Butterfly, yellow

Folic acid is a member of the vitamin B complex found in green plants, fresh fruit, yeast, and liver. Folic acid takes its name from folium, Latin for leaf. Pterin compounds are named from the Greek word for wing because these substances were first identified in insect wings. Two pterins are familiar to any child who has seen (and chased) the common yellow sulfur butterfly and its white counterpart, the cabbage butterfly. Xanthopterin and leu-... 

FIGURE 25.1 (See color insert following page 336.) Larval butterflies have distinctive coloration patterns (a) Monarch (Danaus plexippus yellow, white, and black), (b) Swallowtail (Papilio polyxenes asterius yellow, black, and green), (c) Queen (Danaus gillipus black, white, and yellow, some red coloration is also observable in this specimen), and (d) Atala (Eurnaceus atala florida red with yellow spots). 

The yellow coloration in the Monarch as well as the larva of three other species of butterfly from South Florida is exclusively due to the specific accumulation of exceptionally high levels of lutein producing a pigmented epidermis. This active accumulation, reminiscent of the specific accumulation that occurs in the primate macula, indicates that butterfly larva is an excellent animal model for the study of carotenoid transport and binding. As such, elucidation of the mechanism of transport and binding of lutein in the epidermis and other tissues of these butterfly larvae may provide insight into xanthophyll uptake within the human eye (Bhosale et al. 2004). 

Fig. 27. Active site detail from X-ray structure (CPK coloring) and averaged LFMD structure (yellow) highlighting the putative hydrogen bond (red dashed line) responsible for the butterfly distortion of the [ 20 ]2+ unit in the X-ray which is not seen in the averaged LFMD geometry and the occupation by solvent of the space vacated by the caddie protein in the LFMD simulation.

Interest in pteridines began with Frederick G. Hopkins, who in 1891 started his investigation of the yellow and white pigments of butterflies. Almost 50 years and a million butterflies later, the structures of the two pigments, xanthopterin and leucopterin (Fig. 15-17), were established.339 These pigments are produced in such quantities as to suggest that their synthesis may be a means of deposition of nitrogenous wastes in dry form. 

During the course of screening plants for insect antifeedants, the extract of the bulbs of Lycoris radiata Herb, was found to exhibit antifeeding activity when tested against the larvae of the yellow butterfly Eurema hecabe mandarina (61). 

Even more unusual is the reaction of 9 with the metastable yellow arsenic, from which compounds 135 and 136 are isolated. On longer heating at 95 °C compound 135 rearranges to afford the butterfly-type molecule 136 (equation 31)128. 

Description Adults common white butterflies forewings with black tips and 2 or 3 spots (IV2 -2" wingspan). Larvae up to F velvety green caterpillars with a fine yellow stripe down the back. Eggs yellow cones... 

Control Cover plants with floating row cover handpick larvae in light infestations use yellow sticky traps to catch female butterflies. As a last resort, spray with BTK at 1-2 week intervals. 

The two-electron reduced, or hydroquinone, isoalloxazine is pale yellow. It is an electron-rich heterocycle and, when planar, is antiaromatic according to Hiickel s rule. The ring system of the hydroquinone in some small-molecule structures and some protein structures is bent by as much as 30° along the N5—NIO axis, presumably to relieve the antiaromaticity. However, the majority of hydroquinones bound to proteins do not deviate from planarity much more than oxidized isoalloxazines. This is likely to be influenced by protonation of Nl, whose pA a is 6.7 in aqueous solution. Quantum calculations show that neutral hydroquinone adopts butterfly conformation but the anion is planar. A survey of crystal structures agrees with this correlation — anionic hydroquinones are generally nearly planar, while the few instances of the butterfly conformation belonged to neutral hydroquinones. Hydroquinones react as single-electron donors, as hydride donors, or as nucleophiles at N5 or C4a. 

The yellow and red isomers of [Os6(CO)i6(CHNMe2)(7<4-S)(7/3-S)(//-H)2] characterized by X-ray analysis both contain seven Os-Os bonds the former is a spiked bow-tie cluster (36, see Scheme 5) and the latter a 2-atom-spiked butterfly cluster (37). 36 is partially converted to 37 by heating under reflux in octane in a CO atmosphere. 

Pyrazino[2,3-ti0pyr idines are known as pteridines , because the first examples of the ring system, as natural products, were found in pigments, like xanthopterin (yellow), in the wings of butterflies (Lepidoptera). The pteridine ring system has subsequently been found in coenzymes which use tetrahydrofolic acid (derived from the vitamin folic acid) and in the cofactor of the oxomolybdoenzymes and comparable tungsten enzymes. It is also present in the anti-cancer drug Methotrexate. 

Curlicues are fantastic spirals or twists that seem to be everywhere we look. When we think of examples of curlicues, both the mundane and exotic easily come to mind, such as the gentle curl of a fern tendril, the shape of an octopus s retracted arm, the death-form assumed by a centipede, the spiral intestine of a giraffe, the shape of a butterfly s tongue, the spiral cross-section of a scroll, the shape of the yellow brick road in Munchkinland in the film classic The Wizard of Oz, and even the characters of several written languages such as Farsi and Tamil. 

C21H26N4O6, Mr 430.46, yellow powder. P. II is a pigment in the wings of the swallowtail butterfly Papilio xuthus and other Papilio species, it is composed of l- kynurenine, noradrenaline, and /S-alanine. The yellow color is due to a charge-transfer interaction between the two aromatic rings. 

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