Germination inhibitor

Germination inhibitors present in many seeds of the family Umbelliferae have been identified as phthalides 106). Two of the most active compounds isolated were 3-77-butylhexahydrophthalide and 3-72-butylidenehexahydrophthalide 102). 

Miyamoto (100) extracted and obtained crude crystals of a germination inhibitor from the bark of Syringa vulgaris (lilac). 

The classic seed burial studies of W. J. Beal and his successors have shown seeds of at least one weed species, Moth Mullein (Verbascum blattaria L.) can remain viable in soil for a peiod of 100 years, whereas three species continued to germinate after 80 years of burial (30). Weed seeds not only resist decay by soil microbes, but they vary in dormancy characteristics. There is considerable evidence that chemical inhibitors are responsible for both phenomena. Unsaturated lactones and phenolic compounds in particular, are potent antimicrobial compounds present in many seeds (4J. Fruits and seeds are also known to contain diverse germination inhibitors including phenolic compounds, flavonoids and/or their glycosides and tannins. Unique methods to destroy inhibitors could provide an excellent weed management strategy. 

The final steps in a total synthesis of (+ )-gloeosporone (3, a natural germination inhibitor of a fungus) required oxidation of the acetylene group of 1 to a diketone group. The oxidation was carried out in 74% yield by the catalytic Ru02 procedure of Sharpless. On liberation (pyridine-HF) of the C7-hydroxyl group, the hydroxy... 

This does not mean that analysis of allelopathy in an arid environment should be done differently from that which is customary in a humid environment yet it is important to estimate the extent to which inorganic salts (excreted by the plant or released from its litter) are involved in the allelopathic effect. So far as secondary metabolites are concerned, it should be of interest to compare their production under humid and stressed conditions. It is suggested that for the evaluation of the allelochemical effect, species suppressed in their natural habitat should be preferred over any other standard seeds commonly used for evaluating germination inhibitors. Also, efforts to isolate allelochemicals from soils will assist in the establishment of allelopathy on a more concrete basis than is available at present. 

Figure 5. Scheme of isolation of germination inhibitors from hips of Rosa canina. 

The identification of natural germination inhibitors enables us to study their effect as allelochemicals in detail. Because most of these compounds are natural products not previously known, they have to be synthesized at first in order to obtain sufficient material for such investigations. This work is in progress. 

Ineketone (61) is another growth and germination inhibitor of rice. It has been assigned the unusual rearranged structure with a A -double bond. The metabolites of Acremonium luzulae (Oospora virescens), virescenosides D and H,... 

Phenols and derivatives are the main aromatic compounds of plants, whose structural formulas contain at least one benzene ring. They serve as odors, fungicidals, or germination inhibitors. Coumarins are especially common in grasses, orchids, citrus fruits, and legumes. Plants containing phenols with anticancer properties include the following ... 

Kato, T., Tsunakawa, M., Sasaki, N. Growth and germination inhibitors in rice husks. Phytochemistry 1977 16 45-48. 

A number of 1 /7-pyrido[2,3-c]-l,2,6-thiadiazin-4(3/7)-one 2,2-dioxides and 1 //-pyrido[4,3-c]-1,2,6-thiadiazin-4(3//)-one 2,2-dioxides, for example (403), display herbicidal properties <75USP392064i, 77USP4014888). Four 3-arylpyrido[3,4-e]-1,2,4-triazines (404a-c) and (252) have been studied as germination inhibitors <84Mi 717-03). 

Uses fungicide, germination, inhibitor, coffee, fruit... 

An efficient synthesis of the fungal germination inhibitor Aitemaric Acid required an ester which survived the ruthenium catalyst used in the formation of 103.1 [Scheme 6.103. 232 Since the product 103w2 was also acid-sensitive, an ester... 

In addition to its spore germination inhibitor activity, it shows phytohormone (cytokinine) activity. Its derivative without the 3-methylbut-2-enyl residue, 3-(L-3-amino-3-carboxypropyl)-adenine 2, shows the same regulatory function as discadenine. ... 

A. Furstner and co-workers devised an efficient synthesis of (-)-gloeosporone, a fungal germination inhibitor. They utilized the Keck asymmetric allylation method to create the 7(R>homoallylic alcohol subunit. The reaction of the substrate aldehyde in the presence of the in situ generated catalyst provided the product with high yield and as the only diastereomer. It is important to note that it was essential to use freshly distilled Ti(/-OPr)4 for the preparation of the catalyst in order to get high enantioselectivity and reproducible results. 

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