Morphoanatomical and physicochemical profile of Piper callosum: valuable assessment for its quality control

Piper callosum Ruiz & Pav., Piperaceae, popularly known as “elixir-paregórico” and “matricá” in Brazil, is used in folk medicine to treat gonorrhea, general pain, and digestive disorders, and has repellent, astringent, diuretic, depurative, and haemostatic properties. Despite the fact that this plant is sold as a traditional phytotherapeutic product, we did not find reports on its quality control. We, therefore, performed macroscopic, microscopic, histochemical, and physicochemical analyses using standard methods to establish botanical authentication and purity degree parameters for leaves and stem of this species in two forms: medicinal plant and herbal drug. We observed the size, shape, color, texture, fracture surface and transection characteristics, leaf venation patterns, and calluses are valuable diagnostic characters to identify the herbal drugs when they are not ground or powdered. Since medicinal plants and herbal drugs did not differ anatomically, the following key anatomical characters for P. callosum can be used for diagnostic purposes of both types raw plant materials: epicuticular wax and cuticular flanges patterns; collenchyma features; fibers in the midrib; arrangement pattern of the vascular bundles of the midrib and petiole; shape of the midrib, leaf margin, petiole, and stem; occurrence of raphides; and morphology of the starch grains. Acid lipids, essential oils, oleoresins, steroids, tannins and flavonoids were histochemically identified. Total ash (leaves: 11.25%; stem: 5.25%), sulphated ash (leaves: 68.02%; stem: 12.50%), acid-insoluble ash (leaves: 2.82%; stem: 0.27%), moisture (leaves: 8.60%; stem: 6.10%), loss on drying (leaves: 11.08%; stem: 8.58%), and pH (leaves: 5.57, stem: 5.28) values were determined. The order of analyzed metal levels in leaf and stem herbal drugs was Al > V > Cu > Mn > Cr > Ni. Similar levels of Cd and Co and low levels of Hg were found. The results obtained can be used as quality control parameters for medicinal plants and herbal drugs of P. callosum.