Anthraquinones from the Roots of Kniphofia insignis and Evaluation of Their Antimicrobial Activities

Abstract

Sequential extraction using a cold maceration method and column chromatographic separation of the roots Kniphofia insignis headed to the isolation of three anthraquinones: one monomeric anthraquinone (1) and two dimeric anthraquinones (2 and 3). It was further purified by Sephadex LH-20 and recrystallized. The structures of these compounds were established based on the spectroscopic analyses including NMR (1H-NMR and 13C-NMR and infrared) and comparison with reported literatures. In an in vitro antimicrobial assay of the crude extracts, the isolated compounds were made against four bacterial strains (S. aureus ATCC 25923, B. subtilis ATCC 6633, E. coli ATCC 35218, and P. aeruginosa ATCC 27853) and Fusarium spp. fungal strain. In the crude extracts of chloroform, substantial antimicrobial activity was seen with the highest activity against B. subtilis (16 mm) and E. coli (22 mm). Meanwhile, compound 1 has a better zone of inhibition with 14 mm against P. aeruginosa, whereas compound 2 showed better activity (13 mm) against Fusarium spp. fungal strain.

A comprehensive review of the ethnomedicine, phytochemistry, pharmacological activities of the genus Kniphofia

“…Helmantosporine ( 9 ) was isolated from the acetone fraction of Kniphofia insignis roots and tested for antibacterial and antifungal properties (Tadesse et al. 2021 ). The anti-inflammatory potential of the compound chrsophanol ( 5 ), which was obtained from the methanol crude extract fraction of Kniphofia reflexa rhizome, was also investigated (Sema et al.…”

“…The antibacterial and antifungal properties of asphodeline ( 10 ) derived from the acetone fraction of Kniphofia insignis roots were investigated (Tadesse et al. 2021 ). Microcarpin ( 11 ) was isolated from the rhizomes of a methanol extract of Kniphofia reflexa and tested for cytotoxicity on the LLC-MK2 Monkey Kidney Epithelial cell line using the MTT assay with Gleevec (Imatinib) as a positive control.…”

“…The reported compounds helmantosporine ( 9 ) and asphodeline ( 10 ) were found to inhibit Gram-positive and Gram-negative bacteria with zones of inhibition ranging from 11 to 15 mm, with helmantosporine ( 9 ) having the maximum activity (15 mm) against P. aeruginosa (Tadesse et al. 2021 ). Using the agar disc diffusion method and gentamicin as a positive control, Meshesha et al.…”

“…Helmantosporine ( 9 ) and asphodeline ( 10 ) were also shown to be effective against Fusarium spp ., with zones of inhibition of 12 and 13 mm, respectively (Tadesse et al. 2021 ).…”

In Vitro and in Vivo Evaluation of the Antimalarial Activities of Kniphofia reflexa Hutchinson ex Codd

“…6 Because of the use of Kniphofia reflexa Hutchinson ex Codd. Asphodelaceae in the treatment of relapsing fevers, supported by literature data on the antiplasmodial activities within classes of natural products like terpenes, [7][8][9][10] flavonoids, [11][12][13] alkaloids, [14][15][16][17] quassinoids, 7,18 xanthones, [19][20][21][22] quinones, and anthraquinones, [23][24][25][26][27][28][29] a needed study of this plant was conducted considering its unique endemic nature, coupled to its classification. To the best of our knowledge, no study is reported on the antiplasmodial and antimalarial potential of chemical constituents of K reflexa.…”