Toxic polyacetylenes in the genus Bupleurum (Apiaceae) - Distribution, toxicity, molecular mechanism and analysis

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Bupleurum includes approximately 200 species that are widely distributed in the Northern Hemisphere, Eurasia and North Africa. Certain species of this genus have long been used as antiphlogistic, antipyretic and analgesic agents in traditional folk medicine. As described in the Chinese Pharmacopoeia, the roots of Bupleurum chinense DC. and B. scorzonerifolium Willd. are the herbal materials that compose Chaihu (Radix Bupleuri), a well-known TCM herb.

AIM OF THE REVIEW

This review aims to provide up-to-date and comprehensive information regarding the distribution, toxicity, molecular mechanism and relatively new methods for the qualitative and quantitative determination of polyacetylenes in different Bupleurum species.

METHOD

The information needed for this paper were sourced from publishing sites such as Elsevier, science Direct, PubMed; electronic search engines such as Scopus and Web of Science, Google scholar; other scientific database sites for chemicals such as ChemSpider, PubChem, SciFinder, and also from on line books.

RESULTS

Polyacetylenes, which are widely distributed in genus Bupleurum of the Apiaceae family, have high toxicity. Among polyacetylenes, bupleurotoxin, acetylbupleurotoxin and oenanthotoxin have strong neurotoxicity. Through previous research, it was found that the toxicity of Bupleurum polyacetylenes manifested as epileptic seizures, with the target of toxicity being the brain. The neurotoxicity of polyacetylenes exhibits a relationship with the γ-aminobutyric acid (GABA) receptor pathway, and polyacetylenes have been shown to inhibit GABA-induced currents (I_GABA) in a competitive manner.

CONCLUSIONS

The plants of genus Bupleurum have been used in traditional medicine for thousands of years. However, certain species of this genus are poisonous, and it was attributed to the high content of polyacetylenes. The present review indicates that certain polyacetylenes in the genus Bupleurum have highly neurotoxic effects. The major challenge with regard to toxic polyacetylenes is to test their neurotoxic effects in vivo as well as in further preclinical studies, which will require large amounts of purified polyacetylenes. More reference substances should be prepared, and sophisticated analytical technologies should be developed to comprehensively assess the quality of Radix Bupleuri herbs. These investigations will be helpful for further utilization of the plants of genus Bupleurum.

[Grain filling dynamics and germination characteristics of Bupleurum chinense seeds]

Bupleurum chinense used in the study were cultivated in the experimental fields of Gansu agricultural University for three years. The seeds of B. chinense were collected every 3 days 10 d after the blossom. The result showed that the 1 000-grain fresh weight reached the maximum 43 d after the blossom and then decreased rapidly, at the mature period the fresh weight of seeds were falling to the same level of the dry weight. The dynamic change of the grain dry matter accumulation showed as an S-shape curve, the rapid increase stage was 25-34 d following the flower, and the grain filling was ended 46 d after blossom. Grain filling rate was under the law "fast-slow-fast-slow". And there were two peaks of grain filling rate appeared, after reached the second peak 28 d after the flower the filling rate decreased rapidly and stayed steadily 43 d after flowering. The dehydration rate was also measured at its maximum 43 d following flower. The indexes of seeds all reached the top 52 days following the blossom, when the germination rate reached the peak (34.33%) and water content of seeds was near 10%. The rate of germination and the 1 000-graid weight of seed showed significant positive correlation, while the water content of seeds was found significant negatively correlation with germination percentage. So the best time for harvest should be 52 d after flowering (9 month), the seeds collected at that time showed both high quality and germination rate.

[Effects of hormone treatment, light and temperatures on sprouting characteristics of Bupleurum chinense]

Seeds of Bupleurum chinense cultivar, Zhongchai No. 1, were sowed in plastic pots which used the arable layer soil as the nursery bed and putted in the artificial climate incubator at various temperatures (15, 20, 25, 15-25 degrees C) and light (8,12 h) to germinate, respectively. The lower constant temperature (15 degrees ) and the higher constant temperature (25 "C) were not conducive to the sprouting characteristics of B. chinese. While they were able to enhance root activity to some extent; The seeding growth of B. chinese was significantly better in the variable temperature than correspondence in the constant temperature, significantly. The emergence speed, emergence index, vigor index and root activity of Bupleurum were improved under the 12 h of light-time, but the germination rate was not improved. The sprouting of Bupleurum's seeds could be improved to some extent by soaking with hormone, such as gibberellin, cytokinin, salicylic acid. Gibberellin promoted seeds' sprouting and seedings's root activity of Bupleurum, while salicylic acid increased the root activity of seeding. There is a significant influence of light, temperatures and hormone treatment on the germination of Zhongchai No. 1 seeds, and all three are remarkably interacted; It is beneficial to promote seed germination by the temperature (20 + 5) degrees C, lighting (8 h) and gibberellin concentration (10 x 10(-6)).

[Comprehensive yield and quality comparison of Bupleurum chinense' s seeds of different harvesting time from Qingchuan County with Topsis approach]

In order to investigate the comprehensive quality differences of the seeds harvested in different growing time, and offer theoretical guide for the optimization of seeds' production technology, we analyzed the apparent size, 1 000-grain weight, water absorbency, germination indexes, postharvest embryo rate change, relatively contents of coumarins and the yield of single plant of its seeds of different harvesting time, and compared their comprehensive quality by Topsis analysis. The results showed that there existed obvious differences in yield and quality between seeds of 3 harvesting times. While the harvesting time postponed, the yield of single plant raised, and the shrunken seeds rate decreased, the quality of seedlings increased, while the contents of coumarins showed a steady increase, and the germination rate decreased. The comprehensive quality of the seeds harvested in the black ripe time rank the first place, followed by the brown ripe time and the yellow ripe time. As the harvesting time delays, the seeds' comprehensive quality increases, therefore, we could put off the seeds' harvesting time properly for the high efficient seed production.

[Studies on high efficient plant regeneration system from anther callus of Bupleurum chinense]

The callus of Bupleurum chinense with anthers at the stage of uninucleate was induced. After several subcultures, anther calli of B. chinense were cultured at 20 MS culture mediums with different plant hormones to differentiate into plantlets. Differentiation of callus was detected after 21 and 49 days to select the most effective medium. There were 19 culture mediums in which anther callus could differentiate into plantlets with differentiation rate range from 3% to 60% , and most less than 20%. MS + KT 0.5 mg x L(-1) + sucrose 30 g c L(-1) + phytagel 5 g x L(-1) was the best differentiation medium with the differentiation rate of 60%, followed by MS + ZT 1.0 mg x L(-1) + sucrose 30 g x L(-1) + phytagel 5 g x L(-1) with the differentiation rate of 58%. Then plantlets were transferred to rooting medium to obtain whole plant. All plantlets could root in the rooting medium of MS + sucrose 30 g x L(-1) + phytagel 5 g x L(-1) and 1/2 MS + NAA 0.5 mg x L(-1) + sucrose 30 g x L(-1) + phytagel of 5 g L(-1) with the rooting rate of 100%. As a result, the high efficient and stable plant regeneration system was established from anther callus of B. chinense.

[Induction of hairy roots and plantlet regeneration of Bupleurum chinense DC]

In this study, the induction of hairy roots of Bupleurum chinense DC. was explored and established after experiments at different conditions: A. rhizogenes A4 was used to infect the leaves bases of B. chinense tube seedlings. The explants were co-cultured on Phytagel-solidified media for 3 days and then, were turned into solid media, similar with the co-culture media except that bacteriostat was added. After 10 days, rootlets began to appear and after 4 to 5 weeks, rootlets can be converted into liquid shaking culture stage. Plants regeneration from hairy root was useful for the research of new germplasm production and the variety improvement breeding. In the present study, the regenerated plants were obtained. One approach was to continuously culture under light conditions the seedlings which parting off spontaneously from the hairy roots during liquid shaking culture. The other approach was to culture the callus-like tissues produced by hairy roots with the optimized regeneration media for the induction of regenerated plants. The results of present study provide a technique to induce hairy roots and plantlet regeneration of B. chinense and this technique is helpful for the researches on metabolism, especially on the Agrobacterium-mediated genetic transformation of B. chinense.

[Investigation on bupleurum resources in northwest area of Hubei Province]

OBJECTIVE

To investigate the species and the distribution of Bupleurum genus in northwest of Hubei province and provide basis for the standardization planting of Bupleurum in the region.

METHODS

Investigated and collected specimens on the spot, com- pared them with literatures and specimen collected before.

RESULTS

The main species of Bupleurum plants was B. marginatum, only very few of them was B. scorzonerifolium, no B. chinense was found in northwest of Hubei province.

CONCLUSION

B. marginatum is the mainstream species of Bupleurum plants and the roots of B. marginatum are the actual source of commodity with the name of "Beichaihu (the roots of B. chinense)" in northwest of Hubei province.

[Advances of studies on seed biology of Bupleurum chinense]

Bupleurum chinense is a commonly used Chinese medicinal material, which has been used medicinally in China for over 2000 years, the development of it is of great value. There have been great advances of studies on its embryology and seed biology in recent years. In this paper, we make a review of the growth of its embryo and fruit, the characteristics of dormancy and storage and the germination of its seed. Besides, we summarize the reasons of its low germination rate and the achievements in improving the situation, for the purpose of providing reference in research on seed physiology of B. chinense.

[Cropping patterns of Bupleurum chinense in semi-arid region of Loess Plateau]

Field experiments were conducted to investigate the suitable cropping patterns of grain crops and medical plant Bupleurum chinense in the semi-arid region of the Loess Plateau. Three cropping patterns were designed, including corn-Bupleurum chinense intercropping (corn/Bupleurum chinense), wheat followed by soybean-Bupleurum chinense intercropping (wheat-soybean/Bupleurum chinense), and sequential planting of Bupleurum chinense (wheat-Bupleurum chinense). Of the three patterns, wheat-soybean/Bupleurum chinense was the best in economic yields and ecological benefits. Among the cultivars (cv. Lingchuan, Zuoquan and Wanrong) of Bupleurum chinense tested, the cv. Wanrong originated from relatively high temperature region exhibited the highest yield, while the cv. Zuoquan originated from relatively low temperature region had the lowest one, indicating that introducing Bupleurum chinense cultivars from the areas with higher temperature to lower temperature areas could increase their yield. The cropping pattern of wheat-soybean/Bupleurum chinense was the most effective one, with the yield being 11.6% and 16.8% higher than that of corn/Bupleurum chinense and wheat-Bupleurum chinense, respectively.

[Study on dynamic accumulation of index components from Bupleurum chinense in various collecting periods]

OBJECTIVE

To study the dynamic change law of volatile oil, saikosaponin a, d and alcohol-extract from Bupleurum chinense at Songxian region in Henan province, and to explore the optimal harvest period of Bupleurum chinense.

METHODS

With the contents of saikosaponin a and d, absorbance of volatile oil and percentage of alcohol-extract as indexes, HPLC-ELSD and ultraviolet spectrophotometry were successively used to analyze them.

RESULTS

There are obvious differences among the contents of volatile oil, saikosaponin a, d and alcohol-extract in various collecting periods sample, the absorption of volatile oil in distillation was the highest in October, the content of saikosaponin a was the highest in September, the saikosaponin d in December and the percentage of alcohol-extract in October.

CONCLUSION

The optimal harvest period of Bupleurum chinense at Songxian region in Henan is identified, which can provide scientific basis for crude drug production and processing.

[Breeding of new varieties "zhongchai no. 2" and "zhongchai no. 3" of Bupleurum chinense]

OBJECTIVE

To breed new varieties with better uniformity and commercial quality as well as higher saikosaponin contents.

METHOD

The excellent germplasm resources were selected from "zhongchai no. 1" population. Single plant method was applied to get better varieties. All the breeding material was investigated according to morphological characters, agronomic characters and the contents of saikosaponin a and saikosaponin d. The experiments of comparative test and varieties regional test were carried out.

RESULT

The bred new varieties of "zhongchai No. 2" and "zhongchai No. 3" had better uniformity. The dark brown roots ratios of the two varieties were 83.2%, 89.9%, respectively. The contents of saikosaponins (a + d) of the two varieties reached 1.31%, 1.02%, respectively.

CONCLUSION

"zhongchai No. 2" and " zhongchai No. 3" both had the advantages of better uniformity, darker brown roots and higher saikosaponin contents.

[Study on main inheritable parameters of test-tube plants population of Bupleurum chinense in different growing periods]

OBJECTIVE

To determining the growth status and medicine quality of test-tube plants of Bupleurum chinense.

METHODS

Measuring the field characters of the labeled plants at fixed period after turning green,such as plant height, number of tiller, number of leaves. Using statistical methods to analyse the measured data

RESULTS

Each genetic characters standard deviation and relative standard deviation are all smaller at vegetative growth phase, bud forming phase and seed ripening phase. The test-tube plants population of Bupleurum chinense grows consistently. Its uniformity is higher, variability is low. Bupleurum chinense length and weight of root relative standard deviation are all low. The average root length and weight are more predominant than ordinary seed plants. The roots have high content of effective components. Bupleurum chinense population pharmaceutical character is excellent. The medicinal quality is consistent. The number of branch stem and effective fruit bunch is bigger, The seed production is higher. The aerial part yield is large, The economic value of test-tube plants of Bupleurum chinense is higher. The correlation between each characters of test-tube plants of Bupleurum chinense is different from the ordinary seed plants in different growing periods.

CONCLUSION

The botanical and pharmacognostic characters of test-tube plants of Bupleurum chinense are excellent.

[Studies on fingerprints of Bupleurum chinense and vinegar-baked Bupleurum chinense from Hubei province]

OBJECTIVE

To establish the HPLC Fingerprint of Bupleurum chinense from GAP provenance of Hubei province Baokang, and discuss the changes before and after processing.

METHODS

Using HPLC detection method equipped with Hypersil ODS column (5 microm, 4.6 mm x 250 mm), using acetonitrile-water as mobile phase gradient elution, flow as 1.0 ml/min, UV detector set at 203 nm, column temperature was at 25 degrees C.

RESULTS

Similarity of processed Bupleurum chinense and Bupleurum chinense exceeded 0.95, and there were 13 characteristic fingerprints of processed Bupleurum chinense, 15 characteristic fingerprints of Bupleurum chinense.

CONCLUSION

The HPLC Fingerprint of Bupleurum chinense from GAP provenance of Hubei province Baokang are established, and the difference between Bupleurum chinense before and after processing is studied initially.

[Effects of nitrogenous phosphorus and potassium fertilizer on yield of Bupleurum scorzonerifolium]

OBJECTIVE

To study the effect of different fertilizer assortment (nitrogenous, phosphorus and potassium) on Bupleuram scorzonerifolium yield.

METHODS

Three factors were designed by quadratic regression and D-optimum designation.

RESULTS

As far as the biomass concerned, the best design of fertilizer was N 120. 3 - 333. 3 kg/hm(2) P2O5 0-939. 45 kg/hm(2), K2O 0 - 227. 25 kg/hm(2). As to R/T, the best design was N 62. 66 -333. 3 kg/hm(2), P2O5 0 -922. 54 kg/hm(2) , K2O 0 -227. 25 kg/hm(2). And for the root weight, the best design was N 34. 5 -333. 3 kg/hm(2), P2O5, 0 -939. 45 kg/hm2 , K2O 0-227. 25 kg/hm(2).

CONCLUSION

Application quality of nitrogenous, phosphorus and potassium fertilizer are closely related with yield of B. Scorzonerifolium.

[Preliminary study on N, P, K fertilizer to control of root rot of Bupleurum chinense]

The application of N and K fertillizer could improve the sensibility of Bupleurvum chinense DC. to Root Rot, while large application of P fertilizer could decrase the sensibility. The fertilizer measure which could obtain highest yield but could not increase its disease resistense. To protect Bupleurum chinense against root rot, more phosphorous fertilizer, certain nitrogen and potassium ferilizer should be applied in early elongation stage in the second growing year.

[Preliminary study on the characteristics of Bupleurum chinense in nutrition uptake]

It was studied that the characteristics of Bupleurum chinense DC. in nutrition uptake based on potted and field experiment to provide a properly fertilizer application measure. The result showed that the absorption amounts of N, P and K were in the order of K > N > P under field condition. For one-year-old B. chinesnse DC., the average N, P2O5 and K2O absorption per 100 kg dry matter of root were 11.77 kg, 2.43 kg, 14.07 kg respectively; for two-year-old, the average N, P2O5 and K2O absorption amount per 100 kg dry matter of root were 12.11 kg, 2.74 kg, 18.39 kg respectively. The total absorption amount of N, P2O5 and K2O were lower in the first year, while the percentage of content was higher, that was to say, the demand for N, P and K was urgent in the first year. The accumulation peak of N, P2O5 and K2O occurred regreening to later elongation stage in the second year. The ratio of N, P and K were differential in different growth stages.

Seasonal branch nutrient dynamics in two Mediterranean woody shrubs with contrasted phenology

BACKGROUND AND AIMS

Mediterranean woody plants have a wide variety of phenological strategies. Some authors have classified the Mediterranean phanaerophytes into two broad phenological categories: phenophase-overlappers (that overlap resource-demanding activities in a short period of the year) and phenophase-sequencers (that protract resource-demanding activities throughout the year). In this work the impact of both phenological strategies on leaf nutrient accumulation and retranslocation dynamics at the level of leaves and branches was evaluated. Phenophase-overlappers were expected to accumulate nutrients in leaves throughout most of the year and withdraw them efficiently in a short period. Phenophase-sequencers were expected to withdraw nutrients progressively throughout the year, without long accumulation periods.

METHODS

To test this hypothesis, variations in phenology and leaf NPK in the crown of a phenophase-overlapper Cistus laurifolius and a phenophase-sequencer Bupleurum fruticosum were monitored monthly during 2 years.

KEY RESULTS

Changes in nutrient concentration at the leaf level were not clearly related with the different phenologies. Nitrogen and phosphorous resorption efficiencies were lower in the phenophase-overlapper, and accumulation-retranslocation seasonality was similar in both species. Changes in the branch nutrient pool agreed with the hypothesis that the phenophase-overlapper accumulated nutrients from summer until the bud burst of the following spring, recovering a large nutrient pool during massive leaf shedding. The phenophase-sequencer did not accumulate nutrients from autumn until early spring, achieving lower nutrient recovery during spring leaf shedding.

CONCLUSIONS

It is concluded that phenological demands influence branch nutrient cycling. This effect is easier to detect by assessing changes in the branch nutrient pool rather than changes in the leaf nutrient concentration.

[RAPD analysis of genuiness on source of Bupleurum chinense]

OBJECTIVE

To identify the genuiness on 5 samples of Bupleurum chinense DC. from cultivating base in Dongfeng County, Jilin Province.

METHODS

RAPD was used by 23 primers.

RESULTS

The three primers can effectively identify the genuiness of Bupleurum chinense.

CONCLUSION

The genuiness identification of Bupleurum chinense can be made with RAPD analysis.

[Plant growth analysis of Bupleurum chinense]

OBJECTIVE

To learn the development characteristics of Bupleurum chinense DC. for the cultivation fundament.

METHOD

Mature and intact plant samples of different growing periods are studied by the method of plant growth analysis.

RESULTS

The plant organs are composed of root, root crown, stalk, basal leaves, stem leaves, branches and leaves, apical and lateral inflorescences. Dry substance in the branches of the first and second level was 93.8% of that in all branches. Though the branches of third or fourth level were relatively weak, their amount was large. The root-shoot ratio with the value 0.19 was especially low. Lateral inflorescences of third or fourth level were found commonly in the population, but the first and second ones were the majors part. About 38.1% dry substance was used for the development of propagation organ. The length of main root was only 17.2 cm, its weight was nearly same as that in the lateral roots.

CONCLUSION

Short cultivated history of B. chinense are still maintained some significant wild characteristics, so they don't accord with the demand of the objective gathering in the root. It may be resolved with artifical regulation and breeding.

[Study on organogenesis and dry substance accumulation of Bupleurum Chinense]

OBJECTIVE

To learn the development characteristics of Bupleurum chinese DC. and to provide the cultivation fundament.

METHOD

Plant samples of different growing periods were collected and investigated.

RESULTS

It was found that the development stages of B. chinense could be divided definitely into emergence of seedings, seedling, elongation of internode, flowering and fruiting, and dormancy. During its life, cotyledon, basal leaves and stem leaves appeared and died away in turn, and the stem extended to its full length in one month. The root reached its top length during seedling stage, and its diameter increased quickly from July to August. The dry substance accumulated in aerial part of the plant increased quickly, and that in root increased by 42.4%, 94.0%, or 40.1% respectively, from mid July to mid August after stem elongation beginning, from mid September to mid October, or from mid October to the date of harvesting.

CONCLUSION

Management methods and planting technologies of B. chinense should be mapped out according to the different characteristics of its three key growing stages.

[The influence of seed maturity and seed coat on the germination of Bupleurum chinense and B. falcatum]

OBJECTIVE

To investigate the factors influencing the seed germination of Bupleurum chinense and B. falcatum.

METHOD

The seeds of different maturity, and the seeds whose coat were removed or nicked before dipping in water, were germinated in a light growth chamber.

RESULT

The different inflorescence level represents different development period. Seeds harvested from cultivation have different maturity. The germination rate of the seeds in period I to III was nearly zero, and it was significant different from period IV to VII. The seed coat is not an obstacle for water absorption or gas exchange, but its removal led to significant increase of seed germination rate. However, to dip the seeds without coat into water for 48 h had no more effect on germination.

CONCLUSION

The seed maturity and germination inhibitors in seed coat are two important factor influencing seed germination in B. chinense and B. falcatum.

[Somatic hybridization between carrot and Bupleurum scorzonerifolium and esteras isoenzyme analysis]

OBJECTIVE

To transfer the effective elements of Bupleurum scorzonerifolium into carrot, and provide theoretical data for the exploitation, improvement and selection of the germplasm of Chinese medicinal plants.

METHOD

The protoplasta of Bupleurum scorzonerifolium irradiated by ultraviolet light (UV) at an intensity of 300 microW.(cm2)-1 for 0, 1, 2 min respectively were fused with those of carrot Fisch by PEG method. The regenerated clones, derived form a single fused cell, were examined for their hybrid nature by phenotype and Esterase isoenzyme analysis.

RESULT

Nine clones were identified as the somatic hybrids between B. scorzonerifolium and carrot.

CONCLUSION

This provides a firm foundation for the further analysis of the main active components saikosaponin of somatic hybrids and the screening out of high-medicine-content hybrid cell lines.

[Chemical weed control of medicinal plant Bupleurum falcatum L]

OBJECTIVE

To select low-residue herbicide for cultivation of Bupleurum falcatum.

METHOD

Probing the effect of various kinds of herbicide on the budding, growth and yield of B. falcatum both in laboratory and in the fields.

RESULT AND CONCLUSION

Haloxyfop acts slightly on the growth of B. falcarum, but effectively kills weeds of many kinds. Butralin is a good herbicide for Gramineae.