Antimicrobial effects of catnip (Nepeta cataria L.) essential oil against canine skin infection pathogens.

Background and Aim: Catnip essential oils have antimicrobial effects against bacteria, yeast, and fungi; however, there is limited information regarding their antimicrobial activity against pathogens that cause canine skin infections. This study aimed to identify the phytochemical constituents of catnip essential oil and assay its antimicrobial activity against Staphylococcus pseudintermedius, Malassezia pachydermatis, Microsporum canis, Microsporum gypseum, Microsporum gallinae, and Trichophyton mentagrophytes. Materials and Methods: Catnip essential oil was extracted by hydrodistillation, and its chemical constituents were analyzed by gas chromatography-mass spectrometry (GC-MS). In vitro antimicrobial activity was investigated using broth microdilution and time-kill tests. To evaluate the effect of catnip essential oil on microbial morphology and cell membrane integrity, scanning electron microscopy (SEM) and leakage studies were conducted. Results: GC-MS analysis revealed that the principal components of catnip essential oil were cis- and trans-nepetalactone (57.09% of peak area), trans-, cis-nepetalactone (39.69% of peak area), trans-caryophyllene (1.88% of peak area), and caryophyllene oxide (1.34% of peak area). The minimum inhibitory concentration, minimum bactericidal concentration, and minimum fungicidal concentration values determined by broth microdilution ranged from 0.0625 mg/mL to 4.0 mg/mL. Time-kill testing showed that the germicidal effects of catnip essential oil were time and concentration-dependent, respectively. Environmental SEM and cell leakage analysis indicated that catnip essential oil disrupted the integrity of cell membranes in the tested microorganisms. Conclusion: Catnip essential oil has potential as an alternative antimicrobial against a wide range of canine skin infection pathogens, including S. pseudintermedius, M. pachydermatis, Mi. canis, Mi. gypseum, Mi. gallinae, and T. mentagrophytes.

A taxonomic synopsis of Heliotropiaceae and new combinations in Heliotropium from Thailand.

A synopsis of Heliotropiaceae in Thailand is presented and, as part of this, the taxonomic history, identification keys, distribution maps, herbarium specimen citations and diagnostic characters are provided. Two genera and 12 species are recognised and four new combinations are proposed of Tournefortia under the genus Heliotropium, namely H.hookeri, H.intonsum, H.montanum and H.ovatum. Two species are newly recorded in Thailand: Euplocaovalifolia and H.hookeri. The neotype and lectotype are designated here for Tournefortiamontana and T.boniana, respectively.

Two new species of Phyllanthus (Phyllanthaceae) from Thailand.

Two Phyllanthus species are newly described from a limestone mountain in the north of Thailand. The first species, P. huamotensis Pornp., Chantar. & J.Parn., sp. nov., is one of the most distinct Phyllanthus species easily distinguished by its reddish branchlets and stem, conspicuous reddish venation, especially on the lower leaf surface, red sepals with long fimbriate margin and red capsule with papillose-puberulous surface. The second species, P. chantaranothaii Pornp., J.Parn. & Hodk., sp. nov., is similar to P. pulcher Wall. ex Müll.Arg., but it is distinguished by its puberulous upper leaf surface and pistillate flowers which have red, narrowly lanceolate sepals with a white, long fimbriate margin, puberulous outer side as well as puberulous pedicel.

Anthropogenic effects on a tropical forest according to the distance from human settlements.

The protection of tropical forests is one of the most urgent issues in conservation biology because of the rapid deforestation that has occurred over the last 50 years. Even in protected forests, the anthropogenic effects from newly expanding villages such as harvesting of medicinal plants, pasturing cattle and forest fires can induce environmental modifications, especially on the forest floor. We evaluated the anthropogenic effects of the daily activities of neighboring residents on natural forests in 12 plots extending from the village boundary into a natural forest in Thailand. The basal area per unit land area did not present a significant trend; however, the species diversity of woody plants decreased linearly towards the village boundary, which caused a loss of individual density because of severe declines in small saplings compared with adult trees and large saplings in proximity to the village. An analysis of tree-size categories indicates a lack of small samplings near the village boundary. The current forest appears to be well protected based on the adult tree canopy, but regeneration of the present-day forests is unlikely because of the loss of seedlings.

Revisions and key to the Vernonieae (Compositae) of Thailand.

Seventeen genera and 48 species, in five subtribes, are recognized in Thailand. These include 15 endemic taxa, half of which are in the largest genus, Acilepis, with others in the genera Camchaya, Koyamasia, and Okia. A new monotypic genus, Pulicarioidea, is established with P. annamica, the new name for the species formerly known as Vernonia pulicarioides. New combinations are also made for Acilepis kerrii, Cyanthillium montanum, Koyamasia curtisii and Okia pseudobirmanica. Forty-six characters including habit, leaf, flower, achene and pollen morphology were analyzed using UPGMA. Five clusters of taxa were identified. Keys to genera, species and varieties, descriptions, vernacular names, ecological data and illustrations are provided.

A new species of Camchaya (Asteraceae, Vernonieae) from Thailand.

Camchaya thailandica Bunwong, Chantar. & S.C.Keeley, sp. nov. from Phu Phrabat Historical Park, Udon Thani, Thailandis described as a new species. Plant of this new species are similar to Camchaya gracilis (Gagnep.) Bunwong & H.Rob. but differ in having ovate phyllaries without margin spines, 10-ribbed achenes, and broadly ovate leaves. This species is a rare endemic known only from the type collection and probably confined to open areas of sandstone hills in Udon Thani province.

Hepatoprotective and antioxidant activities of Tetracera loureiri.

Tetracera loureiri is one of the most valued herbs in Thai traditional medicine. In this study, we describe its in vitro and in vivo antioxidant and hepatoprotective activities. The ethanol extract of T. loureiri possessed potent antioxidant and strong free radical scavenging properties assayed using ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), respectively. The cytoprotective effects of T. loureiri were demonstrated in ethanolic extracts of freshly isolated rat hepatocytes against the chemical toxicants paracetamol and tertiary-butylhydroperoxide. The cells pretreated with the extract maintained the GSH/GSSG ratio and suppressed lipid peroxidation in a dose dependent manner. Pretreating rats with the ethanol extract orally, one hour prior to intraperitoneal injection of toxic doses of paracetamol, significantly prevented elevations of plasma ALT and AST. These results suggest that T. loureiri may be of potential therapeutic value in some liver disorders.