Bacterial Growth Stimulation and Antifungal Effects Of The Essential-oil-less-extracts Of The Food Spice Dysphania ambrosioides

Abstract

1D. ambrosioides leaves (DaL) are utilized as food spice. DaL infusion is utilized as antihelminthic in traditional medicine, the extracted essential oil (EO) has been repurposed as biopesticide, in vitro activities include nematocidal and phytotoxic activities by hydrophillic compounds from leaves and the roots. As Da might be a good candidate for circular economy, more potential applications of the essential-oil-less-Da extracts were pursued by applying green chemistry based extraction methods. DaL extracts were prepared by the autoclave method for the sterile-essential-oil-less aqueous extract (SALAEL-Da), butanol fractionating for saponins extraction (SAP) and ethanol boiling method for the saponin-free extract (EtOH-Da). Their effects over clinical isolates of fungi (Candida albicans / CA), gram-negative bacteria (Erwinia carotovora / ErC) and -positive (Methicillin resistant Staphylococcus aureus USA 300 / MRSA-USA-300). were explored. The raw extracts stimulated the bacterial growth of all strains in the pre-screening phase. SALAEL-DaL (at 25 mg/mL) estimulated ErC growth, reducint its doubling time by 35%, microdilutions of EtOH-DaL (at 180 mg/mL) stimulated the growth of MRSA-USA-300 even in the GEN presence at sub-lethal concentrations (MICGEN=1.75{micro}g/mL). SALAEL-Da (at 137 mg/mL) inhibited the growth of CA in agar dilutions, and its fraction SAP showed a moderated fungistatic effect at 100 mg/mL in disk diffusion pre-screening tests. SAP fraction may partially account for the observed antifungal activity. The essential-oil-less-Da aqueous extracts analyzed contained bacterial growth stimulating and antifungal components. Further investigation may lead to commercial opportunities for probiotics and antifungals. 2 ImportanceThe leaves of D. ambrosioides (Da) are utilized as food spice and its infusion as antihelminthic in Latin American folk medicine, with a wide variety of in vitro bioactivities reported. The most studied is Da essential oil (Da-EO) and has been repurposed as insect repellent and pesticide. Which would leave the extracted plant material as a potential raw material for other products. Additionally, Da could be an interesting candidate tobe produced at high-scale in rural communities. The ecofriendly extraction processes yielded an aqueous extract (free of the EO) that enhances the bacterial growth rate of two bacterial strains, which can eventually be useful in the probiotics industry. This extract also inhibited the growth of the opportunistic fungi Candida albicans, becoming a potential source of new antifungals. Further investigation may lead to a circular economy of the agroindustry around D. ambrosioides, probiotics and antifungals, among others.