Haemolytic activity

The difficulty with HLB as an index of physicochemical properties is that it is not a unique value, as the data of Zaslavsky et al. (1) on the haemolytic activity of three alkyl mercaptan polyoxyethylene derivatives clearly show in Table 1. Nevertheless data on promotion of the absorption of drugs by series of nonionic surfactants, when plotted as a function of HLB do show patterns of behaviour which can assist in pin-pointing the necessary lipophilicity required for optimal biological activity. It is evident however, that structural specificity plays a part in interactions of nonionic surfactants with biomembranes as shown in Table 1. It is reasonable to assume that membranes with different lipophilicities will"require" surfactants of different HLB to achieve penetration and fluidization one of the difficulties in discerning this optimal value of HLB resides in the problems of analysis of data in the literature. For example, Hirai et al. (8 ) examined the effect of a large series of alkyl polyoxyethylene ethers (C4,C0, Cj2 and C 2 series) on the absorption of insulin through the nasal mucosa of rats. Some results are shown in Table II. 

Table I. Haemolytic activity of some nonionic surfactants ...

Haemolytic activity and the permeability-enhancing activity of nonionic alkyl ethers correlate well (23). 

McNab, G., and J. S. Harrington (1967). Haemolytic activity of asbestos and other mineral dusts. Nature 214 522—523. 

The function of haemolytic factors in trema-todes may not, however, be exclusive to red cell lysis. A heat-stable haemolytic activity was also... 

Kasschau, M.R. and Prill, M.S. (1 988) Comparative effects of sugars on the haemolytic activity of Schistosoma mansoni and other haemolytic agents. Comparative Biochemistry and Physiology 90, 453 t58. 

Soederlind, E., and L. Karlsson. 2006. Haemolytic activity of maltopyranoside surfadEantsJ. Pharm. 

Some steroidal alkaloids are nitrogen analogues of steroidal saponins, and display similar properties such as surface activity and haemolytic activity, but these compounds are toxic when ingested. These types of compound, e.g. solasonine (Figure 5.88) (aglycone solasodine),... 

One of the most well-known examples of insect toxins is melittin, a bee venom peptide with potent haemolytic activity. Melittin adopts an a-helical conformation, and has been extensively characterised using a range of techniques, including both solution- and solid-state NMR spectroscopy.176 Some helical peptides with antimicrobial activity have also been found in wasps, such as eumenine mastroparan-AF (EMP-AF-NH2) from the venom of the solitary wasp Anterhynchium flavormarginatum micado,177 and the cecropins found in the haemolymph of Hyalophora cecropia.178 Several of these peptides have cytotoxic activity and are potential anticancer agents.179... 

Haemolytic activity in laboratory, or correlated with abundance of P. pouchetii during blooms of natural planktonin mesocosms... 

Haemolytic activity of live Phaeocystis pouchetii during mesocosm blooms... 

Haemolytic activity correlated with P. pouchetii numbers and was absent during the preceding diatom bloom. Samples containing live P. pouchetii cells showed the highest activity, while filtered sea water and cell extracts were less haemolytic or without effect. Dose-response curves were linear up to 70% lysis, and haemolysis in samples containing live P. pouchetii cells reached EC50 values comparable to known toxic prymnesiophytes (1.9 107 cells l-1). Haemolytic activity was enhanced by increased temperature and light. The results indicate that unprotected and thus presumably vulnerable cells present in a P. pouchetii bloom may lyse within days. 

Haemolytic activity was studied in P. pouchetii blooms in experiments conducted from 27 February (experimental day 1) to 3 April 2003... 

The haemolytic activity measured in whole-meso-cosm samples was absent, or very low, during the diatom blooms (Fig. 1). In Ml haemolytic activity in whole mesocosm samples was low during the experiment, increasing from zero at the beginning of the mesocosm experiment to about 10% lysis in the period between day 21 and 29. In M2 and M3 the haemolytic activity was higher. In M2 it exceeded 10 % at day 21, reaching a peak of 70%... 

Fig. 2 Correlation between haemolytic activity of whole mesocosm samples and their chlorophyll a content for the three mesocosms...

In the period 17-23 March, haemolytic activity of the extracts was less than half of activity of whole-mesocosm samples (Fig. 3). Bearing in mind that the extracts are concentrated 50 times... 

Fig. 3 The relation between the haemolytic activity measured in whole-mesocosm samples and the haemolytic activity in GF/F filtrate of the same samples, or the activity in the 50-times-concentrated cell extracts...

Table 2 Densities of the different phytoplankton groups (see Table 1) of 31 mesocosm samples were related to the haemolytic activity of the samples as well as to the densities of non-motile Phaeocystis pouchetii using linear regression...

Density of phytoplankton groups Haemolytic activity Non-motile Phaeocystis ... 

Fig. 4 Relation between the abundance of phytoplankton and the haemolytic activity measured in whole mesocosm samples. The regression line displayed is for non-motile P. pouchetii (i.e., cells present in colonies)...

Haemolytic activity was observed in samples during Phaeocystis pouchetii blooms in mesocosms. The activity measured using incubations of whole mesocosm samples mixed with blood suspensions was proportional with the amount of sample added. The haemolytic activity in the mesocosms correlated best with the density of non-motile P. pouchetii but also with the abundance of the larger phototrophs and heterotrophs. The last two were also positively related to P. pouchetii numbers. Biomass during the P. pouchetii bloom was dominated by non-motile P. pouchetii cells and... 

Fig. 5 Relation between haemolytic activity of whole mesocosm samples and abundance of (A) large phototrophic flagellates and ciliates (10-54 pm) and (B) large heterotrophic flagellates and dilates (10-69 pm)...

Fig. 7 Haemolytic activity observed in mesocosm samples (mesocosms day 24) incubated at different light intensities. Bars represent standard deviation...

From the relationship between cell numbers and haemolytic activity, an EC50 cell density was estimated to 1.86 x 107 P. pouchetii cells I. This value compares favourably with the EC50 densities of other algae that produce harmful algal blooms (Table 3). However, values for the other algae were measured with cell extracts where the EC50 values expressed on a biovolume basis... 

Approximately 14% of the haemolytic activity in whole-mesocosm samples was present in GF/F filtrate, while almost no activity was extracted from the broken cells. It is unlikely that the bulk of the activity was bound to the cell membranes because a substantial part of the cell debris was still present in the extract (own observation). An alternative explanation would be that the live P. pouchetii cells produce an unstable component which greatly enhances haemolysis. In accordance with this is the observation that haemolytic activity did not accumulate over time in the mesocosms, but followed daily variations of chlorophyll a. A mechanism that involves physical contact between Phaeocystis colony and the blood cell could also explain the activity of live Phaeocystis. 

Haemolytic activities observed in the nutrient-enriched mesocosms were higher than those measured in the control bag and values to be expected during blooms in the field. From the data it was possible to estimate the lysis rate at ambient temperature in a natural bloom, based on cell densities or chlorophyll a present. The... 

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