[Study on HPLC fingerprint of Hedyotis chrysotricha].

OBJECTIVE: To establish HPLC fingerprint of Hedyotis chrysotricha. METHODS: Hypersil BDS C18 (250 mm x 4.6 mm, 5 microm) column was used with methanol and 0.1% acetic acid solution as mobile phase in gradient mode, the flow rate was 1.0 mL/ min. The detection wavelength was 345 nm and the temperature of the column was set at 30 degrees C. Using ursolic acid as the reference standard, the mutual mode of Hedyotis chrysotricha containing nine common peaks was set up. The similarity of Hedyotis chrysotricha from different habitats was analyzed. RESULTS: The fingerprints of Hedyotis chrysotricha from different habitats were similar, but also had habitat characteristics. CONCLUSION: The HPLC fingerprint can be used for identification and quality control of Hedyotis chrysotricha.

Optimal oxidative folding of the novel antimicrobial cyclotide from Hedyotis biflora requires high alcohol concentrations.

Hedyotide B1, a novel cyclotide isolated from the medicinal plant Hedyotis biflora, contains a cystine knot commonly found in toxins and plant defense peptides. The optimal oxidative folding of a cystine knot encased in the circular peptide backbone of a cyclotide poses a challenge. Here we report a systematic study of optimization of the oxidative folding of hedyotide B1, a 30-amino acid cyclic peptide with a net charge of +3. The linear precursor of hedyotide B1, synthesized as a thioester by solid phase synthesis, was cyclized quantitatively by a thia-zip cyclization to form the circular backbone and then subjected to oxidative folding in a thiol-disulfide redox system under 38 different conditions. Of the oxidative conditions examined, the nature of the organic cosolvent appeared to be critical, with the use of 70% 2-propanol affording the highest yield (48%). The disulfide connectivity of the folded hedyotide was identical to that of the native form as determined by partial acid hydrolysis. The use of such a high alcohol concentration suggests that a partial denaturation may be necessary for the oxidative folding of a cyclotide with the inverse orientation of hydrophobic side chains that are externalized to the solvent face to permit the formation of the interior cystine core in the circularized backbone. We also show that synthetic hedyotide B1 is an antimicrobial, exhibiting minimal inhibitory concentrations in the micromolar range against both Gram-positive and -negative bacteria.

[Diversity and stability of arthropod assemblage in tea orchard].

Two tea orchards, simplex tea orchard with weeds removed manually or by herbicides (STO) and complex tea orchard with the weed Hedyotis uncinella (CTO), each with an area of 0. 4 hm2, were established in 1995 in Yingde Hongxing Tea Plantation, Guangdong Province. The primary eigenvalues, species richness index (R), assemblage diversity index (H'), evenness index (J) and species concentration index (C) of arthropod assemblage were employed and compared to assess the efficacy of STO and CTO on the diversity and stabilityof arthropod assemblage. Stability indexes Ss/Si and Sn/Sp and variation coefficient of diversity index ds/dm were utilized as well. The results demonstrated that the R of arthropod assemblage in CTO ranged from 4 to 8, with the highest of 7.7403, while that in STO varied mainly between 4 to 6. The average R of arthropod assemblage in CTO was 5.4672 +/- 0.3483, higher than that in STO (4.8809 +/- 0.3175). The H' of arthropod in CTO (3.8535 +/- 0.1232) was higher, in contrast to the value in STO (3.4654 +/- 0.1856). The J in CTO was higher, while the species concentration index (C) was lower, in comparison to STO. The stability indexes Ss/Si and Sn/Sp of CTO were greater than those of STO, while the ds/dm in CTO (0.1107) was lower than that in STO (0.1855). All these indicated that the diversity of arthropod assemblage was better preserved in CTO, and the assemblage in CTO was more stable.

[Observation on biological characteristics of Hedyotis diffusa].

The present work enunciats the phenophase and plant organ development of Hedyotis diffusa Willd, at Nanjing region. These results can give a reference for the plant growing practice.