Catechin, taxifolin, and proanthocyanidin derivatives from Entada elephantina rhizome and their antimicrobial activity assessment

Authors: ZULFIQAR, FAZILA - University Of Mississippi; PANDEY, PANKAJ - University Of Mississippi; ALI, ZULFIQAR - University Of Mississippi; WANG, YAN-HONG - University Of Mississippi; VILJOEN, ALVARO - Tshwane University; CHITTIBOYINA, AMAR - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi

Submitted to: Fitoterapia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2025
Publication Date: 2/7/2025
Citation: Zulfiqar, F., Pandey, P., Ali, Z., Wang, Y., Viljoen, A.M., Chittiboyina, A.G., Khan, I.A. 2025. Catechin, taxifolin, and proanthocyanidin derivatives from Entada elephantina rhizome and their antimicrobial activity assessment. Fitoterapia. 182(2025):106417. https://doi.org/10.1016/j.fitote.2025.106417.
DOI: https://doi.org/10.1016/j.fitote.2025.106417

Interpretive Summary: Entada elephantina (Burch.) S.A.O’Donnell & G.P.Lewis (Synonym: Elephantorrhiza elephantina (Burch) Skeels) (Fabaceae), commonly known as elephant’s root, eland’s bean, eland’s wattle (English); elandsboontjie, (Afrikaan), mupangara (Shona), mositane (sotho,Tswana), intolwane (Xhosa, Zulu), is widely used by indigenous communities in Southern Africa for food, medicine, and dyeing materials. The tuberous rhizomes of E. elephantina, resembling sweet potatoes are widely used in traditional medicine for treating various metabolic and infectious diseases in both humans and livestock. In South Africa, particularly in the Eastern Cape province, there is a strong market for E. elephantina as a herbal medicine. In animal studies, E. elephantina extracts have demonstrated antiparasitic and anti-tick-borne disease activities. An aqueous extract of E. elephantina roots at doses of up to 1600 mg/kg body weight did not cause acute toxicity in the Wistar rats, but higher doses caused a decreased respiratory rate. Diverse classes of compounds including flavonoids, anthocyanidins, anthraquinones, fatty acids, sterols, saponins, tannins, phenolic compounds, sugars, and triterpenoids have been detected from rhizome extracts of E. elephantina. Previous phytochemical studies of E. elephantina were based on spectrometric techniques such as Fourier transform infrared (FTIR), attenuated total reflection (ATR), gas chromatography mass spectrometry (GC-MS), and liquid chromatography electron spray ionization mass spectroscopy (LC-ESI-MS). The limited number of purified chemical constituents from this medicinal plant encouraged us to investigate it further to isolate potential compounds, that could be used as plant specific markers. As a result, 22 specialized metabolites, including five undescribed taxifolin derivatives and one undescribed proanthocyanidin derivative, were isolated from the methanol extract of E. elephantina rhizomes.

Technical Abstract: Twenty-two compounds, predominantly catechin, taxifolin, and proanthocyanidin derivatives, were isolated and characterized from the methanol extract of Entada elephantina tuberous rhizomes. Five taxifolin-based metabolites, elephantinosides A–E and one proanthocyanidin, elephantinoside F, were previously undescribed. Their structures were elucidated primarily based on 1D- and 2D-NMR and HRESIMS data. The absolute configuration of isolates was determined via NOESY NMR technique and experimental and calculated ECD analyses. None of the isolated compounds exhibited antimicrobial activity against a panel of bacterial and fungal strains.