:The major anthocyanins, Ñavonoids and phenolic acids in the tubers (skin and Ñesh), Ñowers and leaves of 26 cultivars of Solanum tuberosum L with coloured skins and/or Ñesh have been identiÐed and quantiÐed using analytical HPLC. Red tubers contained mostly pelagonidin-3-(p-coumaroyl-rutinoside)-5-glucoside (200È2000 lg g~1 FW) plus lesser amounts of peonidin-3-(pcoumaroyl-rutinoside)-5-glucoside (20È400 lg g~1 FW). Light to medium purple tubers contained petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside (1000È 2000 lg g~1 FW) plus small amounts of malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (20È200 lg g~1 FW) whilst dark purpleÈblack tubers contained similar levels of petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside together with much higher concentrations of malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (2000È 5000 lg g~1 FW). Tuber Ñesh also contained chlorogenic acid (30È900 lg g~1 FW) and other phenolic acids plus low concentrations of Ñavonoids (0È 30 lg g~1 FW). Tuber skins showed much higher levels (1000È4000 lg g~1 FW) of chlorogenic acid. The major anthocyanins in Ñowers were present as the rutinosides or other glycosides of pelargonidin, petunidin and malvidin whilst glycosides of cyanidin and delphinidin were found in some Ñowers, together with many of the same phenolic acids as found in tubers. The commonest Ñavonoids included rutin, kaempferol-3-rutinoside and two quercetin-rhamnose-glucosides. Flowers and leaves contained higher concentrations of Ñavonoids which fell into two patterns, with some cultivars containing high concentrations of quercetin-3-glycosides, whilst others had much lower concentrations.1998 SCI. ( J Sci Food Agric 77, 45È57 (1998)

A possible role for G proteins in contributing to the chronic actions of cocaine was investigated in three rat brain regions known to exhibit electrophysiological responses to chronic cocaine: the ventral tegmental area, nucleus accumbens, and locus coeruleus. It was found that chronic, but not acute, treatment of rats with cocaine produced a small (approximately 15%), but statistically significant, decrease in levels of pertussis toxin-mediated ADP-ribosylation of Gi alpha and Go alpha in each of these three brain regions. The decreased ADP-ribosylation levels of the G protein subunits were shown to be associated with 20-30% decreases in levels of their immunoreactivity. In contrast, chronic cocaine had no effect on levels of G protein ADP-ribosylation or immunoreactivity in other brain regions studied for comparison. Chronic cocaine also had no effect on levels of Gs alpha or G beta immunoreactivity in the ventral tegmental area and nucleus accumbens. Specific decreases in Gi alpha and Go alpha levels observed in response to chronic cocaine in the ventral tegmental area, nucleus accumbens, and locus coeruleus are consistent with the known electrophysiological actions of chronic cocaine on these neurons, raising the possibility that regulation of G proteins represents part of the biochemical changes that underlie chronic cocaine action in these brain regions.

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A novel spectrophotometric method for the simultaneous measurement of total starch, amylose and amylopectin in lipid-free samples has been developed using a diode-array spectrophotometer. It involves measurement of the spectrum of the amylose/amylopectin-iodide complexes at six wavelengths and calculation of amylose and amylopectin concentrations using multi-component analysis and a spreadsheet computer program. This method appears to offer some advantages to previous 'iodine-blue colour' assays for the measurement of amylose.