Ethnomedicinal, Phytochemical and Pharmacological Investigations of Tetradenia riparia (Hochst.) Codd (Lamiaceae)

Abstract

Tetradenia riparia Hochsteter codd. (Lamiaceae) in its native African continent, is considered one of the most popular aromatic medicinal plants. In folk medicine it may be used as an infusion to treat respiratory problems, cough, headache, stomach pain, diarrhea, fever, malaria, and dengue; and in the form of compresses it is applied for the relief of headaches and toothaches. The species T. riparia has been researched for decades to isolate and identify chemical constituents present in extracts or essential oil obtained from the leaves, floral buds, or stems of this plant. The present study reviews the scientific literature on ethnomedicinal, phytochemical, and pharmacological aspects of T. riparia. We discuss issues related to the botanical and geographical description of the species, ethnobotanical uses, phytochemical studies on its essential oil and extracts, and biological activities of T. riparia. Several compounds have already been isolated from leaves, such as ibozol, 7α-hydroxyroileanone, 1',2'-dideacetylboronolide, 8(14),15-sandaracopimaradiene-7α,18-diol; 5,6-dihydro-α-pyrone and α-pyrone. Terpenes predominated in the essential oil, comprising monoterpenes, sesquiterpenes, diterpenes, hydrocarbons, and oxygenates. Most phytocompounds were isolated from the leaves and flower buds, namely fenchone, 14-hydroxy-9-epi (E)-caryophyllene, 9β, 13β-epoxy-7-abietene, and 6,7-dehydroroileanone. These compounds provide the species a high pharmacological potential, with antimicrobial, antioxidant, antitumor, analgesic, anti-leishmania, anti-tuberculosis, and anti-parasitic activities. Therefore, this species is a promising herbal medicine.

Keywords: 14-hydroxy-9-epi(E)-caryophyllene; 6,7-dehydroroileanone; 8(14),15sandaracopimaradiene-7 α, 18-diol; computational analysis; diterpenes; ethnopharmacology; traditional folk medicine.

FIGURE 1

T. riparia culture planted in the medicinal garden of Paranaense University. Umuarama, Parana, Brazil. (A): leaves (B): Flower buds (C) Open flowers. Source: the authors.

FIGURE 2

Geographical distribution of T. riparia (Source: Plants of the World Online, Royal Botanic Gardens, Kew. 2022. Licensed under Creative Commons Attribution CC BY).

FIGURE 3

(A) Chemical structure of abietane and royleanone classes of isolated diterpenes from T. riparia. (B) Chemical structure of phytosterols isolated from T. riparia. (C) Chemical structure of α, β-unsaturated δ-lactone moiety-bearing phytoconstituents isolated from T. riparia. (D) Chemical structure of flavonoids isolated from T. riparia.

FIGURE 4

Essential oil obtained by hydrodistillation of T. riparia leaves (A), flower buds (B), and stems (C)—Source: Chemical Laboratory of Natural Products-Paranaense University-UNIPAR, Brazil.

FIGURE 5

Chemical structures of volatile constituents isolated from T. riparia.

FIGURE 6

Fluorescence microscopy. (A–C) Control cells of T. rubrum, T. mentagrophytes and M. gypseum, respectively. (D–F) T. rubrum, T. mentagrophytes and M. gypseum treated with 31.2, 62.5, and 31.2 μg/ml of T. riparia extract, respectively. Scanning Electron Microscopy, (G–I) Control cells of T. rubrum, T. mentagrophytes and M. gypseum, respectively. (J–L) T. rubrum, T. mentagrophytes and M. gypseum treated with one-fold sub-MIC concentrations of T. riparia extract (adapted from Endo et al., 2015 ¹ ).

FIGURE 7

Transmission electron microscopy of L. amazonensis treated with T. riparia essential oil (TrEO) for 24 h. (A) Leishmania promastigotes. (B–F) Promastigotes treated with TrEO (30 ng/ml). N, nucleus; N*, abnormal chromatin condensation nuclear alterations; K, kinetoplast; M, mitochondria; FP, flagellar pocket; F, flagellum; V, vacuoles; LV, lipid vesicles; R, myelin-like figure appears in close association with the flagellar pocket membrane; *membranous profiles; **blebbing; ^#mitochondrial swelling (Adopted from Demarchi et al., 2015 ² ).

FIGURE 8

Protein-ligand interactions of two most potential candidates, stigmasterol and luteolin against selected three candidates. The molecular interactions were presented using the software Discovery studio visualizer.

FIGURE 9

(A–G). Structure-activity relationship analysis among phytochemicals reported from T. riparia with respect to biological activity in the form of generated docking score. The chemical structures are presented with the ChemDraw 18.0 software.