* Distrustful: "After being betrayed by his best friend, John became distrustful of everyone."
* Suspicious: "The detective's suspicious nature led him to investigate the seemingly innocent alibi."
If you want to use "untrusting" in a creative context, you could use it as a noun:
* "The untrusting in society are often the most difficult to reach."
However, it's important to note that using "untrusting" as a noun is not standard English and may sound awkward or unnatural.