GUAVA

Botanical name: Psidium guajava L.

Family name: MYRTACEAE

Thai name: Fa-rang

                     Guava is a plant native to Central America, but typically cultivated in tropical countries. There are many strains. Guava is well known for its high amount of vitamin C, 4-10 times higher than that of an orange. The vitamin C resides in its skin rather than its pulp. The amount of vitamin C is highest when the fruit is mature, and is lower when ripe. The fruit and the leaf contain bitter-tasting substances, such as tannin, and essential oils. The fruit also contains a large number of fibers. Medically, it is used as a treatment for wounds and rashes. Guava extract is effective in protecting against bacteria, which cause diarrhea. The essential oils in guava leaf can help cover an unpleasant smell from decayed teeth or gum disease, or even potent smells from food and beverages. As a result, guava leaves are used as an ingredient in a mouthwash. The essential oils found in guava leaves are a-pinene and Cineole. In research report, it was found the flavonoid compounds such as, quercetin, avicularin, and guaijaverin. They antagonize against several bacteria including the bacterial type causes oral smell and dental caries. Moreover, it was found that quercetin possesses the tyrosinase inhibition, which is caused the skin pigmentation. It is, thus, able to be used the guava extract in the skin whitening products.

ACTIVE INGREDIENTS OF GUAVA EXTRACT

CLINICAL TRIAL ON PIGMENTATION

Inhibition Constants of Quercetin for Mushroom Tyrosinase

IC50	3.8 ± 0.32 mg/ml
Km	1.46 ± 0.20 mM
Ki	10 ± 0.20 mM
Inhibition	Reversible
Inhibition type	Compettitive

Lineweaver-Burk Plots of Mushroom Tyrosinase and L-Tyrosine without (·) and with (o) 0.006 mM and (▼) 0.012 mM Quercetin

Preservatives : None