Performance of Putative Mutants and Genetic Parameters of Plectranthus amboinicus (L.) through Mutation Induction With Colchicine

Genetic enhancement in vegetatively propagated crops can be done through mutation induction. Colchicine-induced mutation is one of the methods that can be employed to increase plant genetic diversity. This study aimed to determine the effect of colchicine on the performance and genetic parameters of MV3 generation of Plectranthus amboinicus (L.). This study was conducted at the Laboratory of Agricultural Seed Management, Plantation Research and Development Center, from June 2018 to June 2019. Nodes and shoots were used as explants. Mutation induction was performed using colchicine at concentrations of 0%, 0.02%, 0.04%, and 0.06%. Explant regeneration and subculture were done on MS0 medium. The number of plantlets yielded were 59 (0% concentration of colchicine), 60 (0.02%), 81 (0.04%), and 80 plantlets (0.06%), respectively. Results indicated that colchicine-induced mutation in an in vitro culture was able to generate high genetic diversity in both quantitative and qualitative characters of the plantlets. At the concentration of 0.04%, colchicine produced the highest frequency of putative mutants (28.4%). Genetic parameters in MV3 generation of P. amboinicus plantlets showed that five quantitative characters, i.e. plantlet height, number of leaves, number of shoots, leaf length, and number of roots had high heritability values at a concentration around the LC50 value (0.0275%).

Phytochemical and antimicrobial analyses of Plectranthus amboinicus leaf extracts

The present study is to evaluate the phytochemical constituents and antimicrobial activity of Plectranthus amboinicus leaf extract using petroleum ether, methanol and water as solvents. The antimicrobial activity of P. amboinicus leaf extracts were examined against the selected bacterial and fungal isolates namely Escherichia coli, Staphylococcus aureus and Aspergillus niger, Candida albicans using agar well diffusion method. FT –IR analysis was performed to identify the presence of functional groups in the methanol extract. The results of the study revealed the presence of distinctive active secondary metabolites in the tested leaf extract. The results revealed that the methanol extract exhibited maximum antimicrobial activity against the tested bacterial and fungal isolates when compared with aqueous and petroleum ether extracts. The FT-IR analysis reveals the presence of functional groups such as hydroxyl, amines, alkynes, ketones and carboxylic acid in the methanolic extract of P. amboinicus. Thus, P. amboinicus leaves are effective against the selected microbes and recommends that the plant derived phytochemicals are comparatively safer than synthetic alternative, thereby contributing insightful remedial benefits for the treatment of diseases.

Óleos essenciais no tratamento de dermatozoonoses – uma revisão de literatura

O uso indiscriminado de medicamentos tem representado uma das maiores ameaças à Saúde Única, haja vista sua atuação na resistência antimicrobiana e seus impactos ao meio ambiente. Assim, busca-se como alternativa sustentável a esses fármacos, os óleos essenciais, substâncias com diversas atividades terapêuticas, destacando a eficácia no tratamento de dermatopatias de origem zoonótica, a exemplo escabiose canina, esporotricose, dermatofitose e leishmaniose tegumentar americana. O presente trabalho tem por objetivo realizar revisão bibliográfica acerca do emprego de óleos essenciais na medicina veterinária, destacando-se o tratamento das dermatopatias de origem zoonótica. Foi demonstrado o efeito acaricida, fungicida e fungistático dos óleos essenciais de Melaleuca alternifolia, Cedrus deodara, Azadirachta indica, Myrtus communis, Thymus vulgaris, Rosmarinus officinalis, Lavandula angustifolia, Cinnamomum cassia, Eugenia uniflora e Plectranthus amboinicus. As dermatozoonoses apresentam crescente resistência a antifúngicos e antibióticos comerciais, o emprego de terapias alternativas utilizando óleos essenciais se faz relevante de forma a amenizar essa resistência, e proporcionar melhoria na sanidade dos animais. Diante disso, dentre os estudos avaliados é demonstrado que os óleos essenciais de Melaleuca alternifolia, Cedrus deodara, Azadirachta indica, Myrtus communis, Thymus vulgaris, Rosmarinus officinalis, Lavandula angustifolia, Cinnamomum cassia, Eugenia uniflora e Plectranthus amboinicus apresentam resultado in vitro satisfatórios na terapêutica de dermatozoonoses de importância clínica, contudo, se faz necessário a realização de estudos in vivo para verificar a eficácia destes compostos, realizando-se um monitoramento de sua ação mediante as barreiras fisiológicas e metabolismo dos animais.

HPLC/DAD, Antibacterial and Antioxidant Activities of Plectranthus Species (Lamiaceae) Combined with the Chemometric Calculations

The increase in antibiotic resistance and the emergence of new bacterial infections have intensified the research for natural products from plants with associated therapy. This study aimed to verify the antibacterial and antioxidant activity of crude extracts of the genus Plectranthus species, being the first report on the modulation of aminoglycosides antibiotic activity by Plectranthus amboinicus extracts. The chemical composition was obtained by chemical prospecting and High-Performance Liquid Chromatography with diode arrangement detector (HPLC/DAD). The antibacterial activities of the extracts alone or in association with aminoglycosides were analyzed using the microdilution test. The antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. The phytochemical prospection allowed the flavonoids, saponins, tannins and triterpenoids to be identified. Quercetin, rutin, gallic acid, chlorogenic acid, caffeic acid, catechin, kaempferol, glycosylated kaempferol, quercitrin, and isoquercitrin were identified and quantified. The principal component analysis (PCA) observed the influence of flavonoids and phenolic acids from Plectranthus species on studied activities. Phytochemical tests with the extracts indicated, especially, the presence of flavonoids, confirmed by quantitative analysis by HPLC. The results revealed antibacterial activities, and synergistic effects combined with aminoglycosides, as well as antioxidant potential, especially for P. ornatus species, with IC50 of 32.21 µg/mL. Multivariate analyzes show that the inclusion of data from the antioxidant and antibacterial activity suggests that the antioxidant effect of these species presents a significant contribution to the synergistic effect of phytoconstituents, especially based on the flavonoid contents. The results of this study suggest the antibacterial activity of Plectranthus extracts, as well as their potential in modifying the resistance of the analyzed aminoglycosides.

Chemical and thermal profile of Plectranthus amboinicus essential oil for its application as a bioherbicide

The species Plectranthus amboinicus is an aromatic herb with great application in popular medicine due to the diversity of biological properties. Chemically, its essential oil (EO) is characterized by two chemotypes, thymol and carvacrol, which vary depending on factors such as seasonality. Despite being an extensively exploited species, studies of the bioherbicidal potential of this species are insufficient. In this context, the EO of P. amboinicus leaves, extracted in two different seasonal periods, were characterized regarding chemical profile (by gas chromatography mass spectrometry - GC-MS) and thermal profile (DTG) and was subjected to bioherbicide tests (germination test and seedling development) against Eragrostis plana, commonly known as capim annoni, an invader of pastures in the Pampas region. P. amboinicus EO was a potent inhibitor of E. plana germination, reducing accumulated germination by over 70% when exposed to 0.1% EO, and a complete inhibition of germination was observed when exposed to 0.5%. Following the effects observed in germination, the initial growth of E. plana was significantly affected by concentrations above 0.05%. The major constituent identified via GC-MS was carvacrol, representing 87.5% of the volatile composition of P. amboinicus leaves. In addition, P. amboinicus EO presented high thermal stability up to 100 °C, which is an interesting result regarding its use as a bioproduct.

Chemical Composition of Hexane-Extracted Plectranthus amboinicus Leaf Essential Oil: Maximizing Contents on Harvested Plant Materials

Plectranthus amboinicus (Lour.) Spreng, also known locally as “Bangun-bangun”, is an aromatic medicinal herb known for its therapeutic and nutritional properties attributed to its terpenoid-rich phytochemicals. Information to assist in initiating appropriate harvesting time to maximize the yield of targeted chemicals in harvested plant tissues remains an issue that is seldom highlighted. This study reports on the essential oil distribution in P. amboinicus leaves, and total phenolic and flavonoid contents, in addition to GC-MS analysis of hexane extracts of the leaf samples collected at various times throughout the day. The influence of environmental factors on γ-terpinene, p-cymene, carvacrol, and thymoquinone are also discussed. Oil Red O staining showed the highest oil deposition at 2 p.m., which was consistent with the phenolic and flavonoid contents of this plant. GC-MS analysis of the leaf extract showed carvacrol (47.00–60.00%), γ-terpinene (8.00–10.00%), caryophyllene (~6.00%), p-cymene (4.90–6.50%), trans-α-bergamotene (4.70–5.00%), and thymoquinone (3.30–5.60%) were the major components of this plant. Interestingly, thymoquinone, a phytochemical associated with Nigella sativa, was also detected in this hexane-extracted sample with maximum accumulation during midday and a decrease at night, which could be due to the lower temperature and dimmer light conditions. The chemical polymorphism in the oil content indicated that environmental factors such as light exposure and temperature should be considered during harvesting to ensure consistent quality of the phytochemicals extracted from the plant materials. This study indicates that oversight in selecting plant materials might compromise the yield of quality phytochemicals extracted from harvested tissues.