Alkaloids and Phenolic Compounds from Sida rhombifolia L. (Malvaceae) and Vasorelaxant Activity of Two Indoquinoline Alkaloids

Abstract

The follow-up of phytochemical and pharmacological studies of <i>Sida rhombifolia</i> L. (Malvaceae) aims to strengthen the chemosystematics and pharmacology of <i>Sida</i> genera and support the ethnopharmacological use of this species as hypotensive herb. The present work reports phytoconstituents isolated and identified from aerial parts of <i>S. rhombifolia</i> by using chromatographic and spectroscopic methods. The study led to the isolation of scopoletin (<b>1</b>), scoporone (<b>2</b>), ethoxy-ferulate (<b>3</b>), kaempferol (<b>4</b>), kaempferol-3-<i>O</i>-β-d-glycosyl-6''-α-d-rhamnose (<b>5</b>), quindolinone (<b>6</b>), 11-methoxy-quindoline (<b>7</b>), quindoline (<b>8</b>), and the cryptolepine salt (<b>9</b>). The alkaloids quindolinone (<b>6</b>) and cryptolepine salt (<b>9</b>) showed vasorelaxant activity in rodent isolated mesenteric arteries.