Identification Of The True Bay Leaf And Its Substitutes

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Bay leaf is a popular household spice used in flavoring foodstuff. The true bay leaf is derived from the bay laurel or sweet bay tree, Laurus nobilis, native to the Mediterranean region. However, leaves of several other species including Cinnamomum tamala (Indian bay leaf), Litsea glaucescens (Mexican bay leaf), Pimenta racemosa (West Indian bay leaf), Syzygium polyanthum (Indonesian bay leaf) and Umbellularia californica (Californian bay leaf) are also often sold as 'bay leaves' and are commonly substituted, adulterated or mistaken for the true bay leaves (Laurus nobilis) due to their similarity in appearance, aroma and flavor [1]. Thus, the name 'bay leaf' in herbal commerce may mean any of these botanicals [2]. The present work provides a detailed morpho-anatomical study of different types of bay leaves for correct identification of the true bay leaf and its substitutes. Acknowledgements: This research is supported by Science Based Authentication of Dietary Supplements and Botanical Dietary Supplement Research funded by the Food and Drug Administration grant # 1U01FD004246 – 05. References: [1] Tabanca N, Avonto C, et al. (2013)J Agric Food Chem 61: 12283 – 12291. [2] Leung AY, Foster S (2003) Encyclopedia of Common and Natural Ingredients used in Food, Drugs and Cosmetics. Wiley & Sons, Hoboken.

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Chinese cinnamon (Cinnamomum cassia) has economic value as an aromatic and medicinal plant, and its bark oil has a very high trans-cinnamaldehyde content. To gain insight into the accumulation of bark oil and the biological mechanisms which permit the accumulation of a high level of aldehydes in C. cassia bark, the morphology and histochemistry of oil cells and the specialization in its walls were assessed by light and fluorescence microscopy. The histochemical tests localized in situ the main chemical classes of metabolites in oil cells, which included aldehydes, lipids and terpenoids. In oil cells the aldehydes distributed in the area surrounding the oil sac were compartmentalized from lipid compounds in the center; the oil sac in an oil cell was attached by multiple cupules rather than one cupule. The autofluorescence of oil-cell walls was attributed to the presence of suberin and lignin, and was confirmed by different methods. The lignified and suberized walls probably serve as protective barriers against the cytotoxicity of high contents of trans-cinnamaldehyde to the surrounding active cells. These results contribute to our knowledge of the structure of oil cells and accumulation of essential oil in Chinese cinnamon bark.
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The California bay laurel or Umbellularia californica (Hook. & Arn.) Nutt., is known as the 'headache tree' because the inhalation of its vapours can cause severe headache crises. However, the underlying mechanism of the headache precipitating properties of Umbellularia californica is unknown. The monoterpene ketone umbellulone, the major volatile constituent of the leaves of Umbellularia californica, has irritating properties, and is a reactive molecule that rapidly binds thiols. Thus, we hypothesized that umbellulone stimulates the transient receptor potential ankyrin 1 channel in a subset of peptidergic, nocioceptive neurons, activating the trigeminovascular system via this mechanism. Umbellulone, from µM to sub-mM concentrations, selectively stimulated transient receptor potential ankyrin 1-expressing HEK293 cells and rat trigeminal ganglion neurons, but not untransfected cells or neurons in the presence of the selective transient receptor potential ankyrin 1 antagonist, HC-030031. Umbellulone evoked a calcium-dependent release of calcitonin gene-related peptide from rodent trigeminal nerve terminals in the dura mater. In wild-type mice, umbellulone elicited excitation of trigeminal neurons and released calcitonin gene-related peptide from sensory nerve terminals. These two responses were absent in transient receptor potential ankyrin 1 deficient mice. Umbellulone caused nocioceptive behaviour after stimulation of trigeminal nerve terminals in wild-type, but not transient receptor potential ankyrin 1 deficient mice. Intranasal application or intravenous injection of umbellulone increased rat meningeal blood flow in a dose-dependent manner; a response selectively inhibited by systemic administration of transient receptor potential ankyrin 1 or calcitonin gene-related peptide receptor antagonists. These data indicate that umbellulone activates, through a transient receptor potential ankyrin 1-dependent mechanism, the trigeminovascular system, thereby causing nocioceptive responses and calcitonin gene-related peptide release. Pharmacokinetics of umbellulone, given by either intravenous or intranasal administration, suggest that transient receptor potential ankyrin 1 stimulation, which eventually results in meningeal vasodilatation, may be produced via two different pathways, depending on the dose. Transient receptor potential ankyrin 1 activation may either be caused directly by umbellulone, which diffuses from the nasal mucosa to perivascular nerve terminals in meningeal vessels, or by stimulation of trigeminal endings within the nasal mucosa and activation of reflex pathways. Transient receptor potential ankyrin 1 activation represents a plausible mechanism for Umbellularia californica-induced headache. Present data also strengthen the hypothesis that a series of agents, including chlorine, cigarette smoke, formaldehyde and others that are known to be headache triggers and recently identified as transient receptor potential ankyrin 1 agonists, utilize the activation of this channel on trigeminal nerves to produce head pain.
Umbellularia californica (California bay laurel) and Laurus nobilis (Mediterranean bay laurel) leaves may be mistaken or used as a substitute on the market due to their morphological similarity. In this study, a comparison of anatomical, chemical features and biological activity of both plants is presented. L. nobilis essential oil biting deterrent and larvicidal activity were negligible. On the other hand, U. californica leaf oil showed biting deterrent activity against Aedes aegypti. The identified active repellents were thymol, along with (-)-umbellulone, 1,8-cineole and (-)-a-terpineol. U. californica essential oil also demonstrated good larvicidal activity against 1-day old Ae. aegypti larvae with a LD50 value of 52.6 ppm. Thymol (LD50 = 17.6 ppm), p-cymene, (-)-umbellulone and methyl eugenol were the primary larvacides in this oil. Umbellulone was found as the principle compound (37%) of U. californica essential oil, but was not present in the L. nobilis essential oil. Umbellulone mosquito activity is here reported for the first time.
Cinnamon spice for cooking, bay leaves for flavoring, camphor for moth repellant and medicinal purposes, myrtlewood and stinkwood furniture, sassafras tea and avocado fruits to eat are all products from the botanical family Lauraceae to which the avocado belongs. The family Lauraceae, which derives its name from the prominent member, the Grecian laurel, Laurus nobilis, is characterized by plants which have prominent oil cells in the leaves, wood and fruit. These oils are mostly aromatic, hence provide a number of flavoring materials and spices. Among the more prominent species in the family, cinnamon, derived from the bark of the Asiatic species, Cinnamomum zeylanicum, is possibly the most widely utilized botanical relative of the avocado. This ancient spice was used in Asia long before it became known in Europe. It is chiefly produced in Ceylon and to a lesser extent in India, Malaya and tropical America. The "quills" of commerce are sections of the inner bark which are dried and scraped free of the epidermis. The Chinese cinnamon or Cassia is an essence distilled from the bark of Cinnamomum cassia. Saigon cassia and Batavia cassia are perfumery oils derived from other species of the genus. Many other edible products from the family Lauraceae are derived from those species which provide teas and flavored drinks. Sassafras tea, a semi-medicinal preparation with several alleged curative properties, has been a home remedy used for many years by rural persons of the Eastern United States. The flavoring derived from the distillation of bark and chipped wood of Sassafras albidum, native to east central United States, is widely used in carbonated beverages and dentifrices. The bark of this species is dried for extraction of the tea. Safrole, used in flavors and medicináis, is derived from the roots of this plant. The culinary flavoring "bay leaf" is obtained from several sources but the generally accepted type is that of the widely planted Grecian laurel, Laurus nobilis. This ornamental plant, known from ancient times as a symbol of "achievement" and "highest honor," was prominent among the ancient Greeks, who honored their heroes and victors of the Pythian games and as a mark of distinction for certain offices by bestowing a garland consisting of laurel branches. A crow of laurel was used to indicate academic honors. The word "laureate," such as in poet laureate, indicates "crowned or decked with laurel as a mark of honor, hence distinguished, worthy of honor especially for poetic excellence." The leaves of Laurus nobilis are dried for use in the culinary arts. The native California bay, Umbellularia californica, commonly found in the Sierra foothill valleys and coastal mountains, has a long, highly aromatic leaf with a strong pungent odor and is frequently substituted for the "true bay" but probably is not as widely accepted for culinary
The essential oils of Laurus nobilis, L. nobilis var. angustifolia and L. azorica were investigated by means of GLC, IR, PMR, CMR and GC-MS. The composition of the oils of the first two mentioned species was about the same with as main constituent 1,8-cineole, whereas the oil of L. azorica was different with low content of 1,8-cineole (10% vice 40-50%), absence of spathulenol, high content of alpha- and beta-pinene and presence of alpha-copaene, cinnamyl acetate, allo-aromadendrene, beta-eudesmol, beta-caryophyllene oxide and 1 (12), 8 (15)-caryophylladiene-9alpha-ol. About 50 components were tentatively identified.
Umbellularia californica, a shrub or tree indigenous to southwestern Oregon and northern California, is commonly known as headache tree, probably because it is reported that its scent can cause headache. Here, we report the case of a 69-year-old Italian gardener, affected during his young adult age by cluster headache, who, 10 years from his last cluster episode, developed shorter-lasting cluster-like headache attacks after and at any time he was exposed to U. californica scent. The present case indicates that, even though endogenous mechanisms causing the cluster headache were no longer present, susceptibility to exogenous triggers remains active in this patient, and suggests that identification of the constituent(s) of U. californica responsible for triggering cluster headache-like attacks may help in the understanding of the hitherto elusive mechanism of cluster headache.
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A, E -in transverse sectional view; all others in surface view
  • G -Normal Light Microscopy
B, C, F, G -normal light microscopy. A, E -in transverse sectional view; all others in surface view; all unstained). A L. nobilis;
Mc: mucilage cell, Oa: oil cell attachment, Oc: oil cell, Oi: oil cell content, Ow: oil cell wall, Pa: palisade tissue, Sk: stalk of oil cell
  • H U Californica Lo
H U. californica. Lo: lower epidermis, Mc: mucilage cell, Oa: oil cell attachment, Oc: oil cell, Oi: oil cell content, Ow: oil cell wall, Pa: palisade tissue, Sk: stalk of oil cell, St: stomata, Up: upper epidermis. Bars: A, H = 20 µm;