Unusual metabolites from some Tanzanian indigenous plant species

Nkunya, Mayunga H.H.

doi:10.1351/pac200577111943

Cited by 31 publications

(21 citation statements)

References 42 publications

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“…45,[107][108][109][110] Their main scaffolds occur as multicyclic structures, e.g. hemi-terpenoids (5 carbon atoms), monoterpenoids (10 carbon atoms), sesquiterpenoids (15 carbon atoms), diterpenoids (20 carbon atoms), sesterterpenoids (25 carbon atoms), triterpenoids (30 carbon atoms), tetraterpenoids (40 carbon atoms), and polyterpenoids (more than 40 carbon atoms), which are all primarily derived from the fivecarbon isoprene units.…”

Section: Terpenoidsmentioning

confidence: 99%

Compounds from African Medicinal Plants with Activities against Protozoal Diseases: Schistosomiasis, Trypanosomiasis and Leishmaniasis

Cv¹,

Ntie‐Kang²,

Sh.³

et al. 2018

Preprint

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An absolute configuration of 5R seems to decrease activity of the compound IntroductionProtozoa may be considered as microscopic, essentially single-celled, eukaryotic organisms that are free-living or parasitic (obtaining their food by eating other organisms or their products) in nature. Parasitic protozoal diseases continue to be a cause of considerable morbidity and mortality globally. 1,2Parasitic protozoal diseases include malaria, 3,4 trypanosomiasis (African sleeping sickness and Chagas disease), 5-7 leishmaniasis 8 and schistosomiasis. 9,10 They threaten almost one-third of the world's population, the most numerous incidents being recorded in over 100 Tropical and developing countries and territories, Figure 1. 11,12 Malaria, for example, was reported by the WHO, to be responsible for approximately 214 million sickness cases and 438,000 deaths globally in 2017. 13 The African region recorded the most death-related cases, especially amongst infants below the age of 5 and pregnant women. Schistosomiasis, caused by parasites of the Schistosoma genus are responsible for about 200 million sickness cases and about 280,000 death-related incidents annually worldwide.9,10,14 Only one drug (praziquantel) has been proven to be effective in the treatment of human schistosomiasis, with no vaccine available or in development so far.15-21 Serious concerns about drug selectivity and resistance were raised in 2013 when over 30 million people were treated in Sub-Saharan Africa. 20 Moreover, observed resistance and reduced efficiency of praziquantel in laboratory strains have prompted the search for alternative therapeutic strategies. Trypanosomiasis, which represents several diseases caused by parasites of the genus Trypanosoma, is also of interest. 5,27,29 This disease, which is much arguably the most important disease of man and domesticated animals, accounts for over 8 million reported annual cases globally, especially in the tropical regions of Latin America and Africa. 30,31 Although the present number of cases seems negligible on a worldwide scale, great socioeconomic effects on the endemic areas by this disease are forecast if inadequate attention (both at the communal, national, and international levels) is not given. 7,29,[32][33][34] Leishmaniasis is caused by parasites of the Leishmania type, which is also transmitted by certain types of sandflies. 35,36 The diseases are reported by the WHO to be responsible for about 1 million new cases leading to approximately 30,000 deaths annually on a global scale. The major cause is linked to environmental changes A R T I C L E I N F O A B S T R A C TArticle history:English abstract: Parasitic diseases continue represent a threat on a global scale, particularly among the poorest countries in the world. This is particularly because of the absence of vaccines, and in some cases, resistance against available drugs, currently being used for their treatment. In this review emphasis is laid on natural products and scaffolds from African medicinal plants (AMPs) for lead drug di...

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Section: Terpenoidsmentioning

confidence: 99%

Compounds from African Medicinal Plants with Activities against Protozoal Diseases: Schistosomiasis, Trypanosomiasis and Leishmaniasis

Cv¹,

Ntie‐Kang²,

Sh.³

et al. 2018

Preprint

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show abstract

“…185 Extracts of this plant are employed in traditional medicine for treatment of wound infections, rheumatism, and tuberculosis. 186 Cleistenolide displays in vitro antibacterial activity against Staphylococcus aureus and Bacillus anthracis , and antifungal activity against Candida albicans. 185 In several earlier synthetic approaches to phomopsolides, Achmatowicz products were converted in γ-hydroxy-δ-lactones, 187-189 Mhaske and collaborators recently reported a protecting-group-free total synthesis of (±)-6- epi -cleistenolide and (–)-6- epi -cleistenolide employing an Achmatowicz reaction as the key step.…”

Section: Introductionmentioning

confidence: 99%

Achmatowicz reaction and its application in the syntheses of bioactive molecules

Ghosh

Brindisi

2016

RSC Adv.

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Substituted pyranones and tetrahydropyrans are structural subunits of many bioactive natural products. Considerable efforts are devoted toward the chemical synthesis of these natural products due to their therapeutic potential as well as low natural abundance. These embedded pyranones and tetrahydropyran structural motifs have been the subject of synthetic interest over the years. While there are methods available for the syntheses of these subunits, there are issues related to regio and stereochemical outcomes, as well as versatility and compatibility of reaction conditions and functional group tolerance. The Achmatowicz reaction, an oxidative ring enlargement of furyl alcohol, was developed in the 1970s. The reaction provides a unique entry to a variety of pyranone derivatives from functionalized furanyl alcohols. These pyranones provide convenient access to substituted tetrahydropyran derivatives. This review outlines general approaches to the synthesis of tetrahydropyrans, covering general mechanistic aspects of the Achmatowicz reaction or rearrangement with an overview of the reagents utilized for the Achmatowicz reaction. The review then focuses on the synthesis of functionalized tetrahydropyrans and pyranones and their applications in the synthesis of natural products and medicinal agents.

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“…Nkunya et al reported3 the isolation of the natural product (–)‐cleistenolide ( 1 ) (Figure 1), which includes this structural motif from Cleistochlamys kirkii Oliver, a plant species ( Annonaceae ) found in Tanzania and Mozambique. Extracts of this plant are used in traditional medicine for the treatment of wound infections, rheumatism, and tuberculosis 4. This traditional knowledge was authenticated by the observation3 that the natural product (–)‐cleistenolide ( 1 ) isolated from this plant has in vitro antibacterial activity against Staphylococcus aureus and Bacillus anthracis , as well as antifungal activity against Candida albicans .…”

Section: Introductionmentioning

confidence: 99%

Protecting‐Group‐Free Diastereoselective Total Synthesis of (±)‐6‐epi‐Cleistenolide and Chemoenzymatic Synthesis of (–)‐6‐epi‐Cleistenolide

2014

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A short, efficient, practical, and protecting‐group‐free diastereoselective total synthesis of (±)‐6‐epi‐cleistenolide (1) has been achieved in five steps in 60 % overall yield. The use of a chemoenzymatic approach also gave (–)‐6‐epi‐cleistenolide (1) (>99.9 % ee). The Achmatowicz reaction, chemoselective oxidation of a hemiacetal, diastereoselective 1,3‐anti reduction of a β‐hydroxy ketone, and enzymatic resolution of a 1,3‐diol are the key features of this linear total synthesis. The synthetic strategy demonstrated in this paper could be extended for an asymmetric total synthesis of (–)‐cleistenolide (1) and related biologically active natural products.

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Unusual metabolites from some Tanzanian indigenous plant species

Cited by 31 publications

References 42 publications

Compounds from African Medicinal Plants with Activities against Protozoal Diseases: Schistosomiasis, Trypanosomiasis and Leishmaniasis

Compounds from African Medicinal Plants with Activities against Protozoal Diseases: Schistosomiasis, Trypanosomiasis and Leishmaniasis

Achmatowicz reaction and its application in the syntheses of bioactive molecules

Protecting‐Group‐Free Diastereoselective Total Synthesis of (±)‐6‐epi‐Cleistenolide and Chemoenzymatic Synthesis of (–)‐6‐epi‐Cleistenolide

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