Since the beginning of the epidemic, human immunodeficiency virus (HIV) has infected around 70 million people worldwide, most of whom reside is sub-Saharan Africa. There have been very promising developments in the treatment of HIV with anti-retroviral drug cocktails. However, drug resistance to anti-HIV drugs is emerging, and many people infected with HIV have adverse reactions or do not have ready access to currently available HIV chemotherapies. Thus, there is a need to discover new anti-HIV agents to supplement our current arsenal of anti-HIV drugs and to provide therapeutic options for populations with limited resources or access to currently efficacious chemotherapies. Plant-derived natural products continue to serve as a reservoir for the discovery of new medicines, including anti-HIV agents. This review presents a survey of plants that have shown anti-HIV activity, both in vitro and in vivo.

The antioxidant properties of five different extracts (Et₂O, CHCl₃, EtOAc, n-BuOH, and H₂O) of Ocimum basilicum L. and Origanum vulgare L. were studied. Antioxidant activity was assessed in six different model systems. Free radical scavenging capacity (RSC) was evaluated by measuring the scavenging capacity of extracts on DPPH, NO, O₂^·- and OH radical, as well as on hydrogen peroxide (H₂O₂). In addition, the protective effects on lipid peroxidation in liposomes (LPx) were evaluated by TBA-assay using the Fe²⁺/ascorbate induction system. The amount of total phenolic compounds and content of total flavonoids was also determined. EtOAc, n-BuOH and H₂O extracts of O. basilicum and O. vulgare expressed very strong scavenger activity. Furthermore, the mentioned extracts showed notable inhibition of LPx. On the other hand, Et₂O and CHCl₃ extracts showed much weaker effect in the neutralization of DPPH, NO and O₂^·- radicals and the neutralization of H₂O₂. When examining the production of OH radicals and inhibition of LPx, the Et₂O and CHCl₃ extracts showed weak prooxidative properties. The observed differences in antioxidant activity could be partially explained by the levels of phenolics and flavonoids in the investigated O. basilicum and O. vulgare extracts.

Although Trifolium pratense (Red Clover) is considered to be one of the leading crops for livestock grazing, it could also be used as a potential source of bioactive compounds in phytopharmacy. The aim of this study was to investigate the phenolic content and its biological activity at the growth phases (30 cm, 50 cm, and bud) of this plant. The phenolic compounds in methanolic extracts of T. pratense leaves at three growth stages, obtained by Microwave Assisted Extraction, were quantified using the HPLC-ESI-MS/MS technique, and their antioxidant and antimicrobial activity were assessed. Isoflavonoids, genistein, and daidzein, as well as other phenols, p-hydroxybenzoic and caffeic acids, kaempferol 3-O-glucoside, quercetin 3-O-glucoside, and hyperoside were found in all the extracts, but the content of these compounds was the highest in the extract of the plant at the lowest growth stage (30 cm, vegetative). Therefore, this extract showed the best antioxidant potential and it was most effective against bacterial strains such as Escherichia coli and Enterobacter aerogenes. These results indicated that red clover has potential health benefits, and that growth phase contributes to its biological activity. The extract of red clover at the growth stage of 30 cm is a great source of bioactive compounds and could be used in phytotherapy and nutrition.

The in vitro and in vivo antioxidant activities of different extracts of laurel leaves were studied. Free radical scavenging capacity (RSC) was evaluated measuring the scavenging activity on the DPPH, NO, O₂^·- and OH radicals. The effects on lipid peroxidation (LP) were also evaluated. Experimental results indicate that ethyl acetate extract of leaves has exhibited the largest RSC capacity in neutralization of DPPH, NO, O₂^·- and OH radicals. The same result was obtained in investigation of extracts impact on LP. The in vivo effects were evaluated on some antioxidant systems (activities of GSHPx, LPx, Px, CAT and XOD, and GSH content) in the mice liver and blood-hemolysate after treatment with the examined laurel extracts, or in combination with carbon tetrachloride (CCl₄). On the basis of the results obtained it can be concluded that the examined extracts exhibited a certain protective effect, which is more pronounced on the liver than on blood-hemolysate parameters. The results obtained indicate toxicity of CCl₄, probably due to the radicals involved in its metabolism. Combined treatments with CCl₄ and the examined extracts showed both positive and negative synergism. Based on the experimental results, the strongest protective effect was shown by the EtOAc extract.