title: Ramalin, a novel nontoxic antioxidant compound from the Antarctic lichen Ramalina terebrata.
abstract: Ramalin (γ-glutamyl-N'-(2-hydroxyphenyl)hydrazide), a novel compound, was isolated from the methanol-water extract of the Antarctic lichen Ramalina terebrata by several chromatographic methods. The molecular structure of ramalin was determined by spectroscopic analysis. The experimental data showed that ramalin was five times more potent than commercial butylated hydroxyanisole (BHA) in scavenging 1-diphenyl-2-picryl-hydazil (DPPH) free radicals, 27 times more potent in scavenging 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid free radicals (ABTS(+)) than the vitamin E analogue, trolox, and 2.5 times more potent than BHT in reducing Fe(3+) to Fe(2+) ions. Similarly, ramalin was 1.2 times more potent than ascorbic acid in scavenging superoxide radicals and 1.25 times more potent than commercial kojic acid in inhibiting tyrosinase enzyme activity, which ultimately leads to whitening of skin cells. Ramalin showed no or very little cytotoxicity in human keratinocyte and fibroblast cells at its antioxidant concentration. Furthermore, ramalin was assessed to determine its antioxidant activity in vivo. One microgram per milliliter ramalin significantly reduced the released nitric oxide (NO) and 0.125 μg/ml ramalin reduced the produced hydrogen peroxide (H(2)O(2)) in LPS (lipopolysaccharide)-stimulated murine macrophage Raw264.7 cells. Considering all the data together, ramalin can be a strong therapeutic candidate for controlling oxidative stress in cells.
authors.affiliation: Korea Polar Research Institute, KORDI, Incheon, South Korea.
authors.forename: Babita
authors.initials: B
authors.lastname: Paudel
authors.forename: Hari Datta
authors.initials: HD
authors.lastname: Bhattarai
authors.forename: Hye Yeon
authors.initials: HY
authors.lastname: Koh
authors.forename: Sung Gu
authors.initials: SG
authors.lastname: Lee
authors.forename: Se Jong
authors.initials: SJ
authors.lastname: Han
authors.forename: Hong Kum
authors.initials: HK
authors.lastname: Lee
authors.forename: Hyuncheol
authors.initials: H
authors.lastname: Oh
authors.forename: Hyun Woung
authors.initials: HW
authors.lastname: Shin
authors.forename: Joung Han
authors.initials: JH
authors.lastname: Yim
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D000975:Antioxidants / Q000302:isolation & purification* / Q000494:pharmacology* / Q000633:toxicity; D001205:Ascorbic Acid / Q000494:pharmacology; D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D002083:Butylated Hydroxyanisole / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D005609:Free Radicals / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D005971:Glutamates / Q000302:isolation & purification* / Q000494:pharmacology* / Q000633:toxicity; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D015603:Keratinocytes / Q000187:drug effects; D008011:Lichens / Q000737:chemistry*; D051379:Mice; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry; D010851:Picrates / Q000737:chemistry; D011753:Pyrones / Q000494:pharmacology; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D002839:Chromans; D005609:Free Radicals; D005656:Fungal Proteins; D005971:Glutamates; D010851:Picrates; D011753:Pyrones; C570208:Ramalin; D013451:Sulfonic Acids; D002083:Butylated Hydroxyanisole; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D009569:Nitric Oxide; C011890:kojic acid; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D014442:Monophenol Monooxygenase; D001205:Ascorbic Acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid