Hypericin

Hypericin which is a hydroxyanthraquinone and the antibiotic nystatin also yield fluorescent zones. A higher fluorescence intensity is frequently obtained by heating to 88° C for 2 — 5 min instead of simply allowing to dry at room temperature. 

Fig. 1 Chromatography of flavonoids. 1. Extract. Solidaginis 2. Rutin — chlorogenic acid — isoquercitrin — quercitrin 3. Extract. Hyperici 4. Hyp>erosid — quercetin-3-arabinosid — hypericin — quercetin 5. Extract. Betulae...

Colored substance zones were obtained which could be analyzed quantitatively. The (visual) detection limits were hypericin 1 ng, rutin and chlorogenic acid 5 ng, hyperoside — quercetin 10 ng per mm chromatogram zone. The detection limits for densitometric analysis are between 20 and 50% of those for visual detection. 

Hypericin, from Hypericum perforatum (St. John s wort)... 

The following fiRf values were obtained quercetin 90 — 95, hypericin 75 — 80, quercitrin 60 — 65, quercetin-3-arabinoside 55 — 60, isoquercitrin 45 — 50, hyperoside 40—45, chlorogenic acid 30 — 35, rutin 20—25 (Fig. 1). 

Hydroxytryptamine 380 5-Hydroxytryptophan 240,241 Hydroxytyramine 392 Hyodesoxycholic acid 334 Hyperici, Extract. 279 Hypericin 148, 279, 280 Hyperoside 149,279,323 -, -quercetin 280... 

It is being recognized increasingly that regulation can have a positive impact on laboratory productivity.36 System suitability testing has been proposed as superior to and supplemental to calibration in the UV-VIS detector.37 Large variations in both response factor and in relative response factors were observed on different instruments. Even on the same instrument, UV-VIS spectra can be extremely dependent on solution conditions, as was observed in a separation of hypericin, the antidepressant extract of St. John s wort.38... 

Balogh, M.P and Li, J.B., HPLC Analysis of hypericin with photodiode-array and MS detection the advantages of multispectral techniques, LC-GC, 17(6), 558, 1999. 

Some herbs are standardized for several active constituents, while others are standardized to a single active ingredient. St. John s wort is standardized to contain 0.3% hypericin, whereas ginkgo is standardized to contain 24% flavone glycosides and 6% ter-pene lactones. However, standardizing an herb product to one or more plant component(s) that are identifiable by assay may be incorrect. Many herbalists believe that the whole plant contributes to the efficacy and that there are many unknown active compounds in each plant [6]. 

Fig. 2.49. Profile of Hypericum perforatum extract with the H LC-MS attributions of the components detected. 1 = chlorogenic acid isomer 2 = 3-0- -coumaroylquinic acid 3 = chlorogenic acid 4 = rutin 5 = hyperoside 6 = isoquercitrin 7 = 3,3, , , 7-pentahydroxyflavanone 7-0-rhamnopyranoside 8 = quercitrin 9 = quercetin 10 = 13,118 tapigenin 11 = pSeudohypericin 12 = hypericin 13 = hyperforin analogue 14 = hyperform dialogue 15 = hyperforin 16 = adhyperforin. Reprinted with permission from M. Brolis eta. [ ].

Agostinis P, Vantieghem A, Merlevede W, de Witte PA (2002) Hypericin in cancer treatment more light on the way. Int J Biochem Cell Biol 34 221 11. 

Extracts of hypericum may vary considerably in terms of the quantity and ratio of their constituents based on the extraction process used. Maximum extraction of hypericin and pseudohypericin is obtained with an 80% methanol solvent at 80°C (Wagner and Bladt 1994). Hyperforin is a lipophilic constituent of hypericum that is present in the oil extract (Chatterjee et al. 1998a). It is not very stable, but its presence is sustained by hot maceration of the flowers and storage in the absence of air (Maisenbacher and Kovar 1992). 

The pharmacokinetics of hypericin and pseudohypericin piasma have been studied as weii (Brockmoiier et ai. 1997). Human subjects receiving piacebo, or 900, 1800, or 3600 mg of a standardized hypericum extract (LI 160), which contained 0, 2.81, 5.62, and 11.25 mg of totai hypericin and pseudohypericin, achieved maximum total plasma concentrations at 4 hours (0.028, 0.061, and 0.159 mg/L, respectively). The half-lives of absorption, distribution, and elimination were 0.6, 6.0, and 43.1 hours, respectively, using 750 pg of hypericin, and are slightly different for 1578 pg of pseudohypericin (1.3, 1.4, and 24.8 hours, respectively) (Kerb et ai. 1996). The systemic availability of the hypericum extract LI 160 is between 14 and 21%. Comparable results are found in another study using LI 160 (Staffeldt et ai. 1994). Long-term dosing of 3 x 300 mg per day showed that steady-state levels of hypericin are reached after 4 days. 

Although the individual inhibition of either MAO or COMT may be comparatively minor in isolation, their combined inhibition along with other monoamine or nonmonoamine actions could have additive if not synergistic effects. For example, a fraction with combined hypericin and flavonoids had antidepressant effects in an animal model (Butterweck et al. 1997). Hypericum is a particular case wherein a single isolated principle may be sufficient for the desired effect, but less effective than the entire plant extract. 

Amino acid neurotransmitter Constituents of hypericum also appear to have effects on amino acid neurotransmission, particularly GABA. Hypericin and a crude extract bind to GABAA and GABAB receptors (Cott 1997). Hyperforin also inhibits synaptosomal GABA reuptake in the low micromolar range (IC50 values of 0.05-0.10 ug/ml). Activity at GABAA benzodiazepine receptors was noted in extracts of four hy-... 

Other mechanisms A few other effects of hypericin, and a crude hypericum extract have been found, including affinity for NMDA, inositol triphosphate, and adenosine receptors. However, these are not likely to be significant to its therapeutic effects because concentrations required for these interactions are not likely to be achieved by oral administration (Cott 1997). Vasoactive effects are possible because hypericum extracts blocked the vasoconstricting effects of histamine and prostaglandin F2o in porcine coronary arteries, and some vasorelaxation occurs in one particular fraction. These effects are hypothesized to be mediated by inhibition of phosphodiesterase (Melzer et al. 1991). 

Finally, a thorough receptor binding study by Raffa and colleagues (1998) showed that hypericin extracts had no effect at adrenergic (alpha or beta), adenosine, angiotensin, benzodiazepine, dopamine, bradykinin, neuropeptide Y, PCP, NMDA, opioid, cholecystokinin A, histamine HI, or nicotinic ACh receptors. Although comprehensive, this study did not look at the binding of any other hypericum constituents. 

---