Cryptomeria japonica, a commercially important tree throughout Asia and the Azores Archipelago (Portugal), is currently waste/by-products of wood processing that can be converted into eco-friendly and high added-value products, such as essential oils (EOs), with social, environmental and economic impacts.
1. Introduction
Numerous plant-derived essential oils (EOs), due to their valuable odoriferous and bioactivity properties, and GRAS (Generally Recognized as Safe) status, have applications in many fields, such as aromatherapy, cosmetic, cosmeceutical, food, beverage, household, pharmaceutical, phytomedicine and pest control. However, the bioactivity and potential commercial use of EOs depends on their complex mixture of organic compounds, produced through the secondary metabolic pathways of aromatic plants
[1][2][3][4], such as the conifer Cupressaceae family
[4].
Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae), commonly called a Japanese cedar or
sugi, is a forest tree endemic to Japan, and widely distributed in warm and cool temperate climates.
Cryptomeria is a monotypic genus that includes only one species with two recognized varieties:
C. japonica var.
japonica and
C. japonica var.
sinensis, the latter being native to China
[5].
C. japonica is a very large, conical, evergreen monoecious tree that can reach up to 70 m (230 ft) in height with a trunk diameter of up to 4 m (13 ft). It is a fast growth tree that prefers moist, deep and well-drained soils
[6]. The bark is reddish-brown, fibrous and peels off in vertical strips. The leaves are odorous due to the presence of EO and are 0.5–1 cm (0.20–0.39 in) long and needle-like in structure. The seed cones are globular up to 1–2 cm (0.39–0.79 in) in diameter with about 20–40 scales
[7].
C. japonica is one of the main plantation forest tree species in Asian countries (Japan, Korea, Taiwan, India and China) and in the Azores Archipelago (Portugal). In Azores, forests account for 31% of the land area, where
C. japonica occupies over 12,698 hectares and is the most commercially important tree species. It was introduced in Azores in the mid-19th century, where it developed very well due the similar pedological and climatic conditions to those of its original country. In Azores,
C. japonica is often planted around farms to create shelter lines, which increase pasture productivity by creating favorable microclimates for crop and livestock
[8].
2. Antimicrobial Activity of C. japonica EO in Food Industry and Human Diseases
EOs are generally accepted as natural antimicrobials and antioxidants that can be used in the food industry as bio-preservatives to increase shelf life and quality of food products
[9]. In addition, infections caused by fungi and bacteria represent a key issue due to the development of resistant species to current fungicides and antibiotics. Therefore, EOs could be an ecological and effective alternative to synthetic antimicrobial agents
[9].
Table 3 1 shows the antimicrobial activity of
C. japonica EO from different tissues and geographical origins, against several gram-positive and gram-negative bacterial strains, as well as against various fungal species. The minimal inhibitory concentrations (MICs) were determined by the broth dilution method.
Table 31. Antimicrobial activities of
Cryptomeria japonica essential oil by plant organ and country of origin.
Origin |
Plant Organ |
Target Species |
Efficiency |
Ref. |
Portugal |
Leaves, heartwood, bark |
Mycobacterium tuberculosis, Botrytis cinerea, Fusarium circinatum, Cryphonectria parasitica, |
| Aspergillus niger, Trichoderma harzianum, Cladosporium cladosporioides, Cladosporium sp., |
| Candida albicans, Candida tropicalis, Saccharomyces cerevisiae, Cryptococcus neoformans, |
| Aspergillus fumigatus, Microsporum gypseum, Trichophyton rubrum, Trichophyton mentagrophytes |
Effective against | M. Tuberculosis | ,
| T. harzianum | , | B. cinerea | , | C. cladosporioides | and | Cladosporium sp. | , MICs range 0.025–0.25 mg/mL |
[10] |
South Korea |
Leaves plus twigs |
Candida albicans, Candida pseudotropicalis, Candida glabrata, Candida tropicalis, |
| Candida krusei, Candida parapsilosis, Cryptococcus neoformans, Aspergillus fumigatus |
Effective, MICs 2.18 mg/mL
or higher |
[11] |
Taiwan |
Leaves, heartwood, sapwood, bark |
Trametes versicolor, Lenzites betulina, Laetiporus sulphureus, Gloeophyllum trabeum, |
| Fusarium oxysporum, Rhizoctonia solani, Ganoderma australe, Fusarium solani, |
| Pestalotiopsis funereal, Collectotrichum gloeosporioides |
Highly effective, IC | 50 | range
0.039 > 0.500 mg/mL,
except bark EO |
[12] |
Japan |
Heartwood |
Staphylococcus epidermis, Trichophyton rubrum |
Effective, MIC = 0.313 mg/mL, except | S. epidermis |
[13] |
South Korea |
Leaves |
Staphylococcus epidermis, Propionibacterium acne |
Effective, MICs range 0.156–10 µL/mL |
[14] |
South Korea |
Leaves |
Escherichia coli, Staphylococcus aureus, Staphylococcus epidermis, Streptococcus pyogenes, |
| Streptococcus mutans, Streptococcus sanguinis, Streptococcus sobrinus, Streptococcus ratti, |
| Streptococcus criceti, Streptococcus anginosus, Streptococcus gordonii, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Prevotella intermedia, Porphylomonas gingivalis |
Effective, MICs range 0.025–12.8 mg/mL, except | E. coli |
[15] |
South Korea |
Leaves plus twigs |
Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii, |
| Acinetobacter calcoaceticus, Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, |
| Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens |
Ineffective, MICs > 21.8 mg/mL |
[11] |
Taiwan |
Leaves, heartwood, twigs, bark |
Legionella pneumophila |
Ineffective, MBC > 2 mg/mL |
[16] |