24 research outputs found
Anti-pathogenic properties of plant peptide hormone phytosulfokines [PSK's] and its selected analogues
Phytosulfokine-α (PSK-α) (H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-Gln-
OH) (I), a sulfated growth factor universally found in both monocotyledons
and dicotyledons, strongly promotes proliferation of plant cells in culture. The
C-terminal truncated analog named PSK-β (Tyr(SO3H)-Ile-Tyr(SO3H)-Thr) (II)
showed a 10-fold lower activity than that of the parent pentapeptide. Because
PSK-α promotes proliferation and differentiation during the plant growth we
undertook the studies on the influence of PSK-α on plant defense mechanisms
in that period. In present studies on PSK-α (I), PSK-β (II), and its analogues, we
performed a search of another biological properties.
The aim of our investigation was evaluation of PSK-α, PSK-β and their selected
analogues in relation to growth and development of plant pathogens, such as
Phoma narcissi and Botrytis tulipae. In these studies we elaborated the synthesis
of PSK-α or PSK-β and their 22 analogues modified by natural and non-natural
amino acid residues.
Peptides were synthesized by the solid phase method according to the Fmoc
procedure on a Wang-resin. Free peptides were released from the resin by 95%
TFA in the presence of EDT.
Biological effect of these peptides was evaluated by test on the growth and
development of pathogens of P. narcissi and B. tulipae.</p
4x4: Four-flanged intrascleral IOL fixation, single-pass four-throw pupilloplasty and vitrectomy with silicone oil tamponade in a patient after blunt trauma
Effect of haloperidol [HAL] on leucopyrokinin [LPK]-induced biphasic hyper- and hypothermic effect in rats
The aim of present study was to evaluate mechanisms involved in
thermomodulatory effect LPK in rats.Experiments were performed on adult
Wistar male rats. LPK was applied either intracerebroventricularly (icv), or
intraperitoneally (ip) using the similar program and technique of experiments
as in our previous study. We confirmed in this paper the results of our previous
reports that icv administration LPK at the dose of 20 nmol induced evident
significant rectal hypothermia, while lower dose LPK of 1 nmol icv exerted
significant hyperthermic effect. Peripherally applied LPK at the range of doses
10-100 nmol/100 g ip displayed slight bimodal (hyperthermic and hypothermic)
effect on rectal temperature. Prior administration of haloperidol, an antagonist
of central dopamine receptors blocked both effects LPK applied either icv or ip.
Obtained results indicate that both hypothermic and hyperthermic effects LPK are
also modulated by central dopaminergic receptors
Biological evaluation of new pyrethroid amides and n-esters in relation to their effects on the domestic fly Musca Domestica L.
Antinociceptive effect of poneratoxin [PoTX] in rats
Poneratoxin (molecular weight 2932) is a 25 amino acid neuropeptide,
isolated from an ant venom. It affects excitability of nerve and muscle fibres by
changing the kinetics of the voltage-dependent sodium channel. The aim of the
study was to investigate the analgetic effect of synthetic poneratoxin (PoTX) in
adult female Wistar rats. In the first part of the study the animals received PoTX
intracerebroventricularly. The analgetic effect was evaluated by a tail immersion
test. In the second part of the experiment the analgetic effect of PoTX was blocked
with naloxone, an opioid receptors antagonist. The study showed that poneratoxin
exerts the analgetic effect in rats and this effect is not mediated by central opioid
system. Therefore it was concluded that other mechanism is resposible for the
effect of PoTX
Antinociceptive effect of MAS MT in rats
MAS MT is a myotropic decapeptide isolated from Manduca sexta.
This peptide exerts stimulatory effect on insects heart-beat frequency. The present
study was undertaken in order to determine a probable antinociceptive effect in
rats of native synthetic decapeptide, MAS MT-I and its two analogs, heptapeptides
MAS MT-II and MAS MT-III. All these peptides were applied directly into the
lateral brain ventricle (icv) at three doses: 10, 25 and 50 nmol. The analgesic
(antinociceptive) effect was evaluated by a tail immersion test. It was found that
two doses of MAS MT-I: 25 and 50 nmol induced significant antinociceptive
effect, while MAS MT-II and MAS MT-III exert a less antinociceptive effect in
comparison with native MAS MT-I. Prior icv administration of naloxone, an opioid
antagonist weakly blocked MAS MT-I effect. We conclude that antinociceptive
effect of MAS MT-I in rats is not mediated by central opioid system
Effects of arginine substitutions on the cardioinhibitory activity of the Led-NPF-I neuropeptide
Effects of structural changes on the cardioinhibitory activity of the
Led-NPF-I peptide (Ala-Arg-Gly-Pro-Gln-Leu-Arg-Leu-Arg-Phe-amide) were
examined by replacing Arg residues in positions 2, 7 and 9. Replacement of L-Arg2
with another basic amino acid, such as Lys, His or D-Arg, did not abolish but rather
promoted cardioinhibitory activity in giant mealworm beetle Zophobas atratus Fab.
Agonistic peptides were also obtained by substitution of Arg residue in position
7 with Lys or D-Arg, and Arg in position 9 with His or D-Arg, respectively. All
these analogues showed stronger cardioinhibitory effects than the native peptide at
low concentration (10-9 M), and [Lys7]-, [D-Arg7]- and [D-Arg9]-Led-NPF-I also
at the higher concentration (10-6 M). However, substitutions of the Arg residues in
position 7 with His or in position 9 with Lys caused a loss of the cardioinhibitory
activity. In addition, the replacement of Arg residues in all three positions with Lys
or Orn caused a reduction of cardioinhibitory activity, although a single substitution
of Arg in positions 2 or 7 with Lys yielded agonistic peptides. We conclude that the
Arg2 position in the N-terminal region is more tolerant to structural modification
than the other two Arg positions located in the C-terminal region