Pericarpium Citri Reticulate, known as "Chen Pi" in Chinese, the dried peel of mature fruit of Citrus reticulate, is commonly used in traditional Chinese medicine to treat respiratory diseases such as cough with sputum. Up to now, over ten different polymethoxylated flavones such as narirutin, nobiletin, and tangeretin have been isolated and characterized from Pericarpium Citri Reticulatae. Nobiletin (5,6,7,8,3',4'-hexamethoxyflavone), and its derivatives have been reported to have a broad range of biological effects including anti-inflammatory and anti-carcinogenic activities, and neurotrophic action. Recently, we are the first team to identify nobiletin having potent anti-angiogenic activity in human endothelial cells and zebrafish embryos. Angiogenesis plays an important pathological role in a wide range of diseases, such as cancer and inflammation. Anti-angiogenesis is demonstrated to be effective therapeutic strategy on inhibitory of tumor growth by cutting down the delivery of nutrient and oxygen to tumor target. Recently, angiogenesis is found to be a prominent feature of the structural tissue remodelling that occurs in various chronic airway diseases associated with regional vascular inflammation, such as asthma and smoking-related Chronic Obstructive Pulmonary Disease (COPD). Pericarpium Citri Reticulate are widely used to alleviate coughs and reduce phlegm in the respiratory tract while compounds isolated from Pericarpium Citri Reticulatae were well reported to have potent anti-carcinogenesis and anticancer effect in several recently published in vitro and in vivo studies. It would be very interesting to explore if underlying mechanism of action of Pericarpium Citri Reticulatae involves anti-angiogenesis. Our results showed that water and ethanol extracts of Pericarpium Citri Reticulate could inhibit inter segmental vessel (ISV) and dorsal anastomotic vessel (DLAV) formation in live transgenic zebrafish embryo (Tg: flil-EGFP) that expresses GFP in the vasculature. We further identified nobiletin as an active constituent to exhibit anti-angiogenic effect, preferentially in 24 hpf zebrafish embryos but less effect on the phenotype of well established vasculature system in 56 hpf zebrafish larva. Nobiletin induced G1/G0 cell cycle arrest in GFP positive cells which represented endothelial cell population in the zebrafish. As in in vitro study, nobiletin inhibited VEGF induced human endothelial cell proliferation by inducing G1/GO cell cycle arrest in a dose dependent manner. The anti-angiogenic effect of nobiletin was found to involve specific upregulation of VEGFa mRNA expression in a dose dependent manner, without alternation of flk-1 flt-1 and flt-4 mRNAs expression. Angiogenesis plays an important pathological role in a wide range of diseases, such as cancer and respiratory inflammatory diseases. In this study, we found that nobiletin exerted anti-angiogenic effect in vitro and in vivo through regulating cell cycle arrest and VEGF pathway. These findings are very important to provide rationales for future development of Pericarpium Citri Reticulate and its constituent nobiletin, on treatment of tumour angiogenesis and various inflammatory diseases.

芸香科柑橘屬(Citrus reticulate)及其栽培變種,它們的果皮經晾乾後,便是傳統 中藥陳皮。陳皮作為傳統中藥的常用藥材,在許多複方中都有以它作為輔藥,而 陳皮的主要功效則是止咳化痰。現今,已從陳皮分離出數十種的多甲氧基黃酮成 份,如:川陳皮素(Nobiletin),紅橘素和柚皮芸香甙等。其中,川陳皮素及其衍 生物在抗炎症,抗腫瘤和神經營養性作用上的有着廣泛的報道,但在血管新生方 面上,仍沒有相關的報道。我們相信是首個在體外人類臍靜脈細胞(HUVEC)模 型和體內斑馬魚胚胎上,發現川陳皮素具有潛在抗血管新生活性的團隊。 血管新生(angiognesis),是指在現有的血管上形成新血管的過程,具有維持人體 正常的生長和平衡的功能。在許多疾病(如癌症的發生,炎症等;)的發生、發 展和轉移等病理過程中,血管新生現象都起着關鍵的角色。抗血管新生成為近年 臨床治療研究上的熱點,它能阻斷對腫瘤組織的供血,從而達到“餓死”癌細胞 的目的,成為一種有效抑制癌症生長的治療策略。最近,在與局部血管炎症相關 的各類長期氣管疾病,如:哮喘和與吸煙相關的慢性阻塞性肺疾,發現血管新生 在氣管組織細胞的重構扮演着重要的角色。陳皮傳統一直廣泛應用於止咳和去 痰,而且很多報道都指出從陳皮中分離的化合物,在體內和體外都有着抗炎症和 抗腫瘤發生功效的相關報道。對於進一步探索陳皮中的抗血管新生功效和其傳統 藥效的機理是一件極具前瞻意義的事。 我們的結果顯示,陳皮水提物和醇提物,在一種能在血管系統中表達綠色熒光蛋 白的(Tg: fli1-EGFP)轉基因斑馬魚胚胎上,能抑制節間血管(inter segmental vessel, ISV)和背部吻合血管(dorsal anatomotic vessel, DLAV)的形成。進一步對陳皮中的 一種活性黃酮成份-川陳皮素的研究發現,它對 24 hpf(hour post fertilization)的 斑馬魚胚胎能起到顯著的抗血管新生效應,但對血管已形成的56 hpf 斑馬魚幼魚 上不具該效應。同時,川陳皮素能對轉基因斑馬魚身上的綠色熒光細胞(相當於 內皮細胞)引起G1/GO期細胞周期滯留。而在人類臍靜脈細胞(HUVEC)的實驗 中,川陳皮素亦能通過引起 G1/GO 期細胞周期滯留,從而抑制由 VEGF 所介導 的細胞增殖作用,並具有濃度依賴性。我們並發現川陳皮素的抗血管新生作用, 是濃度依賴性地通過對 VEGFa表達的上調來調節,並且對 flk-1 flt-1 and flt-4 的 表達並沒有影響,對VEGFa的表達具有明顯特異性。 血管新生在許多疾病中的病理機制都起着重要的作用,在這份論文中,我們披露 了川陳皮素在體外和體內實驗中,通過改變細胞周期和調節 VEGF 途徑來實現抗 血管新生。這裏的發現,對將來陳皮和它的成份-川陳皮素,在腫瘤血管新生和 各類炎症疾病的治療策略上提供了理論上的實驗支持。