I am thinking that you're probably referring to ascorbic acid (vitamin C) ?? It can be used as an antioxidant in winemaking but it must be used in conjunction with SO2 as it produces powerful oxidizing agents as a byproduct of its reaction with oxygen (hydrogen peroxide for example.) It acts as an oxygen scavenger and as such it is most useful to neutralize oxygen incorporated through brief exposure to air such as at crushing or bottling. It can help avoid oxidation of must and wine in such circumstances, but it reacts quickly with oxygen and so its benefits are short-term only and it will not help protect your wine in the long run. In addition, recent research from S. Africa and Australia suggest only using it in white wines (or fruit wines) but not reds. In short, red wines generally bind up more of the SO2 added and so there is not enough free SO2 left to both deal with the by-products of ascorbic acid reactions and also protect your wine against microbial activity, etc. So your wine is compromised and may actually oxidize prematurely or fall prey to spoilage organisms.
Summary: Ascorbic acid has its applications but the only additive proven to have both anti-oxidant and anti-microbial properties is sulphur dioxide. You can make wine without it, but I wouldn't... or I'd just make sure to drink up quickly!! Even organic winemaking regulations allow the use of small amounts of SO2 in most if not all jurisdictions.