Estudo químico e biológico das espécies Manekia obtusa E. Piper cubataonum (Piperaceae) e síntese de estigmast-4-EN-3-ONA, (S)-Aegelina E (R)-6'-Desmetoxi Aegelina
Date
2014Author
Santos, Thalita Gilda
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TeseAbstract
Resumo: No presente trabalho foi determinada a composicao quimica do oleo essencial das
partes aereas de Manekia obtusa e das folhas e galhos de Piper cubataonum, atraves de
CG-EM e CG~CG. A analise por CG-EM revelou para o oleo essencial de M. obtusa 22
constituintes, sendo majoritariamente formado por sesquiterpenos oxigenados. Para o
oleo essencial das folhas e galhos de P. cubataonum, foi possivel identificar 14 e 20
constituintes, respectivamente, sendo que ambos os oleos apresentam os alilfenois,
dilapiol e apiol, como majoritarios. Atraves da analise por CG~CG, foi possivel
caracterizar 128 constituintes diferentes dos tres oleos essenciais analisados, sendo 80
constituintes nas partes aereas de M. obtusa, 57 e 66 constituintes nas folhas e galhos de
P. cubataonum, respectivamente. Realizou-se o estudo fitoquimico do extrato
diclorometanico das partes aereas de M. obtusa, resultando no isolamento de cinco
substancias: duas amidas, aegelina (MO 1) e cinamamida (MO 2), uma mistura dos
esteroides ƒÀ-sitosterol e estigmasterol (MO 3A e MO 3B) e o esteroide estigmast-4-en-3-
ona (MO 4). O estudo fitoquimico do extrato metanolico das raizes de P. cubataonum
resultou no isolamento de onze substancias, sendo quatro alilfenois: miristicina (PCR 1),
apiol (PCR 2), dilapiol (PCR 3) e elemicina (PCR 4); duas lignanas: rel-(7R,8S,7fS,8fS)-
4f,5f-metilenodioxi-3,4,5,3f-tetrametoxi-7,7f-epoxilignana (PCR 5) e epigrandisina (PCR 6);
duas aristolactamas: cefaranona B (PCR 7) e piperolactama A (PCR 8); e tres esteroides
ja isolados anteriormente de M. obtusa, sendo uma mistura de ƒÀ-sitosterol e estigmasterol
(MO 3A e MO 3B) e o estigmast-4-en-3-ona (MO 4). As atividades antimicrobianas e
citotoxidade foram avaliadas para os extratos e oleos essenciais, onde se destaca a forte
atividade antimicrobiana do extrato diclorometanico e do oleo essencial de M. obtusa
contra Candida albicans, sendo superiores ao medicamento de referencia (nistatina)
utilizado. Para o estudo da atividade inseticida, realizado na Universidade de Nevada,
foram sintetizados os constituintes isolados de M. obtusa, nao disponiveis
comercialmente, neste caso, a estigmast-4-en-3-ona (MO 4) e a amida (S)-aegelina (MO
1), sendo esta ultima sintetizada por duas rotas diferentes. Alem disso, realizou-se a
sintese da (R)-6'-desmetoxi aegelina (analogo da aegelina). Os tres constituintes
sintetizados, juntamente com os demais isolados de M. obtusa (adquiridos
comercialmente) foram submetidos a ensaios de atividade inseticidas frente a Spodoptera
exigua, individualmente ou em misturas. O esteroide MO 4, a mistura das amidas e a
mistura total diminuiram a taxa de sobrevivencia de S. exigua. A amida MO2 e a mistura
das amidas reduziram a massa da pupa e retardaram o desenvolvimento larval.
PALAVRAS-CHAVES: Piper cubataonum; Manekia obtusa; oleo essencial; fitoquimica;
lignanas; aristolactamas; amidas; inseticida; sintese. Abstract: In this study, the chemical composition of the essential oil from the aerial parts of
Manekia obtusa and the leaves and branches of Piper cubataonum were analyzed by GCMS
and GC~GC, separately. The M. obtusa essential oil revealed 22 constituents by GCMS,
which were mainly composed by oxygenated sesquiterpenes. Essential oil from
leaves and branches of P. cubataonum, showed 14 and 20 identified constituents,
respectively and both oils presented the allylphenols, dillapiole and apiole, as main
constituents. The GC~GC analysis characterized 128 different constituents of the three
essential oils, of which 80 were constituents for M. obtusa aerial parts, 57 and 66
constituents for P. cubataonum leaves and branches, respectively. The phytochemical
study of the dichloromethane extract from M. obtusa yielded five substances: two amides,
aegeline (MO 1) and cinnamamide (MO 2), a mixture of steroids ƒÀ-sitosterol and
stigmasterol (MO 3A and MO 3B) and the steroid stigmast-4-en-3-one (MO 4). From
methanol extract of the roots of Piper cubataonum, eleven substances were isolated,
including four allylphenols: myristicin (PCR 1), apiole (PCR 2), dillapiole (PCR 3) and
elemicin (PCR 4); two lignans: rel-(7R,8S,7fS,8fS)-4f,5f-methylenedioxy-3,4,5,3f-
tetramethoxy-7,7f-epoxylignan (PCR 5) and epigrandisin (PCR 6); two aristolactams:
cepharanone B (PCR 7) and piperolactam A (PCR 8) and three steroids previously
isolated from M. obtusa: the mixture of ƒÀ-sitosterol and stigmasterol (MO 3A and MO 3B)
and stigmast-4-en-3-one (MO 4). The antimicrobial and citotoxic activities were evaluated
for the extracts and essential oils. The dichloromethane extract and essential oil of M.
obtusa revealed stronger antimicrobial activity against Candida albicans than the
reference drug used. For the insecticidal activity, performed at the University of Nevada,
the isolated constituents of M. obtusa, (which are not commercially available) were
synthesized, in this case, stigmast-4-en-3-one (MO 4) and the amide (S)-aegeline (MO 1),
the later was synthesized by two different routes. In addition, the synthesis of (R)-6'-
demethoxy aegeline (aegeline analog - NMO 1) was performed. The three synthesized
constituents along with other isolates of M. obtusa (commercially available) were
subjected, individually or in mixtures, to insecticides bioassays against Spodoptera
exigua. The MO 4 steroid, the amide mixtures and the total mixture decreased survival
rate of S. exigua. The amide MO 2 and the amide mixtures reduced pupal mass and
increased the period of larval development.
KEY-WORDS: Piper cubataonum; Manekia obtusa; essential oil; phytochemistry; lignans;
aristolactams; amides; insecticide; synthesis.
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