The methanol extract of the underground part of Rhodiola rosea was found to show inhibitory activity against Staphylococcus aureus. Bioactivity-guided fractionation of a 95% ethanol extract from the stems of R. rosea led to the isolation of five compounds: gossypetin-7-O-L-rhamnopyranoside (1), rhodioflavonoside (2), gallic acid (3), trans-p-hydroxycinnamic acid (4) and p-tyrosol (5). Their structures were elucidated by UV, IR, MS and NMR data, as well as by comparison with those of the literature. Compounds 1 and 2 were evaluated for their antibacterial and antiprostate cancer cell activities. Compounds 1 and 2 exhibited activity against Staphylococcus aureus with minimum inhibitory concentrations of 50 microg/mL and 100 microg/mL, respectively. Cytotoxicity studies of 1 and 2 also displayed activity against the prostate cancer cell line with IC(50) values of 50 microg/mL and 80 microg/mL, respectively.

The alcohol extract or Rhodiola rosea has been shown to cause 42 ± 3.2% inhibition of acetylcholine esterase (AChE) when tested at 10 g/L. This AChE inhibition provides a physiological explanation for the reported mental and memory enhancing properties of Rhodiola rosea extracts. Active guided fractionation indicated a multitude of components which are responsible for this plants AChE inhibition. Two flavonoid glycosides (gossypetin-7-O-L-rhamnopyranoside and rhodioflavonoside) were isolated and shown to cause 58 ± 15% and 38 ± 4% AChE inhibition respectively when tested at 5 g/L. In view of this new enzymatic activity and previous clinical work indicating memory and mental enhancing properties with no indication of toxicity, this plant needs to be researched for its potential at treating memory impairing disorders such as Alzheimer's disease.

Activity-guided fractionation of the 95% ethanol extract from the stem bark of Iryanthera megistophylla led to the isolation of two new compounds, named megislignan [2,3-dimethyl-4-(4-methoxyphenyl)-6-hydroxynaphthalene] (1) and megislactone [(2R,3R,4R)-3-hydroxy-4-methyl-2-(hexacos-17-enyl)butanolide] (2), along with seven known compounds, grandinolide (3), iryantherin K (4), iryantherin L (5), cinchonain I b (6), cinchonain I a (7), procyanidin B-2 (8), and cinchonain IIa (9). The structures of the new compounds were elucidated by spectral data interpretation. Isolates were evaluated for their antibacterial, antifungal, antiviral, and antiacetylcholinesterase activities.