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The rationale for the use of Ocimum americanum var. americanum in herbal medicine is largely based on the longstanding experience of traditional medicine practitioners. The genus Ocimum is extensively used in Eastern Africa in folkloric practice against a wide range of illnesses. The present paper intends to bring a comprehensive overview of O. americanum var. americanum in regard to its biological activities, ethnopharmacological uses, phytochemical and toxicological effects. The literature search was conducted using Google, Google Scholar, Chemical abstracts, Sciverse; JSTOR, Medline, PubMed, Science Direct, Scopus and Springer Link. O. americanum var. americanum extracts have been shown to have antimicrobial, antioxidant, antiproliferative, insecticidal, and repellent activities. Literature on the activity of O. americanum var. americanum extracts against metabolic syndromes such as diabetes, hyperlipidaemias and hypertension is scanty. Toxicological data is also limited; however, the accessible information indicates non-toxicity of O. americanum var. americanum extracts. Substantial variations in phytochemical constituents of this particular species are observed, which may be attributed to edaphic differences as well as ecoclimatic regions.

Background. Increasing antimicrobial resistance has led to an arduous search for new potent drugs from nature. In this search, plants have proved to be rich reservoirs of efficacious medicinal components that manage ailments. The current study is designed to investigate the phytochemical composition, antimicrobial activity, and the cytotoxicity of the crude root extracts of Croton dichogamus, a shrub that is commonly used in the eastern Africa for the management of infectious diseases. Methods. The roots of Croton dichogamus were obtained, dried, ground, and extracted using three solvents (acetone, distilled water, and 50% ethanol). The antimicrobial activity was tested using agar well diffusion and microbroth dilution techniques against five human pathogens. The brine shrimp lethality assay was used to assess the toxic effect. Results. The phytochemical screening indicated the presence of terpenoids, flavonoids, tannins, phenols, polyuronides, saponins, and anthracenes. The brine shrimp lethality assay indicated that all the extracts were highly cytotoxic with LC50 values below 100 μg/ml. Acetonic extract had an LC50 value of 4.148 μg/ml, hydroethanolic extract had 76.09 μg/ml, and aqueous extract had 42.61 μg/ml. All extracts showed the antibacterial activity against Gram-positive bacteria (B. cereus and S. aureus) and a fungal organism, C. albicans. The extracts showed no antibacterial effect on the Gram-negative bacterial strains (P. aeruginosa and E. coli) at a concentration of 250 mg/ml. The highest antimicrobial activity was demonstrated by the acetonic extract on B. cereus which had an MIC of 10.42 mg/ml and a zone of inhibition of 17.33 ± 0.58 at a concentration of 250 mg/ml. Conclusion. In this research work, we report that C. dichogamus had the antimicrobial activity confirming the folklore claim. The results made a strong case for isolation of novel anticancer lead compounds.

Plectranthus species are difficult to taxonomically delimit due to lack of clear-cut morphological synapomorphies. This study is aimed at bringing insights into classification of ten Plectranthus species in the Coleus clade by using leaf micromorphology and molecular data. Stomatal counts and observation of microtome leaf sections generated leaf micromorphology data, while molecular data was obtained from sequencing MatK and Rbcl genes from each species. Phylogeny based on the MatK and Rbcl gene sequences clustered four species P. caninus, P. otostegioides, P. barbatus, and P. lanuginosus together (Clusters A and D, respectively), while P. pseudomarrubioides, P. ornatus, and P. aegyptiacus were grouped together into Clusters B and E, respectively, and P. montanus and P. amboinicus were grouped together (Cluster C). A dendrogram was generated through a cluster analysis of the leaf micromorphological characters grouped together, P. caninus, P. ornatus, P. otostegioides, P. montanus, and P. pseudomarrubioides (Cluster F). The dendrogram also grouped together P. aegyptiacus, P. amboinicus, P. edulis, P. barbatus, and P. lanuginosus (Cluster G). The present study has grouped the ten studied Plectranthus species using molecular and leaf micromorphology characters into phylogenies, which are supported by previous studies, and proved that these characters can aid in plant identification and phylogenetic studies.

Cissus rotundifolia Lam. is used as a medicinal herb and vegetable. Flavonoids are the major components for the therapeutic effects. However, flavonoids constituents and expression profiles of related genes in C. rotundifolia organs are unknown. Colorimetric assay showed the highest flavonoid concentration in roots compared to the stem and leaf. Widely target-based metabolome analysis allowed tentative identification of 199 compounds in three organs. Flavonols and flavones were the dominant flavonoids subclasses. Among the metabolites, 171 were common in the three organs. Unique accumulation profile was observed in the root while the stem and leaf exhibited relatively similar patterns. In the root, six unique compounds (jaceosidin, licoagrochalcone D, 8-prenylkaempferol, hesperetin 7-O-(6″malonyl) glucoside, aureusidin, apigenin-4′-O-rhamnoside) that are used for medicinal purposes were detected. In total, 18,427 expressed genes were identified from transcriptome of the three organs covering about 60% of annotated genes in C. rotundifolia genome. Fourteen gene families, including 52 members involved in the main pathway of flavonoids biosynthesis, were identified. Their expression could be found in at least one organ. Most of the genes were highly expressed in roots compared to other organs, coinciding with the metabolites profile. The findings provide fundamental data for exploration of metabolites biosynthesis in C. rotundifolia and diversification of parts used for medicinal purposes.

Background. Herbal plants are a natural source of novel biomolecules used widely in ethnomedicine. The present study was intended to examine the antimicrobial properties, cytotoxicity, and phytoconstituents of Ocimum americanum L., an herb traditionally used by the people of Swahili (Kenya) against microbial infections. Methods. The aerial parts of Ocimum americanum L. were sourced, dried, milled, and extracted using three solvents: aqueous, acetonic, and 70% hydroethanolic. Additionally, fractions of chloroform and ethyl acetate were obtained from all crude extracts of the plant. The antimicrobial property was evaluated using agar well diffusion and microdilution techniques against human opportunistic pathogens including S. aureus, E. coli, and C. albicans. The brine shrimp cytotoxicity test was used to analyze the lethality of the extracts and fractions. Phytochemical screening was used to qualitatively assay the presence of phytoconstituents. Results. The phytochemical assay confirmed the presence of alkaloids, phenols, flavonoids, tannins, saponins, terpenoids, reducing sugars, anthraquinones, and glycosides. The lethality test demonstrated that all the extracts and fractions were toxic against Artemia salina nauplii with LC50 values ranging from 0.59 to 559.71 µg/ml. Chloroformic fraction of the hydroethanolic extract had the highest lethality with an LC50 value of 0.59 µg/ml. Two of the extracts and their fractions displayed antimicrobial activity against the Gram-positive bacteria (B. cereus and S. aureus) and fungus (C. albicans), while the same extracts had no activity against the Gram-negative bacteria (E. coli and K. pneumoniae). The highest antimicrobial activity was seen in the ethyl acetate fraction of the hydroethanolic extract at 250 mg/ml against Bacillus cereus which had an inhibition zone of 26.00 ± 0.00 and MIC value of 62.5 mg/ml. Conclusion. In the current study, we report that Ocimum americanum L. demonstrated moderate antimicrobial activity, contains numerous phytocompounds, and is highly cytotoxic; thus, further research is needed for bioprospecting a novel compound.

There are over 500 species in the Hypericum genus worldwide. Crude extracts from Hypericum species have been reported in folkloric medicine as analgesics, anthelmintics, astringents, antidepressants, diuretics, and anti-inflammatories. The current review aims to provide an in-depth analysis of local uses, pharmacological activities, and phytochemical composition of different extracts generated from Hypericum species. The review data was collected via literature search from Google, Google Scholar, Medline, Pubmed, Mendeley, Science Direct, Chemical Abstracts, Web of Science, and Scopus. The most studied of the entire Hypericum genus is H. perforatum, approved to manage mild depression. Other species that have been reported to have ethnomedicinal value are H. erectum, H. monogynum, H. attenuatum, H. japonicum, H. beanii, H. monantheum, H. wightianum, H. scabrum, H. monogynum, H. monogynum, H. geminiflorum, H. ascyron, H. seniawinii, H. elodeoides, H. petiolulatum, H. wightianum, H. hengshanense, H. japonicum, and H. revolutum. Over 900 phytochemicals have been isolated from the Hypericum genus plant species, mostly phenolics, and terpenoids. Studies have been carried out to validate the ethnopharmacological use of extracts from Hypericum species against depression, cancer, inflammation, and microbial infections. There are limited safety studies involving medicinal plants from the Hypericum genus; however,further investigations on toxic effects, phytochemical composition, and biological activities are necessary to validate the medicinal uses of plant species of the Hypericum genus empirically. The present article reviews ethnopharmacology, phytochemistry, and toxicology of the Hypericum genus, which several communities have used to treat various conditions.

Croton dichogamus Pax (Euphorbiaceae) has been used widely in traditional ethnopharmacological practices against a wide number of ailments. The pharmacological activities, phytochemical composition and its safety aspects have been covered in a number of articles. The present review aims to provide a comprehensive literature overview regarding botanical description, phytochemical composition, local uses, pharmacology and toxicological effects of crude extracts, fractions and isolated compounds obtained using different solvent systems. The review was compiled through a thorough literature search from authentic resources using Google, Google Scholar, Medline, PubMed, Chemical abstracts, Web of Science, Scopus, Science Direct, peer reviewed articles, books and thesis. Croton dichogamus is an important ethnomedicinal plant used traditionally for the treatment of tuberculosis and other respiratory tract infections, stomach ache, fever, sexually transmitted diseases such as syphilis and gonorrhea, impotence, arthritis, tooth ache, infertility and malaria. Pharmacological and toxicological studies performed on the fresh plant parts and crude extracts prepared using different extraction solvents validates the ethnomedicinal utilization of Croton dichogamus. Studies performed validate the use of Croton dichogamus extracts in antimicrobial, antioxidative and antiproliferative therapy. Information on therapeutic validation in analgesia, hypertension, wound healing, gastrointestinal motility and diabetes mellitus is scanty. To further advance the local use of Croton dichogamus in the above-mentioned illnesses, there is an urgent need for further studies to validate the traditionally reported anecdotal efficacy and safety. Data on safety of various crude extracts of Croton dichogamus is also scanty. However, the available information on toxicology of Croton dichogamus suggests it is safe. The current review supports in part, the ethnomedicinal use of the medicinal plant. However, in-depth studies aimed at efficacy and safety evaluation, in addition to identification of compounds responsible for the reported activities is required. This information will support steps towards discovery of novel ligands with activity against illnesses reported above.