Page 252 - Cosmetology

quince seed. Used as a thickening agent in cosmetics, but it also has skin-constricting properties and may
cause skin irritation.

quinoa oil. Derived from quinoa grain; it may have antifungal properties. It may also have emollient
properties for skin, but there is little research showing this to be the case.
R

Ranunculus ficaria extract. May have antibacterial and antifungal properties and is used in the treatment
of hemorrhoids. However, applied topically it can cause skin irritation and may also cause photodermatitis.

rapeseed oil. Nonfragrant oil that has emollient and potential antioxidant properties for skin.

Raspberry Seed Extract. See red raspberry extract.

Raspberry Seed Oil. See red raspberry extract.

Ravensara oil. A plant oil. There is a small amount of research showing it to have antifungal properties, and
when tested on insect larvae it showed antimutagenic properties.

red algae. See algae.

red clover. Can have antioxidant and anti-inflammatory. It is sold as an herbal supplement for relief of
menopausal symptoms such as hot flashes and vaginal dryness. Red clover does contain high
concentrations of four major isoflavones that have been shown to have estrogenic properties. However, in
studies red clover was found to be no better than placebo for menopausal symptoms.

red raspberry extract. Fruit extract that has potent antioxidant properties and antibacterial properties. It can
also cause irritation due to its tannin content.

red sandalwood. Has a phytoestrogen component (, but it can also be a skin irritant.

reducing agent. Substances that have the ability to split or break down the disulfide bonds of hair.
Therefore, they are typically used in hair-straightening or hair-waving products and in depilatories. The
chemical reaction they generate has antioxidant properties, but they can also be strong skin irritants.

Rehmannia chinensis root extract. From the plant also known as Chinese foxglove; there is no research
showing it to have benefit for skin.

Rehmannia glutinosa. Chinese herb known as Di huang that has no known benefit for skin.

Renova. See Retin-A and tretinoin.

resorcinol. Considered an effective topical disinfectant in concentrations of 1% to 3%. However, there is
also research showing it to be overly irritating for skin. As a result it is rarely used nowadays for treating
blemishes.

respiratory enzyme. Type of enzyme that interacts with several other biological and physiological
processes for the activation and use of oxygen in the body. There is no evidence that any respiratory
enzyme can do anything topically for skin.

Resveratrol. A potent polyphenolic antioxidant that is abundant in red grapes and therefore red wine
(unfortunately not white wine). Resveratrol has been reported in numerous studies to be one of the most
potent, natural chemopreventive agents inhibiting the cellular processes associated with tumor development,
including initiation, promotion, and progression. It also has significant anti-inflammatory properties.
Conversely, there is research showing it to be associated with cell death when applied topically if skin is
exposed to sunlight

Retin-A. One of several prescription-only drugs (others include Renova, Retin-A Micro, and Avita) that
contain tretinoin (technically, all-trans retinoic acid), which is the acid form of vitamin A, as the active
ingredient. In skin, tretinoin is the form of vitamin A that can actually affect cell production by binding to the
tretinoin receptor sites on the cell. There is a great deal of research establishing that when skin has been
damaged (often by exposure to sunlight) tretinoin is effective in improving cell production. Tretinoin is a valid
method for addressing wrinkles and, overall, for improving cell production. Applying tretinoin doesn't produce