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.

Triterpenoid constituents of Raulinoa echinata.

A phytochemical investigation of the stems of the South Brazilian endemic species Raulinoa echinata has led to the isolation of two new methoxylated protolimonoid epimers (1 and 2) together with the known melianone and melianodiol. The leaves afforded three glabretal-type triterpene derivatives esterified by N-methylanthranilic acid (3-5). Compounds 1 and 2 displayed weak inhibitory activity when assayed in vitro against trypomastigote forms of Trypanosoma cruzi. Compounds 1-5 were inactive in a brine shrimp (Artemia salina) lethality test.