HPLC-based purification and isolation of potent anti-HIV and latency reversing Daphnane Diterpenes from the medicinal plant Gnidia sericocephala (Thymelaeaceae)

Despite the success of combination antiretroviral therapy (cART), HIV persists in low- and middle-income countries (LMIC) due to emerging drug resistance and insufficient drug accessibility. Furthermore, cART does not target latently-infected CD4+ T cells, which represent a major barrier to HIV eradication. The “shock and kill” therapeutic approach aims to reactivate provirus expression in latently-infected cells in the presence of cART and target virus-expressing cells for elimination. An attractive therapeutic prototype in LMICs would therefore be capable of simultaneously inhibiting viral replication and inducing latency reversal. Here we report that Gnidia sericocephala, which is used by traditional health practitioners in South Africa for HIV/AIDS management to supplement cART, contains at least four daphnane-type compounds (yuanhuacine A (1), yuanhuacine as part of a mixture (2), yuanhuajine (3), and gniditrin (4)) that inhibit viral replication and/or reverse HIV latency. For example, 1 and 2 inhibit HIV replication in peripheral blood mononuclear cells (PBMC) by >80% at 0.08 g/mL, while 1 further inhibits a subtype C virus in PBMC with a half-maximal effective concentration (EC50) of 0.03 M without cytotoxicity. Both 1 and 2 also reverse HIV latency in vitro consistent with protein kinase C activation but at 16.7-fold lower concentrations than the control prostratin. Both 1 and 2 also reverse latency in primary CD4+ T cells from cART-suppressed donors with HIV similar to prostratin but at 6.7-fold lower concentrations. These results highlight G. sericocephala and components 1 and 2 as anti-HIV agents for improving cART efficacy and supporting HIV cure efforts in resource-limited regions.SUPPLEMENTARY MATERIAL : TABLE S1: Anti-HIV replication activity of the positive control efavirenz using the in vitro deCIPhR assay: TABLE S2: Anti-HIV replication activity of G. sericocephala root extracts using the in vitro deCIPhR assay: TABLE S3: Cytotoxicity of G. sericocephala root extracts using the in vitro deCIPhR assay; FIGURE S1: 1H NMR data of yuanhuacine A (1), acquired on a Bruker Avance III HD 500 MHz NMR spectrophotometer with Prodigy Probe, the compound dissolved in deuterated chloroform (CDCl3): FIGURE S2: 13C NMR data of yuanhuacine A (1), acquired on a Bruker Avance III HD 500 MHz NMR spectrophotometer with Prodigy Probe, the compound dissolved in deuterated chloroform (CDCl3): FIGURE S3: The DEBT NMR data of yuanhuacine A (1), acquired on a Bruker Avance III HD 500 MHz NMR spectrophotometer with Prodigy Probe, the compound dissolved in deuterated chloroform (CDCl3).Funding was provided by the South African Department of Science and Innovation (DST/CON 0031/2019), Canadian Institutes for Health Research (CIHR PJT-153057) (I.T.) and the New Frontiers in Research Fund—Explorations (NFRFE-2018-01386) (I.T.). This work was also supported through the Sub-Saharan African Network for TB/HIV Research Excellence (SANTHE) (I.T.; N.G.), a DELTAs African Initiative [grant # DEL-15-006]. The DELTA African Initiative is an independent funding scheme of the African Academy of Sciences (AAS)’s Alliance for Accelerating Excellence in Science in Africa (AESA) and supported by the New Partnership for Africa’s Development Planning and Coordinating Agency (NEPAD Agency) with funding from the Welcome Trust [grant # 107752/Z/15/Z] and the UK government. This work was also supported by grants to L.J.M.: Beyond Antiretroviral Treatment (BEAT)-HIV Delaney Collaboratory Grants UM1AI126620 and UM1AI64570. It was also supported by the Robert I. Jacobs Fund of the Philadelphia Foundation; Penn Center for AIDS Research Grant P30 AI 045880; and the Herbert Kean. The APC was funded by University of Pretoria and Deaprtment of Science and Innovation.https://www.mdpi.com/journal/virusesam2023Chemistr