Plants, methanol metabolism

The methanol molecule is smaller than carbon dioxide and penetrates most plant tissues quickly for rapid metabolism. As a plant source of carbon, methanol is a liquid concentrate 1 cc methanol provides the equivalent fixed-carbon substrate of over 2,000,000 cc of ambient air. Methanol absorbed by foliage is metabolized to carbon dioxide, amino acids, sugars, and other structural components. Two major paths of methanol metabolism are the internal production of carbon dioxide that is then utilized in photosynthesis and the incorporation of methanol as a fixed source of carbon. Briefly stated in field terms, methanol treatments are a means of placing carbon directly into the foliage. Hi li t intensity is necessary to drive photosynthesis at the rates necessary to process the high internal levels of carbon dioxide presented by methanol. Serine formation and carbon dioxide fixation by photosynthesis may lead to the production of su. Increases of su concentration in the presence of moisture lead to increased turgidity. 

Aliphatic compounds Several water-soluble simple organic acids and alcohols are cannon plant and soil constituents. They include methanol, ethanol, n-propanol and butanol (40), and crotonic, oxalic, formic, butyric, lactic, acetic and succinic acids (41, 42), all of which inhibit seed germination or plant growth. Under aerobic conditions, however, aliphalic acids are metabolized in the soil and therefore, should not be considered a major source of allelopathic activity (40). 

The ability of HRP to degrade the plant hormone indole-3-acetic acid (lAA) in the absence of hydrogen peroxide was noted as early as 1955 (136). Plant peroxidases are now known to be of major importance in the metabolism of lAA (137) (note that they are often referred to as indole acetic acid oxidases in the older literature). The mechanism of lAA oxidation by HRP C is complex and has been studied experimentally in great detail by several groups (23, 137). Reaction products include indole-3-methanol, indole-3-aldehyde, and 3-methylene oxin-dole, which is probably a nonenzymatic conversion product of indole-3-methylhydroperoxide. The most important developments in this area have been reviewed (23). 

C]PCNB metabolism was studied in vivo with 30-day-old peanut plants grown in nutrient solution that contained 17.6 ppm [I CjPCNB. Plant tissue was extracted with cold 80t methanol 48 hr after final exposure to PCNB. The extracts were made aqueous and partitioned against chloroform at pH 5.5 and against ethyl ether at pH 2. Water-soluble, chloroform-soluble, and ether-soluble metabolites were isolated by various chromatographic methods and identified by mass spectrometry and/or by synthesis. The details of these studies have been published previously (, X ... 

The alcohol in this equation can be a simple one such as methanol or it can be any of the -OH groups of another sugar molecule. For example, two molecules of a-D-glucopyranose can be joined, in an indirect synthesis, to form maltose (Eq. 4-6). Maltose is formed by the hydrolysis of starch and is otherwise not found in nature. There are only three abundant naturally occurring disaccharides important to the metabolism of plants and animals.38 They are lactose (milk), sucrose (green plants), and trehalose (fungi and insects). 

Fig. 12. HPLC-RC analysis of the metabolism of radiolabelled lAA conjugates by leaf discs from wild-type and RolB tobacco plants. After a 24 h metabolism period leaf discs were extracts with methanol and ca. 10 000 dpm aliquots were analysed by reverse phase HPLC-RC with column and flow rate, as in Fig. 6. Mobile phase 25 min, 10-60% gradient of methanol in 1% aqueous acetic acid. Detector radioactivity monitor operating in homogeneous mode [66,67]. Traces illustrate [ CJIAGluc metabolism by (A) wildBtype and (B) RolB leaf discs [ HJlAInos metabolism by (C) wildBtype and (D) RolB leaf discs [ C]IAAsp metabolism by (E) wildBtype and (F) RolB leaf discs [117],...

There are few reports on metabolism of jasmonic acid in plants (Fig. 4). Studies on the isolation and structural elucidation of the metabolites of 9,10-dihydrojasmonic acid (DJA) have been reported. [2- C] ( ) DJA (racl) was prepared by treating diethyl [2- C] malonate with 2-pentylcyclopent-2-enone [41] and applying this to six-day-old barley seedlings [42,43]. After a feeding period of 72 hr, about 90% of ( )DJA (racl) was taken up by excised barley shoots. Subsequently the radioactivity was almost completely extracted from the plant material by 80% methanol. 

Formaldehyde occurs naturally in the atmosphere at a concentration of about 10 parts per billion (0.000 001%) partly as a by-product of plant and animal metabolism, and partly as a product of the reaction of sunlight with methane (CH4), a much more abundant component of the air. At such low concentrations, it is not a natural source of the compound for commercial or industrial uses and is produced instead by the oxidation of methanol (methyl alcohol CH3OH) or gases extracted from petroleum (such as methane) over a catalyst of silver, copper, or iron with molybdenum oxide. 

Documented effects The plant is used internally to treat eczema, psoriasis, dermatitis and to normalize metabolism. In combination with other preparations, this species is used to treat gastritis, stomach and duodenal ulcers, enterocolitis, food poisoning, dysentery, kidney inflammation, and urinary incontinence. The preparation Mucaltin, which is prepared from the herb, is used as an expectorant to treat bronchitis and pneumonia (Kurochkin 1998). A methanolic extract and a decoction of the roots inhibited a variety of bacteria known to cause periodontal disease (lauk et al. 2003). An extract of the root has been shown to be a potent inhibitor of calcium mobilization associated with UVB-induced pigmentation of skin (Kobayashi et al. 2002a). 

Documented effects Water and alcohol extracts of the plant have been shown to increase the rate of blood coagulation, deaease blood pressure, increase inhalation volume, improve lung function, tone uterine muscles, and increase diuresis. The preparation Avicularen is used in gynecological practice as a hemostatic (Khalmatov et al. 1984). The infusion of the herb is recommended to improve metabolism and treat diabetes (Kurochkin 1998). Experiments indicate that a methanol extract of the plant has anti-fibrotic effects on rats with induced liver fibrosis (Nan et al. 2000). 

Metabolic profiling can be done on freshly harvested, freeze-dried or frozen stored material. This decision depends on the type of tissue to be analysed (whole plants, roots, leaves, fruits, seeds) and on the analytical techniques used. An efficient extraction method should be reproducible and lead to the extraction of a wide range of constituents across the different chemical classes, taking care to suppress enzyme activity that would change the metabolite composition. A common solvent is the methanol/ water mixture, which has been used in different proportions (80/20, 70/30, 50/50 or 20/80) in the case of polar extraction. For instance, De Vos et al. (2007) described a protocol for LC/ MS of plant materials and proposed that 75%... 

It was found recently that treatment of some agricultural crops (e.g., C crop plants) with methanol or nutrient-supplemented methanol under direct sunli t drastically increased turgidity [7]. The treatment stimulated growth rather than merely supported normal growth. This effect far exceeded that expected of a nutrient. However, in the shade or when other crops (e.g., plants with C4 metabolism) were treated with methanol, they showed no growth improvement. This is an interesting finding. More studies are needed to understand the role of methanol and its applicability. 

---