Melanogenesis-Inhibitory Activities of Isomeric C-secoLimonoids and Deesterified Limonoids

Limonoids isolated from Chisocheton ceramicus Miq. and the antiadipogenic mechanism of action of ceramicine B

Different types of limonoids have been isolated from plants of the Chisocheton genus, notably from the species Chisocheton ceramicus  Miq. which is largely distributed in the Indonesian archipelago and Malaysia region. A variety of natural products have been found in the bark of the tree and characterized as antimicrobial and/or antiproliferative agents. The isolated limonoids include chisomicines A-E, proceranolide, and a few other compounds. A focus is made on a large series of limonoids designated ceramicines A to Z including derivatives with antiparasitic activities, antioxidant, antimelanogenic, and antiproliferative effects and/or acting as regulators of lipogenesis. The lead compound in the series is ceramicine B functioning as a potent inhibitor of lipid droplet accumulation (LDA). Extracts from Chisocheton ceramicus and ceramicines have shown anti-LDA effects, with little or no cytotoxic effects. Ceramicine B is the most active compound functioning as a regulator of lipid storage in cells and tissues. Ceramicine B is a transcriptional repressor of peroxisome proliferator-activated receptor γ (PPARγ) and an inhibitor of phosphorylation of the transcription factor FoxO1, acting via an upstream molecular target. Targeting of glycogen synthase kinase-3β is proposed, based on the analogy with structurally related limonoids known to target this enzyme, and supported by a molecular docking analysis. The target and pathway implicated in ceramicine B activity are discussed. The analysis shed light on ceramicine B as a natural product precursor for the design of novel compounds capable of reducing LDA in cells and of potential interest for the treatment of obesity, liver diseases, and other pathologies.

Recent Advancements in Nanocarrier-assisted Brain Delivery of Phytochemicals Against Neurological Diseases

Despite ongoing advancements in research, the inability of therapeutics to cross the blood-brain barrier (BBB) makes the treatment of neurological disorders (NDs) a challenging task, offering only partial symptomatic relief. Various adverse effects associated with existing approaches are another significant barrier that prompts the usage of structurally diverse phytochemicals as preventive/therapeutic lead against NDs in preclinical and clinical settings. Despite numerous beneficial properties, phytochemicals suffer from poor pharmacokinetic profile which limits their pharmacological activity and necessitates the utility of nanotechnology for efficient drug delivery. Nanocarriers have been shown to be proficient carriers that can enhance drug delivery, bioavailability, biocompatibility, and stability of phytochemicals. We, thus, conducted a meticulous literature survey using several electronic databases to gather relevant studies in order to provide a comprehensive summary about the use of nanocarriers in delivering phytochemicals as a treatment approach for NDs. Additionally, the review highlights the mechanisms of drug transport of nanocarriers across the BBB and explores their potential future applications in this emerging field.

Limonoids with anti-inflammatory activity: A review

The natural limonoids distributed mainly in the Meliaceae and Rutaceae plants are known for their unique and complex structure with high degree oxidation and cyclic rearrangement. However, these compounds exhibit a broad range of biological activities such as insecticidal, antibacterial, antifungal, antimalarial, antioxidant, anticancer, antiviral, and anti-inflammatory. There is still limited report about the biological activity of the anti-inflammatory effect of limonoids isolated from plants. Therefore, this study aimed to examine the effect of intact, deformed and rearranged limonoids as anti-inflammatory agents. The majority of anti-inflammatory investigations were evaluated by in vitro and in vivo assays of the isolated pure compounds and their derivatives. For the in vitro study, intact and C-ring seco limonoids showed a potent inhibitory effect against NO production. The in vivo analysis of Intact, C-seco, and AD-seco limonoids showed a potent effect based on the inhibition of pro-inflammatory cytokines expression, indicating their potency as anti-inflammatory agents.

Azadirachta indica (Neem) as a Potential Natural Active for Dermocosmetic and Topical Products: A Narrative Review

Azadirachta indica (Neem) is a large tree that is native to India and is traditionally used due to its several properties, mainly to treat skin diseases, as well as its “herbicidal” activity. Its bark, leaves, seeds, fruits and flowers are widely used in medicinal treatment due to the presence of active secondary metabolites with biological effects, mainly limonoids and tetranortriterpenoids, such as azadirachtin. Thus, A. indica was studied in a variety of conditions, such as anticancer, antiseptic, anti-inflammatory and chemopreventive agents, as well as a biopesticide. Furthermore, differentiated cell tissue in A. indica cultivation was reported to produce active metabolites for different purposes. However, only a few studies have been developed regarding its potential use in cosmetics. For instance, most studies explained the antimicrobial properties in health conditions, such as acne, dandruff and personal health care. Here, we summarized not only the most common cosmetic claims to treat acne but also mitigating other skin disorders related to inflammatory and oxidant processes in recent in vivo studies and patents to aid researchers and industrialists to select A. indica derivatives as novel cosmetic ingredients.

Potential benefits of phytochemicals from Azadirachta indica against neurological disorders

Azadirachta indica or Neem has been extensively used in the Indian traditional medical system because of its broad range of medicinal properties. Neem contains many chemically diverse and structurally complex phytochemicals such as limonoids, flavonoids, phenols, catechins, gallic acid, polyphenols, nimbins. These phytochemicals possess vast array of therapeutic activities that include anti-feedant, anti-viral, anti-malarial, anti-bacterial, anti-cancer properties. In recent years, many phytochemicals from Neem have been shown to be beneficial against various neurological disorders like Alzheimer's and Parkinson's disease, mood disorders, ischemic-reperfusion injury. The neuroprotective effects of the phytochemicals from Neem are primarily mediated by their anti-oxidant, anti-inflammatory and anti-apoptotic activities along with their ability to modulate signaling pathways. However, extensive studies are still required to fully understand the molecular mechanisms involved in neuropotective effects of phytochemicals from Neem. This review is an attempt to cover the neuroprotective properties of various phytochemicals from Neem along with their mechanism of action so that the potential of the compounds could be realized to reduce the burden of neurodegenerative diseases.

Synthesis and biological evaluation of caffeic acid derivatives as potent inhibitors of α-MSH-stimulated melanogenesis

We have disclosed our effort to develop caffeic acid derivatives as potent and non-toxic inhibitors of α-MSH-stimulated melanogenesis to treat pigmentation disorders and skin medication including a cosmetic skin-whitening agent. The SAR studies revealed that cyclohexyl ester and secondary amide derivatives of caffeic acid showed significant inhibitory activities.