Antihypertensive activity of Azadirachta indica roots

Arterial hypertesion (AH) is a disease that causes damage to the arteries and veins by gradually
changing the flow of blood in the body. In Brazil, the prevalence of AH in the population was
22,7% in 2011. AH treatrement has high costs, based on 2005 data the annual value for the
private and public systems was around US$ 671,6 million (0,08% of PIB for the year). As an
alternative for the treatment of diseases, medicinal plants are used because they have a
structural diversity of their constituents. Species of the Meliaceae family have been studied,
especially the neem (Azadirachta indica A. Juss), being one of the most versatile medicinal
plants, with a broad spectrum of activities. A. indica is one of the largest limonoid bioproducers,
which constitute 1/3 of its chemical composition. Given the above, the objective of this study
was to verify the cardiovascular activity in rats using a fraction of terpenoid rich A. indica roots.
The dried and ground roots were subjected to extraction of the secondary metabolites with
methanol and then partitioned with solvents in increasing order of polarity (CH2Cl2, AcOEt and
ButOH). Classic chromatographic methods were used for the fractionation and isolation of the
compounds present in the species. Structural elucidations were performed by one and two
dimensional Nuclear Magnetic Resonance (1H and 13C NMR) and Mass Spectrometry coupled
to a High Performance Liquid Chromatograph. Eight sedated Wistar rats were used to check
blood pressure for catheter insertion into the carotid artery (blood pressure measurement) and
jugular vein (intravenous infusion at a concentration of 30 mg/kg diluted in DMSO with volume
0.1 mL). Prior to testing, only DMSO was infused at the same dose to serve as a control. A
fraction was selected for the antihypertensive trial, in which four limonoids, Nimbandiol, 6-
acetylnimbandiol, Salannina and 3-acetylsalannol, two coumarins, Scopoletin and Isofraxidine,
and one diterpene, Nimbidiol, were identified. Following intravenous infusion in Wistar rats,
these terpenoids significantly reduced the systolic, median and diastolic blood pressures of
individuals.