H.M. Heyman

Identification of anti-HIV active dicaffeoylquinic- and tricaffeoylquinic acids in Helichrysum populifolium by NMR-based metabolomic guided fractionation.

South Africa being home to more than 35% of the worlds Helichrysum species (c.a. 244) of which many are used in traditional medicine, is seen potentially as a significant resource in the search of new anti-HIV chemical entities. It was established that five of the 30 Helichrysum species selected for this study had significant anti-HIV activity ranging between 12 and 21 μg/mL (IC50) by using an in-house developed DeCIPhR method on a full virus model. Subsequent toxicity tests also revealed little or no toxicity for these active extracts. With the use of NMR-based metabolomics, the search for common chemical characteristics within the plant extract was conducted, which resulted in specific chemical shift areas identified that could be linked to the anti-HIV activity of the extracts. The NMR chemical shifts associated with the activity were identified to be 2.56-3.08 ppm, 5.24-6.28 ppm, 6.44-7.04 ppm and 7.24-8.04 ppm. This activity profile was then used to guide the fractionation process by narrowing down and focusing the fractionation and purification processes to speed up the putative identification of five compounds with anti-HIV activity in the most active species, Helichrysum populifolium. The anti-HIV compounds identified for the first time from H. populifolium were three dicaffeoylquinic acid derivatives, i.e. 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid as well as two tricaffeoylquinic acid derivatives i.e. 1,3,5-tricaffeoylquinic acid and either 5-malonyl-1,3,4-tricaffeoylquinic or 3-malonyl-1,4,5-tricaffeoylquinic acid, with the latter being identified for the first time in the genus.

The Only African Wild Tobacco, Nicotiana africana: Alkaloid Content and the Effect of Herbivory

Herbivory in some Nicotiana species is known to induce alkaloid production. This study examined herbivore-induced defenses in the nornicotine-rich African tobacco N. africana, the only Nicotiana species indigenous to Africa. We tested the predictions that: 1) N. africana will have high constitutive levels of leaf, flower and nectar alkaloids; 2) leaf herbivory by the African bollworm Helicoverpa armigera will induce increased alkaloid levels in leaves, flowers and nectar; and 3) increased alkaloid concentrations in herbivore-damaged plants will negatively affect larval growth. We grew N. africana in large pots in a greenhouse and exposed flowering plants to densities of one, three and six fourth-instar larvae of H. armigera, for four days. Leaves, flowers and nectar were analyzed for nicotine, nornicotine and anabasine. The principal leaf alkaloid was nornicotine (mean: 28 µg/g dry mass) followed by anabasine (4.9 µg/g) and nicotine (0.6 µg/g). Nornicotine was found in low quantities in the flowers, but no nicotine or anabasine were recorded. The nectar contained none of the alkaloids measured. Larval growth was reduced when leaves of flowering plants were exposed to six larvae. As predicted by the optimal defense theory, herbivory had a localized effect and caused an increase in nornicotine concentrations in both undamaged top leaves of herbivore damaged plants and herbivore damaged leaves exposed to one and three larvae. The nicotine concentration increased in damaged compared to undamaged middle leaves. The nornicotine concentration was lower in damaged leaves of plants exposed to six compared to three larvae, suggesting that N. africana rather invests in new growth as opposed to protecting older leaves under severe attack. The results indicate that the nornicotine-rich N. africana will be unattractive to herbivores and more so when damaged, but that potential pollinators will be unaffected because the nectar remains alkaloid-free even after herbivory.

Amorfrutin-type phytocannabinoids from Helichrysum umbraculigerum

Abstract Helichrysum umbraculigerum Less. has been reported to be a prolific producer of phytocannabinoids from the alkyl-, aralkyl-, normal-, and abnormal types. Investigation of an acetone extract from the aerial parts of the plant afforded two novel amorfrutin-type phytocannabinoids ( 3b , 4 ) and the new geranylated phloroglucinol 5a . The presence of cannabigerol (CBG, 1a ) and its acidic precursor (pre-CBG, CBGA, 1b ), previously reported from this plant, could not be confirmed, but the phenethyl analogue of CBG (Heli-CBG, 2a) and the methyl ester of its carboxylated version ( 2b ) were isolated. Heli-CBG ( 2a ) was assayed against a series of metabotropic (CB 1 and CB 2 )- and ionotropic (thermo-TRPs) targets of phytocannabinoids, comparing its profile with the one of cannabigerol (CBG). A decreased affinity for cannabinoid receptor was observed, along with substantial retention of the thermo-TRP profile. The biogenetic relationships between the isoprenylated phenolics from H. umbraculigerum are discussed, highlighting the relevance of this species for biogenetic investigations on phytocannabinoids

Reprint of: Amorfrutin-type phytocannabinoids from Helichrysum umbraculigerum

Abstract Helichrysum umbraculigerum Less. has been reported to be a prolific producer of phytocannabinoids from the alkyl-, aralkyl-, normal-, and abnormal types. Investigation of an acetone extract from the aerial parts of the plant afforded two novel amorfrutin-type phytocannabinoids (3b, 4) and the new geranylated phloroglucinol 5a. The presence of cannabigerol (CBG, 1a) and its acidic precursor (pre-CBG, CBGA, 1b), previously reported from this plant, could not be confirmed, but the phenethyl analogue of CBG (Heli-CBG, 2a) and the methyl ester of its carboxylated version (2b) were isolated. Heli-CBG (2a) was assayed against a series of metabotropic (CB1 and CB2)- and ionotropic (thermo-TRPs) targets of phytocannabinoids, comparing its profile with the one of cannabigerol (CBG). A decreased affinity for cannabinoid receptor was observed, along with substantial retention of the thermo-TRP profile. The biogenetic relationships between the isoprenylated phenolics from H. umbraculigerum are discussed, highlighting the relevance of this species for biogenetic investigations on phytocannabinoids