BackgroundBryophyllum pinnatum (Lank.) Oken (Crassulaceae) is a perennial succulent herb widely used in traditional medicine to treat many ailments. Its wide range of uses in folk medicine justifies its being called "life plant" or "resurrection plant", prompting researchers' interest. We describe here the isolation and structure elucidation of antimicrobial and/or antioxidant components from the EtOAc extract of B. pinnatum.ResultsThe methanol extract displayed both antimicrobial activities with minimum inhibitory concentration (MIC) values ranging from 32 to 512 μg/ml and antioxidant property with an IC50 value of 52.48 μg/ml. Its partition enhanced the antimicrobial activity in EtOAc extract (MIC = 16-128 μg/ml) and reduced it in hexane extract (MIC = 256-1024 μg/ml). In addition, this process reduced the antioxidant activity in EtOAc and hexane extracts with IC50 values of 78.11 and 90.04 μg/ml respectively. Fractionation of EtOAc extract gave seven kaempferol rhamnosides, including; kaempferitrin (1), kaempferol 3-O-α-L-(2-acetyl)rhamnopyranoside-7-O-α-L-rhamnopyranoside (2), kaempferol 3-O-α-L-(3-acetyl)rhamnopyranoside-7-O-α-L-rhamnopyranoside (3), kaempferol 3-O-α-L-(4-acetyl)rhamnopyranoside-7-O-α-L-rhamnopyranoside (4), kaempferol 3-O-α-D- glucopyranoside-7-O-α-L-rhamnopyranoside (5), afzelin (6) and α-rhamnoisorobin (7). All these compounds, except 6 were isolated from this plant for the first time. Compound 7 was the most active, with MIC values ranging from 1 to 2 μg/ml and its antioxidant activity (IC50 = 0.71 μg/ml) was higher than that of the reference drug (IC50 = 0.96 μg/ml).ConclusionThese findings demonstrate that Bryophyllum pinnatum and some of its isolated compounds have interesting antimicrobial and antioxidant properties, and therefore confirming the traditional use of B. pinnatum in the treatment of infectious and free radical damages.

BackgroundNaturally occurring flavonoids have been reported to possess various pharmacological properties. The aim of this study was to evaluate the antimicrobial and antioxidant activities of the MeOH extract and flavonoids from the leaves of Oncoba spinosa, a plant used for the treatment of syphilis, wounds and sexual impotence.MethodsThe plant extract was prepared by maceration in methanol and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The MeOH extract and its isolated compounds were evaluated for their antibacterial and antifungal activities by broth microdilution method. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. The samples were tested spectrophotometrically for their hemolytic properties against human red blood cells.ResultsThe fractionation of the MeOH extract afforded five known flavonoids including kaempferol (1), quercetin (2), apigenin-7-O-β-D-glucuronopyranoside (3), quercetin 3-O-β-D-galactopyranoside (4) and quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5). The MeOH extract displayed weak to moderate antimicrobial activities (MIC = 256–2048 μg/ml). Quercetin 3-O-α-L-rhamnopyranosyl (1 → 6) β-D-glucopyranoside (5) and quercetin (2) were respectively the most active compounds against bacteria (MIC = 8–64 μg/ml) and fungi (MIC = 64 – 128 μg/ml). These tested samples also showed high radical-scavenging activities (EC50 = 5.08 – 70.56 μg/ml) and gallic acid equivalent antioxidant capacities (TEAC = 53.76 – 89.86 μg/ml) when compared with vitamin C (EC50 = 4.72 μg/ml). The MeOH extract and compounds 2–5 were non-toxic to human red blood cells indicating their high selectivity to be used as antimicrobial and antioxidant drugs.ConclusionThe MeOH extract of O. spinosa as well as compounds 2 – 5 could be a potential source of natural antimicrobial and antioxidant products.

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Six known compounds: sideroxylin (1), 5-hydroxylmethyl-2-furancarboxaldehyde (2), C-6,O-7-dimethyldenaromadendrin (3), 4-(hydroxymethyl)-5-hydroxy-2H-pyran-2-one (4), 7-deoxy-transdihydronarciclasine or trans-dihydrolycoricidine (5) and farrerol (6) were isolated from Scadoxus pseudocaulus (Björnstad & Friis) Friis & Nordal (Amaryllidaceae), famous for the treatment of liver cancer, cardiovascular disease, microbial diseases and mental disorders in Western region of Cameroon. The flavanone named farrerol (6) was partially modified by esterification reactions to give six novel semi-synthetic flavanone derivatives named 4′,7-diparamethylbenzoylfarrerol (7), 4′,7-dibutyrylfarrerol (8), 4′-butyrylfarrerol (9), 4′-dodecanoylfarrerol (10), 7-octanoylfarrerol (11) and 4′-octanoylfarrerol (12). Structures of isolated constituents and derivatives were elucidated with the aid of their NMR and MS spectral data as well as with the reported data. The antimicrobial, antioxidant and butyrylcholinesterase inhibition activities of the extracts and their isolated compounds as well as the six novel semi-synthetic flavanone derivatives were evaluated. Ethyl acetate fraction (MIC = 64-512 μg/mL) and compounds 6, 7 and 10 (MIC = 2-16 μg/mL) displayed good antibacterial and antifungal activities that varied among the microbial species. Compound 11 is the most potent antioxidant with IC 50 49.7 μM which is comparable to standard butylated hydroxyanisole having IC 50 value of 44.2 μM. Compounds 12, 4 and 6 also have significant antioxidant activity with IC 50 value 56.5, 59.5 and 58.2 μM, respectively. Compound 7 showed excellent butyrylcholinesterase inhibition activity (IC 50 = 12.6 μM) when compared with standard eserine (IC 50 = 7.8 μM). The overall results of this study indicate that most active samples could be used as complementary medicine after due host toxicity testing.

Antimicrobial-guided fractionation of the EtOAc extract of the stem bark of Croton macrostachys afforded five known compounds including two lupane triterpenoids, lupeol (1) and betulin (2), and three clerodane diterpenoids, floridolide A (3), hardwickic acid (4) and 12-oxo-hardwickic acid (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. The EtOAc extract and compounds 1, 2, 4 and 5 were evaluated for their antibacterial and antifungal activities by macro-dilution method. The extract displayed significant antibacterial and antifungal activities (MIC = 31.25-1000 µg/ml). Betulin (2) and 12-oxo-hardwickic acid (5) were the most active compounds (MIC = 7.81-500 µg/ml). The most sensitive microorganisms were Staphylococcus aureus ATCC 25922 for bacteria and two Candida species, Candida albicans ATCC 24433 and Candida krusei ATCC 6258, for fungi. The isolation of these active antibacterial and antifungal principles supports the use of C. macrostachys in traditional medicine for the treatment of microbial infections.