Authors:A. Dvaranauskait?, P. R. Venskutonis and J. Labokas
Thirty-one raspberry (Rubus idaeus L.) plants were collected in different natural habitats of Lithuania located in 17 districts and replanted in the experimental field. The fruits from different accessions were extracted with ethanol and the extracts were tested for their antioxidant activity (AA) by using ABTS·+radical cation decolourisation and DPPH·radical scavenging methods. All tested raspberry fruit extracts were antioxidatively active; their radical scavenging capacity at the applied concentrations varied from 52.9 to 92.6% in DPPH·reaction system and from 52.5 to 97.8% in ABTS·+system. The total amount of phenolic compounds in fruits varied from 5.6 to 13.7 mg of gallic acid equivalents in 1 g of plant extract. However, strong correlation between the radical scavenging capacity and the total amount of phenolic compounds in the fruit extracts was not observed, which indicates remarkable differences in the composition and antioxidant power of phenolic compounds present in the fruits harvested from raspberry accessions collected from different natural habitats. Most likely, environmental conditions and genetic factors should play an important role for the accumulation of active compounds in raspberry fruits.
Authors:A. Dvaranauskaite, P.R. Venskutonis and J. Labokas
Ethanol extracts from 41 raspberry leaf accessions were studied. The plants of
L. were collected in different natural habitats of Lithuania located in 26 districts and replanted in the experimental field of the Institute of Botany, Lithuania. The total amount of phenolic compounds in leaves varied from 0.3 to 2.2 mg of gallic acid equivalents (GAE) in 1 g of dry leaves. Quercetin glucuronide, quercetin-3-glucoside and quercetin glucosylrhamnoside (rutin) were identified in the extracts by HPLC/UV/MS. Remarkable differences in the composition of the extracts were observed indicating that herbal tea preparations containing
leaves, which are used for phytotherapeutic purposes need more detailed examination in order to standardise their possible functional properties and pharmacological effects.
Authors:J. Pokorná, P. R. Venskutonis, V. Kraujalyte, P. Kraujalis, P. Dvořák, B. Tremlová, V. Kopřiva and M. Ošťádalová
Coffee beans contain a large amount of antioxidants, which are subjected to various changes during roasting. In this study, antioxidant potential of raw and roasted to different degree (light, medium, dark) C. arabica and C. robusta coffee beans was evaluated by the four antioxidant assay methods, TPC, FRAP, TEAC, and DPPH˙.
The obtained results revealed significant differences between the coffee types, roasting degree, and antioxidant activity assessment methods. FRAP and TPC appeared to be the most appropriate methods for revealing the differences in antioxidant potential of different coffee types and the effects of roasting. The results obtained by these methods were in good correlation. ABTS and DPPH? methods are not enough sensitive for the determination of roasting degrees.
In general, based on statistical data evaluation, antioxidant activity is more dependent on the coffee type than on the degree of roasting, however, the selection of analytical method may also be significant.