In vitro antimycobacterial activity of six Cameroonian medicinal plants using microplate alamarBlue assay

AbstractObjective/backgroundThe latest incidence of tuberculosis (TB) (per 100,000 people) in Cameroon was 243.00 as of 2011. Over the past 21years, the value for this indicator has fluctuated between 112.00 in 1990 and 320.00 in 2003. Worldwide, this incidence has also increased, bringing back TB as a reemerging disease. On the same note, resistance to anti-TB drugs has increased, urging the search for new molecules.MethodsThis study was carried out to evaluate the antimycobacterial activity of six medicinal plants on the virulent strain, H37Rv, using the microplate alamarBlue assay. Mycobacterium tuberculosis (H37Rv strain) was incubated with decreased concentrations of six plant extracts, ranging from 250μg/mL to 31.25μg/mL. After 7days of incubation at 37°C, the effects of these plant extracts on the viability of the mycobacteria were evaluated. For each plant extract, the minimal inhibitory concentration was determined.ResultsThe results showed that the compounds MBC1, MBC24, MBC68, MBC81, MBC117, and MBC118 were the best candidates with minimal inhibitory concentrations of 31.25, 62.5, 125, 62.5, and 125μg/mL, respectively.ConclusionThese results confirm and validate the traditional use of these plants to treat respiratory diseases, which could be good sources and alternatives of plant metabolites for anti-TB-drug development

Anti-mycobacterial activity of polyketides from Penicillium sp. endophyte isolated from Garcinia nobilis against Mycobacterium smegmatis

Objective/background: According to estimates by the World Health Organization, there were 9.6 million new tuberculosis (TB) cases in 2014: 5.4 million among men, 3.2 million among women, and 1.0 million among children. There were also 1.5 million TB deaths. Although there are potent anti-TB molecules, the misuse of these drugs in addition to inconsistent or partial treatment have led to the development of multidrug-resistant TB and extensively drug-resistant TB. It is established that plants harbor microorganisms, collectively known as endophytes, which also produce metabolites. Exploring the as-yet untapped natural products from the endophytes increases the chances of finding novel and active compounds. The present study was aimed to investigate the antimycobacterial activity of the crude extract and compounds isolated from Penicillium sp. endophyte associated with Garcinia nobilis against Mycobacterium smegmatis. Methods: Liquid culture obtained from the fermentation of Penicillium sp. was extracted using ethylacetate and the liquid chromatography–mass spectrometry monitored fractionation of crude extracts yielded six compounds. Their structures were elucidated with spectroscopic analyses including two-dimensional nuclear magnetic resonance, high resolution mass spectrometry by dereplication using Antibase, and by comparison to literature data. All compounds and the crude extract from the liquid medium were evaluated for their antimycobacterial activity against M. smegmatis. Results: In this study, the activity of penialidins A–C (1–3), citromycetin (4), p-hydroxy phenyl glyoxalaldoxime (5), and Brefeldin A (6) were tested against nonpathogenic M. smegmatis. Penialidin C was the most active compound with a minimum inhibitory concentration of 15.6μg/mL. Conclusion: Isolated compounds from Penicillium sp. harbored in G. nobilis exhibited promising antimycobacterial activity against M. smegmatis thus supporting the immensity of the potential of antimycobacterial drug discovery from endophytes from medicinal plants. Penialidin C could further be investigated for antimycobacterial drug development

Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance

Tseme Wandji N, Bitchagno GTM, Mawabo Kamga I, et al. Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance. Molecules. 2023;28(13): 5278.Four polyoxygenated stigmastanes (1–4) alongside known analogues (7–8) and flavonoids (5–6) were isolated from a dichloromethane/methanol (1:1, v/v) extract of the whole plant of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of 1 under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (1–3) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL

Dewerin and gilbertionol two new secondary metabolites from the stem bark of Gilbertiodendron dewevrei (De Wild) J. Leonard.

Stephanie DM, Stephane FFY, Jules BKJ, et al. Dewerin and gilbertionol two new secondary metabolites from the stem bark of Gilbertiodendron dewevrei (De Wild) J. Leonard. Natural product research. 2020.The phytochemical investigation of the methanol extract of the stem bark of Gilbertiodendron dewevrei led to the isolation of two new secondary metabolites, 5,7-dihydroxy-4'-methoxyisoflavan-2,4-dione (1) and 23-hydroxy-2-tricosanone (2) along with 19 known compounds (3-21). The structure of these compounds were established by interpretation of their spectral data, mainly HR-TOFESIMS, 1D NMR (1H, 13C and DEPT) and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY), and by comparison with those reported in the literature. The methanol extract and some isolates were screened for their antiradical, antibacterial, and inhibitory properties against acetylcholinesterase

One new constituent from the stem bark of Chrysophyllum lacourtianum De Wild. (sapotaceae)

Talla RM, Jouda J-B, Mawabo IK, et al. One new constituent from the stem bark of Chrysophyllum lacourtianum De Wild. (sapotaceae). Natural Product Research . 2021.The phytochemical investigation of the methanol extract of the stem bark of Chrysophyllum lacourtianum led to the isolation and characterization of one new secondary metabolite, lacourtianal (1), together with eight known compounds. Compounds 2; 3; 5; 6; 7 and 9 were reported for the first time from Chrysophyllum genus. The structures of compounds 1-9 were elucidated on the basis of 1D and 2D NMR spectroscopic and mass spectrometric data as well as comparison with the literature. The antibacterial activity of the methanol extract, fractions and compounds 1-9 were evaluated against bacterial strains. The methanol extract exhibited moderate activity against Staphylococcus aureus NR4674 with MIC values of 500g/mL. The n-hexane fraction showed moderate activity against Staphylococcus aureus (ATCC 43300 and ATCC 25923) with MIC values of 125g/mL and ursolic acid (5) exhibited strong activity against Enterobacter aerogenes CPC and Escherichia coli ATCC 25322 with MIC values of 7.8 and 3.9g/mL respectively

Chemical constituents of the fruits of Gambeya lacourtiana (Sapotaceae)

Talla RM, Jouda J-B, Mawabo IK, et al. Chemical constituents of the fruits of Gambeya lacourtiana (Sapotaceae). Phytochemistry Letters. 2020;38:84-89.Phytochemical investigation of the fruits of Gambeya lacourtiana led to the isolation of four new compounds, lacourtianol (1), lacourtianoside I (2), lacourtianoside II (3) and lacourtianamide (4) together with six known compounds: 3-O-acetylbetulin (5), 3-O-acetylerythrodiol (6), beta-amyrincaproate (7), lupeolhexanoate (8), erythrodiol 3-O-palmitate (9), and D-mannitol (10). The structures of 1-10 were elucidated on the basis of 1D and 2D NMR spectroscopic data, mass spectrometry and by comparison of spectroscopic data with those from the literature. Compounds 1-10 were evaluated for their antibacterial activity. Lacourtianoside II (3) exhibited moderate activity against Salmonella typhi CHU, Staphylococcus aureus (ATCC 43300 and ATCC 25923) and Enterobacter cloacae k2 with the same MIC value of 22.3 mu M

A-type doubly linked proanthocyanidin trimer and other metabolites from Canthium venosum fruits, and their biological activities

Dongmo AK, Nono RN, Kaaniche F, et al. A-type doubly linked proanthocyanidin trimer and other metabolites from Canthium venosum fruits, and their biological activities. Phytochemistry Letters. 2020;36:134-138.Phytochemical investigation of Canthium venosum fruits led to the isolation of a new doubly linked A-type proanthocyanidin trimer: epicatechin-(2 beta -> O -> 7, 4 beta -> 8)-catechin-(5 -> O -> 2 beta, 6 -> 4 beta)-epicatechin [venosumtannin A-1 (1)], along with twenty known compounds 2-21. Allyl (9a) and acetyl (9b) derivatives of 9 were prepared. The structures of compounds were established using comprehensive spectroscopic analysis including 1D NMR, 2D NMR (COSY, HMQC, HMBC, and NOESY) and circular dichroism (CD), and by comparison with the corresponding literature data. The antioxidant, cytotoxic, acetylcholinesterase and antibacterial activities of some of the isolated compounds were investigated. In the acetylcholinesterase inhibitory activity test, compounds 2 and 9 (IC50: 0.03 +/- 1.22x10(-3) and 0.04 +/- 1.23x10(-3) mu M) were more active than the references (eserine and tacrine; IC50: 0.77 +/- 1.84x10(-3) and 0.15 +/- 1.04x10(-3) mu M respectively)

Bioguided chemical study of Boswellia dalzielii Hutch. (Burseraceae) for antibacterial agents and a new glucopyranoxylmethoxybenzyle.

Tegasne C, Kapche GDWF, Mawabo IK, et al. Bioguided chemical study of Boswellia dalzielii Hutch. (Burseraceae) for antibacterial agents and a new glucopyranoxylmethoxybenzyle. Natural product research. 2020.Stem barks of Boswellia dalzielii are used traditionally for the treatment of various bacterial infections. A bioassay guided fractionation of the MeOH-CH2Cl2 (1/1, v/v) stem barks extract led to the isolation of fourteen compounds 1-14, identified based on spectroscopic data. Dalzienoside (1) is reported here for the first time. The broth microdilution method was used to evaluate the antibacterial activity of the crude extract, fractions and compounds against six bacterial strains. The crude extract exhibited moderate antibacterial activity with MIC of 250muL/ml; two fractions showed significant activities with MICs ranging from 7.8 to 125mug/ml, while alpha-boswellic acid (2), beta-boswellic acid (3), acetyl-11-keto-beta-boswellic acid (4) from these fractions exhibited strong activities with MIC value of 3.125g/mL against Staphylococcus aureus, Salmonella typhi, Enterobacter cloacae, Streptococcus pneumonia and Pseudomonia aeruginosa. This study gives insight into the antibacterial constituents of the stem bark of B. dalzielii and justifies its use in ethnomedicine

Bioactive Arylnaphthalide Lignans from Justicia depauperata

Tchegnitegni Toussie B, Nguengang Tchuinkeu R, Mawabo IK, et al. Bioactive Arylnaphthalide Lignans from Justicia depauperata . Journal of Natural Products. 2022