Identification Of Germplasm Resources For Pogostemon Cablin And Agatache Rugosa And The Antibacterial Activity Testing Of Their Essential Oil

Pogostemon cablin, a plant of the Lamiaceae family, is extensively cultivated in Indonesia, the Philippines, Malaysia, China, India and Brazil. The aerial part of P. cablin has been used for the treatment of the common cold, headache, fever, vomiting, indigestion and diarrhea as well as an antifungal agent in medicinal materials of China and its surrounding regions. Agastache rugosa, a plant of the Lamiaceae family, is a perennial herb widely distributed in East Asian countries, such as China, Korea, Japan and so on. It is used as a Chinese traditional medicine for the treatment of cholera, vomiting and miasma, and it has been reported to have antitumor, antifungal, antiatherogenic and cytotoxic activities. In our country, P. cablin was only used in area of south of China originally, the use scope of P. cablin was gradually expanded because of the obvious clinical efficacy. Now, it has been widely applicated in Zhejiang, Jiangsu, Hunan, Jiangxi, Sichuan province and so on. Because its aliases, morphological characteristics and efficacies were similar to the local medicinal materials of A. rugosa, P.cablin and A. rugosa were often confused and mistaken in practical use. In order to distinguish them, the morphologies of flowers and pollen grain, chromosome karyotypes, X-ray diffraction spectrums, essential oil chemical compositions and antibacterial activities were compared and studied in this paper.To compare the differences of flower’s morphologies, some researches were done. There were more flowers in the Nanxiang inflorescence than those of other P. cablin. The color of Nanxiang’s calyx was green, while the others were celadon. The upper lip of Nanxiang’s corolla was dark purple, while the others were paler purple. No beard appeared in the three filaments. A. rugosa calyx was yellowish green, and the upper lip of corolla was lavender. There were many beards in the filament. Scanning electron microscopy (SEM) results showed, the shape of Nanxiang’s pollen was subprolate from the equatorial view, while the others were prolate. The arrangement of Nanxiang’s three germinal apertures was symmetrical, while the others were unsymmetrical. The shape of A. rugosa’s pollen was subprolate from the equatorial view, polar diameter ranged from32μm to38μm in length, equatorial diameter ranged from14μm to18μm in length. There were six pollen’s germinal apertures, and exine sculpturing of pollen was striato-reticulate.Chromosome karyotype analysis showed that the chromosome number of four P. cablin populations was2n=64, belonging to the3B type. Their karyotype formulas were2n=2x=64=8m+30sm+16st+2t+8T(Nanxiang)、2n=2x=64=8m+32sm+12st+4t+8T (Zhanxiang、2n=2x=64=8m+30sm+16st+2t+8T(Paixiang)、2n=2x=64=8m+32sm+14st+2t+8T(Zhaoxiang), respectively. Whereas, the chromosome number of A. rugosa was2n=2x=18, and its karyotype formula of A.rugosa was2n=2x=18=2m+14sm+2t.Methodology of X-ray diffraction (XRD) was adapted to make a distinction between P. cablin and A. rugosa, the cosine angle values of four P. cablin populations had some similarities, more than0.600. Whereas, that of A. rugosa was0.325, which was very different from P. cablin. So,0.600was used as the reference standard to differentiate P. cablin and A. rugosa in this paper. According to the difference of characteristic peak’s intensity of P. cablin and A. rugosa, these five samples could be divided into three classes. Paixiang was belonged to I class with a characteristic peak (D=7.5nm), and Zhanxiang, Nanxiang and Zhaoxiang were belonged to Ⅱ class with a characteristic peak (D=4.0nm). While A. rugosa was belonged to Ⅲ class.The chemical compositions of essential oil from A. rugosa and P. cablin had been examined by GC-MS in this paper. A total of23and18compounds were identified, accounting for96.26%and97.00%of the essential oils in branch leaves and flowers of A. rugosa, respectively, whereas a total of26,24and30compounds were identified, which account for98.74%,98.99%and99.61%of the essential oils from Nanxiang, Paixiang and Zhaoxiang of P. cablin, respectively. Estragole was the main constituent of the essential oils from both branch leaves and flowers of A. rugosa, while in the essential oils from three populations of P. cablin, pogostone and patchouli alcohol were the major constituents.The essential oil extracted from the aerial part of P. cablin and the leaves of A. rugosa was evaluated for its antifungal activity against six common phytopathogenic fungi. Results showed that the essential oil of P. cablin had strong antifungal activities against Corynespora cassiicola (Berk.Curt.) Wei, Colletotrichum musae (Berk&Curt) Arx, Fusariun oxysporum f. sp. Niveum and Colletotrichum gloeosporioides Penz (EC50=0.517,0.904,1.196and1.225μg/mL, respectively), and the essential oil extracted from the leaves of A. rugosa had strong antifungal activities against all of the six phytopathogenic fungi (EC50=1.338-1.927μg/mL).