Antimicrobial and Cytotoxic Potential of Helminthosporin from Rumex abyssiniscus Jacq. Discovered as a Novel Source of Syringic Acid and Bis(2-ethyloctyl) Phthalate.

Rumex abyssinicus Jacq. is a perennial medicinal herb widely used in traditional medicine to treat many diseases. Phytochemicals of the plant were isolated using column chromatography and thin layer chromatography techniques. Extract, fractions and pure compounds were screened for antimicrobial activity against sensitive and multi-drug resistant microbes and their cytotoxicity was performed on different cancer cell lines. The mechanism of action of purified helminthosporin as well as the potent fraction containing a mixture of two compounds was assessed. Fraction R7C3 was the most potent antibacterial with the lowest MIC value of 0.12 µg/mL. Helminthosporin was the most potent compound with the lowest MIC value of 1.95 µg/mL. The compound was more potent than the antibiotic chloramphenicol against multi-drug resistant (MDR) bacteria with MIC equal to 16 µg/mL. The fraction and helminthosporin were shown to destroy the cell wall of the yeast and bacteria, and DNA fragmentation effect on the genome of Candida albicans and Bacillus cereus. Helminthosporin was the most cytotoxic compound with IC50 ˂ 10 µM. Fraction R7C3 showed the most potent cytotoxic effects on all cancer cell lines, with IC50 ranging from ˂1 to 4.35 ng/mL. Our study is the first report on the mechanism of action of helminthosporin, a potent candidate in the development of new drugs against multi-resistant bacteria and cancer cells. In addition, this study uncovered Rumex abyssinicus as a new source of syringic acid and bis(2-ethyloctyl) phthalate.

A phenanthridin-6(5H)-one derivative and a lanostane-type triterpene with antibacterial properties from Anonidium mannii (Oliv). Engl. & Diels (Annonaceae).

The chemical investigation of Anonidium mannii root extract by column chromatography techniques led to the isolation of eight compounds among which two previously unreported compounds; a lanostane-type triterpene, lanosta-7,9(11),23-triene-3ß,15α-diol 1 and an alkaloid, 9-hydroxy-8-methoxyphenanthridin-6(5H)-one 2 along with six known compounds: lanosta-7,9(11),24-triene-3ß,21-diol 3, oxoanolobine 4, 3, 4-dihydroxybenzoic acid 5, stigmasterol 6, ß-sitosterol 7 and 3-O-ß-D-glucopyranosyl-ß-stigmasterol 8. Their structures were established from spectral data, mainly HR-ESIMS, 1 D and 2 D NMR and by comparison with literature data. The crude root and stem bark extracts (AMR and AMB) and the isolated compounds (1-8) were tested against nine Gram-negative bacteria using rapid p-iodonitrotetrazolium chloride ≥97% (INT) microdilution technique. It was found that AMR, AMB and compound 5 were active against the nine tested bacteria with MIC values ranging from 64 to 1024 µg/mL. Compounds 1-4 had selective antibacterial activities whilst 6-8 were not active.