20 research outputs found
Conformational study and reassessment of the vibrational assignments for Norspermidine
The present study presents and discusses the conformational preferences of Norspermidine (NSpd). The effects of varying the dielectric constant on the conformational preferences are discussed, with a view to infer which conformation will correspond to the most stable in the pure condensed liquid phase. Within the same context, a set of NSpd-NH3 molecular adducts were simulated in order to determine the relevance of intermolecular hydrogen bonding on the overall stability and relative positioning of the respective vibrational frequencies. The calculations presently performed allowed a reassessment of the vibrational assignments for NSpd. A full assignment of the NSpd vibrational spectra is presented, with special emphasis being given to the vibrational modes that proved to be most affected by hydrogen bonding. The various inconsistencies of a prior study found in the literature were identified and rectified
Conformational analysis of a trihydroxylated derivative of cinnamic acid—a combined Raman spectroscopy and Ab initio study
Caracterização do gene vip3A e toxicidade da proteína Vip3Aa50 à lagarta-do-cartucho e à lagarta-da-soja
Helianthus tuberosus and polyamine research: past and recent applications of a classical growth model
The earlieststudiesconcerningpolyamines(PAs)inplantswereperformedbyusing in vitro cultured
explantsof Helianthustuberosus dormanttuber.Thisparenchymatissuewasparticularlyusefulduetoits
susceptibility toseveralgrowthsubstances,includingPAs.Duringtuberdormancy,PAlevelsaretoolowto
sustaincelldivision;thus Helianthus representsanaturalPA-deficient model.Whencultivated in vitro in
the presenceofauxins, Helianthus tuber dormantparenchymacellsattheG0 stage starttodivide
synchronously acquiringmeristematiccharacteristics.Therequirementforauxinstoinducecelldivision
can besubstitutedbyaliphaticPAssuchasputrescine,spermidineorspermine.Cylindersorslicesof
explantedhomogeneoustuberparenchymawereculturedinliquidmediumforshort-termstudiesonthe
cell cycle,oronsolidagarmediumforlong-termexperiments.Morphologicalandphysiologicalmodificationsofsynchronouslydividingcellswerestudiedduringthedifferentphasesofthecellcycleinrelat
on
to PAsbiosynthesisandoxidation.Long-termexperimentsledtotheidentification ofthePAsasplant
growthregulators,asthesolenitrogensource,astuberstoragesubstancesandasessentialfactorsfor
morphogeneticprocessesandcellhomeostasis.Morerecentlythissystemwasusedtostudytheeffectson
plant cellproliferationofplatinum-orpalladium-deriveddrugs(cisplatinandplatinumorpalladiumbi-
substitutedspermine)thatareusedinhumancancercelllinesasantiproliferativeandcytotoxicagents.
CisplatinwasthemostactivebothincellproliferationinhibitionandonPAmetabolism.Similarexperi-
ments wereperformedusingthreeagmatineanalogous.Differenteffectsofthesecompoundswere
observedoncellproliferation,freePAlevelsandenzymeactivities,leadingtoahypothesisofacorrelation
between theirchemicalstructureandtheagmatinemetabolisminplant