Sunburn (fohia) Healing Effects of Noni: Is it a Mechanism Involving Its Inhibitory Effects on MMP, COX-2 and Cat-G Enzymes?

The aim of the present investigation was to evaluate whether extracts and preparations of noni fruit and leaf, a Polynesian traditional herbal medicine, inhibit MMP, COX-2 and Cat-G enzymes in vitro, as its mechanism of action for healing sun-burn known as fohia in Tonga. Noni leaf ethanolic extract (NLEE) inhibited MMP-1, -2, -3, and -9 enzymes concentration dependently with 0.517, 0.234, 0.184, and 0.302 mg/mL IC50, respectively. Noni fruit juice concentrates (NFJC) in 1 and 5 mg/mL concentrations, inhibited MMP-12 enzymes by 102, and 99%, respectively. NFJC and NLEE inhibited Cat-G enzymes concentration-dependently with 0.125, <0.1, and 0.41 mg/mL IC50, respectively. Noni fruit juice fractions 4 and 6 inhibited COX-2 and Cat-G enzymes by 85 and 89%, and 89 and 78%, respectively. Additionally, the noni fruit puree and noni leaf has 1.91 mg/g and 5.77 mg/g of ursolic acid, respectively. NFJC, and NLEE inhibitory effects on MMP, COX-2 and Cat-G enzymes might help explain the traditional usage of the noni fruits and leaves for treatment of fohia skin as alluded to by Polynesian traditional healers. These results warrant further studies into the skin health benefits of noni fruit and leaf to further assess their efficacies and dosages in human subjects suffering from photoaging.