RESUMO
Inhibition of Angiotensin Converting Enzyme (ACE) is a modern therapeutic target in the treatment of hypertension. Within the enzyme cascade of the renin-angiotensin system, ACE removes histidyl-leucine from angiotensin I to form the physiologically active octapeptide angiotensin II, one of the most potent known vasoconstrictors. Therefore, a rationale for treating hypertension would be to administer drugs or natural compounds which selectively inhibit ACE. The present work constitutes a review of the literature of plants and chemically defined molecules from natural sources with in vitro anti-hypertensive potential based on the inhibition of ACE. The review refers to 321 plants, the parts utilized, type of extract and whether they are active or not. It includes also the names of 158 compounds isolated from higher plants, marine sponges and algae, fungi and snake venom. Some aspects of recent research with natural products directed to produce anti-hypertensive drugs are discussed. In this review, 148 references were cited.
A inibição da Enzima Conversora da Angiotensina (ECA) é um alvo terapêutico moderno e eficaz no tratamento da hipertensão arterial. Na cascata enzimática que envolve o sistema renina-angiotensina, a ECA promove a remoção dos aminoácidos histidil-leucina da angiotensina I para formar o octapeptídio angiotensina II, a qual é fisiologicamente ativa em diversos sistemas, e considerado como um dos mais potentes vasoconstrictores endógenos conhecido. Portanto, uma racionalidade no tratamento da hipertensão seria administrar drogas ou compostos de origem natural que inibam seletivamente a ECA. O presente estudo constitui uma revisão da literatura sobre plantas e moléculas de origem natural com potencial anti-hipertensivo, baseado na inibição in vitro da ECA. A revisão referencia 321 plantas, partes usadas, tipo de extrato e se é ativo ou não. Inclui ainda o nome de 158 compostos isolados de plantas superiores, esponjas e algas marinhas, fungos e venenos de cobra. Alguns aspectos de pesquisa recente com produtos naturais direcionados à produção de drogas anti-hipertensivas também são discutidos. Nesta revisão 148 referências foram consultadas.
RESUMO
This study aimed to investigate the anti-hypertensive potential of crude leaf extracts of Pterocarpus indicus (Narra). Hypertension was induced using Epinephrine HCI, 15-20 ug/kg body weight IV in 6 male cats, followed by an administration of Narra leaf extracts with a concentration of 0.25 g/kg BW IV at the peak of the epinephrines hypertensive effect. To test for the possible dose-response effect, the procedure was repeated using 0.5 and 1 g/kg BW IV Narra extracts. The systolic, diastolic and mean arterial blood pressures, pulse pressure, respiratory rate (SBP, OBP, MABP, PP and RR, respectively), respiratory and ECG (Q-R interval) amplitude, and the time for the Narra extract to effect were monitored using GrassO polygraph. Analysis of the data using General Linear Model (GLM) Repeated Measures showed that crude Narra leaf extracts at 0.25, 0.5 and 1 g/kg BW significantly lowered an epinephrine-induced rise in SBP (p=0.001), MABP (p=0.001), PP (p=0.0001) and ECG (Q-R interval) amplitude (p=0.05). However, there was no observed effect on the DBP (p=0.698), HR (p=0.9), RR (p=0.846) and respiratory amplitude (p=0.762). Moreover, no dose-response relationship was observed among the 3 doses of the narra extract on all physiologic parameters mentioned. Also, none of the doses was able to return the MABP to baseline (p=0.053). The observed decline in the SBP may have probably been due to the resultant decrease in the amplitude or force of contraction of the heart. Concomitantly, this may cause a decrease in the anti-hypertensive effect. (Author)