## 1 Introduction  
Soursop (_Anmonia muricata_ L. or _A. muricata_) is a good source of bioactive compounds such as polyphenols, acetogenins, and alkaloids [1; 2; 3; 4]. Polyphenols and acetogenins are widely investigated in the _A. muricata_ plant. However, alkaloids (ALKs) from _A. muricata_ by-products are little studied. The biological activity of ALKs has been studied since the 19 th century, and they have been used in medicine as anesthetics and analgesics. However, some plants are known to produce toxic ALKs. Therefore, it is necessary to determine the content and type of ALKs present in the herbs or plants to find their potential use in pharmacology [5]. Isoquinoline ALKs (assimilobin, normuciferin, annoain, reticulin, and others) have been extracted from _A. muricata_ leaves, roots, seeds, and pulp and these compounds have been shown to have analgesic, antidepressant, cutotoxic, antitumor, antineoplastic, antiplatelet, and dopaminergic activities [2; 6; 7; 8; 9]. These ALKs are involved in major behavioral disorders such as schizophrenia, Huntington's disease, attention deficit hyperactivity disorder, and Parkinson's disease. Precisely, alkaloids with (R)-apomorphine groups, aporin semi-synthesized from morphine, have been used in the clinic for treating [PERSON]'s disease [10; 11; 12]. Likewise, it has been demonstrated that these alkaloids have an affinity for 5-HT1A receptors in vitro and participate in the biosynthesis of dopamine. It has been proposed that Annone-derived alkaloids could induce antidepressant type effects and cytotoxic activity [6; 7]. However, there are no reports on the content and type of ALKs present in the other parts of _A. muricata_ that are considered as by-products such as the peel or columella of the soursop fruit. Ultrasound-assisted extraction (UAE) is a technology that has been widely used in recent years to extract bioactive compounds from different plants. The mechanism of action of the UAE is to produce cavitation that causes structural changes in the plant material by facilitating the extraction of compounds [13; 14]. Ultrasound offers advantages that can improve extraction, reduce compound degradation, and processing time compared to heat extraction methods [15; 16]. Ultrasonic cavitation allows for high diffusion of extraction solvents, higher mass transfer, and greater plant cell decomposition more than maceration, heating, and the soxhlet method (liquid-solid extraction) [13; 14; 17]. However, the utility or potential of the UAE depends on factors such as: the type of metabolite, the raw material, or the food matrix. Therefore, research on optimization of metabolite extraction by UAE should be established for each plant product [18; 19]. The UAE has been applied for the extraction of ALKs from different plants. [PERSON] et al. [20] used the UAE to extract three bioactive ALKs from _Stephania cambolica_ and, with the response surface methodology (RSM), found the optimal extraction conditions (liquid-solid ratio 26.6:1 mL/g, ethanol 52%, 25 kHz, time 9 min, and 150 W). The authors concluded that the UAE is a practical extraction procedure for obtaining alkaloid-rich extracts for pharmacological research. Meanwhile,Wang et al. [21] applied UAE and RSM to extract ALKs from _Sophora alopecuroides_ seeds, and found that UAE improved yield by 32% to 136% compared to the enzymatic extraction method. On the other hand, [PERSON] et al. [22] found that, when they used UAE (extraction time 30 min, 90 W) on _Radix physochalaine_, the extraction efficiency of ALKs was 121.3% compared to extraction by heating. RSM is a tool to optimize the extraction processes of biological compounds because it considers the operating variables and their simultaneous interactions during the extraction of bioactive compounds from plant tissues [23].