Methyl N-methylanthranilate: major compound in the defensive secretion of Typhloiulus orpheus (Diplopoda, Julida)

The defensive secretion of the julid diplopod Typhloiulus orpheus contains methyl N-methylanthranilate (MNMA), an ester of N-methylanthranilic acid that comprises more than 99% of secretion of this species. MNMA is accompanied by small amounts of methyl anthranilate and two benzoquinones (2-methyl-1,4-benzoquinone and 2-ethyl-1,4-benzoquinone, respectively). MNMA is a known intermediate in the biosynthesis of both benzoquinones (as present in defensive secretions of juliformians) and glomerin-like quinazolines (chemical defense in Glomerida). The compound may have evolved independently in the pathway to glomeridan chemistry, or may even represent a pivotal branching point in the pathway to different chemical classes of diplopod defensive chemistry.

Methyl-N-methylanthranilate, a pungent compound from Citrus reticulata Blanco leaves

CONTEXT

More analgesic compounds are needed in medicine against pain since the available drugs displayed secondary effects. Natural products are a source of molecules to develop new analgesics, using the information of plants, applied against pain, with effects such as pungency, tingling, and needle, due to their possible role in the central nervous system (NCS). Citrus reticulata Blanco (Rutaceae) leaves are usually bitten to flavor the mouth and possess this type effect in lips and tongues; due to this fact the structure of the bioctive compound could be the source of other types of analgesics.

OBJECTIVE

The objective of this study is to determine the causal agent of the pungent effect in mandarin essential oil.

MATERIALS AND METHODS

Mandarin essential oil was obtained and then purified by column chromatography. Each fraction was tested and pungency was detected only in the first fraction which was pure.

RESULTS

The compound responsible for the pungency in the essential oils of leaves from Citrus reticulata (mandarin) was purified and the structure was assigned as methyl-N-methylanthranilate, on the basis of NMR 1D and 2D and MS. This substance corresponds to another type of molecule involving an antinociceptive effect.

CONCLUSIONS

Terpenes are compounds found in essential oils. The compound responsible for the pungency of mandarin and other citrus leaves was isolated, and surprisingly it was identified as a methyl-N-methylanthranilate. This kind of molecules with this activity could be used to discover new analgesics in human therapy against pain.

Designer repellents: combining olfactory, visual or taste cues with a secondary repellent to deter free-ranging house sparrows from feeding

BACKGROUND

Repellents may prevent bird pests from eating crops or protect non-target birds from eating harmful substances. The feeding behaviour of free-ranging house sparrows (Passer domesticus) presented with wheat treated with the secondary repellent anthraquinone (AQ), paired with visual and/or olfactory and taste cues, was recorded in a series of trials. The aim was to determine the suitability of repellent combinations for preventing birds from consuming pest baits.

RESULTS

Anthraquinone significantly reduced wheat consumption. The addition of cinnamon oil did not reduce consumption further, but the addition of either a blue colour or d-pulegone enhanced repellency. Green wheat was consumed more than blue wheat. In a multichoice test, the sparrows did not differentiate between low and high concentrations of AQ on blue-dyed wheat. With treatments on separate tables, the higher concentration was more repellent. Additional olfactory/gustatory cues palatable to pest mammals did not make the AQ-treated wheat more or less acceptable to sparrows. AQ-treated blue wheat with/without cinnamon oil was more repellent than green wheat with cinnamon oil, a colour/odour combination typically used for pest baits in New Zealand.

CONCLUSIONS

These data demonstrate the potential of combining the secondary repellent AQ with additional salient cues for modifying the feeding behaviour of sparrows.

Use and husbandry of captive European starlings (Sturnus vulgaris) in scientific research: a review of current practice

Summary

We reviewed the use of captive European starlings ( Sturnus vulgaris) in scientific research published between 2000 and 2004. We estimated the numbers of birds used and documented their origin and the range of husbandry regimes employed with the aim of comparing current practice with the new European guidelines for husbandry of laboratory animals. Over the five-year period, 106 primary articles report the use of an estimated total of 2490 captive starlings. The majority of birds were caught from the wild either as adults or fledglings, and only 3% were hand-reared from chicks. There was considerable variation in husbandry. In the majority of cases, standards fell below those currently recommended as best practice in the UK and cited in new European guidelines. The median volume of home cages employed was 0.42 m3 (0.13–5.1 m3, interquartile range), whereas current recommendations suggest a minimum of 1.0 m3 for a singly-housed bird. The median volume of space allowed per bird was 0.13 m3/bird (0.08–1.05 m3/bird, Q1–Q3), whereas current recommendations suggest a minimum of 0.33 m3/bird. Only 27% of the articles mentioned providing any form of environmental enrichment for birds in their home cages. We recommend that more research be conducted into the welfare of starlings to inform legislation and guidelines, and thus maximize the welfare of captive animals.