α-Selinene
Alpha-selinene is the amber-woody sesquiterpene hydrocarbon that travels with its more abundant isomer beta-selinene in celery seed, beautyberry, and cypress pine oils. It is chiral, with one natural form found in plants. Published research concerns beta-selinene; none is specific to alpha-selinene.
Aroma
Herbal, Spicy, Woody
Sensory Descriptors
Found In
Celery, Spikenard
Effects
Anti-inflammatory, Anti-microbial
Industries
Aroma and sensory profile
Alpha-selinene is the softer, ambery half of the selinene pair. Fragrance references describe it in a single word, amber, and list an estimated boiling point rather than a measured one, which tells you how rarely it is handled as an isolated material [1]. In celery and beautyberry oils it sits beneath the several-fold more abundant beta-selinene, contributing depth to the woody base rather than a note of its own [3].
The molecule is a eudesmane sesquiterpene with three stereocenters, and the natural material carries the (3R,4aR,8aR) configuration [2]. It differs from beta-selinene only in the position of one ring double bond, and the two occur together almost everywhere, with beta-selinene usually several times more abundant. No panel description of the mirror-image enantiomer was found, so no claim about how the two enantiomers differ in odor is made here.
Natural sources
Alpha-selinene is a celery and beautyberry terpene. In the fruit oil of Callicarpa macrophylla it reached 6 percent against 41.6 percent beta-selinene, and in the leaf oil 1.7 percent against 20 to 29 percent [3]; later work on the same plant found beta-selinene rising to 57 percent in mature fruit [4]. Celery leaf and seed oils carry beta-selinene as a major constituent with alpha-selinene alongside it [5], and maize roots make beta-selinene as the precursor of a defensive acid against fungal pathogens [6]. Fragrance databases log alpha-selinene at 1.5 percent in Vietnamese cajuput oil, 0.6 percent in Callitris columellaris wood oil, 0.5 percent in amyris wood oil, and traces in allspice, bay laurel, basil, calamus, and carrot seed oils [1]. In cannabis it is a trace sesquiterpene, occasionally reported in earthy chemotypes and more often absent.
Boiling point and vaporization
No measured boiling point for alpha-selinene appears in PubChem or in a primary paper found for this profile, so none is listed. The fragrance reference value of 270 °C at 760 mmHg is marked as an estimate [1], and the 240 °C the site previously listed had no traceable source. What can be said is that alpha-selinene is a fifteen-carbon hydrocarbon sesquiterpene in the same family as caryophyllene and humulene, so it belongs in the base-note band, persisting in dried celery seed and in stored oils long after the monoterpenes have gone. No thermal degradation study of alpha-selinene was found.
Industries and uses
Fragrance: alpha-selinene contributes an amber-woody depth in celery, herbal, and woody accords and a mild fixative effect, and is used as a natural constituent of celery seed and beautyberry oils rather than as an isolate [1]. Culinary: it enters food through celery seed and leaf oils, whose savory flavor it rounds without defining, and through the spice blends built on them [5].
References
- alpha-selinene, CAS 473-13-2. The Good Scents Company
- alpha-Selinene, CID 10856614: stereochemistry. PubChem, National Library of Medicine
- Volatiles of Callicarpa macrophylla: a rich source of selinene isomers. Natural Product Communications (2010)
- β-Selinene-Rich Essential Oils from the Parts of Callicarpa macrophylla and Their Antioxidant and Pharmacological Activities. Medicines (2017)
- Determination of Chemical Composition, In Vitro and In Silico Evaluation of Essential Oil from Leaves of Apium graveolens Grown in Saudi Arabia. Molecules (2021)
- Selinene Volatiles Are Essential Precursors for Maize Defense Promoting Fungal Pathogen Resistance. Plant Physiology (2017)