A total of 69 species of lichens have been collected from various locations around New Zealand. Screening of extracts of these species for antimicrobial, antiviral and cytotoxic activity showed a high proportion with biological activity. Active extracts were generally from species known to contain phenolic compounds. Bioactivity-directed isolation work on Cladia retipora, Pseudocyphellaria glabra and P. homoeophylla led to the identification of usnic acid as the main antimicrobial, cytotoxic and antiviral component in these three species.
The catabolism of glucosinolates is reviewed, with particular attention to the formation of "abnormal" products (thiocyanates, and cyano-epithioalkanes). The biological properties of the glucosinolates and catabolites are briefly surveyed. INTRODUC TI ON Some twenty years have elapsed since Ettlinger and Lundeen proposed .!. as the correct structure for glucosinolate anions.
HO~~ OS~N
OH
bso-
HO
OHSince passing that milestone there have been major achievements in identifying glucosinolates (the list of which now exceeds 70), andin mapping the biosynthetic pathways at the substrate level. There are recent and authoritative reviews of these advances (1) and I propose to say no more about them here. There has also been a fresh discussion of the value of glucosinolates in plant systematics (2), and that too I shall leave aside. Instead I have chosen to concentrate upon the catabolism of glucosinolates, and their biological properties.
GLUCOSINOLATE CATABOLISM"Normal Catabolism'~ When plant tissues containing glucosinolates are crushed there is usually formation of isothiocyanates ("mustard oils") (~) corresponding to the aglucone (~). (Itwas the early recognition of this "normal" catabolism which resulted in the old name "mustard oil glucosides" for the glucosinolates).The isothiocyanate-forming enzymes are known as myrosinases and, after soine controversy, it has been established that their role is to function as thioglucoside glucohydrolases (E. C. 3. 2. 3. 1) remarkably catholic in their acceptance of.!. with a wide va:riety of ltsub-197
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