EFFECTS OF TAMARIND SEED COAT EXTRACT ON HUMAN SKIN 19 depression persisted at 72 h after radiation and the extract seemed effective only at the later time. Both the increased secretion of MMP-1 and the reduced procollagen are controlled by the same transcription factor, AP-1, the different time courses suggest other inactions. Some differences may be ascribed to affect cell growth rate and cell death. UVA-induced skin aging correlates with the loss of dermal connective tissue. It has been reported that the loss of type I collagen in photodamage skin is due to the progressive increase in MMP production and hence increased degradation of collagen (40–42), which is not compensated by procollagen production (43,44). Our results correlate with previous study indicating induction of MMP-1 and reduction of procollagen production by UVA-irradiated fi broblasts (3, 36, 44–45). In addition, pretreatment with the extract (200 μg/ml) provided protection against promoted MMP-1 activity. Such inhibition of MMP-1 induction in irradiated fi broblasts, at least partially, by antioxidant effect of the extract against oxidative damage through glutathione in- duction consequently results in lower MMP-1 secretion found in the extract-treated group. The oxidative stress has numerous effects on cell signaling, particularly the Figure 4. (A) Morphology of fi broblasts under 20X microscope and (B) viability of UVA-irradiated fi bro- blasts pretreated with 200 μg/ml tamarind seed coat extract at 24 h after UVA exposure. Data are expressed as percentage of control (no extract, no UVA irradiation), and each bar represents mean ± SD of triplicate study. Signifi cantly different between two group *p 0.05, **p 0.01 (Student’s t-test).

JOURNAL OF COSMETIC SCIENCE 20 Figure 5. (A) Histogram of fl ow cytometric data of fi broblasts in control (no extract, no UVA irradiation) (B) no extract plus UVA irradiation (C) 200 μg/ml extract pretreatment plus UVA irradiation and (D) per- centage of cell number in control, no extract plus UVA irradiation and extract pretreatment plus UVA- irradiated group at different stages of the cell cycle at 72 h after UVA exposure. Each bar represents mean ± SD of triplicate study. Signifi cantly different between two group *p 0.05, **p 0.01 (Student’s t-test). activation of infl ammatory response, nevertheless our tamarind seed coat extract has the potential of protecting cutaneous fi broblasts of intact skin exposed to UV radia- tion.