Chemical and biological progress of Podocarpus nagi

Podocarpus nagi is a tree belonging to the family of Podocarpaceae, which has ever been used for treatment of trauma, stop-bleeding, fractures, knife wounds, gunshot wounds, body odor, eye diseases, colds and rheumatoid arthritis in clinic. Some compounds have been isolated and their biological activities were also evaluated. This review briefly describes the progress of the chemical components and biological activities of podocarpus nagi, for providing a reference for the researchers. *Correspondence to: Jianping Yong, Xiamen Institute of Rare-earth Materials, Haixi Institute, Chinese Academy of Sciences, Xiamen, 361021, China, Tel: +86591-63173162; E-mail: jpyong@fjirsm.ac.cn Canzhong Lu, Fujian Institute of Research on the Structure of Matter, Haixi Institute, Chinese Academy of Sciences, Fuzhou, 350002, China, Tel: +86-59183705794; E-mail: czlu@fjirsm.ac.cn


Introduction
Podocarpus nagi (named Zhubai in Chinese) is a tree belonging to the family of Podocarpaceae, widely distributed in the South District of the Yangtse River, such as Jiangxi, Zhejiang, Fujian, Hunan, Guangxi and Guangdong, etc. In Nanping, Sanming and Zhangzhou of Fujian Province, there are small-scaled natural communities or artificial enclosure planting of Podocarpus nagi, which is a native tree species of local place. The branches of Podocarpus nagi are excellent materials for building, furniture and craft. The oil content of its seeds is higher and can be used for edible after being refined or directly used industrially [1]. Some compounds and biological activities have been studied. In this mini-review, we briefly describe the progress of the chemical components and biological activities of podocarpus nagi.

Chemical components of Podocarpus nagi
According to the reported literatures, there are many active components in the branches, leaves and seeds of Podocarpus nagi, which include volatile oils, terpenoids, cypress lactones, flavonoids, lignin and cyclic peptides. The main components of essential oil in the leaves of Podocarpus nagi are elemene, cadinene, β-palindolene, pinene and caryophyllene.
From the results reported above, we can know that the main components of the volatile oil are terpenes.

Steroids
Wang Qiuxiang et al. [7] obtained 5α,6β-sitosterol from the leaves of Podocarpus nagi, which widely exists in many kinds of plant.

Other components isolated from Podocarpus nagi
Wang Qiuxiang et al. [7] isolated the prinsepiol from the leaves of Podocarpus nagi. According to the literatures reported, there are organic acids in the oil of the seeds of Podocarpus nagi, the nutmeg acid, palmitic acid, stearic acid, oleic acid, 9,12-linoleic acid, paullinic acid, eicosadienoic acid, carbonium are included [8,10]. We also extracted the oil of the seeds of Podocarpus nagi planted in Yangli town of Fujian province and analyzed its components, and palmitic acid, palmitic acid, octanoic acid, stearic acid, oleic acid, linoleic acid, peanut acid, arachidonic acid, α-linolenic acid, arachidonic acid, behenicacid, lignoceric acid are detected.

Biological activities
It was reported that the leaves and bark of Podocarpus nagi can emit the odor similar to clove, which can repel the mosquitoes. In addition, as a kind of traditional Chinese herbal medicine, Podocarpus nagi exhibits hemostasis, bone setting and detumescence. As a kind of folk medicine of Yao nationality, Podocarpus nagi can also be used to treat trauma, stop-bleeding, fractures, knife wounds, gunshot wounds, body odor, eye diseases and colds, etc. The fresh barks or roots of Podocarpus nagi were also used to treat the rheumatoid arthritis [5,6,11].

Anticancer activity
Xu Yaming et al. [7] reported that ngilactone A, 1-deoxy-2β,3βepoxynagilactone A and 1-deoxy-2α-hy-droxynagilactone towards the leukemia, the results showed that these compounds exhibited cytotoxicity against P 338 cell lines, and the inhibitions of these three compounds against P 388 cell lines are 73, 88.5 and 97.4% respectively at the concentration of 10 ug/mL. While the inhibition of ngilactone B towards P 388 cell lines is 98.6% [9]. Lee et al. [12] reported that amentoflavone exhibited higher inhibition to phospholipase C.

Antiviral and other activities
Matsuki et al reported that bilobetin exhibited potent antiviral activity against Epstein-Barr virus, and also stronger against carcinogen than that of vitamin A acid [19]. Feng Zheling et al. isolated some podolactones from Podocarpus nagi and evaluated their anti-inflammatory effect. The results showed that compounds 1 and 2 ( Figure 3) significantly inhibited Nitric Oxide (NO) production on LPSstimulated RAW264.7 macrophages, with IC 50 values of 0.18 ± 0.04 and 0.53 ± 0.03 μM, respectively. Compound 1 suppressed the expression of inducible NO Synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents [20]. Wang Yiping et al. [21] reported that nagilactone B can suppress atherosclerosis in apoE-deficient mice via enhancing apolipoprotein A-I and HDLmediated cholesterol efflux. Berger et al. [22] reported that Podocarpus nagi methyl esters could reduce skin surfaces inflammatory processes and reduce downstream inflammatory products: such as PGE2 and leukotrienes. It could have potential use in treating clinical skin disorders.
Through reviewing the progress of the chemical components and biological activities of podocarpus nagi, we found that only some simple studies have been carried out. These years, our research group carried out the drug design, synthesis, isolation of the plant medicines and their biological evaluation, and we have obtained remarkable results [23][24][25][26][27][28][29][30]. Podocarpus nagi is a kind of native tree species in Fujian province, and there is a large-scaled artificial enclosure planting in Yangli town of Fujian province. Because Podocarpus Nagi is rich in sciadopitysin, amentoflavone, and bilobetin with good biological activity, including bone protection, stop-bleeding, treatment of trauma, fractures, knife wounds, gunshot wounds, body odor, eye diseases, colds and rheumatoid arthritis. Thus, our research group takes the lead to carry out the isolation and biological evaluation of podocarpus nagi planted in Fujian province.