Ethnomedicinal uses, biological activities, phytochemistry and conservation of African ginger (Siphonochilus aethiopicus): A commercially important and endangered medicinal plant.

ETHNOPHARMACOLOGICAL RELEVANCE: In sub-Saharan Africa, African ginger (Siphonochilus aethiopicus) is used for treating common illnesses including colds, coughs, inflammation and related symptoms. The available literature survey on this plant provided scarce anecdotal information, particularly in western and eastern Africa, with a few reports on its bioactivity. In addition, the indigenous knowledge and conservation strategies of this economically important and critically endangered species are currently fragmented. AIM OF THE REVIEW: This review entails a critical appraisal of existing literature on the ethnomedicinal uses, biological activities, phytochemicals, research opportunities and prospects for the sustainable use of S. aethiopicus. MATERIALS AND METHODS: This review was conducted using a comprehensive literature search on the ethnomedicinal uses, biological activities and phytochemistry of S. aethiopicus throughout its distributional range. The conservation status and associated bio-economy potential of African ginger were also assessed. We searched different online databases (e.g. Google Scholar, ScienceDirect, PubMed and Scopus) for peer-reviewed journals, conference outputs, international, regional and national organizational reports, published books and theses. RESULTS: We established that S. aethiopicus is used to treat a wide variety of ailments such as respiratory problems (including cough, influenza), pain, inflammation and malaria. Extracts of African ginger are used as an ingredient in some commercialised products for nutraceutical, cosmeceutical and pharmaceutical purposes. The rhizome extract demonstrated anti-asthmatic, anti-inflammatory, and antiplasmodial activities, which led to the development of a patented novel extract for treating asthma and allergies. Phytochemical analysis of leaf, root and rhizome extracts of African ginger revealed the presence of flavonoids, phenolic acids, volatile and essential oils as the major constituents. These phytochemicals are known to possess bioactivities such as antimicrobial and anti-inflammatory activities. Particularly, the bioactive compounds, siphonochilone and eucalyptol, found in the roots and rhizomes have demonstrated potential to be used in remedies for treating asthma and allergic reactions. Furthermore, extracts of S. aethiopicus contained natural anti-inflammatory mediators with potential to combat and manage chronic inflammation. This plant is classified on the Red List of South African Plants as a critically endangered plant. Its high risk of extinction due to its unsustainable harvesting and exploitation necessitates its rapid propagation and cultivation to meet its increasing demand. CONCLUSIONS: The review highlights the therapeutic potential of S. aethiopicus and rational prioritization of this plant species with the potential for isolating new bioactive compounds. In the light of the use of this plant extract in traditional medicine and many commercial products, there is a heightened need to explore the mechanism(s) of action of the identified extracts and bioactive compounds in order to fully understand their pharmacokinetics and probably elucidate the pathways of their activities.

Grewia mollis Leaf Extracts and Fractions Demonstrated Good Inhibitory Activity on Pro-Inflammatory Enzymes and with Lower Cytotoxicity in vitro.

INTRODUCTION: Plant extracts are used to treat illnesses, promote health, and maintain general well-being in traditional medicine. Grewia mollis Juss (Malvaceae) is one of the medicinal herbs that is used traditionally to treat chronic diseases and related pain because currently used anti-inflammatory drugs may cause severe side effects, and naturally occurring compounds with reduced cytotoxicity could be explored for therapeutic goals. MATERIALS AND METHODS: Dried leaf of G. mollis was extracted with aqueous and organic solvents and partitioned based on polarity using solvent-solvent methods. The extracts were tested in anti-inflammatory assays against cyclooxygenases and lipoxygenase, and the safety profile was determined in a cell-based in-vitro assay. RESULTS: The n-hexane fraction of G. mollis leaf extracts had significant activity against both COX-1 (IC50 =0.97±1.9 µg/mL) and COX-2 (IC50 =1.13±0.2 µg/mL) better than the indomethacin positive control (IC50 =1.3±0.6 and 1.52±0.2 µg/mL), respectively (p≤ 0.05). Also, all the extracts and fractions of G. mollis tested inhibited the activity of 15-LOX (IC50 =12.48±2.9 to 29.43±9.9 µg/mL) better than the quercetin reference control (IC50 =61.82±5.5 µg/mL), with the butanol fraction demonstrating the best anti-15 LOX action (IC50 =12.48±2.9 µg/mL). Furthermore, all the extracts and fractions of G. mollis had relatively lower cytotoxicity on vero monkey kidney cells (LD50 =30.56-479±0.07 µg/mL) compared to the doxorubicin positive control (LD50 =2.59 µg/mL), but the selectivity index (SI=1.04-1.89) determination suggested that some of the extracts may contain toxic constituents. CONCLUSION: Organic extracts of the leaves of Grewia mollis contained bioactive molecules with potent action on COX-2 and 15-LOX. Targeted high-resolution high-performance liquid chromatographic (HPLC) methods have streamlined and enhanced bioactive compound isolation and purification process. This allows for the separation of undesirable compounds that could cause metabolic cytotoxicity in the plant extract mixtures. The method could be used to develop an alternative therapeutic strategy to manage pain associated with chronic inflammation where the use of NSAID is problematic.

Isolation of flavonoids from Musa acuminata Colla (Simili radjah, ABB) and the in vitro inhibitory effects of its leaf and fruit fractions on free radicals, acetylcholinesterase, 15-lipoxygenase, and carbohydrate hydrolyzing enzymes.

Musa species are used traditionally for the management of many diseases. The study evaluated and compared anticholinesterase, anti-inflammatory, antioxidant, and antidiabetic activities of Musa acuminata (Simili radjah, ABB) fruits and leaves fractions and characterized the bioactive compounds using HPTLC-HRMS and NMR. Leaf fractions gave the higher biological activities than the fruit. Ethyl acetate fraction of the leaf had the highest total phenolic content (911.9 ± 1.7 mg GAE/g) and highest 2,2-diphenyl-1-picrylhydrazyl (DPPH· ) scavenging activity (IC50, 9.0 ± 0.4 µg/ml). It also gave the most effective inhibition of acetylcholinesterase (IC50, 404.4 ± 8.0 µg/ml) and α-glucosidase (IC50, 4.9 ± 1.6 µg/ml), but a moderate α-amylase inhibition (IC50, 444.3 ± 4.0 µg/ml). The anti-inflammatory activity of n-butanol (IC50, 34.1 ± 2.6 µg/ml) and ethyl acetate fractions (IC50 , 43.1 ± 11.3 µg/ml) of the leaf were higher than the positive control, quercetin (IC50 , 54.8 ± 17.1 µg/ml). Kaempferol-3-O-rutinoside and quercetin-3-O-rutinoside (rutin) were identified as the bioactive compounds with antioxidant and antidiabetic activities from the ethyl acetate fraction of M. acuminata leaf. PRACTICAL APPLICATIONS: All parts of Musa acuminata are known to be useful ethnomedicinally even as food. The leaves are mostly used to serve food and used for wrapping purposes. However, this study concluded that M. acuminata leaf is rich in bioactive flavonoids such as kaempferol-3-O-rutinoside and rutin, with relatively high antioxidative, antidiabetic, and anti-inflammatory activities. Therefore, aside the fact that the leaves can serve as potential drug leads for pharmaceutical industries, it can also be embraced in the food sector to produce supplements and/or nutraceuticals in the management of Alzheimer's, diabetes and other inflammatory diseases.

Investigation of the Mechanism of Anti-Inflammatory Action and Cytotoxicity of a Semipurified Fraction and Isolated Compounds From the Leaf of Peltophorum africanum (Fabaceae).

Peltophorum africanum extracts have been shown to possess many important medicinal benefits, including anti-inflammatory and antiviral activities. However, the mechanism of action is poorly understood. The mechanism of anti-inflammatory action was determined by measuring the synthesis of cytokines in lipopolysaccharide (LPS) stimulated RAW 264.7 macrophage cells in vitro. Compound 1 (CP1), compound 2 (CP2), and fraction F3.3.0 (F3.3.0) significantly reduced the synthesis of interleukin 1ß (IL-1ß) from RAW 264.7 cells (1.18, 1.32, and 0.92 ng/mL), respectively. Similarly, CP1, CP2, and F3.3.0 inhibited the production of IL-2 and tumor necrosis factor-α (TNF-α) by RAW 264.7 cells (0.41, 0.60, 0.74 and 0.11, 0.27, 0.24 ng/mL, respectively. In addition, CP1 and CP2 had lower cytotoxicity toward RAW 264.7 cells, with CP2 indicating the lowest cytotoxicity (LD50 = 207.88 µg/mL). The mechanism of action was found to be via the inhibition of pro-inflammation cytokines (IL-1 ß and TNF-α). This observation may support the use of P africanum to treat pain-related conditions.

The anti-inflammatory and antioxidant activity of 25 plant species used traditionally to treat pain in southern African.

BACKGROUND: Inflammation is a common risk factor in the pathogenesis of conditions such as infections, arthritis, type 2 diabetes mellitus, obesity and cancer. An ethnobotanical survey of medicinal plants used traditionally to treat inflammation and related disorders such as pain, arthritis and stomach aches in southern Africa led to the selection of 25 plant species used in this study. METHODS: The antioxidant activities of acetone extracts were determined by measuring the free radical scavenging activity and ferric reducing ability, respectively. The anti-inflammatory activities of the extracts were determined by measuring the inhibitory effect of the extracts on the activities of the pro-inflammatory enzyme, lipoxygenase and inducible nitric oxide synthase. RESULTS: Extracts of Peltophorum africanum had good antioxidant activity with IC50 values of 4.67 ± 0.31 µg/mL and 7.71 ± 0.36 µg/mL compared to that of the positive control ascorbic acid (2.92 ± 0.14 µg/mL and 13.57 ± 0.44 µg/mL), using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) methods, respectively. The metabolism of linoleic acid to leukotriene derivatives by 15-lipoxygenase (15-LOX) was also inhibited by the crude acetone extracts of Peltophorum africanum (IC50 = 12.42 µg/mL), Zanthoxylum capense (IC50 = 14.92 µg/mL) compared to the positive control quercetin (IC50 = 8.75 µg/mL). There was a poor correlation between the flavonoid content and 15-LOX inhibition by the extracts (R(2) = 0.05), indicating that flavonoids are not involved in LOX inhibition. Extracts of Clausena anisata, at a concentration of 6.25 µg/mL inhibited nitric oxide production by RAW 264.7 macrophage cell lines in vitro by 96 %. The extracts of Zanthoxylum capense were the least cytotoxic (IC50 > 1000 µg/mL) when the extract toxicity was determined against Vero (African green Monkey) kidney cell lines. CONCLUSION: Some plant species used traditionally to treat pain have reasonable anti-inflammatory activity and flavonoids are probably not involved in this process.