(6R, 10R)-6,10,14-Trimethylpentadecan-2-one, a Dominant and Behaviorally Active Component in Male Orchid Bee Fragrances

Abstract

6,10,14-Trimethylpentadecan-2-one (Hexahydrofarnesyl acetone; HHA) previously has been found to be a major component in tibial fragrances of male orchid bees, Euglossa spp. HHA is a chiral molecule with four possible stereoisomers, (6R, 10R)-, (6R, 10S)-, (6S, 10R)-, and (6S, 10S)-6,10,14-trimethylpentadecan-2-one. In the present study, we characterized HHA extracted from Euglossa as the pure enantiomer (6R, 10R)-6,10,14-trimethylpentadecan-2-one. During bioassays in Mexico and Panama, the synthetic RR-isomer attracted males of six species of orchid bees, including three that were known to contain HHA in their tibial fragrances. Possible sources of HHA for wild bees are flowers of euglossophilous orchids and aroids. With a molecular weight of 268, HHA is the largest natural molecule known to attract male orchid bees in pure form. Its attractiveness to males suggests that low-volatility compounds have a function in male signals, e.g., serve as a "base note" in complex odor bouquets.

Enantioselective Preference and High Antennal Sensitivity for (−)-Ipsdienol in Scent-Collecting Male Orchid Bees, Euglossa cyanura

“…For example, of the 34 compounds listed by Roubik and Hanson (2004), 13 are chiral and, in at least one of them (α-pinene), attraction is mediated exclusively by one isomer [(−)-〈-pinene] (Williams and Whitten, 1983). Another possible case of stereoselective attraction of male orchid bees is to hexahydrofarnesyl acetone, in which the R,R-isomer is more attractive than the racemate (Eltz et al, 2010).…”

The Biosynthesis of Hexahydrofarnesylacetone in the Butterfly Pieris brassicae

“…In the males, 3 is at least in part degraded to 1. This is different from orchid bees that take up 1 from plants (Eltz et al, 2010). The mechanism of this cleavage is unknown, but a plausible explanation is shown in Fig.…”

“…Closely related is the corresponding alcohol, 6,10,14-trimethylpentadecan-2-ol that occurs in the pheromone gland of several Lepidoptera (Mori et al, 1991;Sasaerila et al, 2003;Nieberding et al, 2008). Recently, Eltz et al (2010) showed that Orchid bees are attracted to the (R,R)-enantiomer of 1, produced by many orchids, and store this compound in their tibial fragrance. These authors also established the absolute configuration of insect-derived 1 for the first time.…”

A Non‐Enzymatic Pathway with Superoxide in Intracellular Terpenoid Synthesis

“…Furthermore, non‐C 5 ‐unit terpenoids (norisoprenoids) have also been reported. Norisoprenoids having an acetonyl group (C 5 × n +C 3 ) are widely distributed in nature, especially in crustacean hormones, insect pheromones, plant odorants, and microbial volatiles (Figure ) . Geranylgeranylacetone (a non‐natural product) is used to treat gastric ulcers and is known to induce heat shock proteins (Figure ) .…”