I have found that topical vitamin C provides relief from itching/burning rashes or blisters caused by contact with poison oak or from the toxic saliva of a tick removed before it begins feeding. Instead of scratching the itch, I rub wet sodium ascorbate crystals into the wound, and relief is almost immediate. Apparently, the ability of ascorbate to donate one or two electrons rapidly neutralizes toxins causing the rash.
Here is an interesting article that explains the mechanism by which the ascorbate anion donates an electron. The first electron is released in an energetic reaction which also involves donating a proton, so the ascorbate gives up an entire hydrogen atom, turning the ascorbate into the ascorbyl radical, which itself can donate an additional electron, for a total of two. This ability of ascorbate to donate two electrons appears to exist for both ascorbic acid and for a mineral ascorbate such as sodium ascorbate. The only difference between ascorbic acid and sodium ascorbate is that an H+ cation has been replaced by an Na+ cation, turning the acid into a neutral salt. That appears to have no effect on the ability of ascorbate to donate electrons.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921859/