Propylparaben is a bacteriostatic and fungistatic agent used as a preservative in cosmetic products, food and drugs. As a food additive, it has the E number E216. To increase the activity and reduce its dose propylparaben is used in a mixture with other parabens and in combination with other types of preservatives. Propylparaben is a chemical allergen capable of producing immunologically mediated hypersensitivity reactions. Chemically it is an ester of p-hydroxybenzoic acid.

There is not much information about ammonium phenolate. It is known, that this a salt of phenol and it is toxic if swallowed and is toxic in contact with skin.

Glycol Salicylate is a nonsteroidal antiinflammatory drug, it is an ingredient of many rubefacient creams and sprays for the relief of aches, pains and stiffness in muscles joints and tendons. It is an analgesic and anti-inflammatory agent, used topically. It is also included in preparations for soothing haemorrhoids. Glycol Salicylate is a component of Salonsip Gel Patch. Salonsip Gel Patch, manufactured by Hisamitsu Pharmaceutical Co., Inc. of Tosu City, Japan, consists of Glycol Salicylate 1.25%, l-menthol 1.00%, Tocopherol Acetate 1.0%, dl-camphor 0.1%.

Methyl aminolevulinate is a prodrug that is metabolised to Protoporphyrin IX (a photosensitizer) used in photodynamic therapy. Photosensitization following application of methyl aminolevulinate cream occurs through the metabolic conversion of methyl aminolevulinate (prodrug) to photoactive porphyrins (PAP), which accumulates in the skin lesions to which the cream has been applied. When exposed to light of appropriate wavelength and energy, the accumulated photoactive porphyrins produce a photodynamic reaction, resulting in a cytotoxic process dependent upon the simultaneous presence of oxygen. The absorption of light results in an excited state of porphyrin molecules, and subsequent spin transfer from photoactive porphyrins to molecular oxygen generates singlet oxygen, which can further react to form superoxide and hydroxyl radicals. Methyl aminolevulinate is used for topical use, in combination with 570 to 670 nm wavelength red light illumination, in the treatment of non-hyperkeratotic actinic keratoses of the face and scalp in immunocompetent patients when used in conjunction with lesion preparation (debridement using a sharp dermal curette).

Methylparaben (E number E218) is preservative in the food, cosmetic, and pharmaceutical industries. It is completely absorbed through the skin or after ingestion and and it is hydrolyzed to para-hydroxybenzoic acid, and metabolites are rapidly excreted in the urine. Methylparaben is on the FDA generally regarded as safe list.

Tryptophan is alpha-aminoacid that is used in the biosynthesis of proteins. It is essential aminoacid in humans, meaning the body cannot synthesize and it must be obtained from the diet. Tryptophan is a precursor of serotonin, and as such is sold over the counter in many countries as a dietary supplement for use as an antidepressant, anxiolytic and sleep aid, however application of tryptophan in these indications is not approved by FDA.

Diethylamine salicylate is a salicylic acid salt, that is a cost-effective and simple, first-line treatment for rheumatic and minor musculoskeletal conditions including lumbago, fibrositis, sciatica, bruises, and strains. Salicylic acid directly and irreversibly inhibits the activity of both types of cyclo-oxygenases (COX-1 and COX-2) to decrease the formation of precursors of prostaglandins and thromboxanes from arachidonic acid. Salicylate's antirheumatic (nonsteroidal anti-inflammatory) actions are a result of its analgesic and anti-inflammatory mechanisms.