## 1 Introduction  
\"Smell is a potent wizard that transports you across thousands of miles and all the years you have lived. The odors of fruits walt me to my southern home, to my childhood folrics in the peach orchard. Other odors, instantaneous and fleeting, cause my heart to dilate joyously or contract with remembered grief. Even as I think of smells, my nose is full of scents that start awake sweet memories of summers gone and ripening fields far away.\" The human sense of smell has a powerful effect on our basic emotions, as eloquently described by [PERSON] [1]. [PERSON] _et al_. [2] tried a new approach to prove this phenomenon by analysing autonomic nervous system (ANS) responses, whilst study participants completed a hedonic scale to rate the \"pleasantness\" or \"unpleasantness\" of odours. The pooled results revealed a high correlation between the hedonic evaluation and basic emotions. Camphor was an intermediate, associated with \"happiness\" or \"surprise\"--characteristics of the \"pleasant\" odourants (ethyl acetoacetate and lavelander), but also linked to \"sadness\", which differentiated it from these odours. Despite the \"sadness\" rating, the emotions associated with camphor were all different from those associated with acetic and butyric acids, used as the \"unpleasant\" odourants [2]. Whether camphor makes one think of mothballs or your grandmother, it must surely be one of the most distinctive odours, even having its own adjective to describe it, _i.e._, camphoraceous. The fragrant camphor tree, _Cinnamomum camphora_ ([PERSON] (Lauraceae), occurs naturally in Asian countries including Japan, Taiwan and China, but has been naturalised in other parts of the World. The tree is large with pale brown bark, dark green to yellowish leaves (Figure 1A) and small white flowers followed by small purple berries. All the plant parts have the distinctive, easy-to-recognise camphoraceous odour. The essential oil is distilled from the wood (Figure 1B) which yields the active ingredient (1\(R\))-(+)-camphor, _i.e._, natural camphor [3, 4]. Figure 1: _Cinnamomum camphora_ tree, wood and seeds. Camphor has a long-valued history for its extensive and diverse uses in the East: the Chinese used camphor as a circulatory stimulant and analeptic, whilst the Japanese used it in torch-light material and added small quantities to fireworks to make them brighter [5]. Camphor was used as a fumigant during the Black Death, a plague that spread through Europe in the 14 th century, as well as during outbreaks of smallpox and cholera. Rosewater together with camphor as a perfume ingredient was sprinkled over corpses before shrouding [6]. In India, camphor is commonly burnt in temples during religious rituals because unlike any other aromatic smoke, camphoric fumes are non-irritant to eyes [7]. Camphor has been widely used as a fragrance in cosmetics, as a flavouring food additive and as a preservative in confectionary goods; in homes it is commonly used as an insect repellent, a plasticiser and as an intermediate in the synthesis of aroma chemicals [7,8]. Camphor is one of the most well-known and widespread commercially important aroma chemicals, with an annual market value of 80-100 million US$ [9]. Camphor exhibits several biological properties such as antimicrobial, antiviral and antitussive effects [10, 11, 12, 13, 14]. Camphor is a common ingredient in modern medicine in topically applied analgesics and rubefaciens for treatment of minor muscle aches and pains and it is reported that camphor has been used to relieve pain caused by breast engagement by intramuscular injections [15]. It has been applied as a topical anti-infective and anti-pruritic and internally as a stimulant and carminative [3]. However, camphor is poisonous when ingested and can cause seizures, confusion, irritability and neuromuscular hyperactivity. The lethal dose in humans is reported to be 50-500 mg per kg bodyweight [16].