Myoporum

The dihydrofurans ( )-ipomeamarone (482) and ( )-epiipomeamarone (483) were isolated from Myoporum desertii and exist in mould-damaged sweet potatoes as phytoalexins (73AJC375). The tetrahydrofuran derivatives (484) and (485) are potent antidepressants (74JOC1042). 

Traces of alkaloids had been reported in species of Myoporum. One of these, M. sandwicense, was likewise positive in the tests reported here along with M. crassifolium, Myoporum xp., and Oftia africana. 

These species were negative Eremophila bignonii/Jora, E.free-lingii, E. gilesii, E. la t robe i, E. xlrehlowii, Myoporum acuminatum, M. deserli, M. insulare. 

Eriocitrin (= 5,7,3, 4 - Tetrahydroxyflavanone-7-O- rutinoside) (flavanone O-glycoside) Mentha piperita (Lamiaceae), Myoporum tenuifolium (Myoporaceae), Citrus spp. (Rutaceae) ACE (28% inhibition at 300 pM) [76]... 

Two new toxic sesquiterpenoids, myodesmone (36) and isomyodesmone (37), have been isolated from the essential oils of certain Myoporum species. It has been suggested that these two compounds may be derived from myoporone (38), also found in some specimens of Myoporum deserti, by an in vivo aldolization-dehydration process via the ketol (39). In addition to ipomeamarone (40 R = H), it is reportedthat a new sesquiterpenoid, ipomeamaronol (40 R = OH) also occurs in diseased sweet potato root tissue. 

Myoporum laetum, M. acuminatum, Eremo-phila latrobei... 

The genus Eremophila is one of three genera, together with Myoporum and Bontia, which constitute the small Myoporaceae family. This family is restricted largely to Australia except for species of Myoporum which extend north to China and Japan and to the islands of the Indian and Pacific Oceans, and Bontia, a monotypic genus found only in the West Indies. 

A group of sesquiterpenes which can be regarded as oxygenated famesols characterise the essential oils of a number of Eremophila and Myoporum species. Although the majority of these... 

Occurrence I. was first isolated from the Australian ant Iridomyrmex detectus and the hunting beetle Sta-phylinus olens, Coleoptera Staphylinidae). It was later also found in the essential oil of a not exactly defined Australian species of Myoporum. Nepetalac-tone occurs in the essential oil (51%) of the genuine catmint Nepeta cataria, Lamiaceae) and is an attrac-tant for cats. 

C15H22O3, Mr 250.34, cryst. (CH3OH), mp. 15.5-16.5°C, [ ]d -7° (CH3OH). Occurs together with the (9/ )-alcohol dihydro-M., C15H24O3, Mr 252.35, oil, [a] -3.6° (CH3OH), as stress metabolite in the sweet potato (Ipomoea batatas) and in the Australian bush Myoporum deserti. M. is hepatotoxic, see also ipomeanine and ipomeamarone. 

Myoporum deserti (Myoporaceae), a widespread Australian shrab, has been responsible for serious livestock losses in that region. These plants cause liver and kidney lesions. Mydesmone (53) is one of the active compounds (Fig. 21.15) (Mabry and Gill, 1979). 

Merrekentrone D, a derivative of merrekentrone A cleaved between C-11 and the oxygen at C-4, can be regarded as 6-oxomyomontanone, a derivative of (+)-myomon-tanone, a hepatotoxic furanosesquiterpenoid from Myoporum montanum R.Br. (Myoporaceae). Further relations to this fanoily will be discussed below. 

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