| 摘要: | 部分柃木屬(Eurya)植物為民間藥用植物，在先前的研究中指出，其中有許
多化合物具有良好的藥用活性，但台灣特有種厚葉柃木在醫藥應用方面卻有待深
入了解。此外在野外觀察到厚葉柃木之伴生植物群相當單純，故此研究從天然物
分離及植物相生相剋作用兩方面著手，希望能開發新的藥用植物並解釋厚葉柃木
林下植物組成較少的原因。
本研究從厚葉柃木的甲醇萃取層分到了五個化合物，分別是rengyolone (1),
betulinic acid (2), trans-taxifolin 3-O-β-D–xylopyranoside (3), quercitrin (4) 及
hyperin (5)，此外還將betulinic acid 進行乙醯化反應得到產物3-O-acetyl betulinic
acid (2a)。本研究利用六個化合物進行肝癌細胞毒性測試，其中rengyolone 具有
較好的細胞毒殺效果，經乙醯化反應能提高betulinic acid 的活性，但是這六個化
合物對B 型肝炎病毒均無抑制效果。此外分別以葉子水萃液(1~5%)、淋溶液、
betulinic acid 及hyperin 水溶液對六種測試植物（小白菜、萵苣、小米、九層塔、
小黃瓜、大花咸豐草）進行種子生物分析試驗，測量其植物相剋潛力，結果發現
水萃液及淋溶液會抑制種子胚根延長，但不影響發芽率，而betulinic acid 及
hyperin 均無顯著抑制測試植物種子發芽或胚根延長的效果。
本研究顯示，厚葉柃木之藥用發展可能性較低，但其水萃液具有植物相剋潛
力，其中原因有待更進一步的研究。
In previous studies, some phytochemicals isolated from species of Eurya, a
member of Theaceae family, showed various bioactivities. For example, chrysoeriol
from methanolic extract of leaves of Eurya ciliata stimulated proliferation and
differentiation of osteoblastic MC3T3-E1 cells. E. emarginata is also used as a
traditional folk medicine in Korea to treat ulcers and diuretic. E. glaberrima Hayata is
one of the endemic species distributed in broad-leaved and mixed forest at elevations
between 1500 to 3300 m above sea level in Taiwan. In order to clarify the medical and
ecological roles of E. glaberrima, the natural products of E. glaberrima with
anti-hepatocarcinoma cell, allelopathic activity were investigated. In this study, we
used the methanolic extract of twigs and leaves of E. glaberrima to test the
cytotoxicity and isolated natural compounds. On the other hand, we used the aqueous
extract of E. glaberrima leaves to test the allelopathic potential.
Five known compounds, namely, rengyolone (1), betulinic acid (2), taxifolin
3?O?β?D?xylopyranoside (3), quercitrin (4) and hyperin (5), were isolated from
methanolic extract of E. glaberrima and one acetylated product 3-O-acetyl betulinic
(2a) were identified by NMR and ESI-MS-MS data analyses. Rengylone revealed 50
% inhibitory effect at 40 μg/ml on HepG2 2.2.15. 3-O-acetyl betulinic had better
cytotoxic effect than betulinic acid. All of them didn’t show the anti-HBV effect.
In addition, in order to test the allelopathic potential of E. glaberrima, the
aqueous extracts (1~5%) of leaves of E. glaberrima were bioassayed by using six
tested plants, namely, Brassica chinensis, Lactuca sativa, Setaria italica, Ocimum
basilicum, Cucumis sativus and Bidens pilosa. The results exhibited that the aqueous
extracts of E. glaberrima could inhibit the radicle growth but not seed germination of
the six tested plants. The leachate of E. glaberrima leaves could significantly inhibit the radicle elongation of B. chinensis and S. italica. In our study, betulinic acid and
hyperin didn’t show the allelopathic effect of the tested plants.
In conclusion, E. glaberrima maybe has relative low potential for developing as
a medicinal plant. The aqueous extracts and leachate of E. glaberrima have the
phytotoxic potential, exhibiting suppressive effect on some species underneath the
Eurya vegetation in the field. |
