Endophytic fungi stimulate the concentration of medicinal secondary metabolites in houttuynia cordata thunb.

Endophytic fungi usually establish a symbiotic relationship with the host plant and affect its growth. In order to evaluate the impact of endophytic fungi on the Chinese herbal medicinal plant Houttuynia cordata Thunb., three endophytes isolated from the rhizomes of H. cordata, namely Ilyonectria liriodendra (IL), unidentified fungal sp. (UF), and Penicillium citrinum (PC), were co-cultured individually with H. cordata in sterile soil for 60 days. Analysis of the results showed that the endophytes stimulated the host plant in different ways: IL increased the growth of rhizomes and the accumulation of most of the phenolics and volatiles, UF promoted the accumulation of the medicinal compounds afzelin, decanal, 2-undecanone, and borneol without influencing host plant growth, and PC increased the fresh weight, total leaf area and height of the plants, as well as the growth of the rhizomes, but had only a small effect on the concentration of major secondary metabolites. Our results proved that the endophytic fungi had potential practical value in terms of the production of Chinese herbal medicines, having the ability to improve the yield and accumulation of medicinal metabolites.

[Identification characters of leaf morphological and venation pattern of Houttuynia cordata with its confused herb Gymnotheca chinensis].

OBJECTIVE: To study the identification characters of Houttuynia cordata and its confused herb Gymnotheca chinensis and establish an identification method. METHODS: LMVP (leaf morphological-venation pattern for identification Chinese herbs), and QAERM (quantitatively analyze and evaluate reliability for the method of identification Chinese herbs) were applied for the study. RESULTS: Both venations were brochidodromous-acrodromous and arising from the mid-petiole or the upper section of petiole. The main characteristic of the leaf of Houttuynia cordata: surface with small gray-white stoma protuberances; Ligulate process of stipule-petiole sheath were clear; Primary veins 7 or 5; The innermost pair of primary vein closed up the top of the sinus at blade base or above sinus, and the section of closed vein was straight; Emitted a smell of fish when fresh leaf was kneaded into pieces. The main feature of the leaf of Gymnotheca chinensis: no small gray-white stoma protuberances; Ligulate process of stipule-petiole sheath were not clear; Primary veins 5; The innermost pair of primary vein closed into the sinus at blade base, and the section of closed vein was slightly curve; No smell of fish. With the mentioned key differences, the both plants could be successfully identified from each other. The accuracy of identification results (AC) was 100%, the repeatability of identification results: agreement rate for observation (ARO) was 100% and Kappa value was 1.00. CONCLUSION: The established method is simple, rapid, economic and reliable.

Combined effect of dark and wounding on regeneration potential of Houttuynia cordata Thunb. leaves.

Houttuynia cordata is one of the most potential medicinal and edible wild herb whose resources have decreased sharply due to excessive exploitation. Besides its slow agamic propagation, problems of browning and non-dedifferentiation have prevented the application of micropropagation in H. cordata. Through 4 week pre-culture in darkness and wounding after 1 week pre-culture, the browning rate of leaf explants decreased significantly and resulted in efficient regeneration (20.64 +/- 5.94 adventitious buds per explant) on the induction medium. The protocol shall facilitate conservation and commercial cultivation of the endangered species.

[Comparison of volatile oils of cultivated Houttaynia cordata populations with wild].

OBJECTIVE: To provide scientific proofs for the exploitation, utilization, and normalized cultivation of Houttuynia cordata. METHOD: The underground parts of 17 wild H. cordata populations from different valleys and altitudes of mountain. Emei were transplanted to the same growth conditions. After one year's cultivation, volatile oil was obtained by steam distillation from the aerial part of the materials. The chemical constituents were separated and identified by GC-MS, and the relative content of each constituent was determined by area normalization. RESULT: Totally, 31 chemical components were identified, 19 components could be detected in all materials. The t-test results indicated that the contents of alpha-pinene and D-limonene were extremely significantly higher than that in the wild populations, and the contents of camphene and 2-undecanone were also significantly higher than that in the wild populations. And the reverse was found in the content of trans-beta-ocimene. All these 31 components could be divided into 9 chemical compositions, and 7 chemical compositions could be detected in the wild and cultivated. RSD values of 5 chemical compositions in wild populations were higher than that in the cultivated, except for the contents of diterpenyl alcohols and diterpenyl aldehydes. These five chemical compositions accounted for 84.05% and 90.12% of the whole volatile oils in the wild and cultivated conditions, respectively. CONCLUSION: The components and contents of the volatile oils between wild and cultivated were different. The volatile oils polymorphism decrease distinctively as all the wild populations of H. cordata were transplanted to the uniform environmental conditions.

[Study on HPLC fingerprint of flavonoids from Houttuynia cordata by comparing with fingerprint reference].

OBJECTIVE: To establish a stable and repeatable HPLC fingerprint standard and evaluate the flavonoids from Houttuynia cordata qualitatively and quantitatively. METHODS: HPLC separation was performed on a C18 column with methanol-0.1% phosphoric acid mixed solution as mobile phase in gradient elution mode. The fingerprint reference was determined as one of the most typical chromatograms and used to be compared with other samples through Cosine and Relative Euclid Distance methods, thus the chromatographic fingerprints of flavonoids from Houttuynia cordata were evaluated by constitutes and contents, respectively. RESULTS: Fourteen mutual peaks were fixed in the HPLC fingerprint of flavonoids from Houttaynia cordata. It showed good results in validation tests in which the quercitrin's peak was set as the reference peak to calculate relative retention time and area of other peaks in the chromatograms, and the RSD were less than 0.2% and 5.0%, respectively. The linear ranges for quercitrin was 1.07-83.4 microg/mL (r=0.9999) and the average recovery was 100.3%. CONCLUSION: The method shows good repeatability, ruggedness and reliability. Comparing with the established reference fingerprint, the evaluation system including Cosine and Relative Euclid Distance methods lays dependable foundation for controlling the quality of Houttuynia cordata.

[Effects of fertilizer application on contents of 2-undecanone and soluble carbonhydrate in Houttuynia cordata with different fertilizers].

OBJECTIVE: To investigate the effect of five kinds of fertilizers at three application levels on the content of 2-undecanone and carbohydrate in Houttuynia cordata. METHOD: A single factor randomized block design was used to investigate the content of 2-undecanone and carbohydrate in the plant. RESULT: The results showed that the content of 2-undecanone was the highest both in aerial and underground parts of H. cordata, which was fertilized with complex fertilizers served in conventional way, having the content 18.6 microg g(-1) and 26.0 microg g(-1) respectively. In addition, 2-undecanone contents in aerial parts of H. cordata (14.9 microg g(-1)) fertilized with manure of human were also higher than that with chemical fertilizer, pig and duck manures, but no significant difference were found among the other treatments in aerial or underground parts of the plants, respectively. The results also demonstrated that fertilized with organic fertilizer might be beneficial to enhance the quality of sugar in H. cordata, mainly including the contents of total sugar, solutable sugar, fructose and reduced sugar in the plants, especially with manure of human and pig. CONCLUSION: As the result of this study and the related previous research on yield of H. cordata were considered, the fertilizing ways for increasing quality of H. cordata should take the manure of human as a main fertilizer and mix with the other organic fertilizers, complex fertilizers and chemical ones may be needed to balance the plant nutrient. In the field practice, the amount of organic fertilizer including 108,000 kg hm(-2) human mature, together with some high-efficient complex fertilizer and a small amount of quick-acting chemical fertilizer is recommended.