Hrivera, Plectranthus vettiveroides, is a medicinal plant. The roots of this less common vetiver are used to reduce high blood pressure in Siddha medicine, a traditional system in South India.
Image: Nisheeda Basheer
But does the treatment really work?
Researchers from the SASTRA Deemed University, Thanjavur and the Ayya Nadar Janaki Ammal College, Sivakasi set out to test.
They isolated essential oils, responsible for a plant’s scent and flavour, from the roots of the plant by hydro-distillation – passing steam through the plant material.
Using gas chromatography, they identified 60 volatile compounds in essential oil from Hrivera roots.
The team prepared a nanoemulsion with the essential oil by agitating it with a liquid that lowered the surface tension between the two liquids. The nanoemulsion, with suspended colloidal particulates of submicron size, acted as a carrier for the volatiles in the essential oil.
To check whether the formulation had any relaxing effect on blood vessels, they applied various concentrations of the nanoemulsion on rat aortic rings.
“These sections of main blood vessels from rats are routinely used to identify plant metabolites that influence blood vessels,” explains Govinda Rajan Sailaja, SASTRA Deemed University, Thanjavur.
The nanoemulsion had significant vasorelaxant effect on the aortic rings.
Most vasorelaxants used in clinical medicine act by blocking calcium channels. Does the root extract from Hrivera work in the same way, wondered the team.
To find out, the researchers first contracted aortic rings by adding extracellular calcium. Then, they treated the contracted rings with the nanoemulsion. The aortic rings dilated, suggesting that the nanoemulsion acts as a calcium channel blocker.
Medications that disrupt the movement of calcium through calcium channels can directly influence the biosynthesis of aldosterone. The hormone, produced in the cortex of the adrenal glands, plays a central role in regulating blood pressure.
“Siddha texts do not tell us how to use the essential oil from Hrivera roots to treat blood pressure,” says Ramar Murugan, Ayya Nadar Janaki Ammal College, Sivakasi.
We still need to find the right doses of essential oils for animal and human trials. And there is another challenge: out of the sixty volatiles in the essential oil, which ones block calcium channels?
Journal of Ethnopharmacology, 274: 114048 (1-10) (2021):
STEAMindiaReports: Distilling complex science for the essential oil to lubricate your mind
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