Faryal Vali Mohammad

Symphytoxide A, a triterpenoid saponin from the roots of Symphytum officinale

A new triterpenoidal saponin of hederagenin named symphytoxide A has been isolated from the ethanolic extract of the roots of Symphytum officinale and characterized on the basis of chemical investigations and spectroscopic studies as 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)- alpha-L-arabinopyranosyl] hederagenin. The structure of this new saponin was established on the basis of 1D and 2D NMR experiments including heteroCOSY, COSY-45 degrees as well as HMBC measurements and other spectroscopic techniques. The saponin exhibited hypotensive activity in anesthetized rats.

Isolation, purification, structural elucidation and antimicrobial activities of kocumarin, a novel antibiotic isolated from actinobacterium Kocuria marina CMG S2 associated with the brown seaweed Pelvetia canaliculata

AIMSnScreening of seaweed-associated bacteria capable of producing antimicrobials.nnnMETHODS AND RESULTSnFifteen microbial strains, associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan), were screened. Crude extract filtrates of CMG S2 strain grew on Zobell marine agar (ZMA) had the most remarkable antimicrobial activity. Based on its phenotypic aspects (e.g. Gram-positive, microccoid form), biochemical characteristics (e.g. halotolerance) and genetic analyses, CMG S2 is identified as a putatively new Kocuria marina type strain belonging to the actinobacterias class and micrococcaceae family. Thereby, the nucleotide sequence analysis of its full-length 16S ribosomal ribonucleic acid (rRNA) gene (GenBank accession number EU073966.1) displayed highest identity (i.e. 99%) and score (2630) with K. marina KMM 3905. Phylogenic trees analysis using the neighbor-joining method showed closest evolutionary distance of CMG S2 with KMM 3905 strain and K. carniphila (DC2201) specie. Interestingly, a unique ultraviolet (UV)-bioactive compound was purified from CMG S2 crude extracts by flash silica gel column and thin-layer chromatography (TLC) techniques. Its chemical structure was unraveled as 4-[(Z)-2 phenyl ethenyl] benzoic acid (PEBA, later named kocumarin) by nuclear magnetic resonance (NMR) spectroscopy techniques. Importantly, kocumarin demonstrated prominent and rapid growth inhibition against all tested fungi and pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA), with a minimal fungal inhibitory concentration (MFC) of 15-25μg/mL and a minimal (bacterial) inhibitory concentration (MIC) of 10-15μg/mL.nnnSIGNIFICANCE AND IMPACT OF THE STUDYnKocumarin represents a new promising natural antibiotic for in vivo and environmental applications.