Doctor Dissertation Of Hoa Hoang Quynh

Dissertation: “Research into some medicinal trees belonging to the Ehretia P.Br. and Boraginaceae line in Northern Vietnam”.

Major:Pharmacognosy -Traditional pharmacy Code:
Candidate: Hoang Quynh Hoa
Supervisors: 1. Ass. Prof. Dr. Tran Cong Khanh 
2. Prof. Dr. Pham Thanh Ky
Summary of the thesis’s new contributions:
- According to the analysis of 111 number signs of the botanical specimens from herbarium inside and outside the country and specimens collected in the field, the thesis classified and defined scientific names of species which were of Ehretia P. Br line in Northern Vietnam, including E. acuminata . R. Br; E, asperula Zoll. Et Mor.; E. dichotama Blume; E. dicksonii Hance.; E. laevis Roxbo.; E. longiflora Champ. Ex Benth. And E. tsangil Johnst. The thesis completely described figure features, made the tree dichotonal classification keys and open box of 7 species belonging to Ehretia P. Br line in Northern Vietnam. It was the first time to have proclaimed the seven species’ anatomical specimen features of branches and leaves. The thesis also tested the classification the “Xa Den” species which grow in Hoa Binh town and affirmed its scientific name as Ehretia asperula Zoll. Et Mor.
- Basing on the findings of the survey on public awareness of using drugs, the thesis has listed 7 diseases (in Northern part of VN) treated by using the species in Ehretia P. Br line. They are: fever, protuberance, allergy, post-natal, diarrhea , liver and bone diseases among which, the liver diseases are the most frequent and then protuberance, and post-natal. In addition, 7/8 of the plant (except flower) have been used as medicine. The barks of Ehretia longiflora Champ and leaves or all above-soil parts of E. asperula Zoll et Mor. are most commonly used. At the same time, the results have pointed that the local people have used medicinal plants belonging to Ehretia P. Br. Line in 4 ways. The most common way is infusion, the least common way is application of the fresh leaves on.
- Regarding to biological effect and toxicity, the thesis has confirmed that the leave sample of E. acuminate R. Br. (dose: 3g/kg) and the barks of e. longiflora Champ. Ex Benth (doses 3g/kg and 9g/kg) can improve liver functions, reduce degree of ALT activity to 55,6 %, 34% and 30,5% respectively on the liver model which has been poisoned by using paracetamol. The leave sample of E. tsangii has shown that its effect on liver functions is not as good as of the two species mentioned above. E. acuminata R. Br. Methanol extract and E. longiflora Champ. Ex Benth trunk and bark have effect of suppressing liver cancer cell with the survival cell rate of about 50,23 ± 0,25% and 45,12% ± 0,20% , IC50 value is 20 and 18 μg/ml respectively. E. acuminata R. Br. extract; E. longiflora Champ. ex Benth. trunk and bark and E. tsangii Johnst. leaf have no toxicity when tested by the oral route at the maximum dosage which can be admitted by mice and are 300, 100 and 120 times as high as the common dose. All of these have shown the drugs are highly safe.
- Regarding to the chemical component, the thesis defined that the branches and leaves of 4 species: E. accuminata R. Br., E. longiflora Champ. ex Benth., E. tsangii Johnst. and E. asperula Zoll. et Mor. have flavonoid, tanin, acid amin and reducing sugar. Especially, sterol in E. acuminata R. Br’s leaf and E. longiflora Champ. ex Benth.’s truck, saponin only in E. acuminata R. Br.’s leaf. From E. longiflora Champ. ex Benth’s truck and bark 8 compounds have been isolated, including 4 first compounds isolated from Ehretia P. Br. line which are erogesterol peroxide, menisdaurin, (+)-lyoniresinol and (+)-lyoniresnol 3a-O-b-D-glucopyranosid) and 4 compounds first isolated from E. longiflora Champ. ex Benth, which are b-sitosterol, acid ursolic, daucosterol and acid rosmarinic.
-  For the first time rosmarinic acid (EL8) which has effect of inhibiting the liver cancer cell Hep-G2 in vitro with IC50 as 0,5 μg/ml has been defined.