Activated microglia-mediated neuroinflammation plays a key pathogenic role in neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and ischemia. Sulforaphane is an active compound produced after conversion of glucoraphanin by the myrosinase enzyme in broccoli (Brassica oleracea var) sprouts. Dietary broccoli extract as well as sulforaphane has previously known to mitigate inflammatory conditions in aged models involving microglial activation. Here, we produced sulforaphane-enriched broccoli sprouts through the pretreatment of pulsed electric fields in order to trigger the biological role of normal broccoli against lipopolysaccharide-activated microglia. The sulforaphane-enriched broccoli sprouts showed excellent potency against neuroinflammation conditions, as evidenced by its protective effects in both 6 and 24 h of microglial activation in vitro. We further postulated the underlying mechanism of action of sulforaphane in broccoli sprouts, which was the inhibition of an inflammatory cascade via the downregulation of mitogen-activated protein kinase (MAPK) signaling. Simultaneously, sulforaphane-enriched broccoli sprouts inhibited the LPS-induced activation of the NF-κB signaling pathway and the secretions of inflammatory proteins (iNOS, COX-2, TNF-α, IL-6, IL-1β, PGE2, etc.), which are responsible for the inflammatory cascades in both acute and chronic inflammation. It also upregulated the expression of Nrf2 and HO-1 in normal and activated microglia followed by the lowered neuronal apoptosis induced by activated microglia. Based on these results, it may exhibit anti-inflammatory effects via the NF-κB and Nrf2 pathways. Interestingly, sulforaphane-enriched broccoli sprouts improved the scopolamine-induced memory impairment in mice through Nrf2 activation, inhibiting neuronal apoptosis particularly through inhibition of caspase-3 activation which could lead to the neuroprotection against neurodegenerative disorders. The present study suggests that sulforaphane-enriched broccoli sprouts might be a potential nutraceutical with antineuroinflammatory and neuroprotective activities.

Malathion is an organophosphate with severe neurotoxic effects. Upon acute exposure, malathion initially enhances cholinergic activity by inhibition of acetylcholinesterase, which is its major pathological mechanism. Malathion also induces non-cholinergic neuronal cell death in neurodegenerative conditions; the associated molecular mechanism is not well-characterized. To investigate the molecular mechanism of malathion-induced cell death, N2a mouse neuroblastoma cells were exposed to malathion and cell death-related parameters were examined. Malathion reduced cell viability mainly by apoptosis through mitochondrial dysfunction in N2a cells, as judged by an increase in the level of the pro-apoptotic protein Bax and decrease in the levels of the anti-apoptotic proteins p-Akt and Bcl2, resulting in cytochrome c release and caspase-dependent DNA fragmentation and condensation. Malathion treatment also induced autophagy and lysosomal membrane permeabilization (LMP) in N2a cells. LMP caused a lessening of autophagic flux via inhibition of lysosomal fusion with the autophagosome. LMP-induced cathepsin B release and its proteolytic effect may intensify apoptotic insults. Moreover, malathion-exposed N2a cells showed a marked reduction in the levels of the neuronal marker proteins vascular endothelial growth factor and heart fatty acid binding protein 3, along with diminished neuritogenesis in N2a cells and nerve growth factor secretion in C6 glioma cells. Our data suggest that the non-cholinergic effect of malathion may be mediated by apoptotic cell death via LMP induction in N2a cells. Malathion-treated N2a cells can be utilized as an in vitro model system to screen natural and new chemical drug candidates for neurodegenerative diseases such as Alzheimer’s disease.

Gomisin N, one of the lignan compounds found in Schisandra chinensis has been shown to possess anti-oxidative, anti-tumorigenic, and anti-inflammatory activities in various studies. Here we report, for the first time, the anti-melenogenic efficacy of Gomisin N in mammalian cells as well as in zebrafish embryos. Gomisin N significantly reduced the melanin content without cellular toxicity. Although it was not capable of modulating the catalytic activity of mushroom tyrosinase in vitro, Gomisin N downregulated the expression levels of key proteins that function in melanogenesis. Gomisin N downregulated melanocortin 1 receptor (MC1R), adenylyl cyclase 2, microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2). In addition, Gomisin N-treated Melan-A cells exhibited increased p-Akt and p-ERK levels, which implies that the activation of the PI3K/Akt and MAPK/ERK pathways may function to inhibit melanogenesis. We also validated that Gomisin N reduced melanin production by repressing the expression of MITF, tyrosinase, TRP-1, and TRP-2 in mouse and human cells as well as in developing zebrafish embryos. Collectively, we conclude that Gomisin N inhibits melanin synthesis by repressing the expression of MITF and melanogenic enzymes, probably through modulating the PI3K/Akt and MAPK/ERK pathways.

We already reported that genetically engineered resveratrol-enriched rice (RR) showed to down-regulate skin melanogenesis. To be developed to increase the bioactivity of RR using calli from plants, RR was adopted for mass production using plant tissue culture technologies. In addition, high-pressure homogenization (HPH) was used to increase the biocompatibility and penetration of the calli from RR into the skin. We aimed to develop anti-melanogenic agents incorporating calli of RR (cRR) and nanoparticles by high-pressure homogenization, examining the synergistic effects on the inhibition of UVB-induced hyperpigmentation. Depigmentation was observed following topical application of micro-cRR, nano-calli of normal rice (cNR), and nano-cRR to ultraviolet B (UVB)-stimulated hyperpigmented guinea pig dorsal skin. Colorimetric analysis, tyrosinase immunostaining, and Fontana-Masson staining for UVB-promoted melanin were performed. Nano-cRR inhibited changes in the melanin color index caused by UVB-promoted hyperpigmentation, and demonstrated stronger anti-melanogenic potential than micro-cRR. In epidermal skin, nano-cRR repressed UVB-promoted melanin granules, thereby suppressing hyperpigmentation. The UVB-enhanced, highly expressed tyrosinase in the basal layer of the epidermis was inhibited by nano-cRR more prominently than by micro-cRR and nano-cNR. The anti-melanogenic potency of nano-cRR also depended on pH and particle size. Nano-cRR shows promising potential to regulate skin pigmentation following UVB exposure.

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