M.H.H. Nkunya’s research while affiliated with University of Dar es Salaam and other places
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(-)-5-Acetoxy-6-(1-benzoyloxy-2-acetoxyethyl)-pyr-3-en-2-one (cleistenolide) and (-)-2, 6-diacetoxy-5-hydroxy-cyclohex-3-enylidenemethyl benzoate (cleistodienol) were isolated as novel antimicrobial and cytotoxic constituents of Cleistochlamys kirkii (Annonaceae), together with (Z)-(+)-5-(2, 3-dihydroxy-propylidene)-5H-furan-2-one and its acetyl and benzoyl derivatives, (-)-1, 6-desoxy-β-senepoxide, pinocembrin and polycarpol. Structural determination was achieved based on spectroscopic and other physical data. The structure of cleistenolide was confirmed by single crystal X-ray crystallographic analysis.
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The nor-halimane diterpenoid tessmannic acid and its methyl, 2-methylisopropyl and 1-methylbutyl
esters, the unusual isocoumarins 8-hydroxy-6-methoxy-3-pentylisocoumarin and 7-chloro-8-hydroxy-
6-methoxy-3-pentylisocoumarin, and 5-pentyl-3-methoxy-N-butylaniline were isolated from the stem
and root bark extracts of Tessmannia densiflora Harms (Caesalpiniaceae) that showed mosquito larvicidal
activity. The structures were determined on interpretation of spectroscopic data. Tessmannic acid and its
methyl ester exhibited antibacterial and antifungal activity. The compounds also caused high larvae and
adult Anopheles gambiae mosquitoe mortality effects, and stronger mosquito repellency than that shown
by the standard repellent DEET, hence indicating Tessmannia species to be potential sources of bioactive
natural products.
Keywords: Tessmannia densiflora; Caesalpiniaceae; Nor-halimanoids; Isocoumarins anti-mosquitoes; Antimicrobials
Background & objectives: This paper reports the larvicidal activity of seventeen Tanzanian plant
species against the malaria vector, Anopheles gambiae s.s. Giles larvae. Some of the plants are used
traditionally as sources of insecticidal materials.
Methods: The crude extracts from the leaves, stem and root barks of the investigated plants were
obtained by solvent extraction and then bio-assayed following WHO protocols showed LC50 values
10 to 400 ppm after 24 h exposure. The structures were determined on interpretation of spectroscopic
data.
Results: The most active extracts were those from the stem and root barks of Annona squamosa,
Uvaria faulknerae, U. kirkii and Uvariodendron pycnophyllum, all of which had LC50 values between
10 and 100 ppm. Long-term exposure beyond 24 h also showed more susceptibility of the larvae to
the extracts. Larvae deformities by forming tail-like structures were observed for the methanol
extracts of Tessmannia martiniana var pauloi.
Interpretation & conclusion: The results suggest that the investigated plant extracts are promising
as larvicides against An. gambiae s.s. Giles mosquitoes and could be useful leads in the search for
new and biodegradable plant derived larvicide products.
Keywords Anopheles gambiae s.s. – botanical mosquitocides – IGR activity
Petroleum ether, dichloromethane, and ethanolic extracts of the stem bark and leaves of Uvaria scheffleri Diels (Annonaceae) exhibited antifungal activity against Aspergillus niger (wild strain), Aspergillus fumigatus (wild strain), and a Penicillium species (wild strain). The ethanol extract of the stem bark was also active against Candida albicans (Strain H6392). The dichloromethane extract of the leaves showed the highest antifungal activity and in addition it showed antibacterial activity against Staphylococcus aureus (NCTC 6571). Fractionation of the dichloromethane extract of the leaves yielded nine known compounds. They included a 1 : 1 mixture of stigmasterol (1) and β-sitosterol (2), which showed antifungal activity against Candida albicans. Others were 3-farnesylindole (3), 2′,6′-dihydroxy-3′,4′-dimethoxy-chalcone (4), 2′-hydroxy-3′,4′,6′-trimethoxychalcone (5), 5-hydroxy-7,8-dimethoxyflavanone (6), 5,7,8-trimethoxyflavanone (7), and a 3 : 2 mixture of 2′,6′-dihydroxy-4′-methoxychalcone (8) and 5,7-dihydroxyflavone (9). Compound 7 and the mixture of compounds 8 and 9 showed antibacterial activity against Escherichia coli (NCTC 10418, MIC 125 µg/ml) and Staphylococcus aureus (MIC 125 µg/ml), respectively. The mixture of compounds 8 and 9 was also active against Candida albicans (MIC 31.25 µg/ml), Aspergillus niger, Aspergillus fumigatus, and the Penicillium species (MIC 1000 µg/ml). We conclude that Uvaria scheffleri extracts contain compounds with antifungal and antibacterial activity. The activities observed in this study are weak. Based on previous studies, it is being speculated that, possibly, the most active compounds were lost during fractionation. Further work to isolate more antifungal and antibacterial compounds is suggested.
Long chain aliphatic methyl ketone series of C7-C15 were tested for repellency activity against the malaria transmitting mosquito Anopheles gambiae s.s. All methyl ketones produced a dose dependent (P < 0.001) repellency response with 2-tridecanone giving comparable protection efficacy to DEET at 10% and 1% concentrations. Aliphatic methyl ketones of C7-C10 had lower activity than those of C11-C15. However, within this range compounds with odd carbon atoms (2-undecanone, 2-tridecanone and 2-pentadecanone) were more effective than compounds with even carbon atoms (2-decanone and 2- dodecanone). Comparable repellency activity of 2-tridecanone to DEET show that, it may save as Anopheles gambiae s.s. mosquito repellent.
The ethanol extract of the root bark of Terminalia sericea yielded an unreported stilbene glycoside, 3'5'-dihydroxy-4-(2-hydroxy-ethoxy) resveratrol-3-O-beta-rutinoside (1) together with known compounds resveratrol-3-beta-rutinoside glycoside (2), 3',4,5'-Trihydroxystilbene (resveratrol) (3), triterpenoic acid arjungenin and a mixture of beta-sitosterol and stigmasterol. Structure determination of the isolated compounds was achieved on the basis of spectroscopic measurements.
The trimeric monoterpene and mildly mosquito larvicidal agent, (�)-schefflone, that is an apparent derivative of the antiparasitic
aromatic monoterpene espintanol, was isolated from the antimalarial extracts of the root bark of Uvaria scheffleri, together with
espintanol. Structural determination of (�)-schefflone was achieved from spectroscopic data and confirmed by single-crystal X-ray
diffraction analysis. (�)-Schefflone can be considered a product of a non-enzymatic Diels–Alder-type cycloaddition reaction of the
quinonemethide derivative of espintanol as the diene and dienophile.
Keywords: Uvaria scheffleri; Annonaceae; Trimeric monoterpene; (�)-Schefflone; Espintanol; Mosquitocides
The present study aimed to evaluate extracts and compounds from tubers of Neorautanenia mitis against the malaria- and filariasis-transmitting mosquitoes, Anopheles gambiae and Culex quinquefaciatus, respectively. The extracts exhibited activity against larvae of A. gambiae and C. quinquefaciatus mosquitoes, and were also active against adult A. gambiae mosquitoes. The active extracts yielded the coumarin derivative pachyrrhizine, the isoflavonoids neotenone and neorautanone,
and the pterocarpans neoduline, nepseudin and 4-methoxyneoduline as the active constituents. The activity of the crude extracts
was at about the same magnitude as that of the constituent natural products, the latter's efficacy being almost at the same
level for all the isolated compounds. The mosquitocidal activities of the pure compounds were comparable to those of the standard
mosquitocides deltamethrin and alphacypermethrin. These findings corroborate traditional insecticidal application of N. mitis and the results can be extended for the control of mosquitoes especially at breeding sites.
Citations (21)
... The whole extract of M. senegalensis has been scientifically investigated for potential biological activities both in vitro [15][16][17] and in vivo [18][19][20], demonstrating strong anti-malarial activity. ...
... Thus, it was tentatively identified as Apigenin 7,4 -dimethyl ether (5-Hydroxy-4 ,7-dimethoxyflavone). This compound was previously identified in A. afra (Nkunya et al., 1992) and A. diffusa (Valant-Vetschera and Wollenweber, 1995) and was identified in the first time in A. campestris. ...
... (−)-Cleistenolide (1, Fig. 1) is a naturally occurring α,β-unsaturated δ-lactone isolated from Cleistochlamis kirkii Oliver, a plant species that grows in southeast Africa. 1 The extract of this plant has been used in Tanzania and Mozambique in traditional medicine for the treatment of infected wounds, rheumatism and tuberculosis. 2 Recently, Pereira et al. 3 isolated from the ethanolic extract of C. kirkii a new natural product (−)-cleistenolide, and eight other compounds of different structures: chamanetin, isochamanetin, dichamanetin, echunuline, cissolamine, acetylmelodorinol, polycarpol and benzophenone. ...
... The molting of midgut cells has been disrupted by bioactive components generated from natural resources (Kihampa et al. 2009;da Silva et al. 2013). The cuticle layer, fat body, brush boundary, and nuclei in the midgut and hindgut regions of treated 4 th instar larvae were damaged, according to the histological profile of larvae treated with compound/ fraction. ...
... This is because larval habitat treatment is more localized in time and space resulting in effective control. In tropical countries , plants are known to possess larvicidal, ovicidal and adulticidal activities [34,36373869]. The results of our present study in ovicidal, larvicidal and adulticidal properties of the essential oil of fruits and seeds of S. terebinthifolia have created the necessity of investigating in detail the ovicidal, larvicidal and adulticidal activities of each chemical compound in this plant extract. ...
... This result implies that the plant contains essential component such as crude fiber (51.81 %), total fat (26.19 %) and ash (10.19 % ash), and can be utilized as food and in treating several ailments. This result may also be attributed to genetic composition of the plant The Uvaria chamea(Annonaceae)which has been reported to have potent activity against lymphocytic leukemia in mice [38], anti-malarial activity [39], it also has the anticarcinogenic [40]; [41], exhibited significant in vitro cytotoxicity against the KB cancer cell line [42], has antidiabetic activity [43][44][45][46][47][48][49][50] has antihemolytic properties [50][51][52][53][54][55][56][57], has antimicrobial activity [58][59][60][61][62][63][64][65] has high content of phenolic compounds and high antioxidant activity [46]. The proximate content of the plant with their varying concentration such as that of carbohydrate (6.52 %) and crude fiber (51.81 %) indicates that the plant can be a good source of energy and fiber for animals. ...
... In this report, the biological activity-guided isolation and structural elucidation of six new naturally occurring polyoxygenated cyclohexene derivatives (4 and 6-10) along with eight related known derivatives (1-3, 5 and 11-14) (Fig. 1), two known alkaloids (15)(16), and two known flavonoid derivatives (17)(18) from the ethyl acetate extract of the leaves and twigs of D. sootepense and the biological activities are described. The known compounds were identified as (+)-crotepoxide (1), [9,10] (+)-β-senepoxide (2), [11][12][13][14] ellipeiopsol A (3), [15] (−)zeylenol (11), [16] ellipeiopsol C (12), [15,17] ferrudiol (13), [15,[18][19][20] (−)-zeylenone (14), [21][22][23] asperphenamate (15), [24][25][26] (−)-sinactine (16), [27] epicatechin (17), [28] and flavonol diglycoside 18, [5] on the basis of comparison of their physical and spectroscopic data with those previously reported in the literature. Described herein, is also the first report on the anti-HIV-1 activity of D. sootepense as well as that of naturally occurring polyoxygenated cyclohexene derivatives. ...
... The prenylated indole alkaloids are generally referred to as 'hexalobines' due to their marked presence in the genus Hexalobus Malebo et al., 2014), making them useful as chemotaxonomic markers for this genus. Moreover, this class of compounds have been exclusively isolated from certain genera in the family Annonaceae including Hexalobus, Isolona (Achenbach and Löwel, 1995;Nkunya et al., 2004), Monodora (Adeoye et al., 1986;Nkunya et al., 2004), Asteranthe (Nkunya et al., 1996) and Uvaria (Achenbach and Raffelsberger, 1979), thus extending their chemotaxonomic importance beyond the genus Hexalobus to other closely related genera. This characteristic accumulation of prenylated indole alkaloids in specific genera supports a molecular phylogenetic study on African Annonaceae which revealed Hexalobus, Uvariastrum, Asteranthe, Isolona and Monodora to belong as one sub-clade in the African long-branch clade (ALBC) (Botermans et al., 2011;Couvreur et al., 2008). ...
... The KB cell line is a subline of HeLa. V. lanceolate root ethyl acetate extract was also toxic to HT-29 (colorectal adenocarcinoma) and KB cells, with CC 50 of 30 and 45 µg/mL, respectively, while the leaf extract was significantly less toxic [47]. Cytotoxicity of V. glomerata originating from Tanzania was tested towards RT-4 (urinary bladder, transitional cell papilloma), HT-29, and A413 (epidermoid carcinoma) cells [48], while the extracts from the leaves of V. soyauxii collected in Cameroon against a panel of multi-drug resistant cancer-derived cell lines, including drug-sensitive (CCRF-CEM) and multidrug-resistant (CEM/ADR5000) leukemia cells, breast cancer cells (sensitive-MDA-MB-231, and resistant-MDA-MB-231/BCRP), wild-type colon cancer cells (HCT116(p53+/+)) and their knockout clone (HCT116(p53−/−)), human glioblastoma multiforme (U87MG), and hepatoblastoma cell line (HepG2), showed low CC 50 values, between 4.06 and 13.6 µg/mL [49]. ...
... Since CF lungs are nutrient rich, the authors speculated that biosynthesis genes for these amino acids were rendered non-essential in this environ ment and were consequently lost, thereby explaining the auxotrophic growth of at least some CF strains (89). Since cysteine and methionine concentrations are known to be low in both A. cepa (90) and A. bisporus (91,92) tissues, this mechanism of growth prevention could also contribute to the ex planta avirulence of over 60% of the clinical strains in our B. gladioli library, including the unexpected avirulence of the pehA allele 1-containing clinical strain D1336. Cysteine and methionine restriction appears to occur in several other agricultural crop species (91), including Solanum tuberosum (potatoes), Daucus carota (carrots), and Brassica oleracea (cauliflowers), and whether this prevents maceration by B. gladioli or other CF pathogens will be fascinating to explore. ...
