It is well known that ultraviolet light activates mitogen-activated protein (MAP) kinase by increasing the reactive oxygen species (ROS) in the body, enhancing activating protein 1(AP-1) complexes (c-Jun and c-Fos), increasing matrix metalloproteinases (MMPs) and degrading collagen and elastin. In this study, we confirmed that polyphenolic rich Spatholobus suberectus (SS) stem extracts suppressed ultraviolet (UV)-induced photo-aging. The major active components of SS stem extracts were identified as gallic acid, catechin, vanillic acid, syringic acid and epicatechin. The aqueous and ethanolic extracts of the stem of SS (SSW and SSE, respectively) significantly reduced the elastase enzyme activity. Moreover, both extracts were suppressed the ROS generation and cellular damage induced by UVB in HaCaT cells. Our results also revealed that SSE could regulate the expression of MMPs, tissue inhibitor of matrix metalloproteinase (TIMP)-1, collagen type I alpha 1 (COL1A1), elastin (ELN) and hyaluronan synthase 2 (HAS2) at their transcriptional and translational level. Furthermore, SSE was blocked the UVB-induced phosphorylation of mitogen-activated protein kinases (MAPKs), nuclear factor-kappa B (NF-κB) and c-Jun. Moreover, combination of syringic acid, epicatechin and vanillic acid showed strong synergistic effects on elastase inhibition activity, in which the combination index (CI) was 0.28. Overall, these results strongly suggest that the polyphenolics of SSE exert anti-ageing potential as a natural biomaterial to inhibit UVB-induced photo-aging.

The aim of the present study was to examine the antioxidative activity of (+)-lariciresinol (LRSL), an optically active lignan isolated from Rubia philippinensis in several in vitro assays. LRSL was also subjected to evaluate its inhibitory effect against the generation of reactive oxygen species (ROS) in murine macrophage (RAW 264.7) cells. The results showed that LRSL possessed very strong radical scavenging activity and reducing power, as well as inhibited ROS generation in a dose-dependent manner without showing any cytotoxicity. The transcriptional and translational levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were markedly higher in the sample treated group. LRSL treatment also increased the transcriptional and translational activities of NF-E2-related factor-2 (Nrf-2) with a corresponding increase in the transcriptional and translational activities of the heme oxygenase-1 (HO-1). LRSL activated p38 and treatments with SB239063 (a p38 inhibitor) suppressed the LRSL-induced activation of Nrf2, resulting in a decrease in HO-1 expression. Collectively, the data demonstrated that LRSL has potent antioxidative activity, decreasing ROS generation in RAW 264.7 cells and increasing the transcriptional and translational levels of antioxidant enzymes by activating Nrf2-mediated HO-1 induction via p38 signaling.

The leaves of Lannea coromandelica (Houtt.) Merr. are used in the Garo, Pahan, and Teli tribal communities of Bangladesh as a traditional medicinal plant to treat hepatitis, diabetes, ulcers, heart disease, and dysentery. However, there have been limited phytochemical and biological studies on the bark of L. coromandelica. This study aimed to investigate the antioxidant activities of L. coromandelica bark extract (LCBE) and the underlying mechanism using RAW 264.7 cells. The LCBE was analysed by high-pressure liquid chromatography (HPLC) to detect its key polyphenolic compounds. Various in vitro antioxidant assays were performed using RAW 264.7 cells to assess the antioxidant effects of the LCBE and to understand the underlying molecular mechanism. HPLC revealed the presence of gallic acid, (−)-epigallocatechin-3-gallate, catechin, chlorogenic acid, and caffeic acid in the LCBE. The extract showed a very potent capacity to scavenge numerous free radicals through hydrogen atom transfer and/or electron donation and also quenched cellular reactive oxygen species (ROS) generation without showing any toxicity. The LCBE was found to combat the oxidative stress by enhancing the expression, at both transcriptional and translational levels, of primary antioxidant enzymes as well as phase II detoxifying enzymes, especially heme oxygenase 1, through the upregulation of the nuclear factor erythroid 2-related factor 2 (NRF2)-mediated pathway in RAW 264.7 cells via the phosphorylation of p38 kinase and c-Jun N-terminal kinase (JNK). The LCBE exhibited strong antioxidant activities and mitigated the cellular ROS production. These results provide scientific evidence of its potential as an ideal applicant for a cost-effective, readily available, and natural phytochemical, as well as a strategy for preventing diseases associated with oxidative stress and attenuating disease progress.

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