BackgroundIdentification of novel sources for developing new antibiotics is imperative with the emergence of antibiotic resistant bacteria. The fruits of Terminalia bellirica (Gaertn) Roxb., widely used in traditional medicine, were evaluated for antibacterial activity against multidrug-resistant (MDR) bacteria, antioxidant activity and cytotoxicity.MethodsTwelve solvent extracts of T. bellirica fruits were prepared by direct aqueous extraction and sequential extraction with dichloromethane, methanol and water using Soxhlet, bottle-shaker and ultrasound sonicator methods. Antibacterial activity of the extracts was tested against 16 strains MDR bacteria—methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum β-lactamase (ESBL) producing Escherichia coli and MDR Acinetobacter spp., Klebsiella pneumoniae and Pseudomonas aeruginosa—and 4 control organisms, using the cut-well diffusion method. The minimum inhibitory concentration (MIC) was determined using an agar dilution method. The radical scavenging activity of six antibacterial extracts was screened against 2,2′-diphenyl-2-picrylhydrazyl (DPPH) and correlation was established between EC50 (50% effective concentration) values and the total phenolic content (TPC). Cytotoxicity was determined for the most potent antibacterial extract on baby hamster kidney (BHK-21) cells by Tryphan Blue exclusion method. Statistical analysis was carried out by one-way analysis of variance at significant level p < 0.05 using “SigmaPlot 10” and “R 3.2.0” software.ResultsAll aqueous and methanol extracts displayed antibacterial activity (MIC 0.25–4 mg/mL) against all strains of MRSA, MDR Acinetobacter spp. and MDR P. aeruginosa. The sequential aqueous extracts (MIC, 4 mg/mL) inhibited ESBL producing-E. coli. None of the extracts exhibited activity against MDR K. pneumoniae (MIC > 5 mg/mL). The sequential methanol extract (Soxhlet) recorded high antibacterial activity and the highest DPPH radical scavenging activity (EC50, 6.99 ± 0.15 ppm) and TPC content (188.71 ± 2.12 GAE mg/g).The IC50 (50% inhibition concentration) values of the most potent antibacterial extract—the direct aqueous extract from reflux method—on BHK-21 cells were 2.62 ± 0.06 and 1.45 ± 0.08 mg/ml with 24 and 48 h exposure, respectively.ConclusionsResults indicate that T. bellirica fruit is a potential source for developing broad-spectrum antibacterial drugs against MDR bacteria, which are non-toxic to mammalian cells and impart health benefits by high antioxidant activity.

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Flacourtia inermis Roxb. (Flacourtiaceae), is a moderate sized tree cultivated in Sri Lanka for its fruits known as Lovi. The current study was undertaken to study the biological activity of extracts of the fruits in an attempt to increase the value of the under exploited fruit crops. Fruits of F. inermis were found to be rich in phenolics and anthocyanins. Polyphenol content of the fruits was determined to be 1.28 g gallic acid equivalents per 100 g of fresh fruit and anthocyanin content was estimated as 108 mg cyanidin-3-glucoside equivalents per 100 g of fresh fruits. The EtOAc extract showed moderate antioxidant activity in the DPPH radical scavenging assay with IC 50 value of 66.2 ppm. The EtOAc and MeOH extracts of the fruits also exhibited inhibitory activities toward α-glucosidase, α-amylase and lipase enzymes with IC 50 values ranging from 549 to 710 ppm, 1021 to 1949 ppm and 1290 to 2096 ppm, respectively. The active principle for the enzyme inhibition was isolated through activity-guided fractionation and was characterized as (S)-malic acid. The results of this study indicate that F. inermis fruits have the potential to be used in health foods and in nutritional supplements.

Bipolaris sorokiniana, a fungal endophyte, was isolated from the leaves of Costus speciosus, a popular medicinal plant used to control diabetes. Fermentation of the fungus in potato dextrose broth and chromatographic purification of the ethyl acetate (EtOAc) extracts of the culture broth and mycelium yielded two rare sesquiterpenes helminthosporal acid (1) and helminthosporol (2), together with ergosterol. Compounds 1 and 2 showed a strong phytotoxic effect on lettuce seed germination and toxicity against brine shrimps. Compound 1 also showed antifungal activity. Complete assignments of 1 H and 13 C NMR data of compound 1 are described for the first time.