ABSTRACT
The protecting effect of “Hypporamine PL” compound isolated from dry leaves of seabuckthorn (Hippophae rhamneides L.) on photosystem 2 (PS 2) activity suppression induced by CdCl2 and CoCl2 treatment in the 7 day old wheat seedlings (Triticum aestivum L.) under different pH of growth medium was investigated by measurement of millisecond delayed fluorescence (ms-DF) of chlorophyll intact leaves. The value o-i/p-s of ms-DF ratio was reduced under the Cd2+ and Co2+ treatments on 60 and 65% respectively at pH 6.7. Acidification of medium (pH 5.0) results in decreasing of ratio o-i/p-s only approximately on 30% in average. In the alkaline medium the lowering of o-i/p-s on 41% is observed in both ions treatments. This decreasing of o-i/p-s ratio occurred due to decreasing of fast phase o-i amplitude. At the same time the widening and increasing of slow phase p-s amplitude was observed. The compound “Hypporamine PL” limited the decrease of ms-DF components induced by heavy metals. It is suggested that the protective effect of “Hypporamine PL” on the photochemical reactions in the PS2 is due to catechins, epicatechins, quercetin and other polyphenols, containing in this compound, preventing the free radicals formation in the PS2 under treatment by heavy metal ions.