The structure and physiological activity of bonellin - a unique chlorin derived from Bonellia viridis

Abstract

The echurian worm Bonellia viridis has attracted the attention of both biologists and chemists over a long period of time. A drawing of the female organism is shown in Fig 1. The animal is a deep green all over its surface and is negatively phototactic. The trunk of the animal is generally housed in a burrow system and the proboscis is extended for feeding purposes. There are several points of interest regarding this organism. The first is the marked sexual dimorphism: the female is much larger than the male which is only 1 -3 nnn long.The males live parasitically inside the female after an initial period of settlement on the proboscis. There are usually several rnLes in each female. The eggs hatch into sexually undifferentiated larvae. It has been repeatedly observed that if the indifferent larvae settle on a female they differentiate into males, whilst if they settle away from the female they develop into females. Thus it is clear that an exogenous agent is influencing the determination of the sex of the larvae, rather than this being wholly determined genetically.The larvae seem to be specially attracted to the proboscis of the female on which they settle. When the larvae leave their site of attachment on the female, they leave behind a clear area from which all pigment has been removed,4 something we have been unable to achieve by chemical extraction. This removal of pigment suggests that it is being actively taken up by the larvae and raises the question of whether or not the pigment has anything to do with their masculinisation. Such a question is also raised by the observation that the degree of masculinisation depends on the length of contact between the adult and larvae, * Lecture delivered by Professor A. Pelter. 1847Bonellia viridis Rol. (female)

Biosynthesis of coenzyme F430 in methanogenic bacteria

“…Its conversion to F430 1 proceeds via intramolecular acylation of the nucleophilic meso position C-15 [6], a type of process with many (non-enzymatic) precedents in porphyrin chemistry (see, e. g., the formation of anhydro-bonnelin [37]). Thus, from a chemical point of view, seco-F430 3 can be regarded as a logical precursor of coenzyme F430.…”

Studies in Chlorin Chemistry. II. A Versatile Synthesis of Dihydrodipyrrins

“…30a For example, in companion studies we recently described the enantioselective synthesis of alkyne acid 16j (ee >95%), 30b which we are employing as a ring-C synthon in our work on cobyric acid (Scheme 11). Alkyne acid 16j also has the proper substitution pattern for preparing the A,B-ring portion of bonellin (2). Enantioselective syntheses of 2 and other naturally occurring hydroporphyrins are currently in progress.…”

The structures of (5,10,15,20-tetramethylporphyrinato)nickel(II) and (5,10,15,20-tetramethylchlorinato)nickel(II)

“…Other reduced metaUoporphyin structures, the ethylchlorophyllide a and b dihydrates Serlin et al, 1975), the metal-free chlorins, phyllochlorin ester (Hoppe et aL, 1969), methyl pheophorbide a (Fischer et al, 1972), and the methyl ester of anhydrobonellin (Agius et aL, 1979) are characterized by relatively flat rings in comparison with Ni(tmc). Hence chlorin systems show greater structural variability than do porphyrin systems, a factor of possible biological significance.…”