EFFECTS OF TAMARIND SEED COAT EXTRACT ON HUMAN SKIN 21 CONCLUSIONS Nowadays, botanical extract is playing an increasingly important role in cosmetics. Our study revealed the preventive effects of the tamarind seed coat extract on UVA- induced damage/alterations of fibroblasts, which have a major function in maintain- ing the structural integrity of dermal extracellular matrix by continuously secreting precursors such as procollagen. We have found that the extract could prevent cell damage from H2O2 and UVA exposure. Pretreatment with extract could restore glutathione level and markedly inhibited the MMP-1 induction in UVA-irradiated fibroblasts. The extract was also capable of restoring G0/G1 arrest with increasing G2/M phase in UVA-irradiated cells. All findings suggest that the tamarind seed coat extract has a potential to prevent skin alterations. Clinical studies in human subjects will be needed to determine the efficacy of the extract on UV-induced skin damage. ACKNOWLEDGMENTS We acknowledge fi nancial and facility supports from the Center of Excellence for Innova- tion in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Educa- tion, Thailand. We thank Dr C. Norman Scholfield for useful discussions. GLOSSARY AP-1: The activator protein 1 (AP-1) is a transcription factor, which stimulates gene transcription in response to various stimuli including cytokines, growth factors, and stress. In dermal fi broblasts, it regulates transcription of MMP and procollagen genes. Figure 6. Effect of tamarind seed coat extract on intracellular glutathione level of UVA-irradiated fi bro- blasts. Fibroblasts were pretreated with 200 μg/ml tamarind seed coat extract for 24 h before irradiation. Each point represents mean ± SD of triplicate study. Signifi cantly different when compared to control (no extract, no UVA irradiation) *p 0.05 (Student’s t-test).

JOURNAL OF COSMETIC SCIENCE 22 DPPH: This assay is based on the measurement of scavenging ability of antioxidant test substances toward the stable radical, 2,2-diphenyl-1-picrylhydrazyl (DPPH). Hydrogen atom or electron-donating ability of the test substances is spectrophotometrically mea- sured from the bleaching of the purple-colored methanol solution of DPPH. Fibroblasts: These are the major cells found in the dermal skin. They are responsible for synthesis of extracellular matrix (ECM) components including collagen, elastin, and proteoglycans. Moreover, they secrete matrix metalloproteinases (MMPs), the enzymes that break down collagen and other proteins that comprise the dermal ECM. G0/G1 phase: In normal skin, some 30% of basal cells are preparing for division. Follow- ing mitosis, a cell enters the G1 phase, synthesizes RNA and protein, and grows in size. Later, DNA is synthesized (S phase) and chromosomal DNA is replicated. A short post- synthetic (G2) phase of further growth occurs before mitosis (M). Some basal cells remain inactive in a so-called G0 phase but may reenter the cycle and resume proliferation. MMP-1: Matrix metalloproteinase-1 (MMP-1) is one of catalytic MMPs enzyme pro- duced by fi broblasts. It is also known as fi broblast collagenase. Its major function is to initiate cleavage of fi brillar collagen (type I and III in skin). Once cleaved by MMP-1, collagen can be further degraded by elevated levels of MMP-3 and MMP-9. Figure 7. (A) Effects of tamarind seed coat extract on MMP-1 and (B) type I procollagen production by UVA-irradiated fi broblasts. Fibroblasts were pretreated with 200 μg/ml tamarind seed coat extract for 24 h before irradiation. Each bar represents mean ± SD of triplicate study. Signifi cantly different between two group *p 0.05, **p 0.01 (Student’s t-test).