Bentiamine (also known as dibenzoyl thiamine), a derivative of thiamine, is rapidly absorbed and converted to thiamine. Experiments on rodent have shown that this compound had low toxicity and absence of carcinogenicity.

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. ndole-3-carbinol is used for prevention of breast cancer, colon cancer, and other types of cancer. The National Institutes of Health (NIH) has reviewed indole-3-carbinol as a possible cancer preventive agent and is now sponsoring clinical research for breast cancer prevention. Indole-3-carbinol is also used for fibromyalgia, tumors inside the voice box (laryngeal papillomatosis) caused by a virus, tumors inside the respiratory tract (respiratory papillomatosis) caused by a virus, abnormal cell growth in the cervix (cervical dysplasia), and systemic lupus erythematosus (SLE). Indole-3-carbinol scavenges free radicals and induces various hepatic cytochrome P450 monooxygenases. Specifically, this agent induces the hepatic monooxygenase cytochrome P4501A1 (CYP1A1), resulting in increased 2-hydroxylation of estrogens and increased production of the chemoprotective estrogen 2-hydroxyestrone. Accumulating evidence indicates that the antitumor activity of indole-3- carbinol is attributable to its ability to interfere with multiple oncogenic signaling pathways governing cell cycle progression, survival, invasion, and other aggressive phenotypes of cancer cells. Reported signaling targets of indole-3- carbinol in various cancer cell lines include EGFR/Src, Akt/NF-B, stress responses, elastase, and Rho kinase. Moreover, indole-3-carbinol functions as a negative regulator of estrogen action in hormonesensitive cancer cells through the inhibition of estrogen receptor (ER)-alpha signaling and/or induction of cytochrome P-450-mediated estrogen metabolism, suggesting its clinical use in hormone-sensitive cancers.

Phenethyl isothiocyanate (PEITC) presents in cruciferous vegetables which have been shown to decrease the risk of various types of malignancies. PEITC targets multiple proteins to suppress various cancer-promoting mechanisms such as cell proliferation, progression and metastasis. PEITC induces apoptosis in human colon cancer HT-29 cells, prostate cancer cells, and osteogenic sarcoma U-2 OS cells. Unique to prostate cancer is that PEITC downregulates the transcriptional factor Sp1, a regulator of AR expression. PEITC suppresses 4-(methylnitrosamino)-1-(3-pyridyl)-1-butoneinduced pulmonary neoplasia in A/J mouse lung, exhibits cancer chemopreventive activity in rat and reduces azoxymethane-induced colonic aberrant crypt foci formation. PEITC appears to be a promising agent for cancer therapy and is already under clinical trials for leukemia and lung cancer.

Alpha-carotene is a provitamin A carotenoid present in fruits and vegetables. Higher serum concentrations of α-carotene have been associated with lower risk of cancer and all-cause mortality. It was suggested that genetic variants influence serum concentrations of provitamin A. Recently was found, that α-carotene effectively inhibits Lewis lung carcinoma (LLC) metastasis and suppresses lung metastasis in combination with taxol in LLC-bearing mice, suggesting that Alpha-carotene could be used as an anti-metastatic agent or as an adjuvant for anti-cancer drugs.