Keywords: green synthesis; metallic nanoparticles; myelogenous leukemia line; cytotoxic potential; Lamiaceae

Comparative analysis of essential oils of Baccharis L.: a review

Silver nanoparticles (AgNPs) have extensive applications in nanomedicine due to their physicochemical properties and interactions with biomolecules. One way of obtaining them is through green synthesis with plant extracts containing reducing and capping agents, such as Catharanthus roseus (L.) G Don. This plant has pharmacological applications due to its phytocompounds with biological activity. The C. roseus flowers are rich in alkaloids and phenolic compounds, and have the potential to synthesize AgNPs but have never been used with this purpose. In this study, AgNPs were synthesize with the aqueous extract from the C. roseus flowers, and their cytotoxicity evaluated on A549 lung tumor cells through MTT assay. The AgNP synthesis could be seen visually from the solution's color change and through UV-visible spectroscopy to detect a peak between 400 - 530 nm. FEG microscopy showed AgNPs with variable shapes and sizes. In vitro cytotoxicity assay against A549 cells showed that the C. roseus extract have low toxicity to the lineage, and AgNPs reduced half the viable cells at the 1.5% concentration, demonstrating high cytotoxicity. Therefore, AgNPs from C. roseus were successfully obtained and showed significant cytotoxic activity on A549 lung cancer cells.

Nanoemulsions (NEs), emulsified systems with diameter between 20 and 500 nm, are promising in cosmetic science due to stability and efficient transportation of lipophilic substances, such as volatile oils, favoring the skin penetration to carry out the biological activity. Volatile oil of Matricaria recutita L. (VOMR) has several therapeutic effects, but the lability of the volatile oils requires appropriate vehiculation in NEs. Besides, the hydrophilic-lipophilic balance (HLB) parameter for VOMR is not described in the literature. Therefore, NEs composed of Span^® 80, Tween^® 80, PEG-7 glyceryl cocoate, glycerin and water were developed by the high-energy method. The NEs were characterized by organoleptic, physicochemical and morphological evaluations as well as the stability evaluation was conducted at different temperatures for 60 days. The NEs obtained with and without VOMR exhibited translucent aspect, pH of 4.82 and 5.62; average diameter of 104.97 ± 4.03 and 92.32 ± 6.17 nm; polydispersity index of 0.27 ± 0.06 and 0.31 ± 0.04, and zeta potential of -28.37 ± 3.06 and -36.48 ± 6.56 mV, respectively. The encapsulation of VOMR was around 83% into the NE and confirmed by visualization through scanning electron microscopy - field emission gun. The stability study demonstrated that refrigeration is the optimal storage condition because the conservation of the NEs characteristics. As a result, the present study describes for the first time HLB value near 7 for VOMR. Thus, NE with this volatile oil was developed with suitable characteristics, contributing to technology development of phytopharmaceuticals for topical application to the skin.

Background/Objectives: Metformin, a widely used antidiabetic drug, has recently gained attention in dermatology due to its pleiotropic effects. Given the high prevalence, chronicity, and therapeutic challenges of several dermatological conditions, there is growing interest in repurposing metformin as a topical agent with anti-inflammatory, antioxidant, metabolic, and regenerative properties. This narrative review aimed to synthesize and critically analyze the available preclinical and clinical evidence regarding the mechanisms of action, efficacy, safety, and therapeutic potential of topical metformin across different skin disorders. Methods: A literature search was conducted in PubMed and complementary databases for studies published between 2015 and 2025 addressing topical metformin in dermatology, including experimental, observational, interventional, and review articles. Results: The findings indicate that topical metformin has been associated with beneficial biological effects in conditions such as melasma, photoaging, wound healing, psoriasis, acne, skin cancer, and hair disorders, largely through AMPK activation, modulation of inflammation and oxidative stress, inhibition of melanogenesis, enhancement of tissue regeneration, and regulation of immune and metabolic pathways, although evidence remains predominantly preclinical and methodologically heterogeneous. Conclusions: Topical metformin represents a promising investigational multifunctional dermatological agent; however, its clinical translation depends on well-designed randomized controlled trials with standardized formulations, adequate sample sizes, and long-term follow-up to establish its efficacy, safety, and optimal therapeutic protocols.