Cancer remains a complex and devastating disease that affects millions of individuals. Although cancer treatments such as surgery, chemotherapy, and radiation therapy have shown significant advancements in recent years, allowing for impressive progresses in therapeutic protocols thus increase of survival rates and improve life-conditions for the patients. Yet, conventional anticancer approaches often come with severe side effects and limited effectiveness. Amongst the different cancer treatments, photodynamic therapy (PDT) appears as a promising alternative, to increase efficiency and selectivity of cancer treatment. Indeed, PDT is based on the synergistic effect of a photo-active drug and its activation by an external light stimulus. Differently from conventional chemotherapeutics, the drug is activated only in the body regions exposed to light, hence avoiding, or limiting, systemic toxicity. From a photophysical point of view PDT golden standard relies on the activation of the photosensitizers (PS) using a specific light wavelength to produce singlet oxygen ( 1 O2) and other reactive oxygen species (ROS) that can disrupt cellular macromolecular systems, such as nucleic acids, proteins and lipid membranes, and thus initiate cancer cell death. Interestingly, PDT is not only restricted to cancer treatment and can find useful applications also for antibacterial or antiviral purposes, or for food processing. To assure 1 O2 efficient production, the PS should usually show a facile intersystem crossing leading to a high population of its triplet manifold and the subsequent energy transfer to the molecular oxygen to produce 1 O2 or other ROS. To increase the intersystem crossing probability, heavy metal having high spin-orbit coupling elements may also been used. Even if it is highly promising, PDT may show some drawbacks in particular related to limited selectivity, leading to adverse secondary effects also caused by poor metabolism and metal accumulation in the body. Furthermore, efficient PS should absorb in the red or near infrared region of the electromagnetic spectrum, in particular covering the therapeutic windows, to assure the maximum wavelength penetration in the tissues. While active research lines are operative to decorate PS with peripheral groups specifically recognizing receptors overexpressed in cancer cells to maximize accumulation, drug delivering strategies may also be pursued to counteract the usual poor solubility of PDT agents, which may lead to a globally poor bioavailability. Furthermore, PDT is relying on the activation of molecular oxygen and thus its efficiency is strongly limited in the case of solid tumors under hypoxia. Therefore, alternative cancer treatments need to be explored. In this context light-activated chemotherapy (LAC) is a promising approach, as it is oxygen-independent while maintaining the activation of the drugs by a luminous stimulus. Different strategies for LAC have been reported, for instance the light-activated release of ROS by organometallic, usually Ru-based, compounds have been proposed recently. A slightly different strategy, which we have also explored in the past, relies in the use of molecular photoswitches, such as E/Z isomerizable molecules, as LAC agents. Indeed, upon exposure to light of a specific wavelength, the PS may undergo photoisomerization leading to a significant change in its geometry. If the PS is at the same time interacting with a biological macromolecule, the light-induced large structural change may induce its perturbation and change its properties, eventually triggering apoptotic signals. For instance, if a photoswitch is interacting with a lipid bilayer, its isomerization may drastically change the membrane properties, causing its permeabilization and rupture, eventually followed by the cell death, without the mediation of singlet oxygen. As a matter of fact, the photoisomerization strategy offers several advantages in light-activated chemotherapy, including reduced toxicity and improved efficacy also reducing the risk of adverse effects by limiting the activation of the photosensitizer to specific regions or types of cells. Furthermore, by modifying the structure of photosensitizers, it is possible to change their absorption properties and tune the illumination wavelength required to activate them. Globally, photoswitches comprise several classes of molecules as azobenzenes, spiropyrans, 33,34 diarylethenes, in which light is used to convert the double carbon bond from Eto Z-conformation or to perform photocyclization reactions where the closed-ring specie converts to the open-ring isomer causing changes in the mechanical properties of its environment. The use of non-toxic, natural available, or bio-analogues switches is also particularly attractive to limit general toxicity and side-effects. In our previous work we described, thanks to a combination of experimental and molecular modeling tools, the potentiality of a biomimetic cyclocurcumin derivative (CCBu) for use in light-activated chemotherapy (Fig. ). Indeed, upon light-absorption, CCBu undergoes a structural change from the more stable E-configuration to the bulkier Z-conformation. In particular we have shown that our biomimetic analogues present superior properties over the natural cyclocurcumin, both in term of isomerization quantum yield and interaction with a model lipid membrane, the result having been rationalized via multiscale molecular modeling and simulation. However, both the experiments and modeling were conducted considering a DPPC lipid bilayer membrane only, which is a widely used model to study lipid bilayer interactions. Notably, we have rationalized both the interactions between CCBu and the lipid bilayer, as well as the effects of E/Z-photoisomerization and different CCBu concentrations on these interactions. Specifically, we have shown that CCBu may penetrate the lipid bilayer and remain inside the membrane near the lipid's polar groups stabilized by hydrogen bond mediated interactions. We have also shown that the isomerization of CCBu is indeed altering the membrane properties, three different phases, characterized by different order parameters may be observed depending on the PS concentration. In the present work, we aimed to go a step further and investigate the interactions of CCBu in its E/Z-conformations with a more complex and flexible membrane, which closely mimics the composition of eukaryotic outer membranes. To achieve this, we used a mixed membrane containing three different types of lipids: DPPC, DOPC, and cholesterol, which were chosen due to their abundance and importance in mamalian cell membranes. Indeed, while saturated fatty acids like DPPC are widely recognized for their stiff and well-ordered packing in membranes, DOPC, an unsaturated fatty acid, is a in a liquide disordered phase and leads to more fluid membranes. Finally, steroid such as cholesterol have a crucial role in cell membranes especially for preserving their shape and functionality, controlling the fluidity and permeability of the membrane and assuming a role in cell signaling. As it will be highlited in the following, we show that the interaction of CCBu strongly depends on the membrane composition, and even more stringently, the magnitude of the light-induced perturbation may vary from the model membrane system to the more biological relevant systems.