Cosmetic Raw Material Ingredients – Lightening and Whitening

Today we introduce three commonly used whitening ingredients in cosmetics: resveratrol,  niacinamide and kojic acid.

Part 1: Resveratrol

1. Resveratrol

Resveratrol is a polyphenolic compound with the chemical name 3,4',5-trihydroxy-1,2-diphenylethylene (3,4',5-stilbenetriol), also known as stilbenetriol. It is widely found in plants, including foods such as peanuts, grapes, and pineapples, as well as medicinal herbs like Veratrum nigrum and Polygonum cuspidatum. Resveratrol can be extracted from grape skins or synthesized chemically.

2. Physicochemical Properties

Solubility: Readily soluble in ethanol, methanol, chloroform, acetone, etc.; poorly soluble in water. Solubility: 0.03 g/L (water), 50 g/L (ethanol).

3. Application in Cosmetics

Resveratrol is used in various cosmetic formulations such as creams, lotions, and serums, demonstrating multiple skin care benefits. It not only moisturizes and firms the skin, providing whitening, anti-wrinkle, and anti-aging effects, but also significantly improves overall skin condition in test subjects. Furthermore, encapsulating and delivering resveratrol via a nano-liposome system can significantly enhance its transdermal penetration, further improving its skin care efficacy.

• At an addition level of 0.02%, resveratrol provides whitening effects; at 1.5%, it provides sun protection.

• The maximum historical usage level of resveratrol in leave-on products is 5%.

4. Precautions

Resveratrol has poor stability, is easily oxidized, and is highly photosensitive. It exists in two isomeric forms: cis and trans. The trans form has a planar spatial configuration and is more stable. Resveratrol is unstable under alkaline conditions (pH > 10) and will turn red.

Part 2: Niacinamide

1. Niacinamide

Niacinamide is widely found in animal meat, liver, kidneys, peanuts, rice bran, and yeast. It belongs to the vitamin family and is also known as vitamin B3. Currently, it is produced synthetically.

2. Physicochemical Properties

Niacinamide is a white crystalline powder with a melting point of 129–131 °C. It is odorless or nearly odorless, tastes bitter, and is freely soluble in water or ethanol, soluble in glycerol. 1 g dissolves in 1 mL of water, 1.5 mL of alcohol, or 10 mL of glycerol. The molecular weight of niacinamide is 122.2.

3. Application in Cosmetics

Niacinamide is a component of coenzyme I and coenzyme II, participating in lipid metabolism, the oxidative process of tissue respiration, and anaerobic glycolysis. It can be used as a hair growth agent, moisturizer, and nutrient.

• At 0.1%, it provides moisturizing effects.

• At 1%–3%, it provides significant whitening effects.

Part 3: Kojic Acid

1. Kojic Acid

Kojic acid is a pyran derivative produced by edible Aspergillus species such as Aspergillus oryzae. It is found in fermented products like soy sauce, fermented bean paste, and alcoholic beverages, and can be detected in many fermentation products using Aspergillus species.

2. Physicochemical Properties

Kojic acid forms colorless prismatic crystals with a melting point of 152–155 °C. It is readily soluble in water, alcohol, and acetone; slightly soluble in ether, ethyl acetate, and chloroform; and insoluble in benzene.

3. Application in Cosmetics

• Whitening and anti-inflammatory: Kojic acid has good compatibility and provides whitening and anti-dandruff effects. At 0.1%, it provides whitening effects.

• Antimicrobial: Kojic acid has certain antimicrobial properties and can be used as a preservative in food and cosmetics. It also has some moisturizing ability. It promotes protein aggregation and exhibits an astringent effect on the skin, making it suitable for firming skin products.

• Moisturizing: Kojic acid inhibits hyaluronidase activity, showing potential to suppress skin allergies. At 0.1%, it achieves 86.9% inhibition of hyaluronidase.

4. Precautions in Cosmetic Use (Incompatibilities)

Kojic acid contains phenolic hydroxyl groups in its molecule and is easily oxidized, leading to loss of activity, discoloration, or precipitation. Do not use in combination with compounds such as potassium permanganate, hydrogen peroxide, vitamin C, or compounds containing iron, copper, or zinc.