## 1 Introduction  
The revolutionary development of green technology has made a significant impact on the extraction of natural compounds with use potential for the pharmaceutical industry, due to the development of green extraction methods [1] such as ultrasound extraction. Ultrasound-assisted extraction (UAE) is environmentally friendly because it avoids or reduces the use of organic solvents in the obtention of bioactive compounds, reduces processing time, intensifies heat and mass transfer transport, increases extraction yield, preserves a better extract quality, and reduces energy consumption and CO\({}_{2}\) generation [2; 3; 4]. Green extraction techniques, such as supercritical fluid extraction (SFE), ultrasound-assistedextraction (UAE), and microwave-assisted extraction (MAE), among others, are efficient methods of extracting phytochemicals. This is one of the reasons why many extracts are more bioactive than those extracted by conventional methods [5; 6; 7].  
Some of the main causal agents of dermatophytosis and onychomycosis are the molds _Trichophyton mentagroophytes_ and _T. rubrum_, and the yeast _Candida albicans_[8; 9; 10; 11], while the bacteria _Staphylococcus aureus_ is one of the main causal agents of nosocomial infections [12; 13; 14]. The persistence of these infections is associated with the resistance acquired by microbial strains to commercially available antimicrobials. This situation has become a global public health problem. Infections associated with resistant microbial strains cause about 700,000 deaths per year in the world and, by 2050, they could reach 10 million deaths [15]. Consequently, the search for therapeutic alternatives to treat the causal agents of infectious diseases is a necessity [16; 17], as well as research to identify and elucidate new molecules with antimicrobial potential [18]. Some plant species used in traditional medicine may be a source of molecules with this type of activity.  
_Agave unusaviorum_ A. Garcia-Mend., a species previously confused with _A. potatorum_ [PERSON], is a Mexican endemism that grows in the mountains of the high Mixteca of Oaxaca, where it is locally known as \"papalometl\", \"papalome\" and \"yavi-ticushi\" (Mixtec). In this region, the species is used for artisanal mezcal production, food, and medicinal purposes [19; 20]. An infusion of _A. unusaviorum_ leaves is consumed orally for the treatment of onychomycosis and some problems related to inflammatory processes (documented by the authors). In addition, the cooked or roasted leaves of this plant are applied in the form of a poultice to alleviate the inflammation caused by bumps and falls [19; 20; 21].  
Although _A. unusaviorum_ is a plant used in traditional medicine, the species lacks phytochemical or biological studies that validate its medicinal use. Therefore, it constitutes a valuable and promising natural resource to obtain novel and effective secondary metabolites for the treatment of pathogenic microorganisms that affect humans. Due to the use of _A. unusaviorum_ in the traditional medicine for diseases of fungal and bacterial etiology, evaluating its antimicrobial potential will be interesting. This work aimed to investigate the antimicrobial activity of the hydroethanolic extract obtained by UAE from leaves of _A. unusaviorum_ against pathogenic species with worldwide clinical relevance for humans, such as _Staphylococcus aureus_, and species of _Candida_ and _Trichophyton_.