One aspect of the invention relates to AI-helper compositions comprising an AI compound (e.g., melatonin, alpha-lipoic acid, vitamin E, vitamin D, glutathione, resveratrol, astaxanthin, beta carotene, vitamin A, vitamin C, vitamin B12, vitamin B6, folic acid, and taurine) and one or more helper esters. The AI-helper compositions disclosed herein can be used for effective transdermal delivery of the AI compound to a subject. Another aspect of the invention relates to applications and preparations of the AI-helper compositions.