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A new prenylated kaempferol, conglomeratin ( 1 ), alongside 7 known compounds including flavonoids ( 2 and 3 ), ellagic acid derivatives ( 4 and 5 ), triterpenoids ( 6 and 7 ), and a coumarin ( 8 ) were isolated from the leaves ( 1 - 5 ) and stem bark ( 6 - 8 ) of Macaranga conglomerata . Their structures were elucidated using spectroscopic and spectrometric techniques. The antibacterial assay was performed using disc diffusion method against Gram-positive and Gram-negative microorganisms. Compound 1 was significantly active against Pseudomonas aeruginosa ATCC 27853 (MIC = 7.8 µg/mL) and moderately active towards Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 31488 (MIC = 62.5 µg/mL). Compound 2 showed potency against P. aeruginosa ATCC 27853 (MIC = 1.0 µg/mL) while 4 and 7 were selective towards K. pneumoniae ATCC 31488 (MIC = 7.8 and 1.0 µg/mL, respectively). These findings suggest that prenylation of flavonoids may contribute to improving their broad-spectrum antimicrobial activities.

The root extract of Suregada zanzibariensis Baill. afforded six previously described ent-abietane diterpenoids, namely 7-oxo-ent-abieta-5(6),8(14),13(15)-trien-16,12-olide (1), mangiolide (2), 8,14β:11,12α-diepoxy-13(15)-abietane-16,12-olide (3), 7β,11β,12β-trihydroxy-ent–abieta-8(14),13(15)-diene-16,12-olide (4), 8α,14-dihydro-7-oxo-jolkinolide E (5), jolkinolide A (6), together with 3β-sitosterol (7), scopoletin (8) and vanillin (9). Their structures were deduced through 1D and 2D NMR spectroscopic techniques, and HRESIMS, as well as by comparison of the NMR data with those reported in the literature. The crude extract and compounds 1–9 were evaluated for their antiplasmodial, antifungal and antibacterial activities. Mangiolide (2) showed strong in vitro antiplasmodial activity against chloroquine sensitive (D6) and resistant (W2) strains of Plasmodium falciparum with IC50 values of 0.79 and 0.87 µg/mL, respectively, while 3 (IC50 1.24 and 1.17 µg/mL) was less active than 2. Compound 2 also displayed antimicrobial activity against Cryptococcus neoformans, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) with IC50 values of 1.20, 3.90 and 7.20 µg/mL, respectively. [ABSTRACT FROM AUTHOR]

Introduction: Macaranga species are traditionally used for the treatment and management of coughing, fungal infection, and wounds. In this study, the phytochemical screening and antibacterial activities of nine crude extracts from Macaranga conglomerata, Macaranga kilimandscharica and Macaranga capensis were determined against 13 bacterial strains expressing multi-drug resistance (MDR) phenotypes. Methods: Phytochemical screening of the extracts were carried out according to the standard methods, while the iodonitrotetrazolium chloride (INT) colorimetric assay was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the plants extracts. Results: Flavonoids, terpenoids, saponins and coumarins were the major secondary metabolites found in all the plant extracts. The results of antibacterial studies revealed that all the plant extracts displayed good activities with MIC values ranging from 4 - 128 μg/mL against the tested micro-organisms. Most of the extracts exhibited a bactericidal effect against E. coli, E. aerogenes, K. pneumoniae, P. stuartii, P. aeruginosa, and S. aureus with MBC/MIC ratio ≤ 4. In the presence of efflux pump inhibitor (PaβN), the inhibition potency of all the crude extracts against the tested bacterial strains were substantially enhanced. It is worth noting that the activities of MKL, MCL, and MCR towards P. stuartii (NEA16), E. aerogenes (ATCC13048), and K. pneumoniae (KP55), respectively were improved by more than 8-fold in the presence of PAβN. Conclusion: The findings of this study indicated the possibility of using all the tested plant extracts as a source of therapeutic agents in the fight against multi-drug resistant bacteria. [ABSTRACT FROM AUTHOR]