A Method and Formula for the Quantitative Analysis of the Total Bioactivity of Natural Products

Abstract

Identification of bioactive natural products from plants starts with the screening of extracts for a desired bioactivity such as antimicrobial, antifungal, anti-cancer, anti-inflammatory, or neuroprotective. When the bioactivity shows sufficient potency, the plant material is subjected to bio-activity-guided fractionation, which involves, e.g., sequential extraction followed by chromatographic separation, including HPLC. The bioactive compounds are then structurally identified by high-resolution mass spectrometry and nuclear magnetic resonance (NMR). One of the questions that come up during the purification process is how much of the bioactivity originally present in the crude extract is preserved during the purification process. If this is the case, it is interesting to investigate if the loss of total bioactivity is caused by the loss of material during purification or by the degradation or evaporation of potent compounds. A further possibility would be the loss of synergy between compounds present in the mixture, which disappears when the compounds are separated. In this publication, a novel formula is introduced that allows researchers to calculate total bioactivity in biological samples using experimental data from our research into the discovery of anti-inflammatory compounds from Backhousia myrtifolia (Grey Myrtle). The results presented show that a raw ethanolic extract retains slightly more bioactivity than the sum of all sequential extracts per gram of starting material and that—despite a large loss of material during HPLC purification—the total bioactivity in all purified fractions is retained, which is indicative of rather an additive than a synergistic principle.

Plant Extracts from the Yucatan Peninsula in the In Vitro Control of Curvularia lunata and Antifungal Effect of Mosannona depressa and Piper neesianum Extracts on Postharvest Fruits of Habanero Pepper

“…This is contrary to what was observed against F. equiseti and F. oxysporum, where α-asarone showed lower IC 50 (236 and 482 µg/mL, respectively) compared to the ethanolic extract of M. depressa bark (IC 50 = 468 and 944 µg/mL, respectively) and its acetonitrile fraction (IC 50 = 462 and 472 µg/mL, respectively) [ 29 ]. The loss of activity of the extract when fractionated may be due to the loss of material during the fractionation, degradation, and evaporation of the more potent components; it may also be attributed to the loss of the synergistic effect between the compounds in the mixture when they are separated [ 43 ]. The metabolite α-asarone from M. depressa stem bark could be synergized with other components of the ethanolic extract responsible for the antifungal activity against C. lunata .…”

From the Bush to the Brain: Preclinical Stages of Ethnobotanical Anti-Inflammatory and Neuroprotective Drug Discovery—An Australian Example

“…In summary, Australian rainforests have evolved under unique environmental conditions and thus they typify an outstanding diversity of flora. As a result, it is expected that these rainforests would produce higher concentrations and varieties of pharmacologically active plants and thus serve as an untapped source for novel bioactive compounds [ 97 , 98 , 99 , 100 , 101 ].…”