Highly hydroxylated guaianolides of Achillea asiatica and Middle European Achillea species.

From flower heads of Achillea asiatica (L.) Serg., three new guaianolides were isolated by repeated column chromatography and HPLC. The constitution and the stereochemistry of these new, labile compounds were determined by MS, one ((1)H, (13)C, selective (1)H-TOCSY and (1)H-NOESY) and two-dimensional NMR experiments ((1)H, (1)H-COSY, (1)H, (13)C-HSQC, (1)H, (13)C-HMBC). The substances were identified as 8 alpha-angeloxy-2 alpha, 4 alpha,10 beta-trihydroxy-6 beta H,7 alpha H, 11 beta H-1(5)-guaien-12,6 alpha-olide (1), 8 alpha-angeloxy-1 beta,2 beta:4 beta,5 beta-diepoxy-10 beta-hydroxy-6 beta H, 7 alpha H, 11 beta H-12,6 alpha-guaianolide (2) and 8 alpha-angeloxy-4 alpha,10 beta-dihydroxy-2-oxo-6 beta H,7 alpha H, 11 beta H-1(5)-guaien-12,6 alpha-olide (3). They were also detected in Middle European species (Achillea collina, Achillea ceretanica (2x and 4x), Achillea roseoalba, Achillea asplenifolia) by HPLC, TLC and off line MS and have not been described before. The possibility that these compounds might be products of an oxidation process is discussed.

Microwave diathermy of the retina and choroid.

Microwaves were used to induce chorioretinal scar formation in normal rabbit eyes. We have developed a directional 6.8-gigahertz microwave applicator with a rectangular aperture. It was designed to mimic the shape and function of a T-shaped scleral depressor. For treatment, the applicator was placed on the conjunctiva over the sclera. Then, indentation was used to visualize probe placement during indirect ophthalmoscopy. Thermocouple-controlled heating was initiated such that conjunctival temperatures in a range of 51 degrees C to 65 degrees C were induced for 10 seconds per treatment. We found that treatment at temperatures of 51 degrees C or 52 degrees C for 10 seconds produced circular areas of acute retinal whitening. From these microwave-induced lesions, there evolved chorioretinal attenuation with and without evidence of retinal pigment epithelial hyperplasia. No evidence of scleral damage was noted at these thermal doses.