In vitro activities of crude extracts and triterpenoid constituents of Dichapetalum crassifolium Chodat against clinical isolates of Schistosoma haematobium

The dichapetalins and dichapetalin-type compounds: structural diversity, bioactivity, and future research perspectives

Covering mainly from 2013 up to 2023 with relevant references to work done before 2013First reported in 1995, the dichapetalins and analogous compounds constitute a novel class of natural dammarane-type merotriterpenoids characterized by their unique 2-phenylpyrano moiety annellated to ring A of the dammarane skeleton. They have been reported from only two genera: Dichapetalum (Dichapetalaceae) and Phyllanthus (Phyllanthaceae). About 100 novel dichapetalins and dichapetalin-type compounds, including the acutissimatriterpenes and their antitumour and other bioactivities have been reported. In the present review, we cover the distribution, ethnobotanical and medicinal importance and the diversity of secondary metabolites reported from the two genera Dichapetalum and Phyllanthus from 2013 to date, with appropriate reference to relevant information prior to 2013. We also propose and discuss possible biosynthetic pathways, antitumour activity against a broad range of human and murine cancer cell lines, structure activity relationships, and other biological activities and mechanisms of action. Finally, the review deals with future perspectives which include expansion of the structural diversity and bioactivity scope, possible simplification of the structural complexity of the compounds to enhance their drug-likeness, in silico studies, and continuation of the search for new dichapetalins and dichapetalin-type compounds from the over 200 Dichapetalum and over 1200 Phyllanthus species yet to be investigated. It is envisaged that the present review will stimulate further multidisciplinary and interdisciplinary studies.

Ethnobotanical Survey and Cercaricidal Activity Screening of Medicinal Plants Used for Schistosomiasis Treatment in Atwima-Nwabiagya District, Ashanti Region, Ghana

This study focused on documenting and evaluating the cercaricidal activity of medicinal plants used for schistosomiasis treatment in an endemic area in Ghana. Through semistructured questionnaires, personal interviews with herbalists in communities surrounding the Barekese dam in the Atwima-Nwabiagya district, where the disease is endemic, were carried out. Thirty medicinal plants distributed in 19 families were reported to be used for schistosomiasis treatment in the survey. Information on the plants, including scientific names, common names, families, and the used plant part were recorded. The families Apocynaceae and Euphorbiaceae recorded the highest number of plants (14% each), followed by Asteraceae (10%), Loranthaceae (7%), and Rubiaceae (7%). In vitro cercaricidal activity of methanol extracts of nine out of the thirty plants was performed by exposing human Schistosoma mansoni cercariae obtained from Biomphalaria pfeifferi to various concentrations of extracts over a duration of 240 minutes. All the plants tested demonstrated time- and concentration-dependent cercaricidal activity. With lethality being set at <1000 μg/mL, the cercaricidal activity in order of decreasing potency was as follows: Withania somnifera (LC₅₀ = 1.29) > Balanites aegyptiaca (LC₅₀ = 7.1) > Xylia evansii (LC₅₀ = 11.14) > Jathropha multifida (LC₅₀ = 12.9) > Justicia flava (LC₅₀ = 22.9) > Anopyxis klaineana (LC₅₀ = 182.81) > Ximenia americana (LC₅₀ = 194.98) > Loranthus lecardii (LC₅₀ = 223.87) > Bridelia tenufolia (LC₅₀ = 309.03) > Zanthoxylium zanthoxyloides (LC₅₀ = 851.94). Phytochemicals, including alkaloids, tannins, triterpenes, saponins, phytosterols, and flavonoids were identified in the plants. The result of this study gives scientific credence to the traditional use of these plants in the treatment of schistosomiasis and proves that the rich botanical knowledge of medicinal plants provides an incredible starting point for the discovery of new anti-schistosomal drugs for the local population.

Antimicrobial and in silico studies of the triterpenoids of Dichapetalum albidum

Here we report a new polyhydroxylated triterpene, 2β,6β,21α-trihydroxyfriedelan-3-one (4) isolated from the root and stem bark of Dichapetalum albidum A. Chev (Dichapetalaceae), along with six known triterpenoids (1-3, 5, 6, 8), sitosterol-3β-O-D-glucopyranoside (9), a dipeptide (7), and a tyramine derivative of coumaric acid (10). Friedelan-3-one (2) showed an antimicrobial activity (IC50) of 11.40 μg/mL against Bacillus cereus, while friedelan-3α-ol (1) gave an IC50 of 13.07 μg/mL against Staphylococcus aureus with ampicillin reference standard of 19.52 μg/mL and 0.30 μg/mL respectively. 3β-Acetyl tormentic acid (5) showed an IC50 of 12.50 μg/mL against Trypanosoma brucei brucei and sitosterol-3β-O-d-glucopyranoside (9) showed an IC50 of 5.06 μg/mL against Leishmania donovani with respective reference standards of IC50 5.02 μg/mL for suramin and IC50 0.27 μg/mL for amphotericin B. Molecular docking of the isolated compounds on the enzyme glucose-6-phosphate dehydrogenase (G6PDH) suggested 3β-acetyl tormentic acid (5) and sitosterol-3β-O-D-glucopyranoside (9) as plausible inhibitors of the enzyme in accordance with the experimental biological results observed.

Towards understanding antimicrobial activity, cytotoxicity and the mode of action of dichapetalins A and M using in silico and in vitro studies

Dichapetalum madagascariense Poir (Dichapetalaceae) is traditionally used to treat bacterial infections, jaundice, urethritis and viral hepatitis in Africa. Its root contains a broad spectrum of biologically active dichapetalins. To evaluate the plant's effect on human MCF-7 cells and its' antibacterial and antiparasitic potentials, we isolated and identified the known dichapetalins A and M from the roots. Both dichapetalins were tested on six bacterial strains (Shigella flexneri, Bacillus cereus, Salmonella paratyphi B, Listeria monocytogenes, Escherichia coli, Staphylococcus aureus) and two parasite strains; Trypanosoma brucei brucei, and Leishmania donovani using the Alamar Blue assay system. Dichapetalins A and M were more potent against B. cereus with IC₅₀ values of 11.15 and 3.15 μg/ml, respectively, compared to the positive control ampicillin (IC₅₀ = 19.50 μg/ml). Dichapetalins A (IC₅₀ = 74.22 μg/ml) and M (IC₅₀ = 72.34 μg/ml) were less active against T. b. brucei, compared to the standard Suramin (IC₅₀ = 4.96 μg/ml). Dichapetalin M showed moderate activity against L. donovani (Amphotericin B: IC₅₀ = 0.21 μg/ml) with an IC₅₀ of 16.80 μg/ml. In human MCF-7 cells expressing the NR1I2 receptor, the activity of dichapetalin M was higher (IC₅₀ = 4.71 μM and 3.95 μM) for 48 and 72 h of treatment, respectively compared to Curcumin with IC₅₀ of 17.49 μM and 12.53 μM for 48 and 72 h of treatment, respectively. Results from in vitro expression studies with qPCR confirmed an antagonistic effect of dichapetalin M on PXR (NR1I2) signaling; supporting the PXR signaling pathway as a possible mode of action of dichapetalin M as predicted by in silico results. These findings confirm previous studies that D. madagascariense can be a source of potential lead compounds for development of novel antibiotic, antiparasitic and anticancer medicines, and provide further insights into the mechanism of action of the dichapetalins.