Efficacy of phenolic compounds from bay leaf (Laurus nobilis) as natural antioxidants in the enhancement of edible oil thermo-resistance

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.

<i>Background:</i> <i>Laurus nobilis, </i>commonly known as bay leaf, is widely used in global cuisine for flavouring soups and stews, as well as in baked foods and desserts. The present study aims to characterize the phytochemical composition of chloroform and methanol extracts of <i>Laurus nobilis</i> using Gas Chromatography-Mass Spectrometry (GC–MS) analysis. <i>Materials and Methods:</i> Dried Bay leaves were locally sourced, properly identified, and authenticated. The leaves were extracted using cold maceration to obtain chloroform (CELN) and methanol (MELN) extracts of <i>Laurus nobilis</i>. Qualitative and quantitative phytochemical screening, along with Gas Chromatography-Mass Spectrometry (GC-MS) analysis, was performed following standard protocols. <i>Results:</i> The qualitative analysis of CELN and MELN confirmed the presence of flavonoids, phenols, terpenoids, glycosides, steroids, saponins, alkaloids, and carbohydrates. Quantitative analysis indicated that MELN contained higher levels of phenols (11.34 mg/100g), tannins (5.20 mg/100g), and carbohydrates (16.23 mg/100g). GC-MS analysis identified 87 and 98 compounds in CELN and MELN, respectively, with 10 compounds common to both extracts. The most abundant (≥5%) compounds in MELN were Spiro(1,3,3-trimethylindoline)-2,5’-pyrrolidin-2-one (8.35%), 7,10,13-Hexadecatrienoic acid, methyl ester (12.75%), Azuleno(4,5-b)furan-2(3H)-one, 3a,4,6a,7,8,9,9a,9b-octahydro-6-methyl-3,9-bis(methylene) (9.09%), and n-Hexadecenoic acid (18.25%). For CELN, the most abundant compounds were Buta-1,3-diyne,1,4-bis(2-methoxycarbonylcyclopropyl) (5.11%), Azuleno[6,5-b]furan-2,5-dione, decahydro-4a,8-dimethyl-3-methylene-,3aR-(3aα,4a,7aα,8β,9aα) (5.75%), n-Hexadecanoic acid (5.89%), phytol (7.57%), and Benzene, 1-phenyl-4-(2,2-dicyanoethenyl) (13.91%). <i>Conclusion:</i> This study highlights the rich phytochemical and bioactive profile of <i>Laurus nobilis</i> (bay leaf) extracts, reinforcing their potential in disease management. It also underscores the need for comprehensive pharmacological investigations of its bioactive compounds to support drug discovery efforts.

Isolation and identification of cytotoxic compounds from Bay leaf ( Laurus nobilis)

Numerous in vitro studies using solvent or aqueous extracts of raw dietary plant material have demonstrated modulation of colon cancer cell growth and apoptosis and effects on immune and nonimmune pathways of inflammation. We have developed a generic, 3-staged food-compatible process involving heating for conversion of dietary plants into food ingredients and report results on potential colon cancer-regulating properties of processed forms of Bay leaf (Laurus nobilis). In vitro studies demonstrated inhibition of cancer cell growth by processed Bay leaf products in HT-29, HCT-116, Caco-2, and SW-480 human cancer cell lines, which were accompanied by variable levels of elevated apoptosis. Bay leaf also exerted moderate inhibition of cycloxygenase 2 and 5 lipoxygenase enzymatic activity. In addition, these extracts significantly downregulated interferon-γ production in T helper Type 1-stimulated whole blood from healthy donors. Furthermore, size fractionation of the extracts revealed that antiproliferative and proapoptotic activities were associated with low mass (primarily polyphenolics and essential oils) and high mass (primarily proteins including polyphenol oxidase) chemical classes, respectively. Bay leaf exerted in vitro bioactivity that might be relevant to protecting against early events in sporadic colorectal cancer, with potential for further optimization of bioactivity by size-based fractionation.

Laurus nobilis (Bay leaf), was examined for its capacity to remove hexavalent chromium Cr(VI) poisonous, from aqueous solution. The bio-adsorbent using bay leaf obtained from Laurus nobilis was investigated in batch experiments. The influence of main parameters such as chromium concentration, pH and shaking time are tests. The effect of beginning concentration of Cr(VI) ion (10 to 50 mg/dm ), pH (1 to 6) and shaking time (5 to 180 min) have been reported. The optimum pH was found to be pH 4.. Results show that the most appropriate model was pseudo second-order kinetic and it correlate with the trial statistics well.

The accurate identification of bay leaf in natural products commerce may often be confusing as the name is applied to several different species of aromatic plants. The true "bay leaf", also known as "bay laurel" or "sweet bay", is sourced from the tree Laurus nobilis, a native of the Mediterranean region. Nevertheless, the leaves of several other species including Cinnamomum tamala, Litsea glaucescens, Pimenta racemosa, Syzygium polyanthum, and Umbellularia californica are commonly substituted or mistaken for true bay leaves due to their similarity in the leaf morphology, aroma, and flavor. Substitute species are, however, often sold as "bay leaves". As such, the name "bay leaf" in literature and herbal commerce may refer to any of these botanicals. The odor and flavor of these leaves are, however, not the same as the true bay leaf, and for that reason they should not be used in cooking as a substitute for L.nobilis. Some of the bay leaf substitutes can also cause potential health problems. Therefore, the correct identification of the true bay leaf is important. The present work provides a detailed comparative study of the leaf morphological and anatomical features of L.nobilis and its common surrogates to allow for correct identification.

Chapter 5 - Bay Leaf

Correct identification of the true bay leaf (Laurus nobilis) and its substitutes is important not only for the quality control of the products, but also for the safety of the consumers. L.nobilis is often substituted or confused with other species, such as Cinnamomum tamala, Pimenta racemosa, Syzygium polyanthum, and Umbellularia californica. In the present study, the potential of gas chromatography combined with quadrupole time-of-flight mass spectrometry for the profiling of various bay leaf products was evaluated for the first time. Thirty-nine authenticated samples representing the true bay leaf and the four commonly substituted species were analyzed. An automatic feature extraction algorithm was applied for data mining and pretreatment in order to identify the most characteristic compounds representing different bay leaf groups. This set of data was employed to construct a sample class prediction model based on stepwise reduction of data dimensionality followed by principal component analysis and partial least squares discriminant analysis. The statistical model, with demonstrated excellent accuracies in recognition and prediction abilities, enabled the correct classification of commercial samples including complex mixtures and essential oils. In addition, in-house developed personal compound database and library with retention time locking offered the advantage of combining retention time matching with accurate mass matching, resulting in high confidence of compound identification for each bay leaf subgroup. At least three marker compounds were identified for each bay leaf species that could be used to discriminate among them.

Bay leaf is also called as Laurus nobilis an aromatic evergreen tree or large shrub with green, glabrous leaves, in the flowering plant family Lauraceae. It is native to the Mediterranean region and is used as a bay leaf for seasoning in cooking. Its common names include bay laurel, sweet bay, bay (esp. United Kingdom) true laurel, Grecian laurel, laurel tree or simply laurel. Bay leaf refers to the aromatic leaves of several plants which are used in cooking for their distinctive flavour and fragrance. It has many medicinal properties which can also be used to treat cancer as well as gastric problems. Bay leaf is also commonly used to treat muscles and joint pain. Aqueous extracts of bay laurel can also be used as astringents and even as a reasonable salve for open wounds. The anti-inflammatory activity of bay leaf was determined but its ability to inhibit protein denaturation where denaturation of proteins is a well-documented cause of inflammation. The anti-inflammatory effect of the herb was comparable to reference analgesics and non-steroid anti-inflammatory drugs. The present study makes the herb worthy of further investigation.

Ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. and their antioxidant activity

Although enzymes are effective biocatalysts that are widely used in biosensors, a major drawback that hampers many of these biotechnological applications of enzymes is their limited stability. Applications that use very pure, high value proteins need to employ effective stabilization technology, primarily due to cost considerations and availability of the proteins used. For this purpose, interest in bio-imprinting techniques increases because it allows stability characteristics of enzymes to be improved. In this study, a bio-imprinted Bay leaf (Laurus nobilis L.) tissue homogenate biosensor was devised by a very simple way. For this purpose, the enzymes, polyphenol oxidases in the bay leaf tissue, were first complexed by using their competitive inhibitor, thiourea, in aqueous medium and then this enzyme was immobilized on gelatin by crosslinking with glutaraldehyde on a Clark-type oxygen electrode surface. Similarly, noncomplexed polyphenol oxidase with thiourea was also immobilized on a Clark-type oxygen electrode in the same conditions. The aim of the study was to prepare a new biosensor-based Bay leaf tissue homogenate and to improve the stability characteristics such as thermal stability, pH stability, and storage stability, of the biosensor by bio-imprinting method. The results showed that this simple technique should be effectively used to improve the stabilities of a biosensor.

Bay leaf (Laurus nobilis L.) has been shown to possesses various biological activities such as wound healing activity, antioxidant activity, antibacterial activity, antiviral activity, immunostimulant activity, anticholinergic activity, antifungal activity, insect repellant activity, anticonvulsant activity, antimutagenic activity, and analgesic and anti-inflammatory activity. The present study aimed to investigate whether the bay leaf incense (BL) elicits the memory formation via the action on the cholinergic system using a scopolamine (Sco)-induced rat model. Rats were exposed to BL over 5 min in a smoking chamber apparatus once daily for 22 days, whereas memory impairment was induced by Sco (0.7 mg/kg), a muscarinic receptor antagonist, delivered 30 min before each behavioral test. The phytochemical composition of BL was achieved by gas chromatograph–mass spectrometry (GCMS). Behavioral effects in rats were assessed by Y-maze, radial arm maze (RAM), and novel object recognition (NOR) paradigms. Additionally, the acetylcholinesterase (AChE) activity and the oxidative stress markers in the rat hippocampus were also evaluated. Exposure to BL significantly ameliorated Sco-induced cognitive impairment and oxidative stress in the rat hippocampus. The obtained results suggested that BL-induced ameliorative cognitive effects are mediated by enhancement of the cholinergic system and antioxidant activities.

The effect of different drying treatments on the volatiles in bay leaf (Laurus nobilis L.) was studied. Simultaneous distillation extraction (SDE) and solid-phase microextraction (SPME) were compared by gas chromatography-mass spectrometry (GC-MS) of the volatile components in bay leaves. SDE yielded better quantitative analysis results. Four drying treatments were employed: air-drying at ambient temperature, oven-drying at 45 degrees C, freezing, and freeze-drying. Oven drying at 45 degrees C and air-drying at ambient temperature produced quite similar results and caused hardly any loss in volatiles as compared to the fresh herb, whereas freezing and freeze-drying brought about substantial losses in bay leaf aroma and led to increases in the concentration levels of certain components, e.g., eugenol, elemicin, spathulenol, and beta-eudesmol.

The aim of the present work was the preparation and characterization of o/w/o co-surfactant free olive oil microemulsions with Laurus nobilis (bay leaf) essential oil, in order to obtain a system that could provide a controlled, sustained product with desirable sensory characteristics and prolonged oxidative stability.

Spices and herbs are widely used food ingredients that enhance most organoleptic features of prepared foods. They are also used for medicinal and preservative purposes. Spices and herbs are potential carriers of bacteria, yeasts, and molds due to the nature of cultivation, harvest methods, storage conditions, packaging procedures, distribution, sale, and general handling. Although some fungi have been identified to be associated with most spices and herbs elsewhere in the world, little has been done on the presence of fungi in spices and herbs in Ghana. This study sought to identify the toxicogenic fungal profiles, mycotoxins (aflatoxins) present in some herbs, bay leaf (Laurus nobilis) and garden egg leaves (“gboma”) (Solanum macrocarpon), and spices, ginger (Zingiber officinale) and “dawadawa”(Parkia biglobosa), as well as to investigate the antimicrobial properties of the selected herbs and spices. The decimal reduction technique was used to plate onto Dichloran Rose Bengal Chloramphenicol (DRBC) agar media plates for fungal growth. Aflatoxin detection was carried out with high-performance liquid chromatographer connected to a fluorescence detector (HPLC-FLD). Antimicrobial properties were carried out using the agar diffusion method on solidified, freshly prepared Mueller-Hinton agar. A total of 12 species belonging to 7 genera, Aspergillus (niger, flavus, fumigatus, and ochraceus), Fusarium (oxysporum, verticillioides), Mucor (racemosus), Penicillium (digitatum, expansum), Rhizopus (stolonifer), Rhodotorula sp., and Trichoderma harzianum, were identified as fungal contaminants. Fusarium oxysporum was the most predominant species identified. Fresh ginger recorded the greatest number of colony-forming units (3.71 log10 CFU/g) with bay leaves recording the least number of colony counts (2.36 log10 CFU/g). Mycotoxin concentration detected in gboma was2.06 ± 0.07 μg/kgand in dawadawa was2.13 ± 0.09 μg/kg; however, mycotoxins were not detected in bay leaf and ginger. Ginger exhibited antibacterial activity against all bacteria ranging from 7.0 ± 0.0 mm to 12.0 ± 5.66 mm zones of inhibition. Ginger, bay leaf, and gboma extracts displayed fair antimicrobial activity against the bacteria investigated. On the other hand, dawadawa generally produced the least resistance against the five bacterial species but exhibited the highest zone of inhibition. All samples were slightly acidic with pH readings ranging from 5.81 to 6.76.