METHODS: A crude methanol extract of the aerial parts of Isodon rugosus (Ir.Cr.) was used for both in vitro and in vivo experiments. The plant extract was tested on isolated rabbit jejunum preparations for possible presence of spasmolytic activity. Moreover, isolated rabbit tracheal and aorta preparations were used to ascertain the relaxant effects of the extract. Acetylcholinesterase and butyrylcholinesterase inhibitory activities of Ir.Cr were also determined as well as its antioxidant activity. The in vivo antiemetic activity of the extract was evaluated by using the chick emesis model, while the analgesic and antipyretic activities were conducted on albino mice.
RESULTS: The application of the crude extract of I. rugosus to isolated rabbit jejunum preparations exhibited relaxant effect (0.01-0.3 mg/ml). The Ir.Cr also relaxed K+(80 m M)-induced spastic contractions in isolated rabbit jejunum preparations and shifted the Ca+2 concentration response curves towards right (0.01-0.3 mg/ml). Similarly, the extract, when applied to the isolated rabbit tracheal preparations relaxed the carbachol (1 μM)--as well as K+ (80 mM)-induced contractions in a concentration range of 0.01-1.0 mg/ml. Moreover, it also relaxed (0.01-3.0 mg/ml) the phenylephrine (1 μM)- and K+ (80 mM)-induced contractions in isolated rabbit aorta preparations. The Ir.Cr (80 mg/kg) demonstrated antipyretic activity on pyrogen-induced pyrexia in rabbits as compared to aspirin as standard drug. The Ir.Cr also exhibited anti-oxidant as well as inhibitory effect on acetyl- and butyryl-cholinesterase and lipoxygenase (0.5 mg/ml).
CONCLUSIONS: The observed relaxant effect on isolated rabbit jejunum, trachea and aorta preparations caused by Ir.Cr is possibly to be mediated through Ca+2 channel blockade and therefore may provided scientific basis to validate the folkloric uses of the plant in the management of gastrointestinal, respiratory and cardiovascular ailments. The observed antioxidant activity as well as the lipoxygenase inhibitory activity may validate its traditional use in pain and inflammations.
AIM OF THE REVIEW: Rather than a comprehensive coverage of the literature, this article aims to identify discrepancies between findings in animal and human studies, and to highlight some of the problems in developing plant extract-based medicines that lower blood glucose in patients with diabetes, as well as to suggest potential ways forward.
METHODS: In addition to searching the 2018 PubMed literature using the terms 'extract AND blood glucose, a search of the whole literature was conducted using the terms 'plant extracts' AND 'blood glucose' AND 'diabetes' AND 'double blind' with 'clinical trials' as a filter. A third search using PubMed and Medline was undertaken for systematic reviews and meta-analyses investigating the effects of plant extracts on blood glucose/glycosylated haemoglobin in patients with relevant metabolic pathologies.
FINDINGS: Despite numerous animal studies demonstrating the effects of plant extracts on blood glucose, few randomised, double-blind, placebo-controlled trials have been conducted to confirm efficacy in treating humans with diabetes; there have been only a small number of systematic reviews with meta-analyses of clinical studies. Qualitative and quantitative discrepancies between animal and human clinical studies in some cases were marked; the factors contributing to this included variations in the products among different studies, the doses used, differences between animal models and the human disease, and the impact of concomitant therapy in patients, as well as differences in the duration of treatment, and the fact that treatment in animals may begin before or very soon after the induction of diabetes.
CONCLUSION: The potential afforded by natural products has not yet been realised in the context of treating diabetes mellitus. A systematic, coordinated, international effort is required to achieve the goal of providing anti-diabetic treatments derived from medicinal plants.
AIM OF THE STUDY: Our study focuses on previously unreported anti-depressant activity of E. variegata bark ethanolic extract (EBE) and determination of its mechanism of action possibly through regulation of monoamine oxidase activity in mouse brain homogenates.
MATERIALS AND METHODS: EBE was characterized using standard protocols for phytochemical analysis, followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis. Anti-depressant activity of EBE (50, 100, 200 and 500 mg/kg) was evaluated in Swiss white albino mice using acute and chronic forced swim test (FST) models. Furthermore, the potential use of the extract as an adjunct to selective serotonin reuptake inhibitor (SSRI), escitalopram, was evaluated using the chronic unpredictable mild stress test model wherein inhibitory effects on monoamine oxidase (MAO) A and B were assessed by spectrophotometric-chemical analysis in mouse whole brain homogenates.
RESULTS: The extract showed significant reduction in immobility time periods in both acute (200 mg/kg) and chronic (100, 200 and 500 mg/kg) FST models. When used as an adjunct with escitalopram (15 mg/kg), the extract (100, 200 and 500 mg/kg) showed significantly greater inhibition of MAO-A and B activities when compared to escitalopram alone (30 mg/kg). Phytochemical analysis of EBE revealed presence of sugars, steroids, glycosides, alkaloids and tannins. LC-MS and GC-MS analysis identified components such as 2-amino-3-methyl-1-butanol, phenylethylamine, eriodictyol, daidzein and pomiferin, N-ethyl arachidonoyl amine, inosine diphosphate, trimipramine, granisetron, 3,4-dihydroxymandelic acid, ethyl ester, tri-TMS and dodecane, previously reported for their anti-depressant activity.
CONCLUSIONS: The study thus demonstrated potential for use of the E. variegata bark ethanolic extract as an adjunct to currently available SSRI treatment. The study also identified components present in E. variegata bark ethanolic extract that may be responsible for its anti-depressant activity. Furthermore, the study thus confirms the traditional use of E. variegata barks in improving CNS function through its anti-depressant like activity.
AIM OF THE STUDY: In this context, supported with previous preliminary data of its antiplasmodial activity, this study was undertaken to determine the in vitro antiplasmodial and cytotoxicity activities of G. lanceolatus crude extracts and its major compounds.
MATERIALS AND METHODS: The in vitro antiplasmodial activity was determined by parasite lactate dehydrogenase (pLDH) assay on chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. The cytotoxicity activity was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on hepatocellular carcinoma (HepG2) and normal liver (WRL-68) cell lines.
RESULTS: The root methanol extract possessed potent antiplasmodial activity against both P. falciparum 3D7 and K1 strains (IC50 = 2.7 μg/ml, SI = 140; IC50 = 1.7 μg/ml, SI = 236). Apart from the DCM extract of stem bark and root that were found to be inactive (IC50 > 50 μg/ml) against 3D7 strain, all other tested crude extracts exhibited promising (5< IC50 30 µg/ml, CC50 > 10 µM, respectively), except for the hexane and DCM extracts of root, which exerted mild cytotoxicity on HepG2 cell line (IC50
MATERIALS AND METHODS: Literature abstracts and full text articles from journals, books, reports and electronic searches (Google Scholar, Elsevier, PubMed, Read Cube, Scopus, Springer, and Web of Science), as well as from other relevant websites, are surveyed, analysed and included in this review.
RESULTS: A literature survey of agarwood plant materials showed that they contain sesquiterpenes, 2(-2-phenylethyl)-4H-chromen-4-one derivatives, genkwanins, mangiferins, iriflophenones, cucurbitacins, terpenoids and phenolic acids. The crude extracts and some of the isolated compounds exhibit anti-allergic, anti-inflammatory, anti-diabetic, anti-cancer, anti-oxidant, anti-ischemic, anti-microbial, hepatoprotective, laxative, and mosquitocidal properties and effects on the central nervous system. Agarwood plant materials are considered to be safe based on the doses tested. However, the toxicity and safety of the materials, including the smoke from agarwood incense burning, should be further investigated. Future research should be directed towards the bio-guided isolation of bioactive compounds with proper chemical characterisation and investigations of the underlying mechanisms towards drug discovery.
CONCLUSIONS: The traditional medicinal use of agarwood plant materials has provided clues to their pharmacological properties. Indeed, agarwood contains a plethora of bioactive compounds that now elegantly support their use in traditional medicine. As wild agarwood trees are critically endangered and vulnerable, sustainable agricultural and forestry practices are necessary for the further development and utilization of agarwood as a source of health beneficial compounds.
AIM OF THE REVIEW: The present review aims to compile an up-to-date review of the progress made in the continuous pharmacological and phytochemistry investigation of K. africana and the corresponding commercial and pharmaceutical application of these findings with the ultimate objective of providing a guide for future research on this plant.
METHOD: The scholarly information needed for this paper were predominantly sourced from the electronic search engines such as Google, Google scholar; publishing sites such as Elsevier, scienceDirect, BMC, PubMed; other scientific database sites for chemicals such as ChemSpider, PubChem, and also from online books.
RESULTS: Pharmacological investigations conducted confirm the anti-inflammatory, analgesic, antioxidant and anticancer activity of the extract of different parts of the plant. Bioactive constituents are found to be present in all parts of the plant. So far, approximately 150 compounds have been characterized from different part of the plant. Iridoids, naphthoquinones, flavonoids, terpenes and phenylethanoglycosides are the major class of compounds isolated. Novel compounds with potent antioxidant, antimicrobial and anticancer effect such as verbascoside, verminoside and pinnatal among others, have been identified. Commercial trade of K. africana has boosted in the las few decades. Its effect in the maintenance of skin has been recognized resulting in a handful of skin formulations in the market.
CONCLUSIONS: The pharmaceutical potentials of K. africana has been recognized and have witness a surge in research interest. However, till date, many of its traditional medicinal uses has not been investigated scientifically. Further probing of the existential researches on its pharmacological activity is recommended with the end-goal of unravelling the pharmacodynamics, pharmacokinetics, clinical relevance and possible toxicity and side effects of both the extract and the active ingredients isolated.