MAP(Magnesium ascorbyl phosphate)

Magnesium Ascorbyl Phosphate is a stable, water soluble derivative of Vitamin C (L-Ascorbic acid mono-dihydrogen phosphate magnesium salt). Unlike L-Ascorbic Acid, it does not readily degrade in formulas containing water.  It is considered light-stable and oxygen-stable. Studies of MAP in aqueous solutions indicate it retains over 95% of its potency at 40°C without any pH adjustment.
According to SmartSkincare.com, Magnesium Ascorbyl Phosphate is a water-soluble, non-irritating, stable derivative of Vitamin C. It has the same potential as vitamin C to boost skin collagen synthesis but is effective in significantly lower concentrations, and can be used at concentrations as low as 10% to suppress melanin formation (in skin-whitening solutions). It is also important to note that Magnesuim Ascorbyl Phosphate may be better choice than Vitamin C for people with sensitive skin and those wishing to avoid any exfoliating effects since many Vitamin C formulas are highly acidic (and therefore produce exfoliating effects).
By inhibiting tyrosinase activity, MAP is capable of suppressing skin pigmentation, making it effective in whitening dark skin, or areas of dark skin.  It should be noted, one study indicated it might be needed at a concentration of 10% to be effective at inhibiting melanin production.
Unlike Ascorbyl Palmitate, Magnesium Ascorbyl Phosphate (MAP) appears to have the same potential to boost skin collagen synthesis as does Ascorbic Acid, but at lower concentrations. For those with sensitive skin or those wanting to avoid the exfoliating effects of highly acidic Ascorbic Acid, MAP may be the preferred choice.

In skin care products, Magnesium Ascorbyl Phosphate (MAP) is also used for UV protection and repair, collagen production, skin lightening and brightening, and as an anti-inflammatory. It is also a potent antioxidant. It is considered an excellent non-irritating skin whitening agent that inhibits skin cells to produce melanin and lightens age spots, and is a great alternative to Quinone. Magnesium Ascorbyl Phosphate is a also a potent anti-oxidant that can protect skin from oxidation and UV rays, and is used as an anti-inflammatory .

There are no adverse side effects to using Magnesium Ascorbyl Phosphate (MAP), although those with sensitive skin may need to be aware of Vitamin C’s acidic and exfoliating effects. However, Magnesium Ascorbyl Phosphate (MAP) is generally considered more gentle than traditional Vitamin C and therefore safer on sensitive skin.