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A new sesquiterpene related to the insecticide polygodial was obtained from P. punctatum leaves. Its structure was established as a tricyclic hemiacetal by means of 2D NMR spectroscopy. The compound was inactive against tick (Boophiilus microplus).

Four new phenalenone-type phytoalexins, named musanolones C-F, have been isolated from infected rhizomes of banana plants (Musa acuminata; AAA cultivar Grand Nain). These phytoalexins were biosynthesized de novo by the plants upon infection by Fusarium oxysporum f. sp. cubense race 4, Panama's disease causal agent. The structures of the new phytoalexins were elucidated using spectroscopic data and chemical correlations. Hydroxyanigorufone has been previously described as a constitutive natural product, from Anigozanthos rufus, but it was never described as a phytoalexin. The chemical shift for all of the hydrogen and carbon atoms in the musanolones C-F were unambiguously established by mono- and bi-dimensional, homo- and hetero-nuclear NMR experiments (1H NMR, 13C NMR, COSY, HMQC and HMBC). Preliminary in vitro assays of all the musanolones tested until now show a strong inhibitory activity on the growth of the germination tube of F. oxysporum f. sp. cubense race 4.

A new phytoalexin was induced and isolated from papaya fruit slices treated with copper salts; its structure was established as 3',5'-dimethoxy-4'-hydroxy-(2-hydroxy)acetophenone. This compound showed high antifungal activity against Colletotrichum gloesporioides, a pathogenic fungus of papaya.

Phenalenone-type phytoalexins were obtained for the first time from bananas and identified by COSY 1 H- 1 H, HMQC and HMBC techniques, and X-ray analysis, among other methods. The aminoglycoside kanamycin was studied as a phytoalexin inducer in banana leaves and fruit and compared with the effects produced by the fungus Mycosphaerella fidjiensis. The phenyl side chain in banana phytoalexins is not in the same position as in other plant phenalenones and so an alternative biogenetic pathway has been proposed and is currently being verified

Winston Quinones, Gustavo Escobar, Fernando Echeverri *, Fernando Torres, Yoni Rosero,Vi ctor Arango, Gloria Cardona and Adriana GallegoDepartment of Chemistry, Universidad de Antioquia, P. O. Box 1226, Medellin, ColombiaTel.: (57+4)2105658, Fax: (57+4)2330120, E-mail: echeveri@catios.udea.edu.coReceived : 18 January 2000 ; revised form 14 July 2000 / Accepted : 14 July 2000 / Published : 26 July 2000Abstract: Several perinaphthenone/phenylphenalenone compounds were synthesized to es-tablish a relationship between structure and antifungal activity against Mycosphaerella fijie n-sis. Substitutions on the unsaturated carbonyl system or addition of a phenyl group reducedantibiotic activity.Keywords: phenylphenalenones, synthesis, antifungal activity, Mycosphaerella fijiensis .IntroductionPhytoalexins are natural antibiotic compounds proposed as fungicides or templates for production ofnew pesticides [1]. Recently, the search for novel antifungal compounds has received special attentionas a result of an enhanced microbial resistance to current pesticides.Banana plants are affected by the pathogenic fungi Fusarium oxysporum var. cubensis type 4 andMycosphaerella fijiensis , causal agents of the diseases named Black Sigatoka and Panama Disease, r e-spectively. These diseases can drastically reduce banana production by as much as ca. 20% [2]. Undercolonization by these microorganisms or treatment of the leaves with kanamycin, banana plants producetwo types of phytoalexins, 9-phenylphenalenones (also known as musanolones [3]) and 4-phenylphenalenones [4], The main aim of the present work was to synthesize several structurally-relatedcompounds and to determine the relationship between phytoalexin structure and their antifungal effectsagainst M. fijiensis .Results and DiscussionThe planned synthetic approach involved a 1,4-addition of a Grignard reagent to a perinaphthenone,followed by reduction with DDQ, epoxidation with

Ten flavonoids were isolated from Passiflora foetida L. resin. One of them, ermanin, has a high deterrent activity at 40 ppm against Dione juno larvae.

A new phytoalexin was induced and isolated from papaya fruit slices treated with copper salts; its structure was established as 3',5'-dimethoxy-4'-hydroxy-(2-hydroxy)acetophenone. This compound showed high antifungal activity against Colletotrichum gloesporioides, a pathogenic fungus of papaya.