Uncovering the colorectal cancer immunotherapeutic potential: Evening primrose (Oenothera biennis) root extract and its active compound oenothein B targeting the PD-1/PD-L1 blockade.

BACKGROUND: The emergence of immune checkpoint inhibitors, a novel class of immunotherapy drugs, represents a major breakthrough in cancer immunotherapy, substantially improving patient survival post-treatment. Blocking programmed death-ligand 1 (PD-L1) and programmed death protein-1 (PD-1) has demonstrated promising clinical results in various human cancer types. The US FDA has recently permitted only monoclonal antibody (mAb)-based PD-L1 or PD-1 blockers. Although these antibodies exhibit high antitumor efficacy, their size- and affinity-induced side effects limit their applicability. PURPOSE: As small-molecule-based PD-1/PD-L1 blockers capable of reducing the side effects of antibody therapies are needed, this study focuses on exploring natural ingredient-based small molecules that can target hPD-L1/PD-1 using herbal medicines and their components. METHODS: The antitumor potential of evening primrose (Oenothera biennis) root extract (EPRE), a globally utilized traditional herbal medicine, folk remedy, and functional food, was explored. A coculture system was established using human PD-L1-expressed murine MC38 cells (hPD-L1-MC38s) and CD8+ tumor-infiltrating T lymphocytes (CD8+ TILs) expressing humanized PD-1. The in vivo experiments utilized a colorectal cancer (CRC) C57BL/6 J mouse model bearing MC38 cells expressing humanized PD-L1 and PD-1 proteins. RESULTS: EPRE and its active compound oenothein B effectively hindered the molecular interaction between hPD-L1 and hPD-1. EPRE stimulated tumor-specific T lymphocytes of a hPD-L1/PD-1 CRC mice. This action resulted in the elevated infiltration of cytotoxic CD8+T lymphocytes and subsequent tumor growth reduction. Moreover, the combined therapy of oenothein B, a PD-1/PD-L1 blocker, and FOLFOX (5-fluorouracil plus oxaliplatin) cooperatively suppressed hPD-L1-MC38s growth in the ex vivo model through activated CD8+ TIL antitumor immune response. Oenothein B exhibited a high binding affinity for hPD-L1 and hPD-1. We believe that this study is the first to uncover the inhibitory effects of EPRE and its component, oenothein B, on PD-1/PD-L1 interactions. CONCLUSION: This study identified a promising small-molecule candidate from natural products that blocks the hPD-L1/PD-1 signaling pathway. These findings emphasize the potential of EPRE and oenothein B as effective anticancer drugs.

A Comparative Study on Photo-Protective and Anti-Melanogenic Properties of Different Kadsura coccinea Extracts.

Kadsura coccinea (KC), a beneficial plant for human health, has been used for centuries in China, Thailand, and Korea in folk medicine and food. There is evidence supporting the biological effects of highly bioactive ingredients in KC such as lignans, triterpenoids, flavonoids, phenolic acids, steroids, and amino acids. In this study, we aimed to explore the effects, functions, and mechanisms of the extracts from KC root (KCR), stem (KCS), leaf (KCL), and fruit (KCF) in UVA and UVB-irradiated keratinocytes and α-melanocyte stimulating hormone (α-MSH)-stimulated melanocytes. First, the total polyphenol and flavonoid contents of KCR, KCS, KCL, and KCF and their radical scavenging activities were investigated. These parameters were found to be in the following order: KCL > KCR > KCS > KCF. UVA and UVB-irradiated keratinocytes were treated with KCR, KCS, KCL, and KCF, and keratinocyte viability, LDH release, intracellular ROS production, and apoptosis were examined. Our results demonstrated that KC extracts improved keratinocyte viability and reduced LDH release, intracellular ROS production, and apoptosis in the presence UVA and UVB irradiation. The overall photoprotective activity of the KC extracts was confirmed in the following order: KCL > KCR > KCS > KCF. Moreover, KC extracts significantly decreased the intracellular melanin content and tyrosinase activity in α-MSH-stimulated melanocytes. Mechanistically, KC extracts reduced the protein and mRNA expression levels of tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) in α-MSH-stimulated melanocytes. In addition, these extracts markedly downregulated myophthalmosis-related transcription factor expression and cAMP-related binding protein phosphorylation, which is upstream of the regulation of Tyrosinase, TRP-1, and TRP-2. The overall anti-melanogenic activity of the KC extracts was established in the following order. KCL > KCR > KCS > KCF. Overall, the KC extracts exert photoprotective and anti-melanogenic effects, providing a basis for developing potential skin-whitening and photoprotective agents.

Therapeutic effects of α-iso-cubebenol, a natural compound isolated from the Schisandra chinensis fruit, against sepsis.

α-Iso-cubebenol, a natural compound isolated from the Schisandra chinensis fruit, strongly enhances survival rate in cecal ligation and puncture (CLP) challenge-induced sepsis. Mechanistically, α-iso-cubebenol markedly reduces viable bacteria in the peritoneal fluid and peripheral blood, by increasing production of superoxide anion. α-Iso-cubebenol also significantly attenuates widespread immune cell apoptosis in a mouse CLP sepsis model, and inhibits the production of proinflammatory cytokines including interleukin-1ß (IL-1ß) and IL-6 in CLP mice and lipopolysaccharide-stimulated splenocytes. Taken together, the results indicate that α-iso-cubebenol can reverse the progression of septic shock by triggering multiple protective downstream signaling pathways to enhance microbial killing and maintain organ function and leukocyte survival.

In vitro and in vivo anticancer effects of Lithospermum erythrorhizon extract on B16F10 murine melanoma.

ETHNOPHARMACOLOGICAL RELEVANCE: Lithospermum erythrorhizon has long been used in traditional Asian medicine for the treatment of diseases including skin cancer. In this study, hexane extract from the roots of Lithospermum erythrorhizon (LEH) was chemically characterized and its anticancer activity was tested against the most aggressive form of skin cancer. MATERIALS AND METHODS: The in vitro anticancer studies viz. cell growth, cell cycle and apoptosis, and the expression of tumor regulating proteins were analyzed against B16F10 melanoma cells. In addition, C57BL/6 mice models were used to evaluate the in vivo anticancer potential of LEH. Mice were intraperitoneally injected with LEH at doses of 0.1 and 10mg/kg every 3 days. The tumor inhibition ratio was determined after 21 days of treatment and the histopathological analyses of the tumor tissues were compared. Further, LEH was purified and its active compounds were structurally elucidated and identified by NMR spectra and quantified by HPLC analyses. RESULTS: LEH effectively inhibits the growth of melanoma cells with an IC(50) of 2.73µg/ml. Cell cycle analysis revealed that LEH increased the percentage of cells in sub-G1 phase by dose dependent manner. LEH exhibited down regulation of anti-apoptotic Bcl-2 family proteins and up regulation of apoptotic Bax protein expression. Importantly, LEH induced cleavage of poly (ADP-ribose) polymerase (PARP) and activated the caspase cascade (caspase 3) with this cleavage mediating the apoptosis of B16F10 cells. LEH treatment at a dose of 10mg/kg for 21 days in experimental mice implanted with tumors resulted in significant reduction of the tumor growth (43%) and weight (36%). Histopathology analysis of LEH treated tumor tissues showed evidence of increased necrotic cells in a concentration dependent manner. Meanwhile, five naphthoquinone compounds [Shikonin (1); Deoxyshikonin (2); ß-Hydroxyisovalerylshikonin (3); Acetylshikonin (4) and Isobutyrylshikonin (5)] were purified from LEH and responsible for its anticancer activity. CONCLUSION: LEH induced apoptosis in B16F10 cells by activation of caspase 3 and inducing sub-G1 cell cycle arrest. LEH exhibited both in vitro and in vivo anticancer activity. Shikonin derivatives in the LEH are responsible for the anticancer activity.

Identification of a novel compound that stimulates intracellular calcium increase and CXCL8 production in human neutrophils from Schisandra chinensis.

Schisandra chinensis has been regarded as a useful material in the preventive or treatment of several human diseases. The study of the Schisandra chinensis' molecular identity has been prioritized because it has been found to regulate cellular responses. Here, we examined the effects from various extracts of Schisandra chinensis to monitor the relative intracellular calcium increase in human neutrophils. We identified an active molecule and structural configuration of a new active compound (alpha-iso-cubebene), based on the discovery of a cubebene backbone using NMR, MS, and CD spectral data. In terms of its functional aspect, we observed that alpha-iso-cubebene strongly stimulated CXCL8 production in human neutrophils. Also, alpha-iso-cubebene-induced CXCL8 production was almost completely inhibited by the calcium chelator, EGTA, thus highlighting the role of calcium signaling in the process. Taken together, our results demonstrate that alpha-iso-cubebene is a novel natural compound which stimulates intracellular calcium signaling and CXCL8 production. As a result, alpha-iso-cubebene should be useful for the development of an immune-modulating agent.