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The major objective of this study was to estimate the hypopigmentation function of the essential oil from Vetiveria zizanioides (VZ-EO). Our results indicated that VZ-EO exhibits potent lipid peroxidation inhibitory activity to moderate the bleaching of β-carotene and to maintain the cellular glutathione (GSH) levels. VZ-EO can markedly decrease melanin production and tyrosinase activity in α-melanin-stimulating-hormone- (α-MSH-) stimulated B16 cells. The effect of VZ-EO on melanogenesis is achieved by the suppression of cellular tyrosinase expression. The results demonstrated that the activity of VZ-EO on melanogenesis might be the result of its potent antioxidative ability, which was reflected in the decreased cellular oxidant and malondialdehyde (MDA) levels and the recovered activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) in α-MSH-stimulated B16 cells. The most abundant compound in VZ-EO is cedr-8-en-13-ol (12.4%), which has a strong capability to inhibit lipid peroxidation. Therefore, VZ-EO has the potential to become an ingredient in future hypopigmentation drugs, foods, and cosmetics.

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A cDNA (1890 bp) encoding a putative 1‐pyrroline‐5‐carboxylate dehydrogenase (P5CD) was cloned from Taiwanofungus camphorata. The DNA sequence encodes a protein of 547 amino acid residues with calculated molecular mass of 59.4 kDa. The deduced amino acid sequence is conserved among the reported P5CDs. To characterize the T. camphorata P5CD, the coding region was subcloned into an expression vector pET‐20b(+) and transformed into E. coli Rosetta (DE3). The recombinant His6‐tagged TcP5CD was expressed and purified by Ni2+‐nitrilotriacetic acid Sepharose. The purified enzyme showed a major band of ~59.4 kDa by 12 % SDS‐PAGE. The Michaelis constant (KM) value for 3,5‐dimethoxybenzaldehyde with NAD+ as cofactor was 0.56 mM. The enzyme’s half‐life of deactivation at 45oC was 4.4 min, and its thermal inactivation rate constant kd was 1.23 x 10‐2 min‐1. The enzyme was most active at pH 7.0. The enzyme’s preferred substrate is veratraldehyde. It can also use other aldehyde as substrates including acetaldehyde and propionaldehyde. Grant Funding Source: National Science Council of the Republic of China under grant NSC95‐2313‐B‐019‐007 to C‐T. L.