Methanolic extract of the leaves of Bridelia stipularis was studied. From this study, we isolated three known flavonoids. They were identified as 7-O-methyl luteolin, apigenin and 5, 7, 2', 5' tetrahydroxyflavone by NMR spectroscopic studies. All of them are first time documented for this plant. Different solvent fractions were subjected to in vitro antioxidant and cytotoxicity studies. Both apigenin and ethyl acetate soluble fraction of Bridelia stipularis showed strong antioxidant activity having IC 50 value of 8.005, 8.77 µg/mL respectively. Chloroform soluble fraction of Bridelia stipularis exerted the highest toxicity to brine shrimp and petroleum ether soluble fraction showed moderate toxicity having LC 50 value of 1.05, 1.71 µg/mL respectively.

The background of this study was to investigate the antioxidant, cytotoxic, thrombolytic and antimicrobial activity of the petroleum ether (PE), carbon tetrachloride (CTC), chloroform (CF) and aqueous (AQ) soluble fractions of crude methanolic Zanthoxylum rhetsa root bark with two isolated quinolone alkaloids, 8-methoxy-n-methylflindersine (1) and zanthodioline (2). Structures were characterized by 1D NMR analyses. Antioxidant activity was assessed by using DPPH assay and antimicrobial activity was screened by disc diffusion method. An in vitro thrombolytic model was used to evaluate the clot lysis effect of different extracts of root bark of Z. rhetsa along with streptokinase as a positive control and distilled water as a negative control and the cytotoxic activity of different extracts of Z. rhetsa root bark was evaluated by Brine Shrimp Lethality Bioassay. AQ fraction exhibited strongest antioxidant, cytotoxic and thrombolytic activity among four fractions. The CTC and CF soluble fractions exhibited significant antioxidant, cytotoxic and thrombolytic activity. CTC and AQ fractions gave highest anti-bacterial activity against Vibrio cholera and Klebsiella pneumonia respectively. Compound 1 showed significant activity at a concentration of 100 µgm/disc against Sarcina lutea, Staphylococcus aureus and Salmonella paratyphi-A, Shigella dysenteriae, Shigella boydii and Shigella sonnei with high antioxidant activity. The antioxidant, thrombolytic and antimicrobial activity of 8-methoxy-n-methylflindersine and zanthodioline are the first record from root bark of this plant.

The stem bark of Baccaurea ramiflora was studied. Four aldehydes named as 3 methoxy 4 hydroxy-cinnamaldehyde (coniferyl aldehyde); 3, 4, 5 trimethoxy cinnamaldehyde; 3, 4, 5 trimethoxy benzaldehyde and 3,4 dimethoxy benzaldehyde) (veratraldehyde) have been isolated and then identified by NMR spectroscopy. All of them are first time reported for this plant. Here in vitro biological investigations include antioxidant and cytotoxicity study. Among all fractions, the chloroform soluble fraction exhibited strong free radical scavenging activity having IC 50 value of 12.87 µg/ml compared to BHT (IC 50 value 5.64 µg/ml). On the contrary, aqueous soluble fraction exhibited most toxicity towards brine shrimp compared with vincristine sulphate having LC 50 value of 1.44 and 0.9258 μg/ml respectively.

A total of eight compounds were isolated from the petroleum ether and chloroform extracts of the root bark of Zanthoxylum rhetsa (Roxb.) (D.C). These are a coumarin xanthyletin (1), five quinolone alkaloids zanthodioline (2), arnottianamide (3), skimmianine (4), fagaridine (5), oxynitidine (7), a lignan pluviatilol (6), and a triterpene lupeol (8) were identified. Structures of the isolates were characterized by extensive 1D and 2D NMR analyses and by comparing their spectral data with the published values. The compounds, zanthodioline (2), oxynitidine (7), fagaridine (5), and pluviatilol (6) are the first record from this plant.

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