Impatiens Lawsone

Impatiens balsamina L. I. noli-tangere L. I. textori Miq. Tou Gu Cao or Feng Xian Hua (Garden balsam) (whole plant) Gentisic acid, ferulic acid, p-coumaric acid, sinapic acid, caffeic acid, scopoletin, lawsone, 33 144 This herb is toxic. Treat arthritis, relieve pain. 

Impatiens balsamina L. China Gentisic acid, ferulic acid, p-coumaric acid, sinapic acid, caffeic acid, scopoletin, lawsone.33 Treat arthritis, relieve pain. 

N.A. Impatiens pallida Nutt. I. capensis Meerb. Lawsone, seed oil contains alpha-spinasterol, beta-ergosterol.302 Remedy for rashes, pain caused by insect bites, anti-inflammatory. 

CioHjOs, Mr 174.16. Yellow prisms, mp. 195-196 °C (decomp.), pK i -5.6, pKj2 4.00 (25 °C). L. occurs in various Lawsonia and Impatiens species and is the dyeing constituent of henna. Lawsone methyl ether (2-... 

Juglone (7) (from Jug Ians regia) and lawsone (41) (from Impatiens balsamina) both come from shikimic acid (Fig. 6.8) (Packter, 1980). The initial steps of biosynthesis are identical to those of vitamin K2 (Inouye and Leistner, 1988 Kolkmann and Leistner, 1987). Either l,4-dihydroxy-2-naphthoic acid (40) or 2-carboxy-4-oxotetralone (COT) (43) is incorporated efficiently into both juglone and lawsone (Leistner, 1981). Biosynthesis of juglone proceeds through a symmetrical intermediate 1,4-naphthoquinone (42) is an efficient precursor (Leistner, 1981). In contrast, the biosynthesis of lawsone (41) does not appear to involve a symmetrical intermediate (Haslam, 1974 Inouye and Leistner, 1988). 

Biosynthesis of Lawsone. -The biosynthesis of this naphthaquinone has been investigated for intermediary symmetry by Grotzinger and Campbell. The naphthalene nucleus of lawsone (54) i derived from shikimate with three non-carboxyl carbon atoms of glutamate, and a symmetrical 1,4-naphthaquin-one or the acid (55) are both possible intermediates. Feeding experiments in Impatiens balsamina now establish that [2- C] acetate predominantly labels C-2 of (54), so that the unsymmetrical intermediate (55) must be involved (see Scheme 9). An alternative route from (54) to (55) from that illustrated is via l,4-dihydroxy-2-naphthoic acid, but this could not be detected as an intermediate, nor was it incorporated when fed to the plants. 

---