Derivatization of porphyrins for DNA and metal ion binding, especially by employing secondary sulfonamide links

Porphyrins are of exceptional importance in nature, science and technology: For instance, as ligands for metals in supramolecular synthesis, as photosenstizers in photodynamic therapy (PDT), and as building blocks for electronic devices. In addition to their application in cancer therapy, porphyrin species also exhibit antiviral activity. New meso-tetraarylporphyrins (TArP, Ar = -C6H4-) of the general formula, T(R1R2NSO2Ar)P, with R1 = N-py-n-CH2 (n = 2, 3 or 4) or SO3- and R2 = H or CH3 were synthesized. These groups were linked to the 4-position of the phenylene group of the porphyrin by a secondary (SO2NHR) or tertiary (SO2NR2) sulfonamide group. The sulfonamide group was found to be a versatile way of expanding the porphyrin. The presence of a tertiary sulfonamide group instead of a dissociable proton improved the solubility of the new class of porphyrin compounds synthesized. Adducts having four methylcobaloxime unit (CH3Co(DH)2) bound to the pyridyl nitrogens of T(N-py-4-CH2(CH3)NSO2Ar)P or TpyP(4) were synthesized for the first time and their solution properties studied by 1H NMR spectroscopy. The 1H NMR signal of the axial methyl of CH3Co(DH)2L complexes shifts upfield with increasing L basicity, but the signal of the equatorial methyl is insensitive to L basicity. The axial methyl signal was used to examine the effect of coordination of the CH3Co(DH)2 moiety to the N-pyridyl group of the TpyP(4) and of the newly synthesized porphyrin, T(N-py-4-CH2(CH3)NSO2Ar)P. A new class of water-soluble porphyrins meso-tetraarylporphyrins and some metal derivatives were synthesized from the above class of compounds by simple alkylation and metallation with copper and zinc salt. Interactions of selected porphyrins and metalloporphyrins (Cu(II), Zn(II)) with calf thymus DNA were investigated by visiblr circular dichroism, absorption, and fluorescence spectroscopies. The main aim of studying this class of compounds was to assess whether N-methylpyridinium (N-Mepy) groups must be directly attached to the porphyrin core in order for intercalative binding to DNA to occur. Porphyrins have been known for some years to show antiviral activity against human immunodeficiency virus (HIV) infection in assays that measured inhibition of virus replication. One promising approach receiving increasing attention is the development of microbicides which, when applied topically, can prevent viral infection. These compounds could directly interact with HIV virions to decrease or prevent infectivity, thus providing a defense against sexual transmission of the virus. Sulfonated derivatives of tetraarylporphyrin have also been shown to exhibit activity HIV. A new class of porphyrins containing sulfonamide links was synthesized and characterized by 1H NMR spectroscopy and mass spectrometry

Isolation and Characterization of Precise Dye/Dendrimer Ratios

Fluorescent dyes are commonly conjugated to nanomaterials for imaging applications using stochastic synthesis conditions that result in a Poisson distribution of dye/particle ratios and therefore a broad range of photophysical and biodistribution properties. We report the isolation and characterization of generation 5 poly(amidoamine) (G5 PAMAM) dendrimer samples containing 1, 2, 3, and 4 fluorescein (FC) or 6‐carboxytetramethylrhodamine succinimidyl ester (TAMRA) dyes per polymer particle. For the fluorescein case, this was achieved by stochastically functionalizing dendrimer with a cyclooctyne “click” ligand, separation into sample containing precisely defined “click” ligand/particle ratios using reverse‐phase high performance liquid chromatography (RP‐HPLC), followed by reaction with excess azide‐functionalized fluorescein dye. For the TAMRA samples, stochastically functionalized dendrimer was directly separated into precise dye/particle ratios using RP‐HPLC. These materials were characterized using 1 H and 19 F NMR spectroscopy, RP‐HPLC, UV/Vis and fluorescence spectroscopy, lifetime measurements, and MALDI. High definition : Two approaches for the formation of generation 5 PAMAM samples containing precise dye/dendrimer ratios are presented. The first approach, using direct separation based on dye hydrophobicity, generated a set of TAMRA‐containing dendrimers, and the second, using click chemistry, generated a set of fluorescein‐containing dendrimer (see figure).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106970/1/chem_201304854_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106970/2/4638_ftp.pd

Participant understanding of informed consent in a multidisease community-based health screening and biobank platform in rural South Africa.

BACKGROUND: In low- and middle-income settings, obtaining informed consent for biobanking may be complicated by socio-economic vulnerability and context-specific power dynamics. We explored participants experiences and perceptions of the research objectives in a community-based multidisease screening and biospecimen collection platform in rural KwaZulu-Natal, South Africa. METHODS: We undertook semi-structured in-depth interviews to assess participant understanding of the informed consent, research objectives and motivation for participation. RESULTS: Thirty-nine people participated (individuals who participated in screening/biospecimen collection and those who did not and members of the research team). Some participants said they understood the information shared with them. Some said they participated due to the perceived benefits of the reimbursement and convenience of free healthcare. Most who did not participate said it was due to logistical rather than ethical concerns. None of the participants recalled aspects of biobanking and genetics from the consent process. CONCLUSIONS: Although most people understood the study objectives, we observed challenges to identifying language appropriate to explain biobanking and genetic testing to our target population. Engagement with communities to adopt contextually relevant terminologies that participants can understand is crucial. Researchers need to be mindful of the impact of communities' socio-economic status and how compensation can be potentially coercive

Participant recall and understandings of information on biobanking and future genomic research: experiences from a multi-disease community-based health screening and biobank platform in rural South Africa.

BACKGROUND: Limited research has been conducted on explanations and understandings of biobanking for future genomic research in African contexts with low literacy and limited healthcare access. We report on the findings of a sub-study on participant understanding embedded in a multi-disease community health screening and biobank platform study known as 'Vukuzazi' in rural KwaZulu-Natal, South Africa. METHODS: Semi-structured interviews were conducted with research participants who had been invited to take part in the Vukuzazi study, including both participants and non-participants, and research staff that worked on the study. The interviews were transcribed, and themes were identified from the interview transcripts, manually coded, and thematically analysed. RESULTS: Thirty-nine individuals were interviewed. We found that the research team explained biobanking and future genomic research by describing how hereditary characteristics create similarities among individuals. However, recollection and understanding of this explanation seven months after participation was variable. The large volume of information about the Vukuzazi study objectives and procedures presented a challenge to participant recall. By the time of interviews, some participants recalled rudimentary facts about the genetic aspects of the study, but many expressed little to no interest in genetics and biobanking. CONCLUSION: Participant's understanding of information related to genetics and biobanking provided during the consent process is affected by the volume of information as well as participant's interest (or lack thereof) in the subject matter being discussed. We recommend that future studies undertaking biobanking and genomic research treat explanations of this kind of research to participants as an on-going process of communication between researchers, participants and the community and that explanatory imagery and video graphic storytelling should be incorporated into theses explanations as these have previously been found to facilitate understanding among those with low literacy levels. Studies should also avoid having broader research objectives as this can divert participant's interest and therefore understanding of why their samples are being collected

Process evaluation of peer-to-peer delivery of HIV self-testing and sexual health information to support HIV prevention among youth in rural KwaZulu-Natal, South Africa: qualitative analysis

OBJECTIVE: Peer-to-peer (PTP) HIV self-testing (HIVST) distribution models can increase uptake of HIV testing and potentially create demand for HIV treatment and pre-exposure prophylaxis (PrEP). We describe the acceptability and experiences of young women and men participating in a cluster randomised trial of PTP HIVST distribution and antiretroviral/PrEP promotion in rural KwaZulu-Natal. METHODS: Between March and September 2019, 24 pairs of trained peer navigators were randomised to two approaches to distribute HIVST packs (kits+HIV prevention information): incentivised-peer-networks where peer-age friends distributed packs within their social network for a small incentive, or direct distribution where peer navigators distributed HIVST packs directly. Standard-of-care peer navigators distributed information without HIVST kits. For the process evaluation, we conducted semi-structured interviews with purposively sampled young women (n=30) and men (n=15) aged 18-29 years from all arms. Qualitative data were transcribed, translated, coded manually and thematically analysed using an interpretivist approach. RESULTS: Overall, PTP approaches were acceptable and valued by young people. Participants were comfortable sharing sexual health issues they would not share with adults. Coupled with HIVST, peer (friends) support facilitated HIV testing and solidarity for HIV status disclosure and treatment. However, some young people showed limited interest in other sexual health information provided. Some young people were wary of receiving health information from friends perceived as non-professionals while others avoided sharing personal issues with peer navigators from their community. Referral slips and youth-friendly clinics were facilitators to PrEP uptake. Family disapproval, limited information, daily pills and perceived risks were major barriers to PrEP uptake. CONCLUSION: Both professional (peer navigators) and social network (friends) approaches were acceptable methods to receive HIVST and sexual health information. Doubts about the professionalism of friends and overly exclusive focus on HIVST information materials may in part explain why HIVST kits, without peer navigators support, did not create demand for PrEP

New porphyrins bearing positively charged peripheral groups linked by a sulfonamide group to meso-tetraphenylporphyrin: interactions with calf thymus DNA

New water-soluble cationic meso-tetraarylporphyrins (TArP, Ar = 4-C(6)H(4)) and some metal derivatives have been synthesized and characterized. One main goal was to assess if N-methylpyridinium (N-Mepy) groups must be directly attached to the porphyrin core for intercalative binding of porphyrins to DNA. The new porphyrins have the general formula, [T(R(2)R(1)NSO(2)Ar)P]X(4/8) (R(1) = CH(3) or H and R(2) = N-Mepy-n-CH(2) with n = 2, 3, or 4; or R(1) = R(2) = Et(3)NCH(2)CH(2)). Interactions of selected porphyrins and metalloporphyrins (Cu(II), Zn(II)) with calf thymus DNA were investigated by visible circular dichroism (CD), absorption, and fluorescence spectroscopies. The DNA-induced changes in the porphyrin Soret region (a positive induced CD feature and, at high DNA concentration, increases in the Soret band and fluorescence intensities) indicate that the new porphyrins interact with DNA in an outside, non-self-stacking binding mode. Several new metalloporphyrins did not increase DNA solution viscosity and thus do not intercalate, confirming the conclusion drawn from spectroscopic studies. Porphyrins known to intercalate typically bear two or more N-Mepy groups directly attached to the porphyrin ring, such as the prototypical meso-tetra(N-Mepy)porphyrin tetracation (TMpyP(4)). The distances between the nitrogens of the N-Mepy group are estimated to be approximately 11 A (cis) and 16 A (trans) for the relatively rigid TMpyP(4). For the new flexible porphyrin, [T(N-Mepy-4-CH(2)(CH(3))NSO(2)Ar)P]Cl(4), the distances between the nitrogens are estimated to be able to span the range from approximately 9 to approximately 25 A. Thus, the N-Mepy groups in the new porphyrins can adopt the same spacing as in known intercalators such as TMpyP(4). The absence of intercalation by the new porphyrins indicates that the propensity for the N-Mepy group to facilitate DNA intercalation of cationic porphyrins requires direct attachment of N-Mepy groups to the porphyrin core

New porphyrins bearing pyridyl peripheral groups linked by secondary or tertiary sulfonamide groups: synthesis and structural characterization

New pyridyl meso-tetraarylporphyrins (TArP, Ar = -C(6)H(4)-) of the general formula, T(R(1)R(2)NSO(2)Ar)P (R(1) = N-py-n-CH(2) (n = 2 or 4) and R(2) = CH(3)), have been synthesized by the versatile approach of utilizing meso-tetra(4-chlorosulfonylphenyl)porphyrin. After characterization by mass spectrometry and by visible absorption and (1)H NMR spectroscopy, the porphyrins were converted to various metalloderivatives, including Cu(II) and Zn(II). Treatment of T(N-py-4-CH(2)(CH(3))NSO(2)Ar)P (5) or TpyP(4) (meso-tetra(4-pyridyl)porphyrin) with CH(3)Co(DH)(2)H(2)O (DH = monoanion of dimethylglyoxime) afforded [CH(3)Co(DH)(2)](4)T(N-py-4-CH(2)(CH(3))NSO(2)Ar)P (6) and [CH(3)Co(DH)(2)](4)TpyP(4) (7). Typically, basic pyridines shift the axial methyl (1)H NMR signal of CH(3)Co(DH)(2)L upfield but leave the equatorial methyl signal unshifted. However, both signals for [CH(3)Co(DH)(2)](4)TpyP(4) are approximately 0.2 ppm more downfield than normal, suggesting perhaps an extremely non-basic pyridyl group. However, TpyP(4) forms CH(3)Co(DH)(2)py adducts with binding ability comparable to that of other pyridine ligands with normal basicity and to that of T(N-py-4-CH(2)(CH(3))NSO(2)Ar)P. Consequently, in 7 the deshielding of the methyl signals, even the axial Co-CH(3) signal, is attributed to anisotropy of the porphyrin core. The methyl signals for [CH(3)Co(DH)(2)](4)T(N-py-4-CH(2)(CH(3))NSO(2)Ar)P (6) have normal shifts. The absence of an anisotropic effect is attributable to the large distance of the CH(3)Co(DH)(2) moieties from the porphyrin core caused by the intervening linker in 6. Indeed, the separation led to only a slightly reduced (25%) fluorescence emission of 6 compared to 5, whereas that of 7 is considerably reduced (90%) compared to TpyP(4). The X-ray structures of 5, its Cu(II) complex, and [CH(3)Co(DH)(2)](4)TpyP(4) (7) (all of which have C(i) symmetry) support the spectroscopy. For example, the Co-N(ax) bond lengths of [CH(3)Co(DH)(2)](4)TpyP(4) (2.055(4) and 2.079(4) A) are comparable to that of CH(3)Co(DH)(2)py (2.068(3) A), consistent with the normal coordinating ability of TpyP(4). In an accompanying study, the new pyridylporphyrins have been converted to DNA-binding, water-soluble cationic porphyrins

Process evaluation of peer-to-peer delivery of HIV self-testing and sexual health information to support HIV prevention among youth in rural KwaZulu-Natal, South Africa: qualitative analysis

Objective: Peer-to-peer (PTP) HIV self-testing (HIVST) distribution models can increase uptake of HIV testing and potentially create demand for HIV treatment and pre-exposure prophylaxis (PrEP). We describe the acceptability and experiences of young women and men participating in a cluster randomised trial of PTP HIVST distribution and antiretroviral/PrEP promotion in rural KwaZulu-Natal.Methods: Between March and September 2019, 24 pairs of trained peer navigators were randomised to two approaches to distribute HIVST packs (kits+HIV prevention information): incentivised-peer-networks where peer-age friends distributed packs within their social network for a small incentive, or direct distribution where peer navigators distributed HIVST packs directly. Standard-of-care peer navigators distributed information without HIVST kits. For the process evaluation, we conducted semi-structured interviews with purposively sampled young women (n=30) and men (n=15) aged 18–29 years from all arms. Qualitative data were transcribed, translated, coded manually and thematically analysed using an interpretivist approach.Results: Overall, PTP approaches were acceptable and valued by young people. Participants were comfortable sharing sexual health issues they would not share with adults. Coupled with HIVST, peer (friends) support facilitated HIV testing and solidarity for HIV status disclosure and treatment. However, some young people showed limited interest in other sexual health information provided. Some young people were wary of receiving health information from friends perceived as non-professionals while others avoided sharing personal issues with peer navigators from their community. Referral slips and youth-friendly clinics were facilitators to PrEP uptake. Family disapproval, limited information, daily pills and perceived risks were major barriers to PrEP uptake.Conclusion: Both professional (peer navigators) and social network (friends) approaches were acceptable methods to receive HIVST and sexual health information. Doubts about the professionalism of friends and overly exclusive focus on HIVST information materials may in part explain why HIVST kits, without peer navigators support, did not create demand for PrEP

Isisekelo Sempilo 2x2 factorial randomised controlled trial of the effectiveness of integrating HIV prevention within sexual reproductive health (SRH) services with or without peer support amongst adolescents and young adults in rural KwaZulu-Natal

Background: approximately 200,000 South Africans acquired HIV in 2021 despite universal HIV test and treat (UTT) and Pre-Exposure Prophylaxis (PrEP).Methods: we conducted a 2x2 factorial open label randomised controlled trial. N=3000 potentially eligible 16-29-year-olds, randomly sampled from a population surveillance area in a mostly rural part of KwaZulu-Natal, were randomised to one of 4 arms: 1) enhanced Standard of Care (SoC): access to mobile youth-friendly services for differentiated HIV prevention (condoms, UTT, PrEP if eligible); 2) Sexual and Reproductive Health (SRH): baseline self-collected specimens for sexually transmitted infection testing and referral to differentiated HIV prevention services; 3) Peer-support: referral to a peer navigator for support, condom provision and facilitation of attendance for differentiated HIV prevention services; 4) SRH + peer-support. Co-primary effectiveness outcomes were: 1) linkage to differentiated HIV prevention services within 60 days of enrolment; 2) transmissible HIV (HIV viral load ≥400 copies/mL) measured from dried blood spots (DBS) at 12 months. 3) the proportion of sampled individuals who consented to participation and gave a DBS for HIV testing at 12 months. Logistic regression was used for analyses, adjusted for age, sex and rural/peri-urban area.Findings: between March 2020 and August 2022, 1743/2301(76%) eligible individuals were enrolled, with a 12-month DBS collected from 1168 (67%). Baseline characteristics and 12-month outcome ascertainment were similar by arm. 755 (43.3%) linked to services by 60 days; SRH increased linkage (aOR 1.68;95%CI=1.39-2.04) but peer-support had no effect. At 12 months, 227 (19%) tested ELISA-positive for HIV, of whom 41 (18%) had a viral load ≥400 copies/ml. The overall prevalence of transmissible HIV was 3.5%. There was no evidence of an effect of either intervention on transmissible HIV (main effects: SRH aOR 1.12; 95%CI=0.60-2.11; peer-support aOR 1.03; 95%CI=0.55-1.94). Interpretation: in this representative sample of adolescents and youth in a mostly rural area of South Africa, STI testing and SRH (but not peer support) increased uptake of differentiated HIV prevention. While the UNAIDS target of 90:90:90 was exceeded, neither SRH nor peer support showed evidence of reducing transmissible HIV